BB axle length for Xizang

[tonedeaf101]

Hey there, trying to fit a Middleburn RS3 to my Xizang to finally get it finished after many months sat doing nothing.
After doing research from here I was under the impression 113mm was fine, but I can't get it to change gears well at all.
All parts are pretty much NOS or hardly used so happy with that side of things. Running an M952 mech by the way.
Problem is it is very reluctant to drop down to lower ring, so figured a 118mm may give me some more room to play with. All cables are new and nothing is sticking etc. No matter what adjustment to cable tension or mech angle, it will not do it.

Only thing I thought was I'm running a 46, 34, 22, is the mech height on seat tube the issue where i need to run higher to give outer ring clearance? Have same gearing on my Zaskar, M950 mech and a Syncros crank and that changes sweet.

Cheers

 

[KermitGKona88]

Re:

Have you tried adjusting the stop screws on the mech :?:

 

[tonedeaf101]

Yep tried everything I can adjust. Have never had an issue like this on any bikes so is puzzling me to say the least.
If I adjust the bottom screw too much, it then takes 2 clicks of shifter to get it to go to middle, when it should be 1.
Rings are all same spacing by the way, should have said previoulsy.

 

[hamster]

I've had this problem! The top and bottom screws are nothing to do with the mech pull.
Things to check:
1 Cable clamping on the front mech - is it exactly following the routing, make sure it's not on the wrong side of the bolt and sits exactly in the slot. It's easily mis-located, which completel fouls up the mech movement per click.
2 Put two turns outward on the shifter calbe adjuster. Set the lower screw then clamp the cable just tight. Set the adjuster to bring the mech up cleanly with a single click inner to middle.

Hope this helps.

 

[tonedeaf101]

Cheers will try what you said.
Was yours Middleburn also?

Like I said have never had a problem like this in the past, just set min and max stops, route cable, quick tweak of adjuster and mech position and bang, away!!!

 

[ishaw]

Re:

You need the mech cage to be around 2mm clear of the top ring when in that position. Too much more and the shifting is impacted.

 

[tonedeaf101]

Yeah was about that much Ian. Will have a good play with it soon and get to the bottom of it! Annoying me now.

 

[ishaw]

Re:

Had the same issue with an sram xx mech recently. Could not get it to shift well at all no matter what I did. Swapped it out for a cheaper sram mech and it worked first time and has done since.

As you have found, normally these are simple and work first time, occasionally however.....

Maybe there is too much slop in the mech?