Track crank arm length question

twotiretinker-obra2@yahoo.com

2006-07-05

i'll pipe in. I too have the fuji steel track bike, i am guessing that is what you have... First unless you spend pro hours on a bicycle, changing seat heights, crank length, etc, shouldn't cause you any problems.. (some who spend hours and hours in a certain position can have back or other problems with a slight position change, but for us "recreational" cyclists, its not really an issue, unless of course you do something drastic.. .)

So yes 167.5 shouldn't be a problem. I was using 175 on my road bike and 170 for the track.

But also I would say at Alpenrose its not a huge deal since traction speed is usually maintained. And this speed is enough to keep you from clipping ? .. (ok assuming "track" setup.... ) but there is more to it then just crank length... and BB drop... all needs to be considered of course... for example if you have a frame with only 48 mm BB drop well then you could use 180 cranks... in any case if you are getting close to clipping well you'll just have to speed up...

I think Pedals can be a larger issue. That is, a large platform pedal with 165 would probably clip before a 175 with a good narrow "cornering" pedal. stated In general ... Obviously this an "it depends" situation, dependent on actual pedals..

And then it also depends on the "q-factor" or Tread of the cranks. If you are like me and use a 103 spindle with a road crank that is made for 113 or something, then you get an extra 5 mm inward of the pedal....I think at 45 deg angle that would be same as having 5mm shorter crank ? well for sure at 45 deg angle it would .707*5 less vertical..

Big tires or small tires can make a difference too, clincher width, tubular or not..
if you go to Sheldon Browns site:
http://www.sheldonbrown.com/cyclecomputer_calibration.html
You can see the tubular narrow is listed with radius of 335 and 700x20c clincher is 332. So thats 3 mm difference in BB height off of ground...

The other thing you can do if you are going too slow and concerned with clipping is, well first, speed up !, but also lean your body inward so that you can tilt your bicycle upright (relative to ground angle..)... see the far left picture at this site:
http://www.racelistings.com/rzone/articles/article.asp?recid=320

john


>What is the "recommended" crank arm length for all-around use at
>Alpenrose when used with a track frame with a BB height of 292mm (or 58mm
>BB drop)? I use 172.5 on my road bike and have read that using anything
>less then 167.2 (for me) would be too "extreme". Would 170mm arms work or
>would I run the risk of clipping a pedal?


Mike Murray

2006-07-05

Depends on how fast you are going. If you keep the speed up you could use
175. The shorter the crank arm the slower you can go without the pedal
hitting the track. For mass start racing you will generally be able to get
by with a 170. It will give you more trouble for match sprints. For
pursuits and Kilos, no problem.

Mike Murray

-----Original Message-----
From: obra-bounces@list.obra.org [mailto:obra-bounces@list.obra.org] On
Behalf Of Paul Kanz
Sent: Wednesday, July 05, 2006 14:23 PM
To: obra@list.obra.org
Subject: [OBRA Chat] Track crank arm length question

What is the "recommended" crank arm length for all-around use at Alpenrose
when used with a track frame with a BB height of 292mm (or 58mm BB drop)? I
use 172.5 on my road bike and have read that using anything less then 167.2
(for me) would be too "extreme". Would 170mm arms work or would I run the
risk of clipping a pedal?

Thanks,
-Paul

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Paul Kanz

2006-07-05

What is the "recommended" crank arm length for all-around use at
Alpenrose when used with a track frame with a BB height of 292mm (or 58mm
BB drop)? I use 172.5 on my road bike and have read that using anything
less then 167.2 (for me) would be too "extreme". Would 170mm arms work or
would I run the risk of clipping a pedal?

Thanks,
-Paul