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I have this problem with my bike when I put an amount of pressure on my pedals the chain kinda jumps but doesn’t change to a higher or lower gear and it usually happens when I go on 3X7 and 3X6 when I change it to 2X7 it doesn’t happen as usual as 3X7. I have even changed my chain and derailleur but it still happens what could the cause of this be.

  • What do you mean by "the chain kinda jumps"? Could you give a more detailed description? Is it that the teeth of the cogs temporarily stop gripping the chain so the pedals briefly spin quite freely without driving the chain? (If so, the cogs are worn and you need to replace the front and rear ones.) – David Richerby Jun 24 at 16:45
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    Chain wear, sprocket wear, both, the chain is too long, or the derailer is bollixed. – Daniel R Hicks Jun 24 at 17:45
  • When I pedal at first it feels normal and I mean it is hard under my feet and when I push down on the pedal hard it the pedal gives in and the pedal spin fast for an instant then it goes to its normal hardness – Ss S Jun 24 at 19:27
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    I'd predict this slip problem will grow worse, will happen at lower and lower foot pressures, till the day your foot slips off and you do yourself a mischief with the saddle. Suggest you follow the replacement suggestions in the answers before that level of wear is reached. Source: Personal experience ! – Criggie Jun 26 at 4:03
  • Thanks for the warning I will be sure to change my sprocket – Ss S Jun 26 at 12:22
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Your chain may slipping over the teeth of the cassette sprockets if they are badly worn. This seems the likeliest as the problem occurs when you put increased force on the pedals. Slipping is more likely to happen when on a smaller chainring at the front because the greater leverage is putting more force on the chain. The solution is to replace the cassette.

Another possibility is that you are getting incomplete 'ghost shifting'. The chain is catching the shift ramps on an adjacent sprocket. This should be fixable by indexing the rear derailleur properly.

  • If the cassette is that worn, then likely the chain is worn as well. It's best to replace both unless you've just replaced the chain and then start noticing problems. – Fred the Magic Wonder Dog Jun 28 at 1:06

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