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Sram Rival front mech installation/adjustment

marin_maniacmarin_maniac Posts: 513
edited July 2010 in Workshop
Hope someone can help on this as its driving me nuts.

Recently I've noticed on my Boardman Team Carbon that the front mech drops the chain. The bike has got full Rival with the exception of A DA 7800 chain with KMC link which I've changed within the last 2 mnths.

I had a go at re-positioning the mech last night as it looked a tad high after looking at various how to's inc Park Tool.

I watched the Sram tech vid on you tube over breakfast and will attempt to follow this step by step after work tonight.

Has anyone got any tips on this subject that they would like to share?

Posts

  • softladsoftlad Posts: 3,587
    you probably need to be adjusting the limit screws, not the height, which won't make any difference anyway. Have a look on the SRAM site for the instructions...
  • keef66keef66 Posts: 13,123
    My 105 front mech started over-shifting onto the biggest ring, and dropping the chain onto the crank. A tad inconvenient when going down a 25% hill.

    I just tweaked the upper limit screw a bit at a time until it stopped doing it.
  • marin_maniacmarin_maniac Posts: 513
    Thanks for the replies, however the chain was dropping on BB side even with the chain just about not rubbing while in small chainring and largest sprocket, so I'm not convinced its just a limit stop issue.
  • rakerake Posts: 3,281
    Thanks for the replies, however the chain was dropping on BB side even with the chain just about not rubbing while in small chainring and largest sprocket, so I'm not convinced its just a limit stop issue.
    i was going to say this. put in small big until its not quite rubbing. do you ease off when changing gear. same bike and never had this happen.check the obvious like loose chainring bolts,if youve ever removed the chainrings make sure the tabs are lined up with the crank arm. one is a pin which stops the chain going behind the crank arm the other is a metal tab.other than that i cant say.
  • marin_maniacmarin_maniac Posts: 513
    rake wrote:
    Thanks for the replies, however the chain was dropping on BB side even with the chain just about not rubbing while in small chainring and largest sprocket, so I'm not convinced its just a limit stop issue.
    i was going to say this. put in small big until its not quite rubbing. do you ease off when changing gear. same bike and never had this happen.check the obvious like loose chainring bolts,if youve ever removed the chainrings make sure the tabs are lined up with the crank arm. one is a pin which stops the chain going behind the crank arm the other is a metal tab.other than that i cant say.

    Adjusted the mech from scratch last night, and it seems to be better. Only dropped once or twice, but I was being purposefully hamfisted when changing gears. I have never removed the chainrings, only lubed the bolts, so I don't think that would be the cause.
  • topdudetopdude Posts: 1,557
    It could just be that the DA chain is still fairly stiff laterally, if you compare a new and old chain the old one is much more flexible in a side to side direction.
    I suggest you get the adjustments right as near as possible and fit a Dog Fang to stop the occasional miss shift :D
    http://www.parker-international.co.uk/432/Deda-Dog-Fang.html?referrer=froogle&utm_source=google&utm_medium=froogle&utm_campaign=pid432
    He is not the messiah, he is a very naughty boy !!
  • rakerake Posts: 3,281
    good idea but dont get that specific type of dog fang, it wont fit the boardnam frame because of the bb shape.
  • marin_maniacmarin_maniac Posts: 513
    I had thought about fitting a dog gang, I think I'll keep a check on the mis shifts to see how often it drops.

    Why won't the deda fang not fit?
  • rakerake Posts: 3,281
    dog gangs sit about level with the chainring teeth on the seat tube, on my boardman the tubing flares out into the bottom bracket, the shape/size wouldnt allow it to clamp around the tube. i was going to fit one but am looking for an alternative.
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