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"GHOST" Shifting is Driving Me Mad

BlacktemplarBlacktemplar Posts: 740
edited April 2011 in The workshop
Hi, technically inept (or is that incompetent?), so I thought I'd seek advice from the hive mind....

I have a 2010 Felt QX75 which has about 3,000 miles on the clock, and I've started to get some rather alarming shifting issues over the past few weeks.

When shifting on the flat I have no problems, but as soon as I try and put load on the chain/gears it jumps up/down and takes several shifts to stabilise in one gear. It's particularly bad from 22-32t. It will also "ghost" between gears on occasion, and has jumped from the middle to bottom chainring at the front at times. I've tried adjusting the rear derailleur ad nauseam, to no good effect.

As I commute all winter (in Scotland :shock: ) the entire drivetrain takes a fair pounding, but I've always kept it pretty clean and well lubed. I snapped my rear gear cable a couple of months back, and had new Jagwire sealed cables installed by my LBS. Gears worked fine for a bit but are now driving me mental.

Is this likely to be down to chain/cassette wear, or something else?

Thanks for any advice offered.
"Get a bicycle. You won't regret it if you live"
Mark Twain

Posts

  • The RookieThe Rookie Posts: 27,748
    If you are having problems with the front shifting, why adjust the rear mech?

    Be worth checking to see if you have a stiff link in the chain, easy to do and it makes a mockery of any attempt to get good shifting.

    Simon
  • Sorry, just my inept posting.... :oops: My bad.

    Problem is with the rear mech, only occasionally drops a ring at the front.
    "Get a bicycle. You won't regret it if you live"
    Mark Twain
  • mudcow007mudcow007 Posts: 3,861
    ok quick test shift the rear mech into the smallest sprocket, take a look at the cable to see how much slack its got when the mech is at its lowest point. has the cable to got any slack at all? if it has this is stretch an you need to undo the 10mm bolt or allen key an pull a bit of cable through so the cable is taught

    see how well it shifts

    if its not the cable check you have no stiff links in the chain, this could be causing it to jump outta gear all over the place
    Keeping it classy since '83
  • OK, thanks will check that tonight and see what happens. I cleaned & lubed the chain (again) at the weekend and didn't notice any stiff links, but wasn't looking specifically tbh.

    One other thing that occurs to me is that the jockey wheels are worn to shuriken-like star points, might not be the cause but certainly not helping. Probably worth replacing.

    Could a bent rear hanger cause this? It looks straight, but my eyes are wonky (I blame old age, my wife blames drink...)
    "Get a bicycle. You won't regret it if you live"
    Mark Twain
  • mudcow007mudcow007 Posts: 3,861
    Could a bent rear hanger cause this?

    definitely!

    a bent hanger will move the mech totally out of alignment making it jump all over the place or at least make it super noisey
    Keeping it classy since '83
  • Well, checked out play in the cable - looks fine, and 'stiff' links - nothing obvious. Hanger looks straight, and seems to be in line with the cassette.

    I'm ordering a chain checking tool, as I suspect the chain is gubbed (technical term), and possibly the cassette as well. I've read it's best to replace both at the same time as they wear out together, and putting a new chain on a worn cassette won't neccessarily solve the problem.

    A pal replaces his road bike chain every 1000-1500 miles, so at 3K miles I guess mine's had a good innings!

    So shopping list would be;

    - chain stretch gauge
    - chain whip
    - cassette removal tool
    - new cassette
    - new chain
    - chain splitter
    - powerlink(s)

    Ouch.
    "Get a bicycle. You won't regret it if you live"
    Mark Twain
  • OK, solution found.

    Renewed chain and cassette and hey presto! - no more problems. Obvious, I guess....
    "Get a bicycle. You won't regret it if you live"
    Mark Twain
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