Crank Length Question

I'm 6'3" and I use 175mm. I think it highly likely that you're not riding the best crank length for you.

A 53cm bike should have a 170mm crank to be in correct proportion. What is your wheel size?

yeah, exactly!! I'm 6ft and use 175 or 172.5.
175 is very big for someone 5ft8"

I'd say 170 maximum.

170

Ditto!

rennfahrer said:

I have a problem with my new ride. When I stand up to sprint or climb as my leg speed increases and I reach the point when I will start thinking about adding a gear. My cranks seem to beslower than my leg speed causing a clunking type of pedal motion. Almost like my legs are moving faster than the cranks. Kind of like the timing is off. When I gear up or sit it goes right away. Basically when I slow my leg speed doen a little.
My old bike did not do this. My only guess is that I went from a 170mm crank to a 175mm crank. The 175 mm cranks seem a little long as I am 5'8" and the bike is a 53cm. Could the crank length make that big of a difference?
Any help would be appriciated

Most likely your problem is that your new bike puts you in a different position....saddle height, setback, or hip angle, which is making your stroke feel strange. Really doubt that 5 mm (0.2 inches) difference in crankarm length is the issue.

this is a great little article which sums up the long crank condundrum in a couple of paragraphs

http://www.arniebakercycling.com/pubs/Free/Optimum%20Crankarm%20Length.pdf