Originally Posted by
Mr Pantani
A mountain crank would work fine - though you likely will need a new bottom bracket just to make everything seamless. Additionally, you'll possibly need to swap out your front derailleur for one with a smaller radius, such as a mountain derailleur or possibly a late-90s Shimano RSX road derailleur (I've got one if you're interested)
. Otherwise, sounds like a plan.
Mountain FDs are not compatible with road shifters.
Besides, cage radius isn't that critical; the one he has should work just fine if it's situated & adjusted properly.
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