obiwan kenobi

I have a frame on the way, need to start getting parts, question on crank arm length, I use 172.5 for road and 175 for my TT bike, what should I look for in a track crank?

sideshow_bob

If you want a do everything bike (mass start, sprints, pursuits) either 170 or 172.5.

If you are going to focus on pursuits, 175. Past that trial and error. I ride 175 on my road bike, and have used 170, 172.5 and 175 on track bikes, I've really leaned to 175 across everything these days.

I'm sure the sprinters will all chime in, in a sec and say go tiny, 150mm or you're soft ;p

carleton

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.

chas58

So, what do you expect people should be targeting for a cadence in a standard pace line, and for sprinting (i.e. in a points race)?

carleton

Pacelines are dependent on a lot of things. But, what I've learned is that as one progresses through the ranks, cadence ranges generally stay the same, but gearing goes up. I would say that the cadences in a points race are:
Pacelines: 100-120 RPM
Sprints: 120-140 RPM

A beginner racer would use like a 88-90" gear in such a race. An elite racer might choose 94-99" depending on their riding style.

Disclaimer: This is just from my personal experience and from what I've learned by watching others around me. There are lots of factors that go into this, like for example: Track geo (333M vs 250M, 25 deg vs 44 deg), track surface (Siberian Pine vs concrete). Plus, I'm not much of a points race guy. There are others that know more than me (Paging: Biting Duck).

Kayce

Points races usually arent the best to gauge any sort of standars. More so than most races they break up into seperate groups with people off the front and the back. If there is a good sized group chasing a person or two the pacing may be 90% of a sprint lap, but if most of the field is together, or not wanting to chase it could drop to 60%. And if you are off the front or the back it can vary greatly.

sideshow_bob

I'm a points guy, I'd say I probably tap out about 100RPM, probably only max out about 120-130RPM in a sprint (55-58km/h), pushing generally either 96 or 98 inches. While Kayce is right to some extent, you do find large segments of races that do hang together, where you're sitting on a pretty quick speed, with accelerations on the sprint laps obviously.

I think the standard used to be to go shorter than road setup, and I think this is still very common amongst the guys doing lots of sprint events, but for a lot of mass start riders (ex Kierin) I've seen the lengths creep up over the past 10 years. Same with pursuit, where I'm seeing guys synch with their TT type setups, which are a bit longer (I ride 180mm on my TT setup). If I ever get round to a season focusing on pursuit (rather than a side line, I'll go longer than 175).

My own stats I'm 6'2", 57.5 effective TT (58mm on my road bikes), about the quickest I ride is in scratch races, where I'll hit around 62-63km/h in the sprint. It's one of those things where over time you'll find out what works best for you and what doesn't same with pretty much every other setup aspect on a bike.

I started track racing after a long road career on 170's. While now I'd prefer not to ride that short, I don't think they held me back any.

Lord@banks

That is my question, should i go for 165 or try 167.5mm?

I go 165 with 52/16 i go up at 125 cadence in sprinting.
No so high... as normal Track Drivers done.

I ride in Velodrome wood with 47° banks ... to climb up is pretty hard.

I could go in front with 51T to make it easier.
Or get a 2.5mm longer crank?

To knock on the ground it is to less 2,5mm i thought.

My legs inseam is 84cm feetlenght is 45

On street i go with 172,5

Thanks Cheers

topflightpro

Don't sweat it too much. I run 170s on my track bike. I have long legs, and my fitter said it works for me. (Also, I got a deal on an SRM with 170s). I will say, I do have to be careful to not go too slow on a 250 track, cause I have tapped a pedal.

I previously had 167.5. I really didn't notice a difference in cranklength when going between various bikes.

Lord@banks

Thanks for answering. is your track 47° or less?
I didn't notice it? At different bikes... but maybe on your own bike?

I saw yesterday several videos... about

Power = tourque * speed

165 Pedalspeed is getting faster around at same cadence as a longer one.

To spind up the 165 is better... to get more Power by climbing up or push from the start the longer one is better.

But why are sprinters for standing starts uses 165?
Or do they use in this case 180?

I thing they use 165 because of the short distance the can better sprint high cadence

bitingduck

Responding to Carleton's page about 12 years late...

I rarely raced anything bigger than a 92" gear unless it was a full P/1/2 field where I knew that the "slow" parts would still be horrifically fast. So usually 92" max for points races, 90" for madison. 95" or 96" for a win and out when the really fast guys were in town. I'd just follow them through the first few sprints and eventually the track would be clear of people because they'd either won a lap or run out of gas and I'd snag a few points. There were certainly people riding bigger gears in those races, but if it's a lot bigger you can make their life unpleasant in a paceline.

The 165s are so you don't bang a pedal on the banking when you're riding slow. Match sprinters and madison riders ride slow up high on the banking, and if you ride a variety of tracks you have to be able to deal with all of them. Blaine had a sign in the early days that included "165 mm cranks only", but I don't think it was ever enforced. At least one of the rental bikes had 170s. I've hit a pedal on Blaine without going down - the wood there is (was? it's been a long time) very grainy and you could go very slow in the corners. If you hit a pedal on Carson you're already on your way to the bottom of the track. There was a guy who showed up at Carson from out of town with custom 185 or 190 cranks or something crazy like that. Looked goofy, and he couldn't ride slow, despite being a sprinter, but he didn't crash a lot or anything.

For standing start TTs, people will ride longer cranks for more leverage. I've seen things go horribly wrong a lap or two into a TP where it started to look like a keirin and someone made a hard right in the corner, hit a pedal, and went down.