How do i know what size of crank to order ?

Question

bmx bike sunday 07 wave frame

Answer 1

I answered your other question about the bottom bracket on the Sunday.  Since you're shopping at Dan's, check out their FAQ/Tech questions.....they have a pretty accurate crank selection chart based on your leg inseam.  

It's a pretty standard chart and it's geared more toward track racers....many park and street riders use cranks that are a little shorter than the chart recommendations.  170's and 175's are the most common, but it's all about personal preference, which you get after riding for awhile and trying out different cranks on friends' bikes, etc.  

Hope this helps....enjoy the new ride!   :o)

Answer 2

call and ask a bike shop that carries that brand of bike.

Answer 3

One empirical formula:

Recommended crank length in millimetres = (Inseam in cm  *.216)

If you want to be more conservative, multiply by .21

If you want to have fun with different measures; follow this link:

http://www.machinehead-software.co.uk/bi...

The results will be slightly different with this calculator as it uses a different formula.

Inseam is measured standing flat-footed from floor to crotch with feet about 6" apart.

For road, round down to the closest common length made, for mountain round up.

This is just a starting point and it can different by person for what works best by application. For example, my road= 170. My mtb = 175. My time trial bike = 180. The crank length affects leverage and force. I won't get into that here.

Here's another rule of thumb if you don't want to do calculations:

  * below 5'10 use 170mm cranks  for general (road) riding.

  * 5'10 to 6'1 use 172.5mm cranks,

  * 6'1 plus use 175mm cranks,

And modify for specialized events:

  * subtract 2.5mm for track racing (or more on short steep tracks or short events),

  * subtract 2.5 to 5mm if you have frequent knee problems,

  * add 2.5mm for time trials and hilly races, (and MTB races),

  * add 5mm for pure hillclimbs (for those who don't like to 'spin' up hills)