Bicycle Mechanics - Mountain crank versus road crank

Does a mountain crank come along with the wider Q factor, or can it be fit to my road bike and keep the narrower factor?

I want to drop the teeth count on granny to about 24 or so, to turn my Tricross into a light tourer.

Also: if a crank is "9 speed compatible" does that mean it will only work with 9-speed cassette or could it work with 8?

Thanks.

I can't speak to the Q, but a 9 speed compatible crank has more to do with the chain than the cassette, if it has anything to do with it. My best results are in using a chain that matches the cassette/crank. Other combos will work, but not at all as smoothly.

a road triple with 74BCD inner ring should go down to 24T.
MTB cranksets are usually wide to allow for chainstay clearange, but if you get a square taper crank, they Q-factor is more adjustable.

Does a mountain crank come along with the wider Q factor, or can it be fit to my road bike and keep the narrower factor?

I want to drop the teeth count on granny to about 24 or so, to turn my Tricross into a light tourer.

Thanks.

it came as a surprise to me the other day that mtb (triple deore ca. 1996) and road (double sakae ca 1986) cranks are not interchangeable. even though they both attach to the same type of square tapered BB.

i had an old sakae road crank (very nice) off of a 86 trek elance that i was not using, so i thought i would swap it with the deore (not as nice). i did not attempt to swap BB's.

i removed the chain rings. then attached to sakae to the BB. to my surprise the spider (sans chainring(s)) would not clear the driveside chainstay! endgame!

just for grins, i tried the nondrive side. arm wouldn't clear nondrive side chainstay. apparently, there is more "cup" on the deore spider.

as far as you are concerned going from mtb crank to road, it may fit but check your drive line, it may favor the smaller cogs too much.

huey

it came as a surprise to me the other day that mtb (triple deore ca. 1996) and road (double sakae ca 1986) cranks are not interchangeable. even though they both attach to the same type of square tapered BB.

i had an old sakae road crank (very nice) off of a 86 trek elance that i was not using, so i thought i would swap it with the deore (not as nice). i did not attempt to swap BB's.

i removed the chain rings. then attached to sakae to the BB. to my surprise the spider (sans chainring(s)) would not clear the driveside chainstay! endgame!

just for grins, i tried the nondrive side. arm wouldn't clear nondrive side chainstay. apparently, there is more "cup" on the deore spider.

as far as you are concerned going from mtb crank to road, it may fit but check your drive line, it may favor the smaller cogs too much.

huey

Each crank model requires a specific bottom bracket spindle length to realize the proper chainline; this is independent of whether it is road or MTB.

Edit: See: http://www.sheldonbrown.com/bbsize.html (Unfortunately, Sakae cranks are not listed.)