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help with high gear tuning

Hi guys, I have a problem tuning my altus rear derailleur. I just changed the casette (same shimano 8 speed that was before) but I cannot get the last 2/3 high gear correct (small ones). So basically if I increase the tension of the cable I get good shifting between 7nd and 6nd but I am not able to reach the highest gear. If I decrease the tension I get to the last one but then it jumps from 8th to 6th without getting the 7nd. Any good advice would be highly appreciated! Thanks!


  • steve_sordysteve_sordy Posts: 2,229
    edited September 2020
    The new cassette may be in a slightly different position to your old one. Reset the limit screws.
    In my opinion this is best done by removing the chain and then pushing the mech over with your hand and adjusting the screw until the upper jockey wheel is exactly underneath the big gear. The other limit screw is easier as the mech spring pulls it into place. But still check that the upper jockey wheel is directly underneath the smallest gear. Don't rush this.

    Then start again with the set up, you may find it spot on, but even if not, it shouldn't take much tweaking of the cable tension.

    If all else fails, renew the cables. Many irritating shifting problems are caused by sticky cables. If you do this, be very careful not to step on the inner wire. It's easy to do! I have done it twice to my knowledge. :(
  • oxomanoxoman Posts: 9,133
    tatoxicmsO-w5W, if you cant follow Steve,s instructions, there are loads of how to tutorial,s on youtube to follow.
    Too many bikes according to Mrs O.
  • thx guys, I will try to reset the limit screws. Actually I also tried to adjust a bit the H screw but did not solve much of the problem. However I should perform the reset without chain to really align correctly. I think cables are not a problem as they are new.
  • photonic69photonic69 Posts: 1,105
    Also make sure you have clicked the shifter into the smallest gear position before attaching the cable to the clamp. So when you are setting your limit screws without the chain you should disconnect the cable from the clamp and pull on the end of it whilst operating the shifter index finger lever to make sure it is in the correct position before you clamp it again. It's easy to be one shift out without realising it. Then when reattaching to the clamp wind the adjuster all the way in then two full turns out. Pull hard on the cable with pliers then clamp the bolt tight. Then index as per Park Tool videos etc.
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