chain moving across high gears randomly on rear cassette

willc76
willc76 Posts: 5
edited July 2011 in Workshop
Hi - I recently bought a new old bike, which has all new tiagra gear set but with indexed down tube shifters.

I have now done c.300 miles on it, and I am starting to notice that the indexing isn't quite right on the smaller cogs on the rear cassette.

Sometimes when clicking down a gear it sometimes doesn't move, then will change much later, or just keep changing itself across the smaller 3 cogs or so.

I did have a bit of an over handlebar moment (car pulled out, thanks) and scraped that side of the bike as well as other body parts, but the next 30 miles or so after i didn't notice any problem.

Does it sound like a wee tune up might sort this, as it is down to new cables settling in, or dies it sound more serious?

Thanks to all

Will

Comments

  • keef66
    keef66 Posts: 13,123
    Sounds like the shifters or the cables need some attention.

    Is it also possible that the rear mech hanger got bent in tour altercation with the car? If so that can make it harder / impossible to sort out the indexing properly
  • willc76
    willc76 Posts: 5
    Thanks Keef - when I get round to it I guess I'll go through the tuning process and see what happens (will be a first for me but I need to learn sometime). As it will be my first proper tune up I just thought i'd make sure it wasn;t something else obvious.

    Before that I'll check the mech hanger. I will be very p1ssed off if it is bent, but guess it can be stripped down and bent back.

    Just loving this old bike (Denton steel frame, tiagra gearing) having only had it two weeks we are inseperable and will be very sad if i have to go back to my comparably expensive modern Tifosi!

    Will
  • keef66
    keef66 Posts: 13,123
    Steel frame? Probably not a detachable / replaceable mech hanger then. That's good cos it means if it is bent you can just swing on it with a big adjustable wrench to straighten it. :D
  • Bobbinogs
    Bobbinogs Posts: 4,841
    Might be worth changing to friction shift mode to see if the problem goes away until you get it sorted properly. It should also help narrow the problem down if nothing else.

    Have you also checked the chain and cassette for wear (not sure from your post whether you have done 300M since sorting it all out or 300M since buying it, which means any of the components could have been worn to start with).

    [edit: just saw the bit about all new Tiagra so just worth checking the chain?]
  • willc76
    willc76 Posts: 5
    Thanks Bobbinogs

    all components were new - but i'll stick a new chain on anyway and see what happens. Can always store it for another day if the chain turns out to be ok

    Will
  • Bobbinogs
    Bobbinogs Posts: 4,841
    willc76 wrote:
    Thanks Bobbinogs

    all components were new - but i'll stick a new chain on anyway and see what happens. Can always store it for another day if the chain turns out to be ok

    Will

    Hi Will, you may find it more cost effective to buy a decent chain wear tool. They don't cost that much and you may find that you don't need a new chain after all. In the future, a chain wear tool will come in very handy (I check my chains every few weeks at the mo as I am getting close to replacement time...but not there yet).
  • willc76
    willc76 Posts: 5
    that is a top tip - thanks :lol:
  • John.T
    John.T Posts: 3,698
    Hi Will, you may find it more cost effective to buy a decent chain wear tool.
    The best (and cheapest) is a ruler.
  • meanredspider
    meanredspider Posts: 12,337
    Before you go changing anything, it's worth checking that the cable is moving freely and the deraileur is set up as the designer intended.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH