Help with chainring problem...

becstar71
becstar71 Posts: 9
edited July 2014 in Workshop
Have just upgraded rear mech from Tiagra to 105 and indexed gears - so far so good...BUT when I change from inner chainring to outer chain becomes stuck halfway through transition and jams, however this does not happen when making transition opposite way from outer to inner. Front derailleur is parallel, limit adjustments are good and have fitted new chain. Have looked on internet at tons of videos and done everything possible including fiddling with barrel adjusters. Want to try and do the job myself as trying to learn to be bike self-sufficient to some extent but may have to just admit defeat and go to LBS. Am I being too ambitious? Bike is 10 speed, compact chainset, 105 rear, Tiagra front, STI shifters. ANY suggestions most welcome.

Comments

  • JayKosta
    JayKosta Posts: 635
    So, the only changes were to the REAR derailleur and shifter, and a new chain - no changes to the front derailleur, or chainrings?

    Does the front shifting problems happen regardless of what gear in the rear? Do shifts work ok in some rear gears? My guess is that the chain tension is the trouble, I'd try adding a few links to the chain.

    Jay Kosta
    Endwell NY USA
  • becstar71
    becstar71 Posts: 9
    Hi, thanks for reply. Problem seems to happen when chain is on two larger cogs at back but ok in all others. No changes were made to FD or chainrings, and chain was replaced with same size as old one. Will try adding links if can get a pin today and see what happens...
  • JayKosta
    JayKosta Posts: 635
    Yes, the front shift 'should' work even with the 2 largest gears in the rear, but doing that causes 'cross chaining' and is not good practice.

    My thinking about chain length is that perhaps the springs in the new rear derailleur have more 'pull tension' on the chain, and that inhibits the chain from going from small chain ring to the large one - because that puts even more tension on the chain.

    Jay Kosta
    Endwell NY USA
  • patrickf
    patrickf Posts: 536
    You haven't gone from a short cage derailleur to a long cage, have you?
  • becstar71
    becstar71 Posts: 9
    patrickf wrote:
    You haven't gone from a short cage derailleur to a long cage, have you?

    Hi,
    no it is a short cage mech, direct replacement for previous just upgraded.

    Can't get a pin for chain until tomorrow so will have to wait until then. Have run through gears again and when in smallest two cogs similar thing happens on FD. When you say about the tension, Jay, would that have anything to do with the 'b' screw on RD, as I haven't altered that?
  • JayKosta
    JayKosta Posts: 635
    becstar71 wrote:
    patrickf wrote:
    ...
    Can't get a pin for chain until tomorrow so will have to wait until then. Have run through gears again and when in smallest two cogs similar thing happens on FD. When you say about the tension, Jay, would that have anything to do with the 'b' screw on RD, as I haven't altered that?
    ===========================================================
    I guess you could tinker with the B screw to see if it makes a difference .....

    For FD not shifting on 2 small rear cogs, maybe adjust the FD 'high' limit screw for a little more outward movement.
    And check the RD to make certain the pulleys and chain are well aligned with the gear.

    Jay Kosta
    Endwell NY USA

Categories