Looking for a crank. I'm 5' 10". Have a Giant Omnium. Racing on a mildly banked track (Kissena Velodrome). Most races are less than 10 laps (though I'd like to do longer ones). I'm thinking about getting the Truativ Omnium, but not sure what length I should go for. The bike currently has an old Shimano F600 road bike crank - 165 mm. Feels comfortable. I thought 165 mm was pretty standard, but I'm hearing maybe not. What are advantages/disadvantages of going longer. How long? Thanks much.
I'm 5'10 and ride 167.5 on the track. I've ridden 165 and 170 before as well, and prefer the mid range choice. Generally, shorter cranks are easy to spin at higher RPMs but give less torque to "jump" on. Longer cranks give more torque, and make it slightly easier to pedal a bigger gear up to speed, but are more of a pain when it comes to max-end spinning.
In road riding, a smaller range of RPMs is used and there's a lower top end of what you hit, while on the track where you have one gear to work with for your cruising speed and top end sprint, having a shorter crank and ease of getting to higher RPMs is more ideal. I think the fact that you have a fixed drivetrain assisting you also makes it easier to spin higher RPMs for longer, but that's ATMO.
There's a school of thought that says you should size cranks according to inseam length or some other measurement. IMO everyone has a range they can fit in, and different situations call for different sizes, but unless you're extremely tall or short, it probably doesn't matter.
What length cranks do you use on the road? The informed opinion around here is that you use anywhere from the same length to at most 5mm shorter on the track than on the road. So if you are using 170mm cranks on the road, then you might go down to 167.5mm on the track. It's very difficult for your legs to constantly switch between a bigger difference in road and track. The cadence that you develop on the track will be determined by the gearing that you choose, higher the gearing then lower the cadence and vice versa. Everyone has an optimal power band, and that will ultimately determine your preferred gearing and cadence, not the crank arm length. I know very tall sprinters who use long cranks up to 175mm, and have a very high cadence, and pursuiters that pound huge gears like 96 - 100 with shorter cranks. Myself, I use 165mm cranks for both road and track, but then I'm only 5'-3", so that's about the only choice I have.
im an old hand at Road and Criterium Racing, but with track racing (Kissena) Im still undecided on whats best for me, but I only have 2 sizes to consider, 170 or 172.5mm. If you are new at racing Gene99, then you can probably benefit more with a 170mm unless you have an animal like explosive strength, then you could benefit from 167.5mm since you can spin out your 88-90 inch gear faster, and that could make a real difference at the finish line.
Just think of your top rpms you can turn out, if not much over 120, 170mm will probably be your favorite if you have an average inseam at 5-10, and you may use 172.5mm cranks on the road bike. If you are a Cat 2 and racing the Keiren, then you may want your cranks to be shorter than 170mm.