CityCyclingEdinburgh Forum » Questions/Support/Help

Skipping chainring teething

(23 posts)
  • Started 13 years ago by wingpig
  • Latest reply from wingpig
  • This topic is resolved

  1. wingpig
    Member

    Although I'd like to be able to blame it on the weather-related gak I've accumulated around my components this week (particularly this morning, when I was briefly behind one of those machines with a thing on the back for spitting out grit) I'm wondering whether the multiple instances of my chain seemingly ignoring the crank teeth at inopportune moments (usually when setting off at anything other than extremely low accelerations) and sometimes falling off the chainring altogether is perhaps due to chain wear rather than build-up of mankiness and/or reduced ability of the rear mech to maintain chain tension whilst its spring is coated with horrible brown stuff...

    I'm quite willing to accept that it is just normal wear & tear (the chain's done about four thousand miles whilst the chainrings were fresh on in June), particularly when the chain's sitting quite high on the teeth like that, but find it suspicious that it only started happening since I left work this evening...

    I believe that the chain is relatively fresh underneath the slime (it's been getting lubed like there's no tomorrow and seems to be a better chain than the previous one which suddenly rusted up overnight after a mild rainshower) but I didn't have time to clean it tonight to see if scraping all the built-up sludge off everything solved the problem.

    Is a chain sticking high on the teeth like that typical of a chain which needs to be retired, a gummed-up jockey wheel spring or just simple uncleanliness?

    Posted 13 years ago #

  2. Matchstickwarrior
    Member

    That looks like a really stretched chain having gaps like that, assuming your chain ring is still in good nick.
    It's no secret that the constant stop-starting of urban riding puts a lot of stress on a chain. I am happy to get just 1000 miles of urban riding out of a chain (Shimano HG70, so nothing special) that has to haul my 85kg around. My last chain ring also only gave me 6000 miles before it was "shark finned" a bit too much.
    Use a dry lube in the winter too, that way you can just brush off all the muck once it dries.

    Posted 13 years ago #

  3. Dave
    Member

    If you can pull the chain away from the teeth at the point you've photographed, it's worn. It even looks in the photo like the pitch of the chain is too large for the pitch of the teeth - not good!

    My experience has been only that things start skipping when you match up new and worn components, which is why I'd usually replace them at the same time. You may find if you buy a new chain that it skips on a worn chainring (because riding a worn chain on a new ring will wear it out more quickly) - or it could be fine.

    Posted 13 years ago #

  4. thebikechain
    Member

    Woah - that's what we call 'b*ed' (apologies for language) here at TBC Towers Magicarium Emporium.

    You will need a new chain and cassette minimum as that chain will probably (likely) have worn the cassette too. You may well need new rings too as you will have accelerated the wear.

    If you want, swing by and we will measure it with the magic measuring device too to get an accurate mm of wear.

    Oh and do not press hard when leaving standstill, go easy in big ring and big sprocket - the more teeth in contact the better.

    Posted 13 years ago #

  5. wingpig
    Member

    Presuming a knacked cassette (tested, presumably, by replacing the chain then checking for tooth-skip at the cassette rather than the chainring), how much do localish bike shops usually charge to fit replacement cassettes purchased from them?

    Posted 13 years ago #

  6. chdot
    Admin

    "how much do localish bike shops usually charge to fit replacement cassettes purchased from them?"

    Noticed this the other day -

    http://eastsidebikes.wordpress.com/workshop-and-servicing

    Most comprehensive list I've seen on an Edinburgh web site - not that I look at many that often.

    Posted 13 years ago #

  7. wingpig
    Member

    Hmm. Cost of cassette removal = cost of lockring tool. As luck would have it, I have a recently-expired chain I can make a chainwhip out of, though it might skip a little.

    Posted 13 years ago #

  8. kaputnik
    Moderator

    There are plenty cassette removal tools on here you could borrow I'm sure. I for one have one if you need it.

    Posted 13 years ago #

  9. Dave
    Member

    Swapping a cassette and chain is a no-brainer and you only need a couple of tools which, as mentioned, are easy to find amongst forumites. I think my lockring tool must have paid for itself about fifty times over now...

    I have all the bits and bobs, if you'd like to bring it over and do it here (I need them over the next few days so less convenient to lend). 30 minutes or your money back.

    Send a forum message if you're interested, in case I forget to check this topic for a week!

    Posted 13 years ago #

  10. wingpig
    Member

    Tool-use offers are most kind of people. I shall first cleanse, then measure, then count the teeth on my sockets, then purchase appropriate replacement component(s) then go on the borrow...

    Posted 13 years ago #

  11. wingpig
    Member

    Cleansed things up a bit. Measured the chain. Twelve complete links measure just under 12¼".

    Eeep. Despite its relative youth (fitted in August rather than June) there's some quite severe wear on the middle chainring, too. Suppose I'll have to do some shopping...

    Posted 13 years ago #

  12. wingpig
    Member

    Hmmm. Not many seven-speed cassettes out there.

    One further question: how interchangeable are 130mm BCD chainrings?

    I have one of them, but as I mostly use the middle ring it's only the middle ring which has been eaten by my elongated chain. Is it possible to replace the 42T middle ring with a 39T middle ring so that everything feels a bit more like it did before the previous 30-39-52T chainset was replaced (and what's the difference between type A and B chainrings) or do I have to just get a 2300 42T?

    Posted 13 years ago #

  13. Dave
    Member

    The A and B designations refer to whether the rings are optimally designed for shifting between 52-42 (A) or 52-39 (B). Your chainset is an A because the largest two rings are 52-42.

    In theory if you change to 39t you should replace your 52t ring with a type 'B'. In reality if you buy any 130BCD 39t chainring you won't be able to tell the difference. If you want to give it a try I happen to have just removed such a 39t ring from my lowracer and you could concievably fit it for reassurance that it works satisfactorily.

    (It's part worn, so I might not advise you to use it long term although you're welcome to it either way).

    Posted 13 years ago #

  14. wingpig
    Member

    Heavens to Betsy.

    Wornest middle chainring temporarily replaced with less-severely-worn middle chainring from old chainset, eliminating skippage upon takeoff. Replacement chain swiftly located, ordered and delivered. Replacement old-fashioned seven-speed cassette sought, found, restocked, ordered and picked-up on Thursday. Lockring removal tool borrowed. Replacement middle chainring eventually located in-stock and ordered on Friday. Old chain removed, partially degreased, chopped into pieces and formed into a chainwhip with the aid of an old Allen key, a jubilee clip and a pair of pliers. Then the problems start, most prominently in the form of the lockring removal tool freely rotating inside the lockring rather it than loosening it (I'll happily replace if, upon return, it turns out to be no longer able to remove non-seized-in-place five-year-old lockrings). Unfortunately all the locallest local bike shops were shut today so I'll be lugging a wheel in with me when I walk to work tomorrow and thinking hard about which shop to take it to to get the old one removed. Hopefully it won't turn out to be welded to the hub with dusty sludge.

    On the plus side, the grippy-at-the-side but not-too-deep tyre which I bought for the snow but never tried to fit does actually fit.

    Posted 13 years ago #

  15. Dave
    Member

    Looks good, but I could have brought a whip into PY on Friday ;-)

    Unless it's well out of your way, I'd be taking it to the Bicycle Works. If it's stuck in an interesting way, you might even struggle to force money on them for the job.

    Posted 13 years ago #

  16. wingpig
    Member

    Hurrah for TBW, now at least partially-redeemed.

    IMAG0251 by wingpig, on Flickr

    Posted 13 years ago #

  17. wingpig
    Member

    Dur.

    I wish we were allowed personal insults and swearing: I could then describe exactly which type of ing tube I am.

    I have now ordered an eight-speed cassette to replace the old one which, as clearly visible above, is also eight-speed, not seven-speed like the one I ordered last week and got as far as greasing and enhubbing before I noticed the gap.

    Posted 13 years ago #

  18. ruggtomcat
    Member

    oops, LOL!

    the one the chain is on doesn't count...

    Posted 13 years ago #

  19. thebikechain
    Member

    wingpig - is it the one you got from us? need it swapped?

    Posted 13 years ago #

  20. Smudge
    Member

    @thebikechain, did you get my pm ref wheels? :)

    Posted 13 years ago #

  21. wingpig
    Member

    @tbc If you'll take it back I'd be most grateful, though as it's seen a wee dab of grease (all trace of which successfully removed) and as it was uncommon enough to require ordering-in I'd understand if you didn't. In-stock eight-speed replacement already ordered anyway.

    Posted 13 years ago #

  22. thebikechain
    Member

    No probs. Swing it in. Refund will be issued on your web order.

    Posted 13 years ago #

  23. wingpig
    Member

    Most kind. I'll be there at lunchtime.

    I don't usually mind my mostly-gradually-uphill commute but this morning even the slightest pressure on the pedals meant millions of skippage of the new chain (the old one is now in at least twelve pieces, at least four of which are bent) on the old sprockets. I preferred it when the chainring was skipping. Rolling mostly downhill to the shop for the correct item shouldn't be too bad but it's debateable whether I'd be any faster on the bike on the way back up compared to walking.

    Posted 13 years ago #

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