Forum home Mountain biking forum MTB workshop & tech

New drivetrain slipping under load

Cj83Cj83 Posts: 58
edited April 2010 in MTB workshop & tech
Have tried to find a solution to this using the search button but couldn't find anyone with this particular set of circumstances....

Installed a new cassette (SRAM PG970 9sp 11-32), chain rings (SLX), chain (SRAM PC991 9sp), rear mech (XT Shadow) shifters (LX) and gear cable to bike but something is slipping under load (hard to say but cranks maybe turn 1/8 to 1/4 when it happens). Its not all the time, or even often, but every now and then it does happen and its got to the point where i've lost confidence in putting the chain under a lot of load.

At first I thought the freehub must be on its way out (newish XT hub) but I put in my brothers new DT Swiss wheel with new 9sp XT cassette and it still occurs.

I've thought about it being some sort of mis-shifting but the gears seemed pretty lined up to me. It has only occured in the middle chain ring but to be fair have done nearly all the riding in that ring. Would try it in the other 2 but to be honest don't really like putting the chain under the pressure needed for it to happen knowing something can slip at any moment and it can't be good for the chain when it happens.

With the cassette and hub seemingly not at fault all I can think of is the chain slipping around the chain ring slightly but, at least in my mind, this seems very unlikely? Here are some pics incase anyone can spot anything blindingly obvious in the way i've put it together.







  • ride_wheneverride_whenever Posts: 13,279
    b-screw wound in as much as possible?
  • Cj83Cj83 Posts: 58
    if I wind it in would that mean less wrap around the cassette?
  • Cj83Cj83 Posts: 58
    think i've cracked it - and yep i've embarrassed myself with this one.

    before i put this together the chain rings had been lying around the garage for ages (years) with all the other bike stuff. when i come to putting them on the cranks i found 3 slx chain rings and fitted them. it was only just now when i looked at a picture of the slx crankset on the internet i realised my middle chain ring looks different (3rd picture above). thats because i also had a new shimano saint middle chainring lying around which i've mistakanly put on instead of the proper one (m660). The spacers that seperate it from the outer ring are a slightly different size so i'm hoping thats the cause of the problem. I've just given it a quick run and no slippage so far.

    not sure if this is ever gonna be a help to anyone but guess if anyone was wondering whether they can run a saint chain ring in a triple crankset the answer is no... :oops:
Sign In or Register to comment.