Pandemonium

I'm sure there are folks here with 1st hand experience getting a road crank and FD to work on a mountian bike. Please share your thoughts - I'll steal your good ideas & try to avoid your mistakes!

I'm working towards bigger chainrings on an '05 F2000, fitted with 700 wheels. I really like the shifters & brakes, so we gotta get a FD to work with the XT shifter. I'm concerned with maintaining a decent chainline, having adequate clearance between the chainrings and chainstay, and getting a FD to work nicely.

I know I can get a 48/36/26 crank & FD to fit (I've got that set-up on an F800), but I still spin-out, and never use the small chainring. I'd like to see a 52T big chainring, and could probably do without a triple - maybe a Shimano 105 double on a wider (triple) bottom bracket? Would a double make it easier to get a road FD to work with the mountain shifter (as compared to a triple)?

Your thoughts & experiences most welcome!

HillRider

My experience was that I couldn't get a MTB front derailleur (Deore LX) to shift properly with a 105 8-speed STI shifter even using the LX crank. I wound up using a barcon for the front shifting. I don't know what will happen with a road crank.

Have you tried a cassette with an 11T small cog? A 48x11 with 700c wheels is a 118" high gear. If you can spin that out you must be either a gear-masher supreme or awfully strong.

sydney

The road FD and mtb shifter often works better than the other way around. FWIW, Shimano has a flat bar shifter and FD that are road crank compatible.

roadfix

Make sure when using a double crankset, while maintaining a good chainline, that the big ring clears the chainstay.

Pandemonium

I'm aware that Shimano has the flat-bar shifters to work with their road FDs, they're on my Kona, but I really like the dual-control levers - so I'm looking to get a road FD to play nicely with 'em.

I'm riding 26" wheels with skinny tires on the F800, so I run out of gear... My Kona's got 700 wheels, a 52/42/30 crank, and 11-32 cassette (don't think I've ever been on the small chainring), so I'd like room for a 52T chainring on the F2000 (if I can get it - maybe I end up with a 50/39 or some such). There's also a good possibility I might try a road cassette, too (12T on the little guy).

I know I need chainring clearance. That's #1 on my list of concerns - I don't want to buy cranks to find out they eat the chainstay. Would a BB7703 (triple) bottom bracket paired up with a double crank give me enough clearance? Souldn't I be able to shim the BB to get the crankarms centered? Any reasons ISIS might offer a better solution?

Keep it coming, guys!

sydney

Why do you want a high maintenance DA BB? How can you shim a triple BB to get better chainline with a double? A shim will only put it further out. ISIS offers nothing else, as road chainlines for double and triple are same as current shimano.

rmwun54

A road crank will work with your mtb fd and shifter, you just have to reposition the fd. I have XT shifters and FD working with my road triple on my bike.

Pandemonium

Using a seperate splined bottom bracket (Octalink, ISIS), I can play with different spindle lengths. (Isn't an integrated BB, like Hollowtech, available with only one length shaft, hence a pre-determined chainline?) I believe a road double usually mounts on a 109mm BB, while a triple uses a 118mm. If I put a double crank on the 118 BB it should put my chainline out past 50mm (maybe too far? -and I can't shim it to reduce the chainline, only increase it. Maybe face the frame? -just kidding). Of course Q will move out too.


If you've got a working set-up, I'd love to hear what frame, crank, bottom bracket, and derailluer you're running.