Daxiet Posted February 16, 2009 Share Hi, (pertaining to MTB with XT Shadow rear derailleur) Short of over doing the experiments I thought I would pose the question and hope someone out there has been through this and has the solution. When riding with the chain on one of the 3 to 4 smallest sprockets on the rear cassette, I experience jumping when pedaling on bumpy stretches of terrain. The first thing that comes to mind is checking for bent teeth on the sprockets, however unlikely considering the problem presents itself on at least 3 sprockets (quick check-didn't seem to have any bent teeth). Second thing would be to adjust the screw on the rear derailleur that sets the "pull back tension", for lack of the technical term (I have done this a small amount but no noticable improvement). I have couple other ideasm but they are very unlikely (sprocket wear - not used that much, chain wear - newish chain (500+ kms)) Any idea what is causing this and how to remedy it? Thanks Link to comment Share on other sites More sharing options...
TNT1 Posted February 16, 2009 Share You need to describe what you mean by jumping a little more clearly... Link to comment Share on other sites More sharing options...
NotSoBigBen Posted February 16, 2009 Share What bike? Link to comment Share on other sites More sharing options...
Sammajoor Posted February 16, 2009 Share Daxiet a few things..... a " new" cassette used with a non lubricated chain, will wear just as quick if not quicker than a non lubricated chain. Is you chain properly aligned.. if not correct it will jump, as soon as you put some type of power on the chain Link to comment Share on other sites More sharing options...
Daxiet Posted February 16, 2009 Share Ok, some more detail -the chain is well lubed (Squirt) - cassette is ~3900kms old.-Bike: Scott Genius MC40 -The alignment is as good as I believe I can get it, no issues shifting up or down, nor any strange jumping noise normally. -sprockets 5-9 do not present any issue (maybe even my favourite one no. 4 works fine - to be confirmed) To clarify jumping, when pedaling the chain seems to skip off the sprocket in use and back on, only over bumpy stretches. The frustration is that I briefly pedal against no resistance and the grip back onto the sprocket. Hence the sprockets will wear/get damaged as will the chain. Daxiet2009-02-16 04:46:29 Link to comment Share on other sites More sharing options...
Sammajoor Posted February 16, 2009 Share Sounds like your cassette is past it's expiry date Link to comment Share on other sites More sharing options...
Dirtbreath Posted February 16, 2009 Share Cassette and/or jockey wheels. Link to comment Share on other sites More sharing options...
Johan Bornman Posted February 16, 2009 Share You still haven't given us much detail but here's a scenario. It sounds like you are riding with a newish chain and old cassette. However, you didn't mention fitting a new (or different) just before the occurrence. We need to know if it suddenly happened with an existing chain and sprocket that used to work perfectly together. Whether the cassette has seen several chains replaced in its lifetime or whether it is the first chain. Have you measured your chain for wear? Do a search here for 12 inch rule or "everything you need to know about bicycle chains" and it is all explained in there. Let us know what you come up with. My guess is a mismatch of worn cassette on new chain. Link to comment Share on other sites More sharing options...
Johan Bornman Posted February 16, 2009 Share Daxiet a few things..... a " new" cassette used with a non lubricated chain' date=' will wear just as quick if not quicker than a non lubricated chain.Is you chain properly aligned.. if not correct it will jump, as soon as you put some type of power on the chain[/quote'] Hooi Samjoor, het jy alweer poppie saad gerook? Statement nommer een is nie waar nie. Ketting lube doen niks vir 'n cassette nie, daar's geen skuiwende parte nie. "n Droee ketting eet nie 'n kasset nie maar net homself. Watse alignment praat jy van? Ketting beweeg links en regs of kassette en is nooit "ge-align" nie. Link to comment Share on other sites More sharing options...
Sammajoor Posted February 16, 2009 Share You still haven't given us much detail but here's a scenario. It sounds like you are riding with a newish chain and old cassette. However' date=' you didn't mention fitting a new (or different) just before the occurrence. We need to know if it suddenly happened with an existing chain and sprocket that used to work perfectly together. Whether the cassette has seen several chains replaced in its lifetime or whether it is the first chain. Have you measured your chain for wear? Do a search here for 12 inch rule or "everything you need to know about bicycle chains" and it is all explained in there. Let us know what you come up with. My guess is a mismatch of worn cassette on new chain.[/quote'] Dis wat ek bedoel nou k@k jy my uit op die volgende paragraaf. Ons is nie almal so tegnies soos jy nie. Link to comment Share on other sites More sharing options...
Daxiet Posted February 16, 2009 Share The chain was replaced for good measure 29/12/2008 alas I wrote the kms down on the box when replaced, but I can't make out my hand writing (So exact kms when changed unknown). I suspect ~3100kms on that chain and cassette (I know, left it a bit late, but the chain was only 6 months old). There had always been a tendancy to jump but more on sprocket 1 and 2. The current jumping became much more noticable on Saturday on a long ride. It seems to be much worse. The current chain is thus < 2 months old and has ~800kms on it. The only noticable problem after putting on the new chain was that the 2nd chain ring seemed to have a bit of wear causing a ugly vibration through the pedals. That went away after 2 rides. What I think is pretty obvious is that by leaving the orginal chain on for 3000+kms I have worn out a number of components. I am just surprised the evidence is coming from sprocket 1-3. I don't use them often in training. The most frequently used is 4,6,7,8,9. They all behave well. Other thing to note, in the past 4 months I have focused on climbing in higher gears, using more power and standing a lot more on climbs and short bursts. So I suspect I will wear the chain faster. If it boils down to rear cassette wear, then I know the obvious would be to replace the cassette and chain, but would I have to replace the crank chainrings? I see $$$ signs. Thanks Daxiet2009-02-16 11:04:21 Link to comment Share on other sites More sharing options...
Johan Bornman Posted February 16, 2009 Share Dis wat ek bedoel nou k@k jy my uit op die volgende paragraaf. Ons is nie almal so tegnies soos jy nie. Ek *** jou nie uit nie. Ek verduidelik maar net hoe olie op kettings werk. Stuur asb vir my ook van daai poppiesaad. Vir koekies wat ek wil bak, natuurlik. Link to comment Share on other sites More sharing options...
Sammajoor Posted February 16, 2009 Share Dis wat ek bedoel nou k@k jy my uit op die volgende paragraaf. Ons is nie almal so tegnies soos jy nie. Ek *** jou nie uit nie. Ek verduidelik maar net hoe olie op kettings werk. Stuur asb vir my ook van daai poppiesaad. Vir koekies wat ek wil bak' date=' natuurlik. [/quote'] Jy wil space cakes bak, daai shock darem toe gewerk wat ek jou gestuur het Link to comment Share on other sites More sharing options...
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