Occasional Chain slip

[I like Skol]

IME a worn chain rarely slips on the cogs unless we are talking EXTREME wear and the teeth are little more than ramps. the chain and cassette wear together and continue to mesh well until they just won't anymore.

I think gbb could have a good shout, but also could just be a stiff link. Might be worth closely inspecting the chain link by link for a stiff or broken link.

 

[gbb]

Trouble is it happens very occasionally and only slips slightly so by the time I've noticed it and stopped looking a the scenery, everything is normal again.

That's exactly how my Bianchi started to show problems, just an occasional split second like there was no chain, cranks would lurch forward 1/4 of a turn at the most with no tension, then suddenly engage and away you go, very little noise or other sensation.

 

[battered]

Trouble is it happens very occasionally and only slips slightly so by the time I've noticed it and stopped looking a the scenery, everything is normal again.

It's the freehub then.

 

[Andy in Germany]

It's the freehub then.

Well, poo. Thanks for the help though. Will look for a replacement.

 

[battered]

Well, poo. Thanks for the help though. Will look for a replacement.

Try flushing it out with WD40. It just might clean up, then you can add some light oil and go some more. One snag is that you can't buy just the freehub, you have to buy a hub, and unscrewing the freehub from the hub when it's not in a wheel can be tricky. If you have 2 old spokes and a vice, easy. If not, hmm.

 

[Andy in Germany]

Is this the sort of thing I need? It's a while since I last bought a freehub, so I'm unsure...

https://www.rosebikes.com/xtreme-ae...?product_shape=standard&article_size=Standard

 

[Ajax Bay]

Andy Follow your nose.
Go out a systematically check whether you can induce slip on each sprocket in turn: up a gentle hill and put power down, expecting the slip to minimise the effect if it happens.
Replace the chain and cassette (which I judge is the most likely cause (of the two) mostly because it's far more 'common'). And if that sorts it, great. Only if it doesn't, procure a replacement freehub and fit. Of course then you'll have a nice new cassette and chain combo which your bike will appreciate: it shows you love it/her/him/them. Think you'll need to share the make/model of hub to get an answer on which freehub (but I would hold off its purchase).

 

[battered]

Is this the sort of thing I need? It's a while since I last bought a freehub, so I'm unsure...

https://www.rosebikes.com/xtreme-ae...?product_shape=standard&article_size=Standard

What hub do you have? this dictates the freehub. As said above though, if you don't know then stick a new cassette and chain on it, that's inexpensive and easy.

 

[Andy in Germany]

Andy Follow your nose.
Go out a systematically check whether you can induce slip on each sprocket in turn: up a gentle hill and put power down, expecting the slip to minimise the effect if it happens.
Replace the chain and cassette (which I judge is the most likely cause (of the two) mostly because it's far more 'common'). And if that sorts it, great. Only if it doesn't, procure a replacement freehub and fit. Of course then you'll have a nice new cassette and chain combo which your bike will appreciate: it shows you love it/her/him/them. Think you'll need to share the make/model of hub to get an answer on which freehub (but I would hold off its purchase).

What hub do you have? this dictates the freehub. As said above though, if you don't know then stick a new cassette and chain on it, that's inexpensive and easy.

Hmm. I'm about to start work for an NGO which amongst other things refurbishes and sells used bikes. I think it may be worth holding back on the freehub until I go there; I suspect I can pick up a used rear wheel with hub for not too much.

I'll be following your advice though, thanks...

 

[Gunk]

I built up a bike last summer which did that, a replacement cassette cured it.

 

[I like Skol]

I built up a bike last summer which did that, a replacement cassette cured it.

But I guess you put a part worn chain onto another part worn cassette that had not previously run together?
A chain and cassette that have worn together from new do not often have meshing problems until they are horrendously worn beyond reason.

 

[Gunk]

But I guess you put a part worn chain onto another part worn cassette that had not previously run together?
A chain and cassette that have worn together from new do not often have meshing problems until they are horrendously worn beyond reason.

I had replaced the chain

 

[I like Skol]

I had replaced the chain

So a new chain on an old cassette? Not the OP's problem.

 

[Andy in Germany]

I just tried the bike in different gears and took it out shopping: no slippage whatsoever.

Afterwards it occured to me that the day I got slips was on my commute test run, and I was using the big ring a fair bit. As this happens but rarely I tended to forget and change down on the cassette, and I'm wondering if that was when I was getting slippage.

 

[Ajax Bay]

If, after testing, it's not slipping with some power on, then a cassette and chain change is unlikely to make a difference. I have only ever had one freehub fail on me, and the symptoms were not the same as you described in the OP.