XTR and drops

[peetee]

I have a bike here that needs to be changed to drop bars. It has a XTR 950 front mech and triple cranks and Sora triple sti shifters which are not pull ratio compatible. I have tried a Tiagra 4600 front mech and it doesn't have the sweep range to reach the big chainring (approx 57mm from Centreline of frame)
Any suggestions?

[100%JR]

IIRC XTR isn't compatible with STis?

[peetee]

Doesn't appear to be, no. The answer would be to use a road f mech, which I have tried, but that won't swing out far enough.

[531colin]

Its complex. As a minimum, problems are....
A road mech. won't normally go far enough "out" to reach an "MTB" chainline.
A road STI won't normally pull enough cable to work an "MTB" front mech.

[peetee]

That's where I am with it. If such a thing was made the answer would be an out-spaced mech clamp for a braze on mech.

[531colin]

St John St do an eccentric shim, or you can make one....but the mech. clamp needs to be a lot bigger diameter than the seat tube in order to space it out significantly
Then you can run into trouble if the chainring sizes don't fit the design of the mech. when mixing road and MTB stuff.

[NetworkMan]

Presumably it's one of these new-fangled chainsets with integrated axle so you can't reduce the chainline? I think Thorn do that but they probably use a square taper chainset.

[Brucey]

IIRC the BB is designed to be mounted on a 73mm BB shell and mounts to a 68mm shell with spacers. On a 68mm BB shell the spacers can be arranged to pull the chainline in slightly and this makes for some more choices in FDs. It does make the tread asymmetric though, but in fairness a lot of bikes are actually like that anyway (usually the other way) and folk just don't notice.

cheers

[iandriver]

Friction shifter for the front mech only. Not ideal, but should work in a real push.

[mattsccm]

Does the mech have a braze on boss. I am damn sure that somewhere I have seen spacer. I bet it could be made. Plate that clamps on to the frame boss or an adaptor and has a hole for the braze on type mech. No idea if it would be stiff enough but if you only needed to move the mech say 5 mm it might work.

[peetee]

I have opted to buy an online cable pull converter from sjs so we can have the XTR mech. I had rigged up the Tiagra mech so it was positioned ok but the pull ratio was still off but I believe that was down to flex on the mech mounting bracket.
Thanks for the help.