165-170
 

I want to ask your opinions on crank arm length. I currently ride 170 on an old Fuji road frame and I poop my pants a little when I have to corner sharply, and a lot when I feel those pedals scrape :eek:. (No worries, I got those young jean diapers, skinny fit) I am getting a track frame and can't decide on crank arm length. I want to get as far away from that horrible feeling as possible, and the frame will alleviate a good portion of that, but I'm on the fence at the moment. Is there an extreme difference between the two lengths noticed when riding?

You really shouldn't pick a crank arm length based on your cornering as you spend far more time pedaling in a straight line than you do pedaling around corners. Pick the crank arm length that suits your legs, terrain, and riding style.

Just take it easy on corners.

Right on. Thats kind of what I was looking for: there is a difference insofar as it will effect my normal riding. I'm thinking 170 will be better because the frame should take care of some of it - my riding is mostly a 13mi round trip commute and longer rides througout the week, but a healthy mix of hills, flats and sharp corners.

What carleton said. It might even be a good idea to get 170+ depending on long your legs are. I did the math for myself (I'm 6'3'') and my ideal crank length is around 185mm.

I have 170s but I think I could do just fine with 175s on my conversion. I pedal through most corners on my geared bike and that has 175s

Actually, studies have proved that ideal crank length is a personal preference. The conclusions were basically that riders were most efficient and effective on the cranks that felt good to them. There were no correlations between leg length and ideal crank length.

I'm 6'1" and like 167.5mm.

^agreed.
switched from 170 to 165 this spring mostly so i could spin faster going downhill, and it made a very noticeable difference

Interesting. I am switching for the same reason but from 165 to 170. 170 seem to fit me better

im 6'2, i like 167.5 on fixed, and 172.5 on road...
i had 165s on fixed for a while but it felt a bit short, so i decided to size up, but i was sort of scared of the same cornering problem with pedals and went with 167.5s. they feel perfect on the fixed gear.
i've had 175 on a road bike but that felt a bit much, 172.5 is about the longest i can go and feel comfy.

Thanks!

Yeah crank length is sort of like gearing,whatever you like is cool theres no set rule.As for me I'm 5'10" 150 lbs.I like 165mm 52x21 gearing.

you're switching to longer cranks so you can spin your legs faster going downhill?
what's your logic?
longer radius = larger circumference = longer distance your legs have to travel in the same amount of time (assuming cog and chainring remain the same) = more work

Shorter doesnt always mean better. I have ridden 165,170,and 175. I spin the best on 175s. My height may throw off this observation, but to me it says that different lengths affect your legs' range of movement and that may give or take away from how comfortable you feel spinning

What you are referring to is footspeed, which is the actual speed the foot travels in the circle.

For a given cadence, the bike with the longer cranks will require the rider to have faster footspeed.

So, if you can move your feet in a circle at x meters/second, you will have a higher cadence (and therefore higher bike speed) on shorter cranks....but you give up leverage, so it requires more torque to get the cranks moving. This is really evident on hills, which is why longer cranks are recommended for hills. There are no hills on the velodrome, so shorter cranks are normal.