Help please! xtr front mech and xt compact chainring setup

[Tatsunoko]

having fun and games setting up the front gearing on the p7.
running an xtr m900 front mech and an xt m739 crank 42-32-22 compact drive crank and having a bugger trying to set it up. Is is that the compact drive chainrings are not comparable with the older m900 mech, or am i just not trying hard enough! Any pointers gratefully received

 

[Gruff]

Re: Help please! xtr front mech and xt compact chainring set

Got no idea but am about to try the same set-up with an M901 front mech on my C16-R oh and using Suntour XC Pro thumbies.

 

[Tatsunoko]

Re: Help please! xtr front mech and xt compact chainring set

Hope you have better luck than i did today setting up the P7. Running a new IG chain and m950 shifters, but just cant get it dialed in. I thought maybe the m901 front mech isn't compatible with the xt compact drive. However, i hope it is, and its me that is the weak link, otherwise it'll be back to swaps and sales (i refuse to make it a single speed!)

 

[integerspin]

Re: Help please! xtr front mech and xt compact chainring set

I have an M900 front mech and M739 cranks, no problems at all.
Your chainline OK?

 

[Tatsunoko]

Re: Help please! xtr front mech and xt compact chainring set

Thanks for the comments. Glad to hear its probably me, and not the parts. I'll have to start trying harder to get it dialed in

 

[FluffyChicken]

Re: Help please! xtr front mech and xt compact chainring set

IT's not the most optimised front mech for compact drive with ramps and profiles designed for larger 36 middles and 46/48 big rings. But it should 'work' just not a nicely as the proper era 739 mechs
what's the problem?

 

[Tatsunoko]

Re: Help please! xtr front mech and xt compact chainring set

Just cant seem to get it to index properly across the compact drive rings. I suspected that the older mech may not like the smaller system and prefer older, larger rings. Did a trawl through Sheldon brown site to try make sure all was the right size, but there you go. Now i need to choose different crank and rings m900 or a diff mech to match the rings....

 

[Spudly]

Re: Help please! xtr front mech and xt compact chainring set

What shifters are you running, id guess that your problem lies there, i have a 739 crankset and an m900 front mech on my caldera, shifts fine on mine running xt sti's!

 

[Tatsunoko]

Re: Help please! xtr front mech and xt compact chainring set

Its running xtr m950 sti shifters. I'll give it another go before looking for another chainset (unless a m900 bargain appears that i cant say no to!). Will keep trying!

 

[Gruff]

Re: Help please! xtr front mech and xt compact chainring set

I should be ok, the front mech Suntour thumbie is "friction shift" whereas the rear one is indexed.