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Old 06-09-11, 01:09 AM
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carleton
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Personal preferences aside, the general rule of thumb is 5mm less than your road cranks.
Road 175 - Track 170
Road 172.5 - Track 167.5
Road 170 - Track 165

So, that would put you at 167.5mm, which happens to be what I run.

Anything over 170mm is uncommon (but not unheard of) on the track, just like anything over 175mm is uncommon (but not unheard of) for road riding.

165mm used to be the "sprinters crank length" back when sprinting was done with really high cadences on normal gears (90-94 gear inches). I read an interview where Marty Nothstein at 6'2" rode 165mm cranks. Now sprinting is done on gears in the high 90s and into the 100 gear inches using lower cadences, so some are going with longer crank arms because some want more leverage for the bigger gears. In years past, flying 200M average cadences were in the high 150s-160s. Now they are in the 130s-140s but using much bigger gears.

Note the cadence differences during the final sprints of these World Championship matches 17 years apart:
1994:

2011:


Other generalizations:
- Sprinters/spinners choose shorter than normal crank lengths in order to facilitate higher than normal track racing cadences and max speeds
- Pursuiters choose longer than normal crank lengths in order to get more leverage to roll bigger gears and don't have to worry about speed changes (as in a points race).

On a personal note:
I'm 6'1" and ride a 57/58cm bike (road and track). A 57/58cm road bike would have 175mm cranks and a 57/58cm track bike would come with 170mm cranks. But, I prefer a higher than normal cadence on the road and I often reach high RPMs on the track (when I'm lucky), so I use 170mm on the road bike and 167.5 on the track.

Just like Bob above, some people run the same crank length on their road and track bikes to keep the same feel. I'm tempted to do this myself, especially being that my road bike setup like a track bike with gears and brakes (low bars, forward saddle, etc...). My road bike is not setup for comfort at all. Any ride over 1.5-2 hours is tough on my arms and back.
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