derailleur problems

luigi_t8

I am looking to upgrade the derailleur's and shifters on the 2006 Specialized Stumpjumper S-Works to the current XT spec. I have had problems with the front derailleur since i got it a few years ago (second hand) as when you adjust it so the chain doesn't quite hit the guide cage at one end of the sprocket range and then switch up through the sprockets the chain hits the cage in the top 3 or 4 sprockets. As far as i can work it is the same type of mech that originally came with the bike (top swing deore XT). Can anyone help me resolve the problem or guide me on which type of front derailleur to buy so this wont happen when i buy my new gearset?

Louis Tate

nicklouse

sorry not happening. All mechs will rub at each extreme. but it can be reduced a bit by careful set up.

luigi_t8

ok but on all my other bikes it's fine and you dont get rub but this rub's a lot. it's as if the cage inst wide enough or maybe i have weird chain ring spacing?

Shackster

I've got the current XT stuff (10 sp) and like Nick says, you can't eliminate rub. However, I find it's best to adjust it so that you get no rub with the chain on the middle chainring, and largest sprocket. Then you should only get rubbing on the outer face of the front mech, when you're in the highest 2 or 3 sprockets. You can then achieve the same gear ratios by going to the largest ring and shifting down a few sprockets, with no rub. Shimano's instructions include a leaflet that tells you to do this when it rubs.

Cable tension is quite important here - you need to set the mech with the limit adjuster so that it's in the right place on the smallest chainring (with zero tension), then adjust the tension so that when you shift up, the mech ends up in the position described above - just clear of the chain when in middle/largest. If it isn't tight enough it won't shift far enough, and you'll have trouble on the largest chainring too. Too much tension and it will shift too far.

I think front mech rubbing is more of an issue with the increase in the number of sprockets, certainly wasn't much of a problem on my 7 speed Bear Valley in '93!

Alternatively, you can go a bit retro and use gripshift - then you can adjust the front mech position as much as you want, and avoid any rubbing at all.

luigi_t8

ok, thanks for your help. i'll have a bit of a play about to try and get it a bit better