Rim vs. disc brakes

I don't understand why disc brakes exist on bicycles. Are
they better? It looks like the rim has better leverage, and
no added weight.

--
Leo Lichtman
l.lichtman@worldnet.att.net

Tandems have so much weight and go so fast downhill with all that weight and only slightly higher aero resistance over single rider bikes that if rim brakes were relied upon soley one could overheat and blow the tube.

Rim brakes are substantially affected by mud, dirt, and water, so mountain bikes in environs likely to recieve this exposure need a braking system that won't fail due the environs.

Commuting bikes need reliable rain brakes, so a drum or disc can satisfy that requirement.

Road bikes and recumbents generally riding on dry pavement usually rely on the lighter and less expensive rim brakes.

On Sun, 11 Jul 2004 03:00:30 GMT, "Leo Lichtman"
<l.lichtman@worldnet.att.net> wrote:

>I don't understand why disc brakes exist on bicycles. Are
>they better? It looks like the rim has better leverage, and
>no added weight.

They exist because people will buy them, and in most cases
pay a premium to get them.

Whether thay are needed or valuable is a matter of
opinion in some cases, and a matter of specific
circumstances in others.

In long descents at speed, a disc brake will not cause rim
overheating; for those who use tubulars, this could be a
crucial advantage.

In very wet and muddy conditions, a disc brake's performance
can be better or more predictable than a rim brake's, though
this is almost entirely dependent upon the specific systems
being compared; I personally have a front disc that's not as
effective as the rim brake on two of my other bikes, either
wet or dry.

Many disc brake users find that the discs' stopping power is
easier to modulate; others find that to achieve the same
level of braking, the disc must be applied with much greater
force. These varying (but not necessarily conflicting)
observations may be due in part to the fact that there is no
standard for comparison; there's quite a bit of variation in
rim brake performance, and in disc brake performance.

Only the individual rider can determine if discs provide any
advantage *for them*, and it should be noted that in some
cases, the advantage (in either direction) may be definable
only as "they're better because I like them more than the
other ones."

--
Typoes are a feature, not a bug. Some gardening required to
reply via email. Surrealism is a pectinated ranzel.

Leo-<< I don't understand why disc brakes exist on bicycles.
Are they better? It looks like the rim has better leverage,
and no added weight. >><BR><BR>

Great for muddy, really wet conditions, huge downhills,
rides where wacking a rim is a large proibability. NO use on
a standard road bike. Unique forks, hubs, levers(Hydraulic)
framesets, higher weight, cost, complexity. Answer to a not
asked question, like tubeless on a road bike.

Mavic sure is behind this 'craze' 100%. A way to sell more
of their goofy wheel.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali
costruite eccezionalmente bene"

"Leo Lichtman" <l.lichtman@worldnet.att.net> writes:

> I don't understand why disc brakes exist on bicycles. Are
> they better? It looks like the rim has better leverage,
> and no added weight.

I can save you some time and the rest of us some bandwidth.
Go to www.google.com and click on 'Groups.' Then navigate
your way to rec.bicycles.tech and search for 'disk brakes'
and read the thousands of posts already written about this.

The short answer is that disk brakes are good for muddy
conditions. Disk or drum brakes are good for tandems being
ridden in mountainous terrain where lots of braking can
cause problems with rims overheating. Other than that, they
are an answer to a problem that didn't exist.

The cons for disk brakes are weight, incompatibility with
road levers (IIUC), and the risk of your front wheel coming
out of the dropouts.

"Leo Lichtman" <l.lichtman@worldnet.att.net> wrote in message news:<i32Ic.81232$OB3.77463@bgtnsc05-news.ops.worldnet.att.net>...
> I don't understand why disc brakes exist on bicycles. Are
> they better? It looks like the rim has better leverage,
> and no added weight.

I find a rear disc on my tourer is less easily fouled by
luggage than conventional brakes, where stuff on the rack or
the tops of paniers did get in the way of the brakes.

Also more consistent in the wet than rim brakes, easier to
adjust for optimal performance.

Still works without rubbing when I buckle the wheel.

But performance gains in good conditions, no.

Andrew Webster

Like usual -- in this group you get "experts" chiming in
with their half baked knowledge.

I have built up a Kona Major Jake with disc brakes, I use
this both as a CX bike and my city bike. Its wonderful to
fly through the city, and know that you can easily stop from
any speed with two finger pressure. On big decents, you can
control your speed without worrying about fade, as these
puppies work better once their hot.

I have Avid Ball Bearing mechanical brakes, which are
specifically for road levers, and are 100% compatible with
them (I guess the experts don't know everything).

"Tim McNamara" <timmcn@bitstream.net> wrote in message news:m2wu1a5rpl.fsf@Stella-
Blue.local...
> "Leo Lichtman" <l.lichtman@worldnet.att.net> writes:
>
> > I don't understand why disc brakes exist on bicycles.
> > Are they better? It looks like the rim has better
> > leverage, and no added weight.
>
> I can save you some time and the rest of us some
> bandwidth. Go to www.google.com and click on 'Groups.'
> Then navigate your way to rec.bicycles.tech and search for
> 'disk brakes' and read the thousands of posts already
> written about this.
>
> The short answer is that disk brakes are good for muddy
> conditions. Disk or drum brakes are good for tandems being
> ridden in mountainous terrain where lots of braking can
> cause problems with rims overheating. Other than that,
> they are an answer to a problem that didn't exist.
>
> The cons for disk brakes are weight, incompatibility with
> road levers (IIUC), and the risk of your front wheel
> coming out of the dropouts.

---
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"Qui si parla Campagnolo " <vecchio51@aol.com> wrote in message
news:20040711093410.04264.00001272@mb-m15.aol.com...
> Leo-<< I don't understand why disc brakes exist on
> bicycles. Are they
better?
> It looks like the rim has better leverage, and no added
> weight. >><BR><BR>
>
> Great for muddy, really wet conditions, huge downhills,
> rides where
wacking a
> rim is a large proibability. NO use on a standard road
> bike. Unique forks, hubs, levers(Hydraulic) framesets,
> higher weight, cost, complexity. Answer
to a
> not asked question, like tubeless on a road bike.
>
> Mavic sure is behind this 'craze' 100%. A way to sell more
> of their goofy wheel.
>
Heh heh, yeah Mavic goofy wheels. I couldn't agree more on
that one. I'll never buy another Mavic.

BTW, I remember mountain biker Roland Green held out on disc
upgrades for his trusty XTR v-brakes for about 2 years
before the powers that be forced his hand. He's now riding a
dual suspension disc beast (not sure if it's helping him).

"JayofMontreal" <winickj0spam@vif.com> writes:

> Like usual -- in this group you get "experts" chiming in
> with their half baked knowledge.

Whereas you know better, eh?

> I have built up a Kona Major Jake with disc brakes, I use
> this both as a CX bike and my city bike. Its wonderful to
> fly through the city, and know that you can easily stop
> from any speed with two finger pressure. On big decents,
> you can control your speed without worrying about fade, as
> these puppies work better once their hot.

Huh. I can stop my road bike with one or two finger pressure
with my rim brakes (Campy 9 sp Ergo levers and Sun Tour
Superbe Pro calipers). Not a problem. I've never experienced
brake fade in the 35 years I've been riding bikes. Oh well.
Perhaps I'm just not an extreme rad cool biker dude like
you, eh? Or perhaps I just know how to descend.

At least I know enough not to top post, however.

> I have Avid Ball Bearing mechanical brakes, which are
> specifically for road levers, and are 100% compatible with
> them (I guess the experts don't know everything).

*I'm* not an expert, didn't know that and thank you for the
data point.

In article <i32Ic.81232$OB3.77463@bgtnsc05-
news.ops.worldnet.att.net>,
l.lichtman@worldnet.att.net says...

>I don't understand why disc brakes exist on bicycles. Are
>they better? It looks like the rim has better leverage, and
>no added weight.

If you bend your rim, you still have brakes. Some claim more
braking power, but canti's have plenty of power for me.
-------------
Alex

In article <6f3aac0b.0407111129.39ffc891@posting.google.com>, Andrew
Webster <awebster@littleheath.org.uk> wrote:

> "Leo Lichtman" <l.lichtman@worldnet.att.net> wrote in
> message news:<i32Ic.81232$OB3.77463@bgtnsc05-
> news.ops.worldnet.att.net>...
> > I don't understand why disc brakes exist on bicycles.
> > Are they better? It looks like the rim has better
> > leverage, and no added weight.
>
> I find a rear disc on my tourer is less easily fouled by
> luggage than conventional brakes, where stuff on the rack
> or the tops of paniers did get in the way of the brakes.
>

Good racks like those made by Old Man Mountain do not have
these issues. In fact, cheapo racks do not hold up to the
abuse of long distance touring anyhow.

> Also more consistent in the wet than rim brakes, easier to
> adjust for optimal performance.
>

If you use good pads -- Koolstop Salmon or another one a
friend is using which is a triple compound, stopping in the
wet is no problem. I know this well because I live in the
wet coast of Vancouver.

> Still works without rubbing when I buckle the wheel.
>

Except that it doesn't work when the rotor gets warped.
Prolong heating of the rotor or even during transport can
warp it. It's harder to true a warped rotor than a wheel. I
know.. A friend of mine had 2 rotors damaged during his
flight to Moab. SOL I guess.

> But performance gains in good conditions, no.
>

Cable disc brakes can suffer the same performance
degradation as rim brakes -- cable friction caused by water
accumulation and muck. When the cables get muck and
corrosion due to you not cleaning them, their performance
will degrade overtime. That's why hydraulic is a bit more
superior in this department. By hydro brakes can be messy to
set up and touring with hydros mean you need to carry a
bleed kit and oil.

Disc brakes are good for what they are and if you get them
free already with the new bike, I see no reason to do
anything but ride the bike. But if the original poster is
contemplating on putting disc to increase stopping power, I
would suggest the poster to replace brake cables, housings
and good pads before plunging mega bucks on a disc system.

In article <r8jIc.1228$RD4.231227@news20.bellglobal.com>, JayofMontreal
<winickj0spam@vif.com> wrote:

> Like usual -- in this group you get "experts" chiming in
> with their half baked knowledge.
>
> I have built up a Kona Major Jake with disc brakes, I use
> this both as a CX bike and my city bike. Its wonderful to
> fly through the city, and know that you can easily stop
> from any speed with two finger pressure. On big decents,
> you can control your speed without worrying about fade, as
> these puppies work better once their hot.
>
> I have Avid Ball Bearing mechanical brakes, which are
> specifically for road levers, and are 100% compatible with
> them (I guess the experts don't know everything).
>

Regular brakes, be it caliper or V-brakes, will stop easily
with 1 or 2 finger pressure on big descents. In fact, I do
it all the time on my full suspension and my folding Bike
Friday.. What most people don't realise is that, what make
the brakes stop well are good brake pads.

Sadly, stock pads or cheap replacement pads are just plain
useless. They do not stop very well and require too much
pressure to achieve any decent braking. For example, the
lousy pads that came with my Bike Friday were the no names
POS. I can't even stop properly on a 4% grade downhill -- I
have to put my foot down. It's that bad. Guess what.. Once I
have upgraded the pads to Koolstop Salmon pads on the front
and rear, they stop my bike even on a long Mt Seymour
downhill ride (10% grade) with little to no effort at all.
That's how much an improvement good pads can stop a bike.

"Leo Lichtman" <l.lichtman@worldnet.att.net> wrote:

> I don't understand why disc brakes exist on bicycles. Are
> they better? It looks like the rim has better leverage,
> and no added weight.

Others have mentioned discs' improved stopping power over
rim brakes, but this simply isn't true. Those who say discs
stop harder are unaccustomed to how powerful rim brakes can
be, and are probably in no position to be able use that kind
of braking power anyway.

Others have mentioned discs' tolerance of wet and messy
weather conditions and rim damage. These are genuine
benefits They also eliminate rim abrasive wear and a large
amount of the filth that gets splattered all over rim-braked
bikes in wet weather.

However, I see the chief benefits of discs in their
separation of braking issues from other design choices
related to the rims and tires. There are many "given" design
attributes of bicycles that are not in fact preferred, but
rather imposed by the design of rim brakes.

Use discs, and your bike no longer cares what wheel size you
are using. All rim brakes place _some_ constraint on tire
size, for instance. Discs do not. Rim brakes work with at
most a couple of similar rim diameters. Discs will brake
whatever is laced to them.

Discs allow the use of any rim width that fits within a
given frame. Snowbikes, for instance, use extra-wide rims
for flotation, and brake stud placement was nonstandard as a
result-- meaning that the only wheels that would go in your
snowbike were snowbike wheels. With discs, you can put
snowbike wheels and cross-country racing wheels and road
bike wheels all on the same frame.

Likewise, discs allow the rim to be composed of any
material, regardless of whether that material is suitable to
withstand braking friction. Carbon fiber, wood, nylon,
painted metal; it doesn't matter.

Discs allow vehicles with stub axle wheels (trikes, quads,
Cannondale Lefty etc.) to have adequate braking without
gratuitous arches over the tires. Drum brakes were formerly
used for this and have many of the benefits of discs, but
strong braking is not one of them.

Disc brakes can be placed elsewhere in the drivetrain than
at the wheel (like on the axle of a trike).

These are some of the advantages and possibilities that disc
brakes make available. If no such advantages apply, then rim
brakes will do the job more cheaply, with less weight. But
to say rim brakes are better for all bikes is defining
"bikes" pretty unimaginatively.

Chalo Colina