Crank length.

[Saddle bum]

I used to ride 172.5 cranks in the early 90s, but settled for 170s when I got a new iron a few years back. I've just upgraded again to 172.5s, it makes a big difference, a positive one.

Any similar experiences?

 

[Night Train]

I've never considered crank length either. How do you work out what length you need?

 

[gavintc]

There are ratios based on leg length. Google for it. I fitted 175mm following my research a couple of years ago.

 

[Steve Austin]

Lots of theories on this, most of them complete conkers.

long legs = long cranks. Its that simple

I use 175 on my Roadbikes and MTBs as it feels very different when changing bikes. And i've got long legs

 

[piedwagtail91]

a clubmate had his best ever racing season using different length cranks(by accident) he didn't realise until mid season but was going so well didn't want to risk changing them.
i had to use odd length cranks in our clubs 150 mile ride. the spider came loose on the crank so i had to put a spare on which was a different length, after a couple of miles i couldn't tell the difference.it was only 2.5 mm.
I've different lengths on all 3 bikes but haven't found much difference. clumbates swear the can and will only use certain lengths.
i buy what is going cheap in the sale which explains the differences!

 

[Saddle bum]

On the wild assumption that many years ago, Britain set certain standards in bicycle technology, 6-3/4-in was the standard crank length. This translates to 171.4mm. So 170s are shorter than the old fashioned standard.

I would propose that 172.5 should be the norm for any male person of 5ft 8in high or over. Different reasoning may apply to the ladies, with certain notable exceptions, I am not an expert on female physiology.