Radical gearing change: advice needed...



In message <[email protected]>
Rob Morley <[email protected]> wrote:

>>>Although I find my hill climbing ability is usually limited by the
>>>slowest speed at which I can still balance not by the gears.
>>
>> Also - if you get down to walking speed, may as well walk (on a solo).
>>
> Why do you say that? When you're on a bike most of your leg effort goes
> into propulsion, but when you're walking most goes into keeping your bum
> off the ground and moving your legs.

And when walking is difficult - I can't use my right leg at all well -
then spinning is worth it, as long as I can balance well.

The two wheeled wheelchair is wonderful.


--
Charles
Brompton P-type T6 in Motspur Park
 
On Tue, 21 Aug 2007 08:31:50 +0100, charlesA wrote:
>
> Ooh, something to save for! Thanks, Tony.
>
> I wonder if any Brommies have reviewed it?

http://www.foldsoc.co.uk/pantour.html

>
> I must work out what gearing inches/numbers mean, to a simpleton; are
> there any suggested links?

Its the diameter of the rear wheel times the number of teeth on the front
sprocket divided by the number of teeth on the back sprocket. Or put
another way its the distance the bike will move for one turn of the
pedals divided by 2*pi. If you want an easy calculator, as usual Sheldon
has the answer: http://sheldonbrown.com/gears/

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell
 
[email protected]m wrote:
> In message <[email protected]>
> Tony Raven <[email protected]> wrote:
>
>> Quite a few Brompton
>> owners have fitted them as the other options are quite limited on a
>> Brompton. Not cheap but by the time you've added up all the bits to do
>> it another way.....
>
> Ooh, something to save for! Thanks, Tony.
>
> I wonder if any Brommies have reviewed it?

A pal of mine has a Brom with a Mountain Drive. I've only heard him say
Very Nice Things about it (aside from the initial price). Says he can
trundle up just about anything with a road on it.

> I must work out what gearing inches/numbers mean, to a simpleton; are
> there any suggested links?

Gear inches are a bit of a stupid number: it's the diameter of an
imaginary wheel with direct drive pedals (like a penny-farthing or a
kid's trike or unicycle) that would have that gear. So my 26" wheel
unicycle has a natural 26" gear.
In itself the number is a bit meaningless IMHO, but you soon get a feel
for what you're after once you've pedalled a few known sizes of gear. I
have a ~ 20" at the bottom of the range for my heavy recumbent tourer
where I can't stand on the pedals and may be carting four panniers of
camping gear up a *big* hill, and not many folk except tricyclists have
much use for anything too far below that, because balancing a bike at
that sort of speed gets hard. Bottom end of serious MTB gearing is
usually about 17". My freighter bottoms out at just under 30", and I
can get 50 Kg of coal up a reasonable size hill with that without
standing up (I don't like turning big gears any more).

Note that metric gear sizes are done in a different way, which is how
far you'll move on the ground for one turn of the cranks. Again, really
a case of getting used to a known number and comparing to that to know
what it means to your legs rather than your head.

HTH, Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/
 
In article <[email protected]>,
[email protected]m says...

> And when walking is difficult - I can't use my right leg at all well -
> then spinning is worth it, as long as I can balance well.
>
> The two wheeled wheelchair is wonderful.
>
Much better than a regular wheelchair at going down steps too. :)
I've broken my legs a couple of times, and both times I was cycling
comfortably long before I was walking well.
 
In article <[email protected]>, Tony Raven
[email protected]lid says...

> Its the diameter of the rear wheel times the number of teeth on the front
> sprocket divided by the number of teeth on the back sprocket. Or put
> another way its the distance the bike will move for one turn of the
> pedals divided by 2*pi.

Circumference is pi.diameter, not 2.pi.diameter :)
 
Rob Morley wrote:
> In article <[email protected]>, Tony Raven
> [email protected]lid says...
>
>> Its the diameter of the rear wheel times the number of teeth on the front
>> sprocket divided by the number of teeth on the back sprocket. Or put
>> another way its the distance the bike will move for one turn of the
>> pedals divided by 2*pi.
>
> Circumference is pi.diameter, not 2.pi.diameter :)

Someone ate half the Pi...
IGMC.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/
 
On Tue, 21 Aug 2007 09:14:22 +0100, Rob Morley wrote:
>
> Circumference is pi.diameter, not 2.pi.diameter :)

Doh! Messrs Fingers, let me introduce you to Mr Brain. The perils of
typing before first coffee. ;-)

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell
 
Tony Raven wrote:
> On Mon, 20 Aug 2007 12:48:30 +0100, Bonge Boo wrote:
>> To give you some idea, one of the hills I was gonna use is 30%. It
>> completely bypasses a really unpleasant and dangerous stretch of road.
>> If I don't use that, another option is the ride I did yesterday. Only
>> 15-20%. Even the main road is about 10% average, with stretches of 15%.
>>
>
> Where on earth do you live?

Bradford-on-Avon. Nr Bath.
 
Ace wrote:
> On Mon, 20 Aug 2007 12:48:30 +0100, Bonge Boo <[email protected]>
> wrote:
>
>>> My advice would be, fit a compact double (e.g. 50-34) at
>>> the front and wider range cassette (e.g. 12-27) on the back.
>>>
>>> If you did this you'd only have to replace chainset and cassette;
>>> everything else would be fine. And, as you get your fitness back, it would
>>> be reasonably simple to change back to your current gearing.
>> This is were I am reading contradictory stuff. I didn't think I could
>> replace the front rings with anything smaller without screwing the
>> indexing? And as far as I know, the rear mech only works over a 13-tooth
>> spread. But are you saying I can push these figures by a few teeth
>> either way and not notice the difference?
>
> As I've said in another post, the indexing is only dependant on the
> spacing between rings - the tooth difference between them is
> irrelevant, so yes, you can swap the rear cassette and/or chainrings
> with impunity. And not necessarily only by a few teeth. A rear
> cassette with a huge granny ring is also a possibility.

Speaking to 2 of my local bike shops, they both came up with the same
solution. 8-speed rear MTB mech and cassette.

Cost about £60, should give me a 39 to 34 lowest gear. I'm going
calculate that in inches, find out the nearest equivalent on the MTB and
do the ride in that gear on the MTB. If I can do it, then I think that
will have be the solution.
 
Roger Merriman wrote:
> Bonge Boo <[email protected]> wrote:
>
>> I hope someone has some suggestion on how I should best proceed?
>>
>> After a very very long time off the bike, I recently started riding my
>> ancient mountain bike again. However off-road isn't an option any more,
>> so I decided to get a racer so I could go faster and further. Commuting
>> to work (2.5 miles) is the plan. I have some steep hills around me.
>>
>> Ebay came up trumps and I got myself a slightly scruffy, but
>> mechanically sound Specialized Allez. It's great! Apart from the fact
>> that the gears are way to long. You'd need to live in Holland to make
>> use of the gearing, unless you've got the thighs of Ullrich and oxygen
>> carrying capacity of Armstrong...
>>
>> Today I decided to see how feasible it would be to ride to work. Getting
>> there is great. Getting back is purgatory. I was on the lowest gear and
>> couldn't possibly do anything but stand up and stamp on the pedals.
>> Really exhausting, bad for the joints, etc.
>>
>> The bike has a Sora 2005 groupset, apart from a 9 speed Tiagra rear
>> mech. Chainset is a 52x39 and the cassette is a 12-25.
>>
>> Having done these rides on my mountain bike, which has a front 48x38x28
>> and 12-30 rear, I frequently have to get in the lowest gear and just
>> spin up the hills.
>>
>> So my question is really this. What is the most cost effective way of
>> getting myself some gearing that is going to be more usable? If I could
>> get to near a 1:1 ratio I'll be fine.
>>
>> I believe that if I try to put a triple on the front I'll have to
>> replace the chainset, mech and STI lever? Is that right?
>>
>> So another alternative might be to swap the rear cassette with an
>> 8-speed 34 tooth "mega-range" and put a MTB rear mech on it? That would
>> mean a new chain as well I s/pose.
>>
>> Alternatively I could try to find a much smaller front chainring. I
>> reckon a 30x44 would do the job nicely. But I'm guessing that will balls
>> up the STI?
>>
>> Help! Any suggestions gratefully received.
>
> hello there clive.

Hi Roger.

> one other option is to keep the road bike as it is and put slicks on the
> old MTB while has lower gearing, and use the old MTB for the commutte,
> though knowing the area ish you live in you'll probably want to lower
> the gearing any way, for the road bike.

I had considered putting fatboys on the Rockhopper, but frankly the
bike's a wreck. I've given it no love in years. And the newer shiny toy
is providing me with more motivation to actually ride, which is important..

> i find that having my old MTB with road tires, that i can get up some of
> the 30% and more hills arond my folks place with too much problems, the
> bike has 22/32/42 to a 28-11 cassette.

It's certainly an option. But I love the extra efficiency of the Allez.
With my limited physical capabilities, the extra range it offers is so
tempting...

Have to give it some thought. Many thanks to all respondents.
 
David Damerell wrote:
> Quoting Bonge Boo <[email protected]>:
>> MTB is rigid (1990 Rockhopper). 29lbs. The rolling resistance and weight
>> was where I was hoping to make all the gains, and on level-ish ground
>> the difference is stunning. The bike feels so much more alive!
>> But as soon as the incline goes beyond 3-4%, frankly that makes no
>> difference. And when you get to 10%+ its so irrelevant.
>
> Uh - as distinct from the psychosomatic effects, it's exactly on a steep
> incline where weight matters.

Err. How so? I weigh 150lbs. Bikes weight between 22lb and 29lbs. As a
proportion that's sod all.

Unless my basic physics it wrong, the work required to lift that mass is
only about 5% more. Even accounting for extra rotational mass on the
MTB, it's not that large a difference.
 
Bonge Boo wrote:
> David Damerell wrote:

>> Uh - as distinct from the psychosomatic effects, it's exactly on a steep
>> incline where weight matters.
>
> Err. How so? I weigh 150lbs. Bikes weight between 22lb and 29lbs. As a
> proportion that's sod all.

But it's only if you're accelerating, or fighting active deceleration
via gravity, that the mass difference is going to do much. On the flat,
once you've got up to speed the weight is mostly a non-issue.

> Unless my basic physics it wrong, the work required to lift that mass is
> only about 5% more. Even accounting for extra rotational mass on the
> MTB, it's not that large a difference.

5% is 5%, and is 5% more than you're gaining on the flat outside of your
initial acceleration to speed. If serious athletes could get 5% for
nothing they'd be queuing round the block, as that's far more difference
than you usually get if you factor out machinery.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/
 
David Damerell wrote:
> Quoting Bonge Boo <[email protected]>:
>> MTB is rigid (1990 Rockhopper). 29lbs. The rolling resistance and weight
>> was where I was hoping to make all the gains, and on level-ish ground
>> the difference is stunning. The bike feels so much more alive!
>> But as soon as the incline goes beyond 3-4%, frankly that makes no
>> difference. And when you get to 10%+ its so irrelevant.
>
> Uh - as distinct from the psychosomatic effects, it's exactly on a steep
> incline where weight matters.

Agreed; but the reason a road bike is so much faster
on the flat is aerodynamics and rolling resistance.

Crawling up a hill reduces the benefits of the
road bike in these areas.

On weight, yes, it makes a difference when climbing,
but judging from Clive's comments, I reckon
a good riding position is probably at least
as important.

Peeking at a contour map of the area, some

http://www.streetmap.co.uk/streetmap.dll?G2M?X=381500&Y=161500&A=Y&Z=4

of the minor roads and paths are very steep,
although the roads only make "single chevron"
grade (1:7 - 1:5) as opposed to "double chevron"
(worse than 1:5) where marked.

BugBear
 
Bonge Boo <[email protected]> wrote:

> Roger Merriman wrote:
> > Bonge Boo <[email protected]> wrote:
> >
> >> I hope someone has some suggestion on how I should best proceed?
> >>
> >> After a very very long time off the bike, I recently started riding my
> >> ancient mountain bike again. However off-road isn't an option any more,
> >> so I decided to get a racer so I could go faster and further. Commuting
> >> to work (2.5 miles) is the plan. I have some steep hills around me.
> >>
> >> Ebay came up trumps and I got myself a slightly scruffy, but
> >> mechanically sound Specialized Allez. It's great! Apart from the fact
> >> that the gears are way to long. You'd need to live in Holland to make
> >> use of the gearing, unless you've got the thighs of Ullrich and oxygen
> >> carrying capacity of Armstrong...
> >>
> >> Today I decided to see how feasible it would be to ride to work. Getting
> >> there is great. Getting back is purgatory. I was on the lowest gear and
> >> couldn't possibly do anything but stand up and stamp on the pedals.
> >> Really exhausting, bad for the joints, etc.
> >>
> >> The bike has a Sora 2005 groupset, apart from a 9 speed Tiagra rear
> >> mech. Chainset is a 52x39 and the cassette is a 12-25.
> >>
> >> Having done these rides on my mountain bike, which has a front 48x38x28
> >> and 12-30 rear, I frequently have to get in the lowest gear and just
> >> spin up the hills.
> >>
> >> So my question is really this. What is the most cost effective way of
> >> getting myself some gearing that is going to be more usable? If I could
> >> get to near a 1:1 ratio I'll be fine.
> >>
> >> I believe that if I try to put a triple on the front I'll have to
> >> replace the chainset, mech and STI lever? Is that right?
> >>
> >> So another alternative might be to swap the rear cassette with an
> >> 8-speed 34 tooth "mega-range" and put a MTB rear mech on it? That would
> >> mean a new chain as well I s/pose.
> >>
> >> Alternatively I could try to find a much smaller front chainring. I
> >> reckon a 30x44 would do the job nicely. But I'm guessing that will balls
> >> up the STI?
> >>
> >> Help! Any suggestions gratefully received.
> >
> > hello there clive.
>
> Hi Roger.
>
> > one other option is to keep the road bike as it is and put slicks on the
> > old MTB while has lower gearing, and use the old MTB for the commutte,
> > though knowing the area ish you live in you'll probably want to lower
> > the gearing any way, for the road bike.
>
> I had considered putting fatboys on the Rockhopper, but frankly the
> bike's a wreck. I've given it no love in years. And the newer shiny toy
> is providing me with more motivation to actually ride, which is important..
>
oh absoulty.


> > i find that having my old MTB with road tires, that i can get up some of
> > the 30% and more hills arond my folks place with too much problems, the
> > bike has 22/32/42 to a 28-11 cassette.
>
> It's certainly an option. But I love the extra efficiency of the Allez.
> With my limited physical capabilities, the extra range it offers is so
> tempting...
>
fair enought sounds like dropping the chainset down so the lowest is the
20's is probably to way forward.

and as you say the enjoyment will make you ride etc.

> Have to give it some thought. Many thanks to all respondents.


roger
--
www.rogermerriman.com
 
In message <[email protected]>


[snip]

>> I must work out what gearing inches/numbers mean, to a simpleton; are
>> there any suggested links?

> Its the diameter of the rear wheel times the number of teeth on the front
> sprocket divided by the number of teeth on the back sprocket. Or put
> another way its the distance the bike will move for one turn of the
> pedals divided by 2*pi. If you want an easy calculator, as usual Sheldon
> has the answer: http://sheldonbrown.com/gears/

Thanks, Tony - it already begins to make sense... Ratios! i remember
the struggle...

--
Charles
Brompton P-type T6 in Motspur Park
 
In message <[email protected]>
Peter Clinch <[email protected]> wrote:


[snip]

> A pal of mine has a Brom with a Mountain Drive. I've only heard him say
> Very Nice Things about it (aside from the initial price). Says he can
> trundle up just about anything with a road on it.

Thanks; I think I would be honour bound to say that about an
investment like that! But I did when I bought a n overdrive for a
LandRover for about that money... And investing in the pleasure of
cycling must be justifiable...

>> I must work out what gearing inches/numbers mean, to a simpleton; are
>> there any suggested links?

> Gear inches are a bit of a stupid number: it's the diameter of an
> imaginary wheel with direct drive pedals (like a penny-farthing or a
> kid's trike or unicycle) that would have that gear. So my 26" wheel
> unicycle has a natural 26" gear.
> In itself the number is a bit meaningless IMHO, but you soon get a feel
> for what you're after once you've pedalled a few known sizes of gear. I
> have a ~ 20" at the bottom of the range for my heavy recumbent tourer
> where I can't stand on the pedals and may be carting four panniers of
> camping gear up a *big* hill, and not many folk except tricyclists have
> much use for anything too far below that, because balancing a bike at
> that sort of speed gets hard. Bottom end of serious MTB gearing is
> usually about 17". My freighter bottoms out at just under 30", and I
> can get 50 Kg of coal up a reasonable size hill with that without
> standing up (I don't like turning big gears any more).

> Note that metric gear sizes are done in a different way, which is how
> far you'll move on the ground for one turn of the cranks. Again, really
> a case of getting used to a known number and comparing to that to know
> what it means to your legs rather than your head.

Thank you, I get the feel for it.

(What /is/ a Freighter?)


--
Charles
Brompton P-type T6 in Motspur Park
 
[email protected]m wrote:

> (What /is/ a Freighter?)

In my case, this...
http://www.personal.dundee.ac.uk/~pjclinch/8f-sofa.jpg

Not the best picture in the world, but you can learn more at
http://www.velovision.com/mag/issue9/8freight.pdf

also google for "bakfiets" and "cargobike"

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/
 
bugbear wrote:
> David Damerell wrote:
>> Quoting Bonge Boo <[email protected]>:
>>> MTB is rigid (1990 Rockhopper). 29lbs. The rolling resistance and
>>> weight was where I was hoping to make all the gains, and on level-ish
>>> ground the difference is stunning. The bike feels so much more alive!
>>> But as soon as the incline goes beyond 3-4%, frankly that makes no
>>> difference. And when you get to 10%+ its so irrelevant.
>>
>> Uh - as distinct from the psychosomatic effects, it's exactly on a steep
>> incline where weight matters.
>
> Agreed; but the reason a road bike is so much faster
> on the flat is aerodynamics and rolling resistance.
>
> Crawling up a hill reduces the benefits of the
> road bike in these areas.
>
> On weight, yes, it makes a difference when climbing,
> but judging from Clive's comments, I reckon
> a good riding position is probably at least
> as important.
>
> Peeking at a contour map of the area, some
>
> http://www.streetmap.co.uk/streetmap.dll?G2M?X=381500&Y=161500&A=Y&Z=4
>
> of the minor roads and paths are very steep,
> although the roads only make "single chevron"
> grade (1:7 - 1:5) as opposed to "double chevron"
> (worse than 1:5) where marked.

I live at Great Ashley and work down near the Tithe Barn. The purple
road is narrow, steep (15-20%) and really dangerous. But direct.

The orange road out towards the Moulton factory (yes, they are made
there) is probably only about 10-15% in pitches, but even narrower.
Often 2 cars can't fit side by side.

The road out past Turleigh is the most civilised and least steep route.
It's only 15% in places. And then there's my lung-bursting shortcut
through Newtown that's not even shown. It's without question 30+%.

However you do it, it's sit and spin time.

A mega-range MTB cassette with the current front chainset will give me a
31in gear. That's the same as the second lowest gear on the MTB. And
I've used that before to get up through Turleigh. So I have a plan of
attack....
 
On Wed, 22 Aug 2007 08:40:48 +0100, Bonge Boo wrote:
>
> The road out past Turleigh is the most civilised and least steep route.
> It's only 15% in places. And then there's my lung-bursting shortcut
> through Newtown that's not even shown. It's without question 30+%.
>
> However you do it, it's sit and spin time.
>
> A mega-range MTB cassette with the current front chainset will give me a
> 31in gear. That's the same as the second lowest gear on the MTB. And
> I've used that before to get up through Turleigh. So I have a plan of
> attack....

Another option is to get a nanomotor either fitted to your bike or as a
Brompton Nano. Very effective at taking the sting out of hills for those
unable to cycle up them normally and so discrete users have found people
staring in disbelief at their apparent fitness as they saunter up steep
hills. Developed and made not to far from you in Marlborough and getting
very good reviews. The added bonus of the Brompton Nano is you fold it
up and take it inside with you saving the hassle and worry of locking it
up all day. It has a really neat mod to the Brompton luggage carrier so
you just clip the battery bag on the carrier and it connects up.
http://nano-motor.co.uk/index.php

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell
 
Quoting Rob Morley <[email protected]>:
>[email protected] says...
>>Also - if you get down to walking speed, may as well walk (on a solo).
>Why do you say that? When you're on a bike most of your leg effort goes
>into propulsion, but when you're walking most goes into keeping your bum
>off the ground and moving your legs.

That's very true on the flat. It's not so true when you are trying to do
work against gravity, and when staying on the bike requires low-speed
steering effort.
--
David Damerell <[email protected]> flcl?
Today is Olethros, August - a weekend.
 
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