Chain skipping in top gear only

[Gixxerman]

I have an issue with my Trek 8500.
The chain seems to "skip" every so often but only when under high load and it only happens on the smallest cassette ring (regardless of what front chainring is being used).
I can't quite see what the actual problem is. I have looked at cassette whilst riding slowly and getting the chain to skip, but I can't see what is actually happening. The symtoms are a loud clunk accompanied by the cranks skipping foward a few inches
I have checked the rear derailleur limit screws and they are fine.
I have a KMC powerlink. I checked it and it also looks fine.
Some time ago I noticed that the cassette lock ring was lose and I tightened it.
Thinking about it, the problem started soon after a trip to Sherwood pines and where I believe that the cassette lock ring came lose as I noticed it a few weeks later.

I have also noticed that the rear brake makes a low squealing sound when freewheeling, as if the rear brake is catching the disk.
I thought that it might be the rear wheel moving in the drop-outs. But I have have checked that quick release and it is done up correctly. I've tried to move the wheel in the drop outs but it Iis solid.

So could the lose lock ring have caused some damage that is now causing the skipping issue?
Could the rear wheel thing be connected?
Rear hub issue maybe?

Any ideas or things I should check?

 

[jack smith]

Is your rear mech hanger bent?

 

[Sharky]

Any stiff chain links?
Are the stops on the RD allowing the chain to go far enough?
Should only be using the big ring with the smallest cog combination. If you are using the small rings on the front, it won't give the best chain line and could be causing the chain to start lifting and then dropping back?

Only a few guesses I'm afraid. Hope you can find the cause.
Cheers keith

 

[Gixxerman]

@jack smith
A fellow Smith eh? Not many of us about .
I don't believe that the hanger is bent. I will check. How would that cause skipping though?
@Sharky
Chain is good (almost new). The high limit screw is a long way out so the mech is (I believe) certainly far enough over to be well engauged with the top gear.
I know about cross chaining, and I never use the top 3 gears when on the smallest chainring. I just mentioned the chainrings to get across the point that it doesn't seem to be an issue with the front mech / chainrings.

What I did notive though is that the rear changer is quite stiff to operate. The cables seem fine and well lubed. Maybe I could take the cables off and give the inners a real good clean. Not sure if this will improve the skippign but it might make it easier to shift.

 

[jack smith]

Not many at all.. Mine was skipping in just the hardest gear and it was due to my hanger being bent in such a way the rear mech couldnt be inward enough to properly engage the gear, if its a 10 speed on an 11 speed wheen check the spacer is the correct width as that will stop it engaging properly too

 

[Yellow Saddle]

A stiff link would have caused such a skip on all cassette sprockets. You probably use your smallest sprocket more than most people and because of its size, it wears much quicker than other sprockets. Therefore, it is now out of pitch with the chain and "skates" over the top. Skipping refers to switching between sprockets whereas skating is when it rides over the top. Cable adjustment and limit screw positions can cause skipping but not skating. The remedy is a new small sprocket. Luckily, these are freely available from bike shop bins. Most cassettes are dumped because two or three of the mid-range sprockets are worn and seldom because the 11-tooth one is worn. Most of us don't grind away in that gear and you may be lucky to find such a sprocket in a rubbish bin. Give it a try.

 

[goldie42]

Noob poster here and only have junk bikes, with similar issues. Stretched chain from over exuberant use, lose or worn wheel bearing, damaged deraliers seized chain links or stiff from crud/rust. Buckled wheels. Wheel bearing was my most recent cause,and because I left it (it didn't jump tooo badly) I actually managed to snap the top gear.

 

[goody]

Have another look at your limit screw. Sounds like the chain is too close to the next sprocket and catching it occasionally.

 

[mustang1]

I have this problem too but so far no solution (actually I juspped using the smallest so that's my solution).

Everything was working fine until one day I noticed the drivetrains squeezing so I squirted some oil in the general direction of the chain and cassette and the next hour I noticed this problem occurred. Men, I might fix it one day or more likely just get a new chain and cassette. Say, might just get a new bike :thumb:

 

[PatrickPending]

New chain - old cassette? That's what it sounds like to me.....
Unless you change your chain before its worn past a certain point you need to change the chqain and the cassette to avoid this problem.

 

[cyberknight]

Have another look at your limit screw. Sounds like the chain is too close to the next sprocket and catching it occasionally.

thats my guess too.

 

[Colin_P]

I'd look at the 'B' tension adjustment. If the chain is too slack it could jump.

 

[screenman]

Start at the beginning every time, this means alignment.

 

[goldie42]

Having re-read your description, it sounds like you May have bent the hub axel when your lockring got lose. Might only be very slight and hard to spot, but enough to catch the chain and cause it to ride up and skate.

 

[screenman]

How often do you use the smallest sprocket? How old is the chain.

I still go back to my other post.