Internally Geared Shimano Hub + Shaft Drive = Carefree Chicago Winter Bike Commute?

[[email protected]]

On Feb 2, 7:56 pm, "Jay" <[email protected]> wrote:
> "Kristian M Zoerhoff" <[email protected]> wrote in messagenews:[email protected]...
>
> > On 2008-02-01, [email protected] <[email protected]> wrote:
> >> On Feb 1, 1:54 pm, "[email protected]"
> >><[email protected]> wrote:
>
> >>> Chicago is pretty flat, so I'd go for single speed. No cables so
> >>> easier to deal with than Nexus if you need to change the tube, and
> >>> much cheaper and less chance of breaking than a Nexus hub.
>
> >> I was thinking this also. Chicago is as flat as a pancake. If ever a
> >> city was made for single-speeds, that is it.
>
> > Chicago is flat, but the 'burbs aren't necessarily so. A Nexus hub is
> > probably Jay's ticket, at the cost of slightly more maintenance than a
> > fixie.
>
> > Jay, you bike over the Des Plaines River, or is that a bus ride for you?
>
> > --
>
> > Kristian Zoerhoff
> > [email protected]
>
> At that point of my commute, I am on the CTA Blue Line. I am on the train
> from Rosemont to Jeff Park.
>
> Chicago is indeed mostly flat, including the burbs where I live. However, I
> think I need multiple speeds because of the wind. There is a two mile
> stretch which is out in the open, without buildings or trees to block the
> wind. And also a little uphill, in the evening.
>
> My cargo is distributed between the rear rack and a small Deuter backpackhttp://deuterusa.com/products/productDetail.php?packID=speedlite20&su....
> My heaviest loads are groceries, for instance canned goods. Perhaps 30 lbs
> total cargo weight maximum. I don't think I would want to climb that hill,
> into a strong wind, with groceries, with only single-speed. Plus, I am more
> comfortable riding upright rather than drop, so into a strong wind, that is
> a huge drag.
>
> J.

A Nexus hub will probably be the thing, but it is worth checking out
how the rear wheel is removed so you see what you are up against if
you flat in a way that requires removing the wheel. And I don't just
mean look at how the cable goes, watch someone actually remove the
wheel.

But there is some funny psychological effects to single speed that
make it more appealing that it might seem at first glance. I ride a
fixed gear track bike with obvioulsy only one speed for most of my
rides on rolling hills. I use a pretty big gear, so sometimes into a
stiff headwind up a hill it can be tough, as I am heavier than you.
But it doesn't seem to make a difference. When I am on my road bike
with 20 gears to choose from, I shift up and down the whole time. When
I meet a headwind and hill combo, I find myself shifting to a much
smaller gear than I have on my track bike and still feeling punished
by the wind. On my road bike I end up feeling like I NEED to switch
gears all the time, but I know from my other bike that I do not.

It's almost like all the brain activity that goes into chosing a gear
is somehow related to the part of my brain in charge of belly-aching.
With single speed, that whole part of my brain gets a "shut-up and
ride" from the rest of my brain, and it's more than happy to do it.

Joseph

 

[Hank]

On Feb 1, 7:14 pm, Tom Sherman <[email protected]>
wrote:
> Chalo Colina wrote:
> > Jay wrote:
> >> My main concern with the Crosstown 7 is frame strength. Is the aluminum
> >> frame strong enough for my load?
>
> > The frame is probably fine; I'd be far more concerned about the
> > durability and strength of the bevel gear driveshaft. When you add
> > the intrinsic losses of a Nexus 7 hub (which doesn't even have a 1:1
> > ratio) to the intrinsic losses of two sets of bevel gears, you'll be
> > going noticeably slower than you do now for the same effort.
>
> > Consider instead a bike with a Nexus 8, SRAM S7 or iMotion 9-speed
> > hub, in combination with a Hebie Chainglider or other full chain
> > case. That would be at least as easy to live with, a lot more
> > efficient, and almost certainly more reliable in the long run.
>
> >> DB will use a front disk brake, as an upgrade. Would this be a good idea? I
> >> really want to get away from any variation of rim brakes, because of weather
> >> maintenance issues, like daily cleaning of the rims in the winter.
>
> > Drums are a better match for the low-maintenance city bike role in my
> > opinion. They are not as strong as discs or good rim brakes, but they
> > get better with use and they seem to ask nothing of you in return.
> > Unlike a disc brake's rotors, drums are completely out of harm's way,
> > as well as out of the weather.
> > ...
>
> It should be noted that hub brakes become more effective with a
> reduction in wheel diameter, which is another reason for staying with a
> small wheel bicycle.
>
> Is there a dynamo hub that includes a drum brake?
>

Yup. The Sturmey-Archer X-FDD. I have one on my Nexus-8 cruiser. It
seems to work well so far. I'm still breaking in the brake, so I
expect it to improve.

Available through QBP, probably around $85 or so at an LBS. 36H only.

 

[Andre Jute]

On Feb 2, 6:13 pm, "[email protected]"
<[email protected]> wrote:
> On Feb 2, 5:23 pm, Andre Jute <[email protected]> wrote:
>
>
>
> > On Feb 2, 6:06 am, Chalo <[email protected]> wrote:
>
> > > Andre Jute wrote:
> > > >  Chalo wrote:
>
> > > > > The Shimano front roller brake has an anti-braking "feature";
>
> > > > I don't agree. I find that the anti-lock feature helps make the roller
> > > > brake more progessive and controllable. By comparison the rear roller
> > > > brake, which doesn't have the anti-lock feature, locks up too easily
> > > > and with a jerk, which you never feel with the front one.  Nor does
> > > > the anti-lock feature decrease the strength of the roller brake.
>
> > > There is a very grave problem with Shimano's approach to "anti-lock"--
> > > it isn't really anti-lock at all.  It's nothing more than a braking
> > > torque limiter.  Than means that for riders of the intended weight on
> > > the intended terrain and using the intended wheel size, the brakes
> > > work as intended.  A very lightweight rider or one using a small
> > > diameter wheel can lock it up just as readily as with any other
> > > brake.  And a heavy rider like myself, especially one using large
> > > diameter wheels, might never get a useful and safe amount of braking
> > > force at all.
>
> > > Chalo
>
> > Jay and I weigh just about the same; I'm about 215 pounds and my bike
> > with normal gear weighs about 50 pounds. I have my brakes set up up
> > high and I routinely brake late and hard -- and have never found
> > Shimano's 75 series roller brakes wanting; in fact, I think the torque
> > limiter is A Good Thing because without it the brakes would lock up
> > and, unlike at the back where a lockup is merely a small irritation,
> > at the front it could be dangerous. I wasn't so keen on Shimano's
> > earlier roller brakes, because I thought them a spot limp, suitable
> > for undemanding commuters but not much chop on my hills, but now I'm a
> > big fan of Shimano's 70/75 series R/F roller brakes; they do the
> > business with aplomb and make virtually zero maintenance demands,
> > unlike any other kind of brake. I think Jay will be as happy with the
> > Shimano roller brakes as I am.
>
> > Andre Jute
> > It is a hallmark of intelligence to change one's mind when justified
>
> Locking up a front brake on anything except sand or ice isn't really
> possible. Ideally brakes should be able to flip you over the bars, but
> it should be up to you to modulate. Anything less and you are missing
> potential stopping power that could come in handy.

No, by the time you get to the Shimano 75 series roller brake, you
need that torque limiter to keep Joe Public from braining himself at
slow traffic speeds where one tends to jam on the brake with your
attention elsewhere. (The solution is to teach yourself always to
engage the rear brake a millisecond before the front so that it
becomes reflex action. Or in town you could use the rear brake
exclusively, but Sheldon will not be pleased.) At high speeds you
modulate the front brake well before the torque limiter cuts in. I for
one am not going to brake right up to the torque limiter under speed;
I like my head just the shape it is.

Shimano's 70/75 series rollerbrake is limited, like all other good
brakes, by the friction between the tyre and the road. Its stopping
distances are no longer than those of a similar bike equipped with a
disc brake at the front; I tested that extensively because I have very
similar bikes, one with a disc brake, one with the roller brake. The
75 rollerbrake at the front will plant Chalo on his toupee for sure if
he is careless. On one hill here where I get up to somewhere in the
40kph region without even trying, there's gravel at the bottom on a
curve, and a couple of times that I didn't remember the gravel until I
was close enough to see it on the road, quite a bit of skill was
required to modulate the brakes so that I would slow without going
over the handlebars; on one occasion I ended up with a smoking rear
tyre because the rear brake (which doesn't have the torque limiter)
locked up and I left it locked up to concentrate on controlling the
front so as not to take a flyer over the handlebars onto my new City
helmet. On another occasion when a pickup with a trailer pulled
entirely across the road out of a co-op just as a car was passing me,
I slowed from about 30kph in less distance than the car, an ABS
equipped BMW; I saw the driver's foot go down hard on the brake as I
caressed my brake lever gently with two fingers. I think the roller
brake in question meets your parameters, Joseph; it may be that
Chalo's opinion was formed by older, much less capable models.

> I've never used the roller brake in question, so it may well be up to
> the task, I'm just pointing out they may not be as effective as other
> solutions.

The other brands of roller brakes Chalo mentions may have some
advantage but it would have to be controllability, because the Shimano
lacks nothing you could want in stopping power, and it is essentially
service-free. However, a well set-up rim brake is equally efficient,
it just requires more attention at more frequent intervals to keep it
that way. The point about a roller brake is no longer how well it
brakes but that people buy them to keep their hands clean -- forever.

Andre Jute
http://members.lycos.co.uk/fiultra/BICYCLE & CYCLING.html

 

[Andre Jute]

On Feb 2, 9:47 pm, "[email protected]"
<[email protected]> wrote:
> On Feb 2, 7:56 pm, "Jay" <[email protected]> wrote:
>
>
>
> > "Kristian M Zoerhoff" <[email protected]> wrote in messagenews:[email protected]...
>
> > > On 2008-02-01, [email protected] <[email protected]> wrote:
> > >> On Feb 1, 1:54 pm, "[email protected]"
> > >><[email protected]> wrote:
>
> > >>> Chicago is pretty flat, so I'd go for single speed. No cables so
> > >>> easier to deal with than Nexus if you need to change the tube, and
> > >>> much cheaper and less chance of breaking than a Nexus hub.
>
> > >> I was thinking this also.  Chicago is as flat as a pancake.  If ever a
> > >> city was made for single-speeds, that is it.
>
> > > Chicago is flat, but the 'burbs aren't necessarily so. A Nexus hub is
> > > probably Jay's ticket, at the cost of slightly more maintenance than a
> > > fixie.
>
> > > Jay, you bike over the Des Plaines River, or is that a bus ride for you?
>
> > > --
>
> > > Kristian Zoerhoff
> > > [email protected]
>
> > At that point of my commute, I am on the CTA Blue Line. I am on the train
> > from Rosemont to Jeff Park.
>
> > Chicago is indeed mostly flat, including the burbs where I live. However, I
> > think I need multiple speeds because of the wind. There is a two mile
> > stretch which is out in the open, without buildings or trees to block the
> > wind. And also a little uphill, in the evening.
>
> > My cargo is distributed between the rear rack and a small Deuter backpackhttp://deuterusa.com/products/productDetail.php?packID=speedlite20&su....
> > My heaviest loads are groceries, for instance canned goods. Perhaps 30 lbs
> > total cargo weight maximum. I don't think I would want to climb that hill,
> > into a strong wind, with groceries, with only single-speed. Plus, I am more
> > comfortable riding upright rather than drop, so into a strong wind, thatis
> > a huge drag.
>
> > J.
>
> A Nexus hub will probably be the thing, but it is worth checking out
> how the rear wheel is removed so you see what you are up against if
> you flat in a way that requires removing the wheel. And I don't just
> mean look at how the cable goes, watch someone actually remove the
> wheel.

It's less of a problem than you might fear but you definitely need to
read and understand the instructions, and perhaps do it at home,
before you try to do it on the road. Basically you crack open the
chaincase and remove the shells toollessly. Now undo the rollerbrake
torque arm from the chainstay and slide the rollerbrake cable off;
there's a knack to it even after you penetrate the Japlish that looks
just like real English. Then you loosen the gear control cable. Both
these jobs might require a small 8x10mm spanner I carry with the bike
(Park Tool sells an 8x10mm open spanner loose). Next you need a 15mm
spanner to undo two axle nuts on the hub gear axle just a few turns.
Leave the nuts on to retain the parts. For this I carry a compact and
lightweight Park Tool 36x15mm headset/pedal spanner, which bolts up
behind a water bottle because the rest of my toolkit is so small, it
fits into a specatacles case. Undo whatever quicklink you have on your
chain (I use SRAM and Connex chains which baiscally last forever) with
your fingers. Now you slide the wheel out, noting the way the keyed
washers and the chain tensioner stops fit. All of this the second time
you do it takes about a minute, mainly because those nuts are torqued
up and the spanner is short. Fix your flat. Refitting is the reverse
of this dismantling procedure. The only tricky bit is that you must
fit a nut on the gearchange cable into a slot not accessible to
fingers; it slides in easily with the application of a 2mm hex key as
a pusher. This isn't difficult once you grasp what is intended by
twisting the cable but I wouldn't want to do this in the dark without
having practiced it at home. Go straight home and torque the axle
nuts correctly. Order Marathon Plus or Bontrager Satellite Elite
Hardcase tyres so that you never have to go through this ********
again. I've never had a flat with those tyres. A flat on the front
wheel is even easier than with rim brakes; the roller brake cable
slides off just like the rear roller brake cable on a fitting whose
purpose is to maintain your setting so that you don't even have to
reset the brake cables after refitting the wheels.

> But there is some funny psychological effects to single speed that
> make it more appealing that it might seem at first glance. I ride a
> fixed gear track bike with obvioulsy only one speed for most of my
> rides on rolling hills. I use a pretty big gear, so sometimes into a
> stiff headwind up a hill it can be tough, as I am heavier than you.
> But it doesn't seem to make a difference. When I am on my road bike
> with 20 gears to choose from, I shift up and down the whole time. When
> I meet a headwind and hill combo, I find myself shifting to a much
> smaller gear than I have on my track bike and still feeling punished
> by the wind. On my road bike I end up feeling like I NEED to switch
> gears all the time, but I know from my other bike that I do not.
>
> It's almost like all the brain activity that goes into chosing a gear
> is somehow related to the part of my brain in charge of belly-aching.
> With single speed, that whole part of my brain gets a "shut-up and
> ride" from the rest of my brain, and it's more than happy to do it.
>
> Joseph

I have had an automatic bike for 9 months now, and I still set the
computer to tell me which gear I"m in... Pathetic geek!

Andre Jute
Lazy

 

[Peter Cole]

Andre Jute wrote:
> On Feb 2, 6:13 pm, "[email protected]"
> <[email protected]> wrote:
>> On Feb 2, 5:23 pm, Andre Jute <[email protected]> wrote:
>>
>>
>>
>>> On Feb 2, 6:06 am, Chalo <[email protected]> wrote:
>>>> Andre Jute wrote:
>>>>> Chalo wrote:
>>>>>> The Shimano front roller brake has an anti-braking "feature";
>>>>> I don't agree. I find that the anti-lock feature helps make the roller
>>>>> brake more progessive and controllable. By comparison the rear roller
>>>>> brake, which doesn't have the anti-lock feature, locks up too easily
>>>>> and with a jerk, which you never feel with the front one. Nor does
>>>>> the anti-lock feature decrease the strength of the roller brake.
>>>> There is a very grave problem with Shimano's approach to "anti-lock"--
>>>> it isn't really anti-lock at all. It's nothing more than a braking
>>>> torque limiter. Than means that for riders of the intended weight on
>>>> the intended terrain and using the intended wheel size, the brakes
>>>> work as intended. A very lightweight rider or one using a small
>>>> diameter wheel can lock it up just as readily as with any other
>>>> brake. And a heavy rider like myself, especially one using large
>>>> diameter wheels, might never get a useful and safe amount of braking
>>>> force at all.
>>>> Chalo
>>> Jay and I weigh just about the same; I'm about 215 pounds and my bike
>>> with normal gear weighs about 50 pounds. I have my brakes set up up
>>> high and I routinely brake late and hard -- and have never found
>>> Shimano's 75 series roller brakes wanting; in fact, I think the torque
>>> limiter is A Good Thing because without it the brakes would lock up
>>> and, unlike at the back where a lockup is merely a small irritation,
>>> at the front it could be dangerous. I wasn't so keen on Shimano's
>>> earlier roller brakes, because I thought them a spot limp, suitable
>>> for undemanding commuters but not much chop on my hills, but now I'm a
>>> big fan of Shimano's 70/75 series R/F roller brakes; they do the
>>> business with aplomb and make virtually zero maintenance demands,
>>> unlike any other kind of brake. I think Jay will be as happy with the
>>> Shimano roller brakes as I am.
>>> Andre Jute
>>> It is a hallmark of intelligence to change one's mind when justified
>> Locking up a front brake on anything except sand or ice isn't really
>> possible. Ideally brakes should be able to flip you over the bars, but
>> it should be up to you to modulate. Anything less and you are missing
>> potential stopping power that could come in handy.
>
> No, by the time you get to the Shimano 75 series roller brake, you
> need that torque limiter to keep Joe Public from braining himself at
> slow traffic speeds where one tends to jam on the brake with your
> attention elsewhere. (The solution is to teach yourself always to
> engage the rear brake a millisecond before the front so that it
> becomes reflex action.

I don't see how that accomplishes anything.




> The other brands of roller brakes Chalo mentions may have some
> advantage but it would have to be controllability, because the Shimano
> lacks nothing you could want in stopping power, and it is essentially
> service-free. However, a well set-up rim brake is equally efficient,
> it just requires more attention at more frequent intervals to keep it
> that way. The point about a roller brake is no longer how well it
> brakes but that people buy them to keep their hands clean -- forever.

From the data sheet:

"avoid continuous braking when riding down long slopes ... may weaken
braking performance ... may cause reduction of brake grease .. . may
cause abnormally sudden braking"

"If the overall weight exceeds 100kg, the braking force may be
insufficient ... durability of the system may be reduced"

"the turning of the wheel may be slightly heavier, particularly in cold
weather"


I'll pass.

 

[Andre Jute]

Peter, when you read this you have to keep in mind that Chalo later
told us he was talking about earlier Shimano roller brakes. I am
talking about the very latest Shimano roller brakes. We were
essentially comparing apples and oranges, because Chalo likes the drum
(Roller is Shimano house vernacular for "drum") brakes by other
manufacturers...

Chalo wrote:
> >>>>>> The Shimano front roller brake has an anti-braking "feature";

Andre Jute wrote:
> >>>>> I don't agree. I find that the anti-lock feature helps make the roller
> >>>>> brake more progessive and controllable. By comparison the rear roller
> >>>>> brake, which doesn't have the anti-lock feature, locks up too easily
> >>>>> and with a jerk, which you never feel with the front one.  Nor does
> >>>>> the anti-lock feature decrease the strength of the roller brake.

Chalo:
> >>>> There is a very grave problem with Shimano's approach to "anti-lock"--
> >>>> it isn't really anti-lock at all.  It's nothing more than a braking
> >>>> torque limiter.  Than means that for riders of the intended weight on
> >>>> the intended terrain and using the intended wheel size, the brakes
> >>>> work as intended.  A very lightweight rider or one using a small
> >>>> diameter wheel can lock it up just as readily as with any other
> >>>> brake.  And a heavy rider like myself, especially one using large
> >>>> diameter wheels, might never get a useful and safe amount of braking
> >>>> force at all.

Andre:
> >>> Jay and I weigh just about the same; I'm about 215 pounds and my bike
> >>> with normal gear weighs about 50 pounds. I have my brakes set up
> >>> high and I routinely brake late and hard -- and have never found
> >>> Shimano's 75 series roller brakes wanting; in fact, I think the torque
> >>> limiter is A Good Thing because without it the brakes would lock up
> >>> and, unlike at the back where a lockup is merely a small irritation,
> >>> at the front it could be dangerous. I wasn't so keen on Shimano's
> >>> earlier roller brakes, because I thought them a spot limp, suitable
> >>> for undemanding commuters but not much chop on my hills, but now I'm a
> >>> big fan of Shimano's 70/75 series R/F roller brakes; they do the
> >>> business with aplomb and make virtually zero maintenance demands,
> >>> unlike any other kind of brake. I think Jay will be as happy with the
> >>> Shimano roller brakes as I am.
> >>> Andre Jute
> >>> It is a hallmark of intelligence to change one's mind when justified

Chalo:
> >> Locking up a front brake on anything except sand or ice isn't really
> >> possible. Ideally brakes should be able to flip you over the bars, but
> >> it should be up to you to modulate. Anything less and you are missing
> >> potential stopping power that could come in handy.

Andre:
> > No, by the time you get to the Shimano 75 series roller brake, you
> > need that torque limiter to keep Joe Public from braining himself at
> > slow traffic speeds where one tends to jam on the brake with your
> > attention elsewhere. (The solution is to teach yourself always to
> > engage the rear brake a millisecond before the front so that it
> > becomes reflex action.

Peter Cole:
> I don't see how that accomplishes anything.

It transfers weight rearwards and keeps the rear wheel straight when
you apply the front brake.

Andre:
> > The other brands of roller brakes Chalo mentions may have some
> > advantage but it would have to be controllability, because the Shimano
> > lacks nothing you could want in stopping power, and it is essentially
> > service-free. However, a well set-up rim brake is equally efficient,
> > it just requires more attention at more frequent intervals to keep it
> > that way. The point about a roller brake is no longer how well it
> > brakes but that people buy them to keep their hands clean -- forever.

Now Peter comes out with this lot of warnings from that prissy
convention of old women who are Shimano's lawyers:

>  From the data sheet:
>
> "avoid continuous braking when riding down long slopes ... may weaken
> braking performance ... may cause reduction of brake grease .. . may
> cause abnormally sudden braking"
>
> "If the overall weight exceeds 100kg, the braking force may be
> insufficient ... durability of the system may be reduced"
>
> "the turning of the wheel may be slightly heavier, particularly in cold
> weather"
>
> I'll pass.

That's your privilege, Peter. But the bunch of warnings you print
above are intended to protect Shimano against stupid cyclist who do
themselves harm and then sue. Their irrelevance to the latest series
of Shimano roller brakes can be judged by the fact that the warnings
are carried over from earlier versions of roller brakes of different
construction, as I shall demonstrate in a moment. The whole business
of these warnings is ridiculous: earliest roller brakes, which were
weaker than the current ones, also carried a warning not to brake
suddenly or you could go over the handlebars; the same warning was
carried forward to the current roller brakes, where it has great
relevance. In the light of this, let's look at your particular
prejudices as reinforced by Shimano's consumer protection lawyers (ie
lawyers for protecting Shimano against stupid consumeers):

> "avoid continuous braking when riding down long slopes ... may weaken
> braking performance ... may cause reduction of brake grease .. . may
> cause abnormally sudden braking"

This is about heat generion and dispersion. I don't know what the
earliest Shimano roller brakes did about heat dispersion but I have
Shimano roller brakes used on top city bikes a few years ago and also
the latest 70/75 series used on only the most expensive bikes. There
is a difference that is pretty obvious by simple inspection. The older
series has a flat, thin, loosely attached heat dispersion disc with a
few small fashionable slots in it. The 70/75 series has a thick,
slotted *and deeply finned" disc that is firmly attached; it is a
bigger drum brake than found on the back of racing Minis. I don't have
any Alpine mountains to ride down but I live in hilly country with
several steep hills of a couple of miles long on the way home. I rode
the 70/75 brakes down several of these hills for a test after I filled
them up with grease, pedalling hard all the time, modulating the brake
to knock 25km off the natural speed down those hills. The 70/75 brakes
would get tepid if at the bottom you were quick to dismount and feel
them, otherwise they were back to ambient temperature. Even the old
050 series on my Gazelle Toulouse at the back never got so warm you
could not hold it with bare skin.

> "If the overall weight exceeds 100kg, the braking force may be
> insufficient ... durability of the system may be reduced"

So what? No brake has an unlimited rating. This is lawyer talk of the
"without prejudice" type; if they could get away with it, the lawyers
would print on the spec sheet: "This brake is for display purposes
only. Use it at your own risk. This advice too may be a lie but you
cannot hold us responsible."

Experience shows that heavyweight Dutchmen have not strained the limit
of even the older types of drum brakes (not just Shimano but several
other respected makers). Increasingly European touring bikes are being
fitted with roller brakes.

So, if the latest series of Shimano roller brake, the 70/75, is so
heavily cooled that it won't fade because of heat, what does limit its
braking power? The answer is the same for all bikes: the friction of
the tire on the road. Thus the roller brake, which can be counted on,
if adequately cooled, always to provide the same stopping torque, is
superior to the rim brake, which has to cope with the interference of
all kinds of crud on the rim, with the unevenness of rims, with the
uneven wear on rims caused by the brake blocks, and so on.

> "the turning of the wheel may be slightly heavier, particularly in cold
> weather"

First, all hubs (unless you know of hubs that aren't greased) turn
slower in cold weather, though I daresay you can get low-temp grease
that will ameliorate the effect. This sentence you quote is a true
reflection of the mindlessness of the lawyers who wrote it -- they are
stating the obvious portentously.

Second point. The first part of that sentence just states another
obvious matter pompously: roller brakes are heavier than the default
of rim brakes. No ****, Sherlock!

Thirdly, there is no free lunch. If you add the weight of a roller
brake, energy must be expended in moving its mass. Energy must be
expended in carrying along the weight of rim brakes. You pay for the
weight saving of rim brakes in less efficient brakes except under
ideal circumstance, in greater service expenditure, in faster
component wear, in substantially greater expense over the life of the
bike.

Or, if you're me, you see the marginal extra energy expenditure for
propelling roller brakes as a marginally faster way to get your heart
rate into the aerobic bracket, a clever way to ensure consistent
braking performance in all weathers, a brilliant way of reducing
tiresome fiddling with the bike in time better spent cycling, and a
cost saving over the life of the bike.

We know a disc brake is logically better suited to purpose than a rim
brake. I have proven to my own satisfaction, by comparing two
otherwise similar bikes over 5000km, that a late series Shimano roller
brake is as good as a disc brake. Therefore a 70/75 series Shimano
roller brake is better than rim brakes, for me.

If your mileage varies because you want to believe a purselip of
lawyers, that's your lookout and your right. If your mileage varies
because you're a weight weenie, that leads to a different approach to
braking which may be equally valid to you, but you don't need to
justify your choice by claiming there are problems with the current
crop of roller brakes.

Andre Jute
http://members.lycos.co.uk/fiultra/BICYCLE & CYCLING.html

 

[Peter Cole]

Andre Jute wrote:
> Peter, when you read this you have to keep in mind that Chalo later
> told us he was talking about earlier Shimano roller brakes. I am
> talking about the very latest Shimano roller brakes. We were
> essentially comparing apples and oranges, because Chalo likes the drum
> (Roller is Shimano house vernacular for "drum") brakes by other
> manufacturers...

The data sheet I was referencing was for the BR-IM75-F, which seems to
be the latest.

>>> (The solution is to teach yourself always to
>>> engage the rear brake a millisecond before the front so that it
>>> becomes reflex action.
>
> Peter Cole:
>> I don't see how that accomplishes anything.
>
> It transfers weight rearwards and keeps the rear wheel straight when
> you apply the front brake.

I don't think either of those things happen.

It's a bad habit. If you use both brakes, and brake the front hard
enough to mostly unweight the rear, applying the rear brake makes the
rear tire more prone to skid sideways.

> If your mileage varies because you want to believe a purselip of
> lawyers, that's your lookout and your right. If your mileage varies
> because you're a weight weenie, that leads to a different approach to
> braking which may be equally valid to you, but you don't need to
> justify your choice by claiming there are problems with the current
> crop of roller brakes.

I just go by the spec sheets. I won't use a component that's not rated
for my weight, even the ones that are, or are unrated, break too often.
A front brake is something I take very seriously. I wouldn't have a
problem with a roller rear, but I don't really see the benefit.

 

[Chalo]

Peter Cole wrote:
> Andre Jute wrote:
[re: braking first at the rear]
> >
> > It transfers weight rearwards and keeps the rear wheel straight when
> > you apply the front brake.
>
> I don't think either of those things happen.
>
> It's a bad habit. If you use both brakes, and brake the front hard
> enough to mostly unweight the rear, applying the rear brake makes the
> rear tire more prone to skid sideways.

I think the custom may have carried over from the motorcycling world,
where the intention is to settle the bike down on its suspension
before coming in with a lot of front braking. On a non-suspension
bike I doubt it offers much benefit, unless it's to give a
reassuringly familiar feeling to those who picked up the habit from
their motorcycling experience.

I imagine that a dual-suspension MTB might behave better in a hard
stop if the rear brake is used first. Even then, the radically
different center of mass for the system (compared to a moto) might
make it a pointless exercise.

Chalo

 

[Andre Jute]

On Feb 18, 9:25 pm, Peter Cole <[email protected]> wrote:
> Andre Jute wrote:
> > Peter, when you read this you have to keep in mind that Chalo later
> > told us he was talking about earlier Shimano roller brakes. I am
> > talking about the very latest Shimano roller brakes. We were
> > essentially comparing apples and oranges, because Chalo likes the drum
> > (Roller is Shimano house vernacular for "drum") brakes by other
> > manufacturers...
>
> The data sheet I was referencing was for the BR-IM75-F, which seems to
> be the latest.

Sure. So did I. But perhaps you missed where I wrote of the warnings
on that datasheet that their "irrelevance to the latest series
of Shimano roller brakes can be judged by the fact that the warnings
are carried over from earlier versions of roller brakes of different
construction" etc.

What you seem not to have understood, Peter, is that the 100kg limit
has nothing to do with the particular brake and everything to do with
a European legislation standard setting a 100kg minimum. It tells you
so on the datasheet if you know how to read Eurobureaucratspeak, in
the bit where it mentions the CE standard by number. In effect Shimano
is saying, "We meet the minimum, we're not stating a maximum," and you
are supposed to understand that the maximum is much higher because the
minimum is enforced with such horrendous penalties (Gazelle got fined
12 million Euro for a mere trade practices transgression, not even a
safety transgression) that everyone overspecs parts in a big way.
Notice that the specified dynohub for this rollerbrake has a 140kg
limit... This happens not because Shimano screwed up, but because the
legislators are inconsistent. If I were a product manager at Shimano,
I would absolutely insist that two parts intended to work together had
the same capability. And I would, in selfprotecting, guarantee the
parts, whatever their capability, only for the lowest rating demanded
by legislation. Then I would tell the biggest market, the OEM, quietly
what the real rating is. Consumers, like you and me, then look to what
reputable bike manufacturers fit on their biggest bikes, clearly
intended for heavyweights, and therein read the runes. It is a skill
like any other in bicycling. If you're too rigidly insistent on the
sanctity of the datasheet, you'll miss out on the good stuff.

SNIP

> A front brake is something I take very seriously. I wouldn't have a
> problem with a roller rear, but I don't really see the benefit.

You're entitled to your prejudices. I once shared this particular
prejudice. After experience and comparison of a disc front brake
against a roller front brake on similar bike for 5000km, I no longer
share your prejudice. Roller brakes work superbly for me. If rim
brakes work for you, great.

Andre Jute
http://members.lycos.co.uk/fiultra/BICYCLE & CYCLING.html

 

[Clive George]

"Andre Jute" <[email protected]> wrote in message
news:[email protected]...

>You're entitled to your prejudices. I once shared this particular
>prejudice. After experience and comparison of a disc front brake
>against a roller front brake on similar bike for 5000km, I no longer
>share your prejudice. Roller brakes work superbly for me. If rim
>brakes work for you, great.

I think it's useful in these kinds of discussions to compare the expected
use - some people will stress brakes a lot more than others.

Eg somebody riding hard in a city may well have different experiences to
somebody who pootles round country lanes. (though of course couriers seem to
get away with no brakes...)

clive

 

[Peter Cole]

Chalo wrote:
> Peter Cole wrote:
>> Andre Jute wrote:
> [re: braking first at the rear]
>>> It transfers weight rearwards and keeps the rear wheel straight when
>>> you apply the front brake.
>> I don't think either of those things happen.
>>
>> It's a bad habit. If you use both brakes, and brake the front hard
>> enough to mostly unweight the rear, applying the rear brake makes the
>> rear tire more prone to skid sideways.
>
> I think the custom may have carried over from the motorcycling world,
> where the intention is to settle the bike down on its suspension
> before coming in with a lot of front braking. On a non-suspension
> bike I doubt it offers much benefit, unless it's to give a
> reassuringly familiar feeling to those who picked up the habit from
> their motorcycling experience.
>
> I imagine that a dual-suspension MTB might behave better in a hard
> stop if the rear brake is used first. Even then, the radically
> different center of mass for the system (compared to a moto) might
> make it a pointless exercise.
>
> Chalo

Sorry, I still don't see it. I've never ridden a motorcycle or FS MTB,
but I'm having difficulty what you mean by "settle down". Both the front
& rear brakes will apply a torque, both in the same direction. The
difference is that the torque increases the contact pressure on the
front while lowering on the rear.

If you have any lateral forces on a bike (cornering), reduction of
traction may cause the wheel to slide sideways. Adding rear braking (to
hard front braking) in these circumstances only increases this tendency,
since a locked rear wheel has less resistance to side slip than a
turning one. I have had the rear wheel "come around" on me several times
when I wasn't careful about using the rear brake.

The only situations where I find a rear brake useful are: front failure
(never happened), slick surfaces (balance the limited traction budget
between 2 wheels) and long braking descents (where you can balance the
thermal load over 2 wheels).

 

[Peter Cole]

Andre Jute wrote:
> On Feb 18, 9:25 pm, Peter Cole <[email protected]> wrote:

>> The data sheet I was referencing was for the BR-IM75-F, which seems to
>> be the latest.
>
> Sure. So did I. But perhaps you missed where I wrote of the warnings
> on that datasheet that their "irrelevance to the latest series
> of Shimano roller brakes can be judged by the fact that the warnings
> are carried over from earlier versions of roller brakes of different
> construction" etc.

No, I got that.

> What you seem not to have understood, Peter, is that the 100kg limit
> has nothing to do with the particular brake and everything to do with
> a European legislation standard setting a 100kg minimum.

Not being an industry insider, I just take specs on face value. Perhaps
you're right that critical components (and what isn't on a bike?) are
over-spec'ed in reality, but that doesn't agree with my (limited)
experience. Even if I were convinced of that, I'd hesitate to hand it
out as advice.

>> A front brake is something I take very seriously. I wouldn't have a
>> problem with a roller rear, but I don't really see the benefit.
>
> You're entitled to your prejudices. I once shared this particular
> prejudice. After experience and comparison of a disc front brake
> against a roller front brake on similar bike for 5000km, I no longer
> share your prejudice. Roller brakes work superbly for me. If rim
> brakes work for you, great.

As I said, I don't see the benefit. It's not a matter of prejudice. I
find rim brakes to be simple and reliable, so I'd need a reason to
change. The only drawbacks I've experienced with rim brakes are: weak
initial braking with wet rims and rim wear. I suppose both disc and hub
brakes eliminate/reduce those weaknesses. I'm not a weight weenie,
cheapskate or Luddite, but the added cost, complexity and heft of those
alternate brakes would have to be balanced by some advantages. For me,
the "pros" don't outweigh the "cons", others may reach different
conclusions.

Lastly, the idea of a limiter on a front brake is a complete non-starter
for me. This is an idea Shimano seems to return to. I could accept that
this brake might not be the best choice for alpine descents, and that
isn't an issue for a commuter bike, but I'd not want anything less than
full power braking available when riding in traffic. This brake seems to
have been designed for "recreational" cycling. That's not my category.

My idea of an ideal commuter bike for areas with snowy winters and
flattish terrain is a fixed gear. A compelling reason for me to prefer
the simplicity of a standard hub is that it allows me to have studded
tires mounted on an extra wheel set that I can swap in & out for the
weather. I also give a lot of thought to the issue of fixing flats in
really bad weather, simplicity is an asset there, too.

 

[dabac]

... by the time you get to the Shimano 75 series roller brake, you
need that torque limiter to keep Joe Public from braining himself at
slow traffic speeds where one tends to jam on the brake with your
attention elsewhere.

That's a line of reasoning that I find highly questionable. There are any number of ways for Joe Public to mess himself up while riding, so why should the brake be singled out for "improvement" through limitation?
How about a steering damper?
Although perhaps not as likely to send you over the bars a too sharply applied twist of the handlebars most certainly can send you face first into the gravel.
Or something to prevent you from locking up the rear wheel, maybe make it impossible to engage that brake unless your weight is firmly pressing down on the saddle?
With a machine that is so extensively dependent on rider input for its performance as a bike, operator error will always carry a penalty.

I've ridden a bike with a v-brake noodle with an integrated modulator, and I found it rather awkward. It adds a link to the chain, instead of modulating the brake you end up modulating the modulator, trying to second-guess how it will affect your input.
I can honestly say that the only time I've been troubled by excessive brake performance was when I switched from the crudest of caliper brakes acting on a stainless steel rim over to a first-generation MTB with proper cantis, but after that not even going to hydraulic discs has required more than marginal learning phase.

 

[Andre Jute]

Peter Cole <[email protected]> wrote:

> Andre Jute wrote:
> > On Feb 18, 9:25 pm, Peter Cole <[email protected]> wrote:
>
> >> The data sheet I was referencing was for the BR-IM75-F, which seems to
> >> be the latest.
> >
> > Sure. So did I. But perhaps you missed where I wrote of the warnings
> > on that datasheet that their "irrelevance to the latest series
> > of Shimano roller brakes can be judged by the fact that the warnings
> > are carried over from earlier versions of roller brakes of different
> > construction" etc.
>
> No, I got that.
>
> > What you seem not to have understood, Peter, is that the 100kg limit
> > has nothing to do with the particular brake and everything to do with
> > a European legislation standard setting a 100kg minimum.
>
> Not being an industry insider, I just take specs on face value. Perhaps
> you're right that critical components (and what isn't on a bike?) are
> over-spec'ed in reality, but that doesn't agree with my (limited)
> experience. Even if I were convinced of that, I'd hesitate to hand it
> out as advice.

Hang on a minute. I didn't make any generalization about over-specced
bike components. In fact, if you asked me for an opinion, I would say
that on components for racing bikes the temptation would be to build
only as strong as needs be in order to save the weight; note
"opinion", not fact.

On the matter of the dynohubs and rollerbrakes alone, matters where
weight are of secondary consideration in the market where 99 per cent
of these will be sold (city bikes via the OEM market) and where there
is a very strong legislative background, an observably stronger brake
is accompanied by the same rating and the same warnings as earlier,
weaker brakes. Those are observable facts, with observable results on
my own bikes. But still I made no recommendation: I said I was happy
that for you rim brakes work.

> >> A front brake is something I take very seriously. I wouldn't have a
> >> problem with a roller rear, but I don't really see the benefit.
> >
> > You're entitled to your prejudices. I once shared this particular
> > prejudice. After experience and comparison of a disc front brake
> > against a roller front brake on similar bike for 5000km, I no longer
> > share your prejudice. Roller brakes work superbly for me. If rim
> > brakes work for you, great.
>
> As I said, I don't see the benefit. It's not a matter of prejudice. I
> find rim brakes to be simple and reliable, so I'd need a reason to
> change. The only drawbacks I've experienced with rim brakes are: weak
> initial braking with wet rims and rim wear. I suppose both disc and hub
> brakes eliminate/reduce those weaknesses. I'm not a weight weenie,
> cheapskate or Luddite, but the added cost, complexity and heft of those
> alternate brakes would have to be balanced by some advantages. For me,
> the "pros" don't outweigh the "cons", others may reach different
> conclusions.

I'm not a weight weenie either but I do demand that expenditures be
justified by a quantifiable advantage. Nor am I anyone's early adopter
(aka unpaid tester of products not quite there yet). So, after initial
skepticism verging on prejudice against drum brakes (brought forward
from my automobile days) and for disc brakes, on hand of an extended
test of 5000km I changed my mind. I might add that some of my early
prejudice was based on reading the same spec sheet that puts you right
off. It is the 75 series roller brake in use that changed my mind. I
was absolutely prepared to swap my disc brake back in if the 75 series
front roller brake didn't work for me on my latest bike with the
automatic gearbox. One of the grand things about the Cyber Nexus and
Nexus components from Shimano is that they are so widely
interchangeable between groupsets, it's mix and match heaven. But, as
we have seen, I was hugely impressed with the 75 series roller brake
and decided to keep it.

> Lastly, the idea of a limiter on a front brake is a complete non-starter
> for me. This is an idea Shimano seems to return to. I could accept that
> this brake might not be the best choice for alpine descents, and that
> isn't an issue for a commuter bike, but I'd not want anything less than
> full power braking available when riding in traffic. This brake seems to
> have been designed for "recreational" cycling. That's not my category.

Alpine descents are a straw man at this table; when will you next be
making one on your bike? I ride hard in the traffic here, darting in
and out of unpredictable stop-start traffic and fastflowing sections
to get to my favourite lanes, and I live among hills. None of this has
faded the 75 series rollerbrakes in the least. If you ever look at the
cooling discs pictured on my netsite and on Shimano's own site, you
will see why. Furthermore, far from considering the torque limiter on
the front brake a nuisance, I wish there were one on the rear 70
series brake as well because it locks up far too easily. Also, it is
precisely in traffic that you are likely to jam the brake on hard and
exceed the coefficient of friction between tyre and road, thereby
increasing stopping distance and perhaps losing control, so that is
where the torque limiter is most useful. On fast descents on the open
road it is easy to beat the torque limiter, that is to have to back
off the brake before the torque limiter comes into play because the
front wheel is already close to skidding or you are in danger of going
over the handlebars. I was horrified when Chalo told us this is how he
judges a good brake! That's macho ********. A good brake is one that
maximizes friction between tyre and road to within a fraction of
skidding, neither too weak nor too strong but better slightly limp
than fiercely macho. In this regard Shimano's 70 series rear
rollerbrake can benefit from a torque limiter to make it less "strong"
at the high end, and the 75 series even with the torque limiter is
overkill for the most spirited riding.

In my opinion Shimano's 70/75 series roller brake is far superior to a
rim brake, precisely as good as a disc brake, and in practice a little
more controllable than a disc brake; of course, a roller brake
requires just about zero service while a disc brake requires
adjustment, new pads, new disc every so often. Far from making it
more fierce, Shimano should work on making their current top model
smoother, perhaps by progressive torque control on the 75 front brake,
perhaps by adding torque control to the 70 rear brake and making it
kick in earlier than on the 75 at the front to give a form of ABS. (On
my Gazelle Toulouse with the older and weaker 050 roller rear and the
disc front brake it is a pleasure to brake in the wet because relative
strengths of the two brakes makes for a form of skid control.)

Sales lost to holdouts for obsolete technology who think that "the
idea of a limiter on a front brake is a complete non-starter" will be
insignificant; Shimano was never likely to get the hardcore rim brake
brigade anyway -- until they make hydraulic rim brakes to compete with
Magura's. Not that I think hydraulic rim brakes are necessary, you
understand (I think they just wear rims out faster), but because
Shimano traditionally come out in a rash if they aren't in every
market segment, no matter how unnecessary.

And I certainly hope Shimano doesn't listen to the macho crowd and add
the complication of hydraulics to their roller brakes to make them
"stronger". It is an unnecessary purpose and an unnecessary
complication.

> My idea of an ideal commuter bike for areas with snowy winters and
> flattish terrain is a fixed gear. A compelling reason for me to prefer
> the simplicity of a standard hub is that it allows me to have studded
> tires mounted on an extra wheel set that I can swap in & out for the
> weather. I also give a lot of thought to the issue of fixing flats in
> really bad weather, simplicity is an asset there, too.

This is a complete misconception which arises because you don't have
hands-on experience of the Shimano roller brake. Nothing stops you
from having two wheels with rollerbrakes, one with summer tyres, one
with winter tyres. It is actually simpler and much quicker to take off
and refit a wheel with a roller brake than to take off and refit a
wheel with a disc brake or a wheel with rim brakes. To remove a roller
braked wheel, you slide off a fitting holding the cable, change
wheels, slide on the fitting again -- and the cable is held in the
same position and works perfectly, that is, no set-up is required. You
don't even require tools! With rim brakes, you must slacken the cable,
change the wheel, then reset the cable, then adjust the brake to work.
A disc brake also needs adjustment to allow for even tiny differences
in centering on refitting. Both rim the rim brake and the disc brake
requires at least one tool to do the simplest thing! Simplicity and
speed of interchange thus is on the side of the roller brake, not
either the disc or the rim brake. Ditto for fixing a flat. Even with a
dynohub added to the roller brake, that's just one extra plug to pull
and push back in.

Andre Jute
http://members.lycos.co.uk/fiultra/BICYCLE & CYCLING.html

 

[Andre Jute]

On Feb 20, 2:53 pm, dabac <dabac.353...@no-
mx.forums.cyclingforums.com> wrote:
> Andre Jute Wrote:
>
> >  ... by the time you get to the Shimano 75 series roller brake, you
> > need that torque limiter to keep Joe Public from braining himself at
> > slow traffic speeds where one tends to jam on the brake with your
> > attention elsewhere.
>
> That's a line of reasoning that I find highly questionable. There are
> any number of ways for Joe Public to mess himself up while riding, so
> why should the brake be singled out for "improvement" through
> limitation?
> How about a steering damper?
> Although perhaps not as likely to send you over the bars a too sharply
> applied twist of the handlebars most certainly can send you face first
> into the gravel.
> Or something to prevent you from locking up the rear wheel, maybe make
> it impossible to engage that brake unless your weight is firmly pressing
> down on the saddle?
> With a machine that is so extensively dependent on rider input for its
> performance as a bike, operator error will always carry a penalty.
>
> I've ridden a bike with a v-brake noodle with an integrated modulator,
> and I found it rather awkward. It adds a link to the chain, instead of
> modulating the brake you end up modulating the modulator, trying to
> second-guess how it will affect your input.
> I can honestly say that the only time I've been troubled by excessive
> brake performance was when I switched from the crudest of caliper brakes
> acting on a stainless steel rim over to a first-generation MTB with
> proper cantis, but after that not even going to hydraulic discs has
> required more than marginal learning phase.
>
> --
> dabac

This is getting way off the thread topic, so I've answered this post
in a new topic
"Tomorrow's bike: anti-lock roller brakes -- and???" at
http://groups.google.ie/group/rec.b...78cfd/6d10e443693fffa3?hl=en#6d10e443693fffa3

Andre Jute
He counted several Popes among his ancestors -- character in a novel

 

[Chalo]

Peter Cole wrote:
>
> Chalo wrote:
> >
> > Peter Cole wrote:
> >>
> >> It's a bad habit. If you use both brakes, and brake the front hard
> >> enough to mostly unweight the rear, applying the rear brake makes the
> >> rear tire more prone to skid sideways.
>
> > I think the custom may have carried over from the motorcycling world,
> > where the intention is to settle the bike down on its suspension
> > before coming in with a lot of front braking.
>
> Sorry, I still don't see it. I've never ridden a motorcycle or FS MTB,
> but I'm having difficulty what you mean by "settle down". Both the front
> & rear brakes will apply a torque, both in the same direction. The
> difference is that the torque increases the contact pressure on the
> front while lowering on the rear.

The front brake of a moto compresses the fork by two means: weight
shift and simply riding up the slope of the front fork (which is very
slack by bicycle standards). Using the front brake alone (which is
what I usually do) causes a definite "standing on nose" pitch change
to the bike.

The rear brake tends to compress the rear suspension if, as in most
motorbikes, the statically sagged position of the swingarm is angled
down below the suspension pivot with respect to the horizontal. Drag
at the rear wheel "stretches out" and flattens that angle. The
feeling of using the rear brake alone is quite different, with a sense
of the bike remaining more or less level as it drops closer to the
ground. On my motorbike, this is disorienting enough to me that it
makes me feel like the deceleration is weaker than it actually is.

So when you get the bike to squish down at both ends with the rear
brake, not only is the bike a little lower and thus harder to pitch
up, but the fork is already loaded so that it doesn't jab as sharply
downwards when the front brake is applied.

Chalo

 

[Peter Cole]

Andre Jute wrote:
> Peter Cole <[email protected]> wrote:
>
>> Andre Jute wrote:

>>> What you seem not to have understood, Peter, is that the 100kg limit
>>> has nothing to do with the particular brake and everything to do with
>>> a European legislation standard setting a 100kg minimum.

> Hang on a minute. I didn't make any generalization about over-specced
> bike components.

See above.


> I'm not a weight weenie either but I do demand that expenditures be
> justified by a quantifiable advantage. Nor am I anyone's early adopter
> (aka unpaid tester of products not quite there yet). So, after initial
> skepticism verging on prejudice against drum brakes (brought forward
> from my automobile days) and for disc brakes, on hand of an extended
> test of 5000km I changed my mind. I might add that some of my early
> prejudice was based on reading the same spec sheet that puts you right
> off. It is the 75 series roller brake in use that changed my mind. I
> was absolutely prepared to swap my disc brake back in if the 75 series
> front roller brake didn't work for me on my latest bike with the
> automatic gearbox. One of the grand things about the Cyber Nexus and
> Nexus components from Shimano is that they are so widely
> interchangeable between groupsets, it's mix and match heaven. But, as
> we have seen, I was hugely impressed with the 75 series roller brake
> and decided to keep it.

I still don't see the benefit (even from your POV).



>> Lastly, the idea of a limiter on a front brake is a complete non-starter
>> for me. This is an idea Shimano seems to return to. I could accept that
>> this brake might not be the best choice for alpine descents, and that
>> isn't an issue for a commuter bike, but I'd not want anything less than
>> full power braking available when riding in traffic. This brake seems to
>> have been designed for "recreational" cycling. That's not my category.

> Alpine descents are a straw man at this table; when will you next be
> making one on your bike?

As I said above, I wouldn't on a commuter bike, but sometimes when
touring there are long descents that require steady braking, enough that
I worry about overheating rims.

> I ride hard in the traffic here, darting in
> and out of unpredictable stop-start traffic and fastflowing sections
> to get to my favourite lanes, and I live among hills. None of this has
> faded the 75 series rollerbrakes in the least.

I wouldn't expect that to cause fade, it's long continuous braking
that's the problem. Besides, with the Shimano roller brake it isn't fade
that concerns me, it's the Shimano warnings:

"avoid continuous braking when riding down long slopes ... may weaken
braking performance ... may cause reduction of brake grease .. . may
cause abnormally sudden braking"

Shimano may be only talking about alpine type descents, but somehow I
doubt it.


> Furthermore, far from considering the torque limiter on
> the front brake a nuisance, I wish there were one on the rear 70
> series brake as well because it locks up far too easily.

Sounds like a non-linear response problem. Perhaps that's inherent to
the design. If so, then the torque limiter is really a kludge. It's not
a feature, it's a slap-on fix to a bad design (not the first).

> Also, it is
> precisely in traffic that you are likely to jam the brake on hard and
> exceed the coefficient of friction between tyre and road, thereby
> increasing stopping distance and perhaps losing control, so that is
> where the torque limiter is most useful.

If you skid a front tire, you'll go down. With normal (dry road)
traction, you will lift the rear wheel before that happens. With
experience you can accurately judge this and achieve minimal stopping
distance. On surfaces with reduced traction, your torque limiter would
not act like an ABS and eliminate lockup, so if you became accustomed to
using it you'd likely be in trouble.

Also, the torque limiter should be adjustable to reflect rider weight.
Since it isn't, it will always (ideally) produce too little braking for
the heavy and too much for the light. This is really a hopeless design.

> On fast descents on the open
> road it is easy to beat the torque limiter, that is to have to back
> off the brake before the torque limiter comes into play because the
> front wheel is already close to skidding or you are in danger of going
> over the handlebars. I was horrified when Chalo told us this is how he
> judges a good brake!

How do you know when the torque limiter comes into play? I can tell
easily enough when my rear wheel lifts. On a dry road that's still
nowhere near front wheel skid.

> That's macho ********. A good brake is one that
> maximizes friction between tyre and road to within a fraction of
> skidding, neither too weak nor too strong but better slightly limp
> than fiercely macho.

I prefer a front brake that can stop a bike in the shortest distance.
That's (unarguably) a brake that can lift the back wheel. It doesn't
sound like you have much experience with braking a bike hard.


> In my opinion Shimano's 70/75 series roller brake is far superior to a
> rim brake,

You never say why...

>> My idea of an ideal commuter bike for areas with snowy winters and
>> flattish terrain is a fixed gear. A compelling reason for me to prefer
>> the simplicity of a standard hub is that it allows me to have studded
>> tires mounted on an extra wheel set that I can swap in & out for the
>> weather. I also give a lot of thought to the issue of fixing flats in
>> really bad weather, simplicity is an asset there, too.
>
> This is a complete misconception which arises because you don't have
> hands-on experience of the Shimano roller brake. Nothing stops you
> from having two wheels with rollerbrakes, one with summer tyres, one
> with winter tyres. It is actually simpler and much quicker to take off
> and refit a wheel with a roller brake than to take off and refit a
> wheel with a disc brake or a wheel with rim brakes. To remove a roller
> braked wheel, you slide off a fitting holding the cable, change
> wheels, slide on the fitting again -- and the cable is held in the
> same position and works perfectly, that is, no set-up is required. You
> don't even require tools! With rim brakes, you must slacken the cable,
> change the wheel, then reset the cable, then adjust the brake to work.

Not really, at least not on any of my 6 bikes, wheels and brakes have
quick releases, no tools, no adjustments. I can swap any wheel between
any of the 8 or so family road bikes and 8 or so MTB's, something I'm
always doing, especially with studs.

Compared to my fixer, your geared hub, shaft drive, roller-braked bike
looks like a Rube Goldberg contraption. Sorry, it's hardly my idea of
"carefree".

 

[Peter Cole]

Chalo wrote:
> Peter Cole wrote:
>> Chalo wrote:
>>> Peter Cole wrote:
>>>> It's a bad habit. If you use both brakes, and brake the front hard
>>>> enough to mostly unweight the rear, applying the rear brake makes the
>>>> rear tire more prone to skid sideways.
>>> I think the custom may have carried over from the motorcycling world,
>>> where the intention is to settle the bike down on its suspension
>>> before coming in with a lot of front braking.
>> Sorry, I still don't see it. I've never ridden a motorcycle or FS MTB,
>> but I'm having difficulty what you mean by "settle down". Both the front
>> & rear brakes will apply a torque, both in the same direction. The
>> difference is that the torque increases the contact pressure on the
>> front while lowering on the rear.
>
> The front brake of a moto compresses the fork by two means: weight
> shift and simply riding up the slope of the front fork (which is very
> slack by bicycle standards). Using the front brake alone (which is
> what I usually do) causes a definite "standing on nose" pitch change
> to the bike.
>
> The rear brake tends to compress the rear suspension if, as in most
> motorbikes, the statically sagged position of the swingarm is angled
> down below the suspension pivot with respect to the horizontal. Drag
> at the rear wheel "stretches out" and flattens that angle. The
> feeling of using the rear brake alone is quite different, with a sense
> of the bike remaining more or less level as it drops closer to the
> ground. On my motorbike, this is disorienting enough to me that it
> makes me feel like the deceleration is weaker than it actually is.
>
> So when you get the bike to squish down at both ends with the rear
> brake, not only is the bike a little lower and thus harder to pitch
> up, but the fork is already loaded so that it doesn't jab as sharply
> downwards when the front brake is applied.
>
> Chalo

OK, I can see how rear braking with a swing arm suspension can compress
both F&R, but it seems that momentary rear braking followed by hard
front braking (in a panic stop) as AJ suggests would only pogo the rear
and wouldn't help the minimum braking distance, the net fork dive would
be the same (although in 2 stages). It doesn't strike me as a useful
technique even on a FS bike, and (as I can attest by experience) it's a
really bad idea on a road bike.

 

[[email protected]]

Peter Cole writes:

>>>>> It's a bad habit. If you use both brakes, and brake the front
>>>>> hard enough to mostly unweight the rear, applying the rear brake
>>>>> makes the rear tire more prone to skid sideways.

>>>> I think the custom may have carried over from the motorcycling
>>>> world, where the intention is to settle the bike down on its
>>>> suspension before coming in with a lot of front braking.

>>> Sorry, I still don't see it. I've never ridden a motorcycle or FS
>>> MTB, but I'm having difficulty what you mean by "settle down".
>>> Both the front & rear brakes will apply a torque, both in the same
>>> direction. The difference is that the torque increases the
>>> contact pressure on the front while lowering on the rear.

>> The front brake of a moto compresses the fork by two means: weight
>> shift and simply riding up the slope of the front fork (which is
>> very slack by bicycle standards). Using the front brake alone
>> (which is what I usually do) causes a definite "standing on nose"
>> pitch change to the bike.

>> The rear brake tends to compress the rear suspension if, as in most
>> motorbikes, the statically sagged position of the swing arm is
>> angled down below the suspension pivot with respect to the
>> horizontal. Drag at the rear wheel "stretches out" and flattens
>> that angle. The feeling of using the rear brake alone is quite
>> different, with a sense of the bike remaining more or less level as
>> it drops closer to the ground. On my motorbike, this is
>> disorienting enough to me that it makes me feel like the
>> deceleration is weaker than it actually is.

>> So when you get the bike to squish down at both ends with the rear
>> brake, not only is the bike a little lower and thus harder to pitch
>> up, but the fork is already loaded so that it doesn't jab as
>> sharply downward when the front brake is applied.

> OK, I can see how rear braking with a swing arm suspension can
> compress both F&R, but it seems that momentary rear braking followed
> by hard front braking (in a panic stop) as AJ suggests would only
> pogo the rear and wouldn't help the minimum braking distance, the
> net fork dive would be the same (although in 2 stages). It doesn't
> strike me as a useful technique even on a FS bike, and (as I can
> attest by experience) it's a really bad idea on a road bike.

To see more clearly what this is about, one need only to attend a
motorcycle road race where customarily solo finishes are done with the
bike tilted forward at about 30° riding on the front wheel, the brake
being skillfully modulated by the rider. We have guys around here who
do that often on the highway.

This story about the rear brake holding the bike down has been part of
motorcycling myth and lore for more than 60 years from my experience.
Those who purvey this tale are themselves not riders who brake an M/C
hard enough to raise the rear wheel.

Jobst Brandt

 

[Chalo]

Jobst Brandt wrote:
>
> This story about the rear brake holding the bike down has been part of
> motorcycling myth and lore for more than 60 years from my experience.
> Those who purvey this tale are themselves not riders who brake an M/C
> hard enough to raise the rear wheel.

Track racers, who routinely use maximum braking and thus can't use
their rear brakes at all under those conditions, still use the rear
brake to set up the bike for a hard deceleration or a turn. Because
they must be so delicate with it on their high performance, short
wheelbase machines, many racers use rear brakes connected to a thumb
lever rather than a foot pedal as is usual for a street bike.

Chalo