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Replaced (not very old) chain, now rear mech won't shift

UnWeaveUnWeave Posts: 33
edited July 2010 in MTB workshop & tech
tl;dr: I just replaced my chain (drivetrain has done <150 miles, wanted removable, stronger chain), and now the rear mech won't shift properly, particularly on the largest ~5 cogs. Is it normal to need re-indexing?

Got a Carrera Fury a few weeks ago, mostly it was fine (aside from some turkey gobbling on the rear Juicy 3 - but that's a whole other matter). Anyway, stock chain was proving difficult to clean so I ordered a KMC X9.93, since it came with KMC's 'magic link' (wasn't sure if I could just attach these to my current chain, having not had one before, so just bought a new one. Seems like I didn't need to but too late now).

Shortened the chain to the same length as my previous one (which was largest cogs + 2 links, as it happens) and now shifting on the rear is all messed up. It doesn't want to sit in 1 (largest cog), and going 1->2, 2->3, 3->4, 4->5 is pretty bad, in decreasing order of, er, roughness. Once you're at 5 things start to smooth out and it isn't jumping between cogs too much, but it still isn't right.

Did I do something wrong? I wasn't aware that the rear mech would need indexing again just because I changed the chain. Also, I've never indexed before (only just getting into 'proper' bike maintenance, let alone setting one up). So, er, did I mess up or does it sound like there's something else wrong? Thanks.

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    largest plus one full link (1") including the joining link.

    yes having to reset the gears would be expected.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • CraigXXLCraigXXL Posts: 1,852
    Check the chain routing over the wheels on the derailurer
  • UnWeaveUnWeave Posts: 33
    nicklouse wrote:
    largest plus one full link (1") including the joining link.

    yes having to reset the gears would be expected.
    If by 'full link' you mean 1 inner and 1 outer then that's what I did (the manual says 2 links, but clearly shows 1 inner and 1 outer...) Anyway, if resetting is normal then I guess I'll crack out the X5 manual. Like I said, I've not indexed gears before, any tips?
    CraigXXL wrote:
    Check the chain routing over the wheels on the derailurer
    Er, I think it's fine. It definitely loops over in all the right directions, should I be checking anything more specific, e.g. slack between the guide and tension wheels (there isn't much)?
  • CraigXXLCraigXXL Posts: 1,852
    Making sure it's threaded the correct way through so that it doesn't drag on the plate that runs adjacent between the wheels. I've seen a few people, myself included, that have done this so the chain is running over the plate creating a shorter chain by making a longer route.
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