172.5 cranks to long for cross?

[rosss]

dont know to much about cross and wanting to put one together

i usually ride 170's on road, and was wanting 172.5's for cross, is that to long? bottom bracket's are usually further from the ground in cross correct?

[caleb]

172.5 for cross, road, tt, and commuting for me.

I doubt you'll be able to tell the difference if it's 2.5mm longer.

[jtferraro]

If you usually ride 170's on the road, I'd either stick w/them for cross or go w/172.5's. For me, I ride 172.5's for both road & cross, 170's on my fixed gear, and 175's on the mtb. I believe Simon Burney recommends going longer for cross, but not all agree with that thinking. Re: BB's being further from the ground...it used to be that way (primarily b/c of toe clips/straps) but most cross bike's now have reduced their BB height (or increased their drop). Don't forget, even w/the same BB drop (as a road bike), the BB will actually be higher from the ground (on the cross bike) due to the higher volume/knobby tires.

[riceburner]

Agreed with JT above. What is the real concern here? cornering clearance? straightaway obstacle clearance? doubt the 2.5mm will make or break it either way, but shouldn't fit issues as it relates to crankarm length govern more???

[rosss]

yea guess the question deals with cornering, steep hills you attack at an angle, anything you could pedal strike on, etc
sounds like 172.5's it is then, i need those on the roadie as well..
thanks gentlemen

[Shinomaster]

I raced my first three seasons of cross on 170's which was what I used on the road since 1993. I changed over to 172.5's a couple of years ago and immediately felt a difference. It's easier to grind through muddy crap and up steep hills with longer arms.

[Roman]

I raced my first three seasons of cross on 170's which was what I used on the road since 1993. I changed over to 172.5's a couple of years ago and immediately felt a difference. It's easier to grind through muddy crap and up steep hills with longer arms.

Yes, you do know about these things.

[Too Tall]

dont know to much about cross and wanting to put one together

i usually ride 170's on road, and was wanting 172.5's for cross, is that to long? bottom bracket's are usually further from the ground in cross correct?

Glasshoppah Ross, read the tea leaves and follow your intuition. Change is bad.

The clearance issue is a myth bro. Ride it like you mean to do some damage.

Report back.

[fixednwinter]

I use 170mm for everything except cross, which are 172.5mm.

They help when grinding up hills & lower rpm off-road, and the 2.5mm difference is not so drastic that it feels weird when switching from road bikes to cross and back again. As for clearance, I've never had an issue, even with today's slightly lower bb height cross frames.

[WadePatton]

my trick for using different crank lengths. measure saddle height from pedal at bottom of stroke, not BB. keep 'em all real close.

[Shinomaster]

Yes, you do know about these things.

I know about my legs and my bike and my experiences. I can not speak for other people.

[csbmo]

175s are the definition of sexy

[dang]

I guess I'd ignore the clearance issue in this context. For one thing, 2.5mm is only 2.5mm; for another, just starting out (or maybe for quite a while) are you really going to be pedaling hard through very tight and steeply cambered turns? If you're comfortable turning the 172.5, I'd just take the very slight extra leverage and go for it. If you're not comfortable turning 172.5s (you notice the difference and don't like it, and that's with the mtb pedals and shoes you'll be using for cross), then don't go there just on the theory that extra leverage is a bonus.