New cranks length

kmackdci

I am looking to buy a new crankset, mainly at a set of sram red as they are at a bargain price.
Only thing is they are 177.5mm.
The bike I initially bought had 175mm but the frame was slightly too big for me( defy large) during a full group set change I swapped out to a 172.5mm, I have to say barring the slight bit extra height from the seat post there wasn't alot of difference.
I am now building a correct size frame (54cm scott cr1)and my question is would the 177.5mm crank male that much difference? There doesn't seem to be a definitive guide to crank length?
Any help with this much appreciated

sungod

177.5 sounds long for someone who fits a 54cm frame, but there's no definitive answer as crank length, like many other sizing/bikefit factors, depends on both size etc. and type of riding

fwiw this...

http://www.cptips.com/crnklth.htm

pinarellokid

or briefly i liked this quick snippet of info from the above link

inseam < 29 inches - 165 mm crank
inseam 29 - 32 inches - 170 mm crank
inseam 32 - 34 inches - 172.5 mm crank
inseam > 34 inches - 175 mm crank...

currently on 31" leg and 172.5 but just bought new crank with 170mm

so will be interesting if there is any difference.

Herbsman

OnYourRight wrote:

pinarellokid wrote:

currently on 31" leg

Any plans to upgrade?

pinarellokid

you never know i might grow a little more !!!!

andrewjoseph

i've got 170mm cranks on road/tourer, 175 on mtb. moving between is seamless, my knees can't tell the difference.

my wife has 160/165 between both bikes. no issues there either.