You've really got to consider your bottom bracket height & the banking on the track. OK if you're going to stick to pursuits & kilos but I'd be on my ar$e on Manchester with long cranks in a scratch or points race when it all slows down. If You mostly ride tracks with shallower bankings then this isn't an issue. Manchester is 250 m & 42.5 degrees at the steepest point, a bit like the Dunc Gray stadium, & it's a long, long way down from the top. It does nothing for the confidence if you're worried about catching a pedal when you're slowing down at the top of the banking.
I rode Kirkby recently on an older frame with 170 cranks & a 10.5 bottom bracket. Kirkby's 485 metres & fairly shallow compared to Manchester, I caught the pedal a few times & have switched back to 165s for there. An additional factor is BB length (width?) which is anything but standard, The narrower the BB then I guess the longer the crank length you can get away with.
Conventional wisdom has lankier riders needing longer cranks to suit their propotionately bigger levers and shorter riders looking at the shorter crank lengths. Millar rode 180s to win the world TT champs last year.
I'm bang on 6 foot tall & ride 170s on the road & am quite happy with 165s on the track although I'm usually riding 84" to 88". Hope that helps
from here... http://www.bcf.uk.com/features/2003/...ck_bikes.shtml
Cranks: Because of the banking on the track, I went to someone who coaches at Calshot, Tim Knight, and asked what length cranks should be used. "It is pretty standard to use something like 165s. A 165 is ideal for Calshot (with 11 inch Bottom Bracket height), but 170 with a higher bottom bracket like 11.25" is also ideal. Again, if in doubt, contact a coach at any of the velodromes who can advise.