Gears Jumping, new cassette needed?

kev_gray
kev_gray Posts: 44
edited April 2010 in The workshop
Hey all.
I changed my chain on my bike on Friday when giving it the weekly post working week scrub down after noticing the chain was getting to around 1% wear on the checking tool. Well I thought that would be all good except when riding in today at first I thought I heard a very slight click when pedalling (not sure as the wind was gale force so hard to hear). Later on my ride in when I hit the hilly section and changed gears the chain started jumping a lot in one or two of the back gears while in the middle cog on the front. Is this a sign of the cassete also needing changed as the new chain is not shaped as the old one? I'm pretty new at all this maintenance stuff so will it just mean I need to change the rear cassete? Also if the cassette is worn how early should I be thinking of changing the chain in order to save this sort of thing happening again?
Any help/advice is most appreciated!
Kevin

Comments

  • UndercoverElephant
    UndercoverElephant Posts: 5,796
    It does sound as though your cassette needs changing too. It sounds as though you did the right thing changing the chain at just under 1%, this usually minimises the number of times you need to change the cassette, you may have just been unlucky.

    My old BSO had the annoying habit of teeth snapping off the rear cogs, have a good look at the cassette, you may have had the same thing happen.
    Sun - Rain - Snow
  • kev_gray
    kev_gray Posts: 44
    Cheers for the tips! Will monitor it closely on way home and hopefully have time for a proper look this evening! I had a quick look on wiggle and its only around £20 to replace the rear cassette anyway so not a major cost!
  • kurako
    kurako Posts: 1,098
    Could be a combination of a stretched cable and the fact you've cleaned off all the sticky gunk.

    Have you tried giving the cable a slight adjustment? There should be an adjustment barrel at one (or mabye both) ends of the cable. Try adjuting that to see if it helps. It shouldn't need anything major. Maybe a quarter or half turn.

    Read part 3 here:

    http://sheldonbrown.com/derailer-adjustment.html
    Univega 700
    Univega Via Strato
  • Clever Pun
    Clever Pun Posts: 6,778
    I was just about to ask the same question first ride with the new chain it skips away frequently on one particular gear and occasionally if I put real power/torque down on other gears

    I'm assuming it's new cassette rather than the chain taking time to bed in
    Purveyor of sonic doom

    Very Hairy Roadie - FCN 4
    Fixed Pista- FCN 5
    Beared Bromptonite - FCN 14
  • kev_gray
    kev_gray Posts: 44
    Yeah I've just bitten the bullet and went for a new cassette and lockring remover. Would of also gone chain whip but wiggle has none in stock! Halfords it is for that one! Tried messing with gears cable last night but now I have my SPD shoes on bike i've noticed its a few gears jumping when applying power to the pedals.
  • jairaj
    jairaj Posts: 3,009
    The new chain should bed down after a few rides. As said above replacing within 1% wear should be fine.... maybe you're just a bit unlucky?
  • kev_gray
    kev_gray Posts: 44
    Yeah, unlucky could be my middle name! I'll give it till the end of the week to see if the chain beds in at all and if not will just change the cassette with the new one i've ordered up. Will this damage the chain at all doing this if the cassette is worn?
  • jairaj
    jairaj Posts: 3,009
    Im no expert, but depending on the mileage you do and how much its jumping, I would've thought not too much damage could be caused.
  • rolf_f
    rolf_f Posts: 16,015
    Look at the cassette teeth. This happened to me when I put a new chain on. Noticed that the smaller gears had become shark toothed - no amount of bedding in would cure that. I have a new cassette but not sure when to fit it. I still have two chains around 1% stretch and the old cassette works fine with them so when do I change?
    Faster than a tent.......
  • jairaj
    jairaj Posts: 3,009
    Rolf F wrote:
    Look at the cassette teeth ... Noticed that the smaller gears had become shark toothed - no amount of bedding in would cure that.

    Good point, I was assuming the teeth were still in good shape.
    Rolf F wrote:
    so when do I change?

    I guess this is a bit of a grey area. Its when the teeth look sufficiently shark toothed to the user that they believe even a new chain won't help with the poor shifting and chain jumping etc??? :?
  • rolf_f
    rolf_f Posts: 16,015
    jairaj wrote:
    I guess this is a bit of a grey area. Its when the teeth look sufficiently shark toothed to the user that they believe even a new chain won't help with the poor shifting and chain jumping etc??? :?

    It's the other way round! The old chains work fine on the old cassette - possibly a bit odd as most of the cassette gears look fine. The new chain doesn't work on the old cassette at all (in the small gears). So, for now, everything is working pretty well ok most of the time as long as I use my old chains. All I'm concerned about is if the chain breaks and if the stretched chain knackeres the chainrings up.
    Faster than a tent.......
  • agg25
    agg25 Posts: 619
    I replaced my chain on the weekend as well and mine is skipping like a bastard now as well. It only really seems to stay on the ring when in a big to big chainring, other than that couldn't put power down.

    So, guess I'm up for a new cassette too eh? I haven't tried adjusting the gears but I wouldn't have thought you'd have to if just changing the chain. Am I wrong?

    Also, the link that I used to join the chain back together is really stiff and no amount of flexing it side to side and a bit of lube would loosen it up. Any ideas where I went wrong here?
  • davis
    davis Posts: 2,506
    edited April 2010
    When you say "skip", do you mean "flipping between gears", or do you mean "the chain rides over a tooth of the correct sprocket" You'll get a big snap and a step in the resistance from the pedals with the latter.

    You got the length of the new chain correct, right? I.e. measure it against the old one, or do the big cog->big sprocket game

    I've had a chain skip because the tension wasn't correct once, but mostly because the sprockets were nicely worn.
    Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.
  • rolf_f
    rolf_f Posts: 16,015
    Is it skipping between cassette gears or on one? The chain shouldn't (afaik) result in any other adjustments being needed but if there is slight cable stretch, I'd imagine it might encourage a new chain to slip between gears. Also, which gears are the problem - the small gears are going to shark tooth before the larger ones. The sharks teeth are very obvious on the two smallest gears on my cassette.

    Mind, big to big (assuming you mean big chainring to big cassette ring) you shouldn't be using anyway and if that's the only one that works I'd think your gears are needing adjusting.

    As for the link - are you using a powerlink? Should eliminate any risk of stiff links at the split.
    Faster than a tent.......
  • wgwarburton
    wgwarburton Posts: 1,863
    Rolf F wrote:
    jairaj wrote:
    I guess this is a bit of a grey area. Its when the teeth look sufficiently shark toothed to the user that they believe even a new chain won't help with the poor shifting and chain jumping etc??? :?

    It's the other way round! The old chains work fine on the old cassette - possibly a bit odd as most of the cassette gears look fine. The new chain doesn't work on the old cassette at all (in the small gears). So, for now, everything is working pretty well ok most of the time as long as I use my old chains. All I'm concerned about is if the chain breaks and if the stretched chain knackeres the chainrings up.

    Sounds like your whole drivetrain is worn. A new chain skips on the sprockets 'cos the teeth are worn down but your old chains are OK as they have the same spacing (same wear).
    You are, essentially, on borrowed time as you'll need a new chain + cassette at some point in the fairly near future. Your chainrings may, or may not, be worn, too but if they arn't they soon will be.

    I see three choices:
    1) Replace everything now
    2) Accept that your chainrings are probably stuffed. keep going with your old chains until the wear causes problems, then replace everything.
    3) Get a new chain & cassette now- try them on your existing chainrings, and if they work OK then you have caught the wear in time and you can use them for a while longer. If the new chain skips on the old rings, then they are worn, too. Put the old cassette and old chains back on and wear them out, then replace the chainrings and put the new chain & cassette back on with them.

    Cheers,
    W.
  • rolf_f
    rolf_f Posts: 16,015
    I've already got new cassette and chain but am holding off partly as I'm doing high miles anyway so I may as well use what I have up properly!

    Thing is, only the smaller rings on the cassette look worn. The chainrings look fine (even the smallest) but the middle has a slight wobble which annoys so I'd not miss that one.

    What I heard somewhere here is that whilst a stretched chain will kipper a cassette, it won't wreck the chainrings in the same way. If that's the case, I'll not mind leaving them on after I put the new cassette and chain on.

    When I put the new chain on, it skipped on the cassette but seemed ok on the chainrings.
    Faster than a tent.......
  • telemark
    telemark Posts: 18
    Before you spend a small fortune replacing things, get your LBS to check you don't have a bent derailleur hanger. Symptoms include gears jumping especially in the middle gears on the cassette. You may find the chain jumps on one cog or between cogs. A small bend can make a big difference.
  • kev_gray
    kev_gray Posts: 44
    Hey guys, sorry to bring this one back up! Changed my cassette and did notice a lot of wear on the old cassette when I removed it and compared to new one! Well after a few days of fine riding the chain is jumping on the cassette again on the mid to smaller sprockets. I had it up on the stand and could see that it appears to jump up as if it is missing going into the slot on the cog but is not being moved to either above or below cogs if you understand? Sort of jumping up and out on same gear on the cassette. Is this fixable easily?

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