Is there really much difference to be felt / measured in regards to performance between 170 & 172.5mm cranks?

The reason I ask is, I thought I had 172.5mm ones but it turns out I’ve been riding 170mm ones for 2 years.

I have 2 road bikes which I ride regularly

One has 175mm cranks, the other 172.5mm

Guess what?
I cant tell the difference

2 page article in Cyclist magazine this month about the different effect of crank lengths (or lack thereof).

Long and the short of it is that there’s no difference that can be measured performance wise, within quite a wide range of lengths. The only reason to change would be personal preference, or any knee pain issues.

I always used to get bad knee pains with 175’s on an MTB, now I run 170’s religiously on everything as it’s what I prefer. That said I couldn’t tell if I was riding 172.5’s in a blind test as it’s such a small difference, but I can tell the difference going up to 175.

Oh, and shorter cranks promote a higher cadence.

IMO Steve, if you’ve no cause for concern, I wouldn’t change your 170’s.

I don’t think any harm can be done by riding cranks that are too small, but riding cranks that are too long for you is a different story

I do notice the difference in crank length from 170mm to 175mm, but I doubt I would notice a 2.5mm change

performance wise the only difference I really notice is I can spin out faster on the 170mm

Funny you should say that mboy as my mate commented the other week that I appeared to be a very spiny rider.