Road Cycling - crank length, 170mm vs 172.5 vs 175, who really cares?

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supernova87a
12-18-03, 09:17 PM
is it just me, or does anyone else not understand why the crank length options
are so ridiculously gauged?

If you're going to offer the option of different crank lengths, what's the point of
making the difference so small as to be negligible? I mean, how much can 2.5mm
mean to a rider? Seriously, 2.5mm is like the width of two pennies.

maybe it's just me. can someone explain why it's important?

prestonjb
12-18-03, 09:37 PM
Try changing your cleats on your shoes by moving them forward or backward 2mm. You should notice the difference, esp on a long ride.

Once your bike is dialed in, any adjustent of 2mm or more you will probably notice.


When my left ITB went south I lowered my saddle 3mm and was able to run that way throughout the season.

I thought I could leave the saddle at that height until I started to experience some pain on the inside of my knee to which I discovered the cure is raising the saddle. Put it back to the pre-injury height and two rides later all pain went away.

On another note, it is recommended that changes in crank, cleats and shoes that cause a difference up to 2mm is prefered to using shims.

Think of balance and comfort. A difference of 2.5mm is really a differnece of 5mm from pedal to pedal which could make a differnce (1/4 of an inch) esp over a long time.

Most of my setup issues don't affect me until around 80 miles.