Going from 172.5mm to 170mm cranks

[Soloist604]

Hi all,

So a crankset that I recently bought only comes in 165mm, 170mm, and 175mm sizing. I've generally been running a 172.5mm on my bikes for years. I ended up buying the new crankset in the 170mm size and did a test ride yesterday.

Didn't think I'd notice a difference but when out on the test ride everything just felt "right". I couldn't have imagined that a 2.5mm change would make that much difference, but something just felt better. The q-factor on the new cranks is also about 5mm wider so this could also have contributed.

Thoughts from those with a bit more experience appreciated.

[ducati2]

What do you need to know if it felt “right”

[fignon's barber]

Different crank length also slightly changes your bb-saddle height feel as well.

[Ken Robb]

Check the archives for MANY opinions on this subject.

[shinomaster]

I started out in 170's and rode them for years, then I switched to 172.5's for cycocross and have them on 4 bikes. I've thought about switching back as it them helped me spin better but I don't think I can easily replace all my campy cranks.

[skouri1]

You have to make some adjustments in my experience but they are not prohibitive. Rode 172.5 for many years. Think I like the 170 better. Slightly higher saddle. Kept the same setback as that feels like the appropriate balance point . I would err towards shorter

[eddief]

If it makes you happy it can't be that bad.

[fourflys]

Originally Posted by Soloist604

Hi all,

So a crankset that I recently bought only comes in 165mm, 170mm, and 175mm sizing. I've generally been running a 172.5mm on my bikes for years. I ended up buying the new crankset in the 170mm size and did a test ride yesterday.

Didn't think I'd notice a difference but when out on the test ride everything just felt "right". I couldn't have imagined that a 2.5mm change would make that much difference, but something just felt better. The q-factor on the new cranks is also about 5mm wider so this could also have contributed.

Thoughts from those with a bit more experience appreciated.

cue all the "subject matter experts" chiming in that you really don't feel a difference, the feel is from something else, some long engineering thesis on crank length, etc..

Glad it made your ride better, that's all that matters! If it works for you, it works period..

Ride on!