I would probably not go -2 on the front, it's apparently better to go up on the rear if possible due to the smaller sprocket being able to wear the chain faster at the front. Of course I may be wrong on this :roll:

-2 F is not equivelant to -2 R anyway due to the different size of the sprockets.

adam,

Ive got -1 +3 on my bike and the chain just fitted in, but i suspect after a long ride there would be a lot of crap collected in there and It will get all over your chain. Im going to get an ally one off ebay and mod it a little to make a bit of extra room.

If you go 1t down on the front it is the equivalent of 3 up on the rear and that way you can use the standard 108 link chain and go back to 15 front if you don't like it!!!!!