180mm vs 175mm cranks

gregw

gregw

New Member
Just picked up a Haro Mary SS and took it out on Sunday in some pretty rocky terrain. It currently has 180mm cranks on it and I noticed that I'm smacking my pedals into stuff an awful lot. I ride these same trails on my full suspension bike and don't have nearly as many "incidents". As the ride went on I got a little better with adjusting my pedal stroke but then as I got tired I got a little sloppy and got a few good whacks in. Is this a case where I just need to work on my being more conscious of my pedal stroke or would switching to 175mm cranks help? It doesn't seem like 5mm is going to make a world of difference but these were pretty familiar trails that I normally don't have this many issues with.

On a side note, I definitely dug the SS!
 
gregw said:
Just picked up a Haro Mary SS and took it out on Sunday in some pretty rocky terrain. It currently has 180mm cranks on it and I noticed that I'm smacking my pedals into stuff an awful lot. I ride these same trails on my full suspension bike and don't have nearly as many "incidents". As the ride went on I got a little better with adjusting my pedal stroke but then as I got tired I got a little sloppy and got a few good whacks in. Is this a case where I just need to work on my being more conscious of my pedal stroke or would switching to 175mm cranks help? It doesn't seem like 5mm is going to make a world of difference but these were pretty familiar trails that I normally don't have this many issues with.

On a side note, I definitely dug the SS!
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It could be a number of factors. 5mm makes the pedals about 0.2 inches longer. Not that much -- but combine that with the fact this is a rigid bike, your pedaling may be "off" because you are using a different gearing going through rock gardens, the bottom bracket may be a different height, etc. These all could throw your timing off.

I have three bikes -- one Trance X, one Giant XTC 29er and one 29er Monocog. The Trance is my main ride, so whenever one I choose one of the other two, it takes me a few moments to get "reaquainted" with the ride before I feel I can rip.

Also, I agree -- the SS is a lot of fun. I am just happy it is not my main ride. 🙂
 
I agree w/ Joe.

I would guess that the bottom bracket height is lower on the Haro than your FS. Most FS frames have higher BB's to account for the action of the suspension. I have an Foes Fxr FS and a Surly 1x1 with the same length cranks and the bottom bracket on the Surly is way lower than the Foes, that being said there is more evidence of rock rash on the 1x1 pedals.

I suspect your issue is getting used to the lower BB height when you are on the Mary.
 
I didn't really account for the bottom bracket height which would seem like a fairly obvious thing. Thanks for that. I'll keep spinning the 180's and see where it goes - it was only my 2nd ride on the bike. It got a little frustrating as I went though since there were a couple that knocked me off my line and I had to get restarted again.

+1 on the SS not being my main ride. Great for a change but I love my squishy bike 😀
 
Without looking up numbers, it for sure is the BB height. Just something you will get used to.
 
Well, I checked and its for sure the bb height. Many thanks for pointing me in the right direction.
 
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