Highest gear on cassette slipping

[Archie]

Hey folks, so last weekend I installed a new 7 speed cassette and 8 speed chain, mostly because the old drivetrain was knackered, but partly to put an 11 tooth high gear on instead of 12 to give a slightly higher gear.

Everything's working fine apart from the high gear now occasionally slips when putting pressure on the pedals. I've checked the indexing and tweaked the high adjuster screw to allow the mech slightly more movement out so the chain now sits straight over the cog, so I'm pretty sure it's not an indexing issue. Of course, when running the gear in the workstand it works fine. That seems to indicate it's the power that's causing the slip.

Can anyone give some inspiration on what to check next? I'll be looking the bike over again at the weekend so would appreciate any ideas.

 

[RecordAceFromNew]

Can anyone give some inspiration on what to check next? I'll be looking the bike over again at the weekend so would appreciate any ideas.

With both cassette and chain being new, if it is the rear that is slipping then the likelihood is worn spline, ratchet teeth or pawls in the freehub, which are usually not serviceable. Whether a worn freehub is replaceable is dependent on the make/model of the hub.

 

[Tim Hall]

Or it might be a stiff link, from when you joined the new chain. The smallest sprocket puts the chain through a tighter radius, and if there's a stiff link, the chain doesn't quite get round, IYSWIM.

Run the chain backwards and watch for it skipping. If you do find a stiff link, loosen it either by using your chain tool on the upper ledge, or by flexing the link across the way it travels.

 

[the_mikey]

I had this problem with a new chain and cassette, but swapped to another cassette by a different brand, problem went away. (the problem cassette was made by BBB, the good cassette was made by SRAM)

 

[Hip Priest]

Or it might be a stiff link, from when you joined the new chain. The smallest sprocket puts the chain through a tighter radius, and if there's a stiff link, the chain doesn't quite get round, IYSWIM.

Run the chain backwards and watch for it skipping. If you do find a stiff link, loosen it either by using your chain tool on the upper ledge, or by flexing the link across the way it travels.

I just had this exact problem with a stiff link on a new chain. Although the fact that it's only slipping in one of Archie's gears suggests there might be another cause IMO.

 

[TheDoctor]

11T sprockets use a different (smaller) lockring. Did you use the locking that came with the cassette?
And is the 11T sprocket properly seated on the splines?

 

[Broadside]

I'll go with RAFN as he has never said anything I have ever disagreed with! BUT, I recently got a new bike and when standing up to sprint in top gear the chain did slip a few times but now with 400 miles on the bike it is totally fine. The initial lube on the chain can be quite heavy and so I have put it down to the chain being a bit sticky and perhaps not wrapping around the cassette as well as it ought to until it freed up (thanks for that idea Tim H) who knows though. Annoyingly it caused the chain to bounce and it stripped some paint from the bottom of the seat stay which is really annoying but there you go...

 

[Shut Up Legs]

Or it might be a stiff link, from when you joined the new chain. The smallest sprocket puts the chain through a tighter radius, and if there's a stiff link, the chain doesn't quite get round, IYSWIM.

Run the chain backwards and watch for it skipping. If you do find a stiff link, loosen it either by using your chain tool on the upper ledge, or by flexing the link across the way it travels.

Ah, thanks for that comment! I had exactly this issue with a new chain/cassette/front chain rings installation, so I'm guessing it was 1 or more tight chain links.

 

[Archie]

Thanks for the ideas guys. Disappointingly it looks like rain here so I probably wont check until tomorrow. However;

RAFN: Would you expect a worn freehub to show these symptoms on the highest gear only?

themikety: It's a Shimano cassette, so should be pretty kosher I'd have thought.

TheDoctor: Used the lockring provided, but I can't say it looks much different to the old one.

dmoran: That's an interesting theory. Fair to say, there's a fair amount of grease/oil with the new chain so it will take a while to wear that away.

 

[Archie]

Been meaning to post an update on this for a while. The issue was caused by the quicklink I'd installed when changing the chain. I could only isolate the problem when actually riding - on the workstand the load wasn't enough - but after riding the gear and getting the skipping I'd backpedal slightly and get the skip again. A few repetitions and careful observation identified the culprit.

After re-inserting the missing half link (not straightforward) all is running fine.