[AC/BC]

Ok, first ive just replaced my cassette with XTR and my chain with a Scram PC99. I took it into a shop to get the shifting adjusted. It shifts wonderfully now. Although when I pedal really hard up hill the cassette breaks loose, it feels like it slips for a pedal stroke then engages like normal. I don't think the chain is jumping to another gear because it stays in the same gear and everything shifts fine. Do I need to torque my cassette down harder? I only tightened it to where it felt good... but im second guessing whether i should have used a torque wrench. Or, is it something in the wheel like the sealed bearings going bad? It didnt do this before I replaced all this stuff.

 

[Jayem]

It's probably slipping on your chainrings, which were worn out by your old chain.

 

[AC/BC]

It's probably slipping on your chainrings, which were worn out by your old chain.

Chainrings (new xtr cassette) are new, and so is the chain.

 

[245044]

He's talking about the chainrings......on the crank. If they are badly worn, the chain can jump on them.

 

[AC/BC]

He's talking about the chainrings......on the crank. If they are badly worn, the chain can jump on them.

Im pretty sure its coming from the back. My crankset is only 2.75 years old but i've done some hard riding. It might be time to replace them. But im pretty sure its coming from the back. Is there anything on the back that would cause this? Possible something in the hub? I will look into buying a new set of chainrings though, thanks.

 

[mtb_biker]

3years on a set of chainrings is alot if you ride your bike.

If you know how a cassette works you should know that it sits on a fixed slots so if you overtighten it, its not going to make it any snugger. Its possible that the pawls in your hub aren't engaging (ie your hub needs some service). does the skipping happen in every single gear?

 

[mjenkins]

I agree that it is probably the chainrings. 3 years seems way too long if you ride quite a bit. I had the same skipping problem when I replaced my chain after about 8 months of riding. Try putting the chain in the largest gear in the front. Chances are that ring gets used less and you won't have the skipping problem. On most cranks you can replace the chain rings independently, so you may only need a middle and/or small ring.

 

[willtsmith_nwi]

Rings ...

When you've worn a chain ... thats it. All the components working with that chain are now married to one another. You will have worn the pitch of that chain into your cassette and your rings. Especially if they are aluminum.

I know from first hand experience. If you wear a chain, you have to replace all of them together. The solution to your problem is to replace the rings as well. While you're at it, buy a chain checker and a spare chain. As soon as the chain shows any where whatsoever, replace it. This will save you a considerable amount of money in the long run as chains are less expensive than rings and cassettes.

 

[watermoccasin]

Sounds like your freehub body is toast. If it's a Shimano or Mavic hub, it's even more likely. Sometimes they are fixable, other times you have to buy a new hub/wheel. What kind of hub is it?

 

[Jayem]

Sounds like your freehub body is toast. If it's a Shimano or Mavic hub, it's even more likely. Sometimes they are fixable, other times you have to buy a new hub/wheel. What kind of hub is it?

Not likely, when the freehub goes, you know it and it doesn't work any thereafter.

 

[dhpimp]

Ok, first ive just replaced my cassette with XTR and my chain with a Scram PC99. I took it into a shop to get the shifting adjusted. It shifts wonderfully now. Although when I pedal really hard up hill the cassette breaks loose, it feels like it slips for a pedal stroke then engages like normal. I don't think the chain is jumping to another gear because it stays in the same gear and everything shifts fine. Do I need to torque my cassette down harder? I only tightened it to where it felt good... but im second guessing whether i should have used a torque wrench. Or, is it something in the wheel like the sealed bearings going bad? It didnt do this before I replaced all this stuff.

If the chain slips on the cassette then you will be able to see it. If the Cassette isn't on tight enough then it will do it in any gear - but mostly the ones that you can really torque in. However, if it just when you climb then I would say have your freehub body serviced - and don't worry you won't have to replace the whole wheel. If you have a Shimano freehub body you can either replace it or have a mechanic use a tool called the 'freehub buddy' to pump oil into it and make it smooth again. Hugi uses a star rachet design so those could be worn. Mavic's pawls tend to wear quickly. There are tons of possibilities. What kind of hub is it??

 

[Stalk]

Check if skips are still happening on the largest cog of casette.
The good chances are shifting is not tuned very well. It doesn't require a lot of precission to get shifting of lightly loaded drivetrain, grinding uphill it's were the trick is.

Preloaded bike due the flex of the rear (applied to hardtails as well) will cause different angle of chain engagement.
If you using Shimano, try 1-2 clicks on the rear cable adjuster both direction, On SRAM, I found it's translates into quite more clicks on the trigger shifter.

And no, you can't see chain dragging/skipping due slight missalignment unless you filming it with high framerate camera.

 

[tick]

I just had an identical problem with my bike. I swore up and down that the chain was slipping on the casette (both brand new), but it was actually the front chainrings.

Does your problem occur on only one chainring, or several? If your front chainrings aren't brand new, you should probably go ahead and replace them (or at least the one causing the trouble).

And this thread may be of some help: http://forums.mtbr.com/showthread.php?t=207904

 

[Jayem]

Check if skips are still happening on the largest cog of casette.
The good chances are shifting is not tuned very well.

No. When the derailer's out of tune it "jumps", not "skips". It's a different action.

 

[shiggy]

No. When the derailer's out of tune it "jumps", not "skips". It's a different action.

But does the OP know the difference?

 

[Stalk]

exactly.
At the end you feel like spinning pedals more then moving wheel. And by coincident I just went through swapping casette/chain and retuning shifters. Once I put casette, the old setting starts showing "skipping" on the tough uphil or out-of-saddle cranking, hence few turns of the adjusting nut and all crisp and clean.

 

[danoalb]

I had the same thing happen

Im pretty sure its coming from the back. My crankset is only 2.75 years old but i've done some hard riding. It might be time to replace them. But im pretty sure its coming from the back. Is there anything on the back that would cause this? Possible something in the hub? I will look into buying a new set of chainrings though, thanks.

I was sure it was the rear cassette but it ended up being the front rings. I replaced all 3 front rings and it ran like a dream under any load and condition.