Roadbike Crank on a Mountainbike

[Rich8P]

Hi

I've got Shimano XT 9 speed rear and Deore LX 3 ring front changers on my mountainbike. I'm thinking of abusing the bike as a trainer on the road for the winter months.

I'd like to put on a set of roadbike chain rings to increase the gearing ratio. Anyone tried this? Do I need to lengthen the chain? Anything else to take into account?

Rich

 

[rek]

Your frame's chainstays might flare out too quickly for a big 53 (or thereabouts) tooth ring to fit. May need a bit of stuffing about with BB spindle length/chainline to get it to work.

(That's been my experience, anyhoo)

 

[gclark8]

A 48t big ring and an 11 tooth sprocket in the rear is higher gearing than 52-12 road gearing.

http://sheldonbrown.com/gears Plug your possibilities into here.

The other problem, as well as chainstay clearance, is you will need a different Front Derailleur for the road crankset, probably a FD-R443 would work, but then chainline and bottom bracket... it just goes on....

 

[garage sale GT]

Your frame's chainstays might flare out too quickly for a big 53 (or thereabouts) tooth ring to fit. May need a bit of stuffing about with BB spindle length/chainline to get it to work.

(That's been my experience, anyhoo)

I roughly calculated a 53 will have an 8.45 inch/215mm diameter at the chain pin centerlines, so add the height of the teeth above the centerlines of the chain pins, and then measure your bike.

If the chainline is close to the same I don't see why you can't just move the stock derailleur upward on your seat tube. I've never tried it myself, though.