Chain skipping on smallest sprocket..

[wafter]

Unfortunately I continue to have problems with the gears on the Fuji..

A brief recap; the bike was bought used and as-received I had a problem with it "ghost shifting" at one point on the cassette; any attempts to tune this out typically meant that the affected gears just altered; i.e. the problem would remain but shuft up and down the cassette depending on my adjustment. It's been suggested that this might be an RD hanger issue, but I'm yet to pull my finger out and make a tool to check its alignment.

I've been running the shifters in friction configuration to minimise the effect of this problem. As received the drivetrain was predictably filthy; however what appeared to be the original chain was still within wear limits. Despite this I struggled to get the chain clean so replaced it with a new, waxed alternative.

In recent weeks I've noticed the chain slipping on the smallest sprocket on the cassette. This started off as occasional but now it barely retains any engagement at all.

To me this smacks of a worn sprocket (and "new chain, old cassette" syndrome), however I'm skeptical of this since the chain wasn't excessively worn and cassettes usually last longer than chains... whilst the smallest sprocket is a bit of an odd one to wear (yes it has fewer teeth, but should see a lot less use than those in the middle of the range unless the previous owner's riding style was a bit odd).

I recall I had similar on my old giant after replacing the chain and sorted that by apply more RD spring tension on the "B screw" however am struggling to find similar on the Fiju's RD. All being well I'll maybe take a look later and make sure the RD is moving correctly etc, but would welcome any thoughts people might have.

I don't really want to replace the cassette, however at least they're not particularly expensive and if the wear's limited to only the smallest sprocket I could maybe use individual sprockets off the current one in future..

Cheers

 

[Ajax Bay]

but I'm yet to pull my finger out and make a tool to check its alignment.

chain slipping on the smallest sprocket . . .

whilst the smallest sprocket is a bit of an odd one to wear . . .

unless the previous owner's riding style was a bit odd).

I could maybe use individual sprockets off the current one in future..

Your phrases above caught my eye.
I shall assume that the bike has been ridden in the small sprocket 'all the time' but odd that the chain is still well within spec but has managed to wear said sprocket.
Yes: use a small/outer sprocket from an old cassette (LBS bin) which has worn in those middle sprockets: will be fine (doesn't need to be exactly same speed btw).
Check that hanger alignment: a tool will do it accurately, but (search on here) you can bodge a first effort, which may be enough to fix your shifting issue.

 

[Dogtrousers]

To me this smacks of a worn sprocket (and "new chain, old cassette" syndrome), however I'm skeptical of this since the chain wasn't excessively worn and cassettes usually last longer than chains...

Could it be that the not very worn chain on the bike when you bought it was a replacement for a previous one one that was worn to buggery?

 

[wafter]

Thanks both

Your phrases above caught my eye.
I shall assume that the bike has been ridden in the small sprocket 'all the time' but odd that the chain is still well within spec but has managed to wear said sprocket.
Yes: use a small/outer sprocket from an old cassette (LBS bin) which has worn in those middle sprockets: will be fine (doesn't need to be exactly same speed btw).
Check that hanger alignment: a tool will do it accurately, but (search on here) you can bodge a first effort, which may be enough to fix your shifting issue.

Indeed.. I guess it would be reasonable that while a cassette should easily out-last a chain if the wear has been distributed across all its sprockets, if, for whatever reason the rider had a particular fetish for the smallest and used this significantly more than the others then this could account for the situation.

I do absolutely need to do the hanger alignment; but am caught between being too tight to buy a proper tool, too untrusting to take it to a shop and too unproductive to knock one up myself.. nearly scored a suitable bit of steel angle last week as it happens, but it turned out to be a bit to thin and manky.

So, do you think it's safe to assume that the skipping problem on the smallest sprocket is due to wear rather than a hanger issue? Since I noticed it, it's deteriorated very rapidly and it certainly doesn't seem to be a shifting-related problem (i.e. the chain is straight riding over the teeth on the sprocket, rather than losing engagement because it's trying to climb up to the next one).

I have been looking at replacement sprockets on ebay; yes - I believe that sprocket thickness is constant across most "speeds" (I'd certainly think 8/9/10/11 sp) so in theory anything Shimano / compatable would fit. I can't find exactly what I'm after (HG400), am dubious of aftermarket or used but there are some new Shimano items on there. Thing is they seem to start at about £8 (for a Deore XT item), while I could get a complete replacement HG400 cassette for £30.

Also, interestingly one listing shows different parts for an 11T sprocket for 11-32 and 11-34 cassettes; not sure why this would be...

Could it be that the not very worn chain on the bike when you bought it was a replacement for a previous one one that was worn to buggery?

Yes; it certainly could. While the bike's evidently not had an easy life it's not hugely old (2016) and the once cleaned up the drivetrain components look pretty good tbh (although granted it's not easy to identify sprocket / chainring wear by eye).

 

[Dogtrousers]

I suppose the cheapest solution would be - don't ride in the littlest sprocket.

 

[All uphill]

Could it be that the limit screw is preventing the derailleur going far enough for the chain to sit happily on the smallest cog?

Sorry @wafter for implying you could make such a simple error; please forgive me.

 

[Ajax Bay]

I have been looking at replacement sprockets on ebay; yes - I believe that sprocket thickness is constant across most "speeds" (I'd certainly think 8/9/10/11 sp) so in theory anything Shimano / compatable would fit. I can't find exactly what I'm after (HG400), am dubious of aftermarket or used but there are some new Shimano items on there. Thing is they seem to start at about £8 (for a Deore XT item), while I could get a complete replacement HG400 cassette for £30.

If you haven't got a 'maybe I can use this sometime' cassette to cannibalise, honestly think your LBS will have used cassettes in their bin and can fish out an 11t sprocket for you for free. That will not be worn (because 'normal' riders don't ride around lazily or ignorantly on that sprocket). Just needs to be Shimano/SRAM. Could use a 12t (assume next one up is 13t) but would need a 12t lockring.
Meanwhile, adopt the @dt approach.

 

[wafter]

I suppose the cheapest solution would be - don't ride in the littlest sprocket.

Indeed - this has been my option until now, however I like things to be right and obviously the gear's there to be used!

Could it be that the limit screw is preventing the derailleur going far enough for the chain to sit happily on the smallest cog?

Sorry @wafter for implying you could make such a simple error; please forgive me.

That was my first thought / hope; however I gave it half a turn the other day whilst out (to no avail) and upon closer inspection recently the RD cage was actually sitting excessively outboard..

If you haven't got a 'maybe I can use this sometime' cassette to cannibalise, honestly think your LBS will have used cassettes in their bin and can fish out an 11t sprocket for you for free. That will not be worn (because 'normal' riders don't ride around lazily or ignorantly on that sprocket). Just needs to be Shimano/SRAM. Could use a 12t (assume next one up is 13t) but would need a 12t lockring.
Meanwhile, adopt the @dt approach.

Thanks - unfortunately I don't have an old spares cassette and tbh would feel bad bothering the LBS for freebies as I rarely use them for anything else. I've put my hand in my pocket for a replacement cassette - which I think was cracking value at £20 posted for a new, genuine Shimano (Alivio / HG400).

I'll keep the old one for spares as you suggest; although hopefully with the waxed drivetrain it should be a very long time before they're required

 

[cheys03]

Edit: apologies, didn’t refresh to see your last post, Wafter. The below is largely irrelevant now

Perhaps fit new cassette and chain, knowing you’ll need to replace them eventually. They can be left fitted or removed and put on the shelf depending how the further testing goes.

Test using the new components to confirm/rule out wear or incorrect adjustment being the cause.

If it’s perfect with new parts after readjustment you have the cause.
You can then decide to leave the parts fitted or further diagnose which sprockets are worn to make a frankencassette.

If it’s the same, you know it’s not cassette+chain wear causing it.

 

[T4tomo]

I do absolutely need to do the hanger alignment; but am caught between being too tight to buy a proper tool, too untrusting to take it to a shop and too unproductive to knock one up myself.. nearly scored a suitable bit of steel angle last week as it happens, but it turned out to be a bit to thin and manky.

there are plenty on ebay for about £20 which work perfectly fine. if you have a few bikes and or your mates come to you with bike problems then its a damn good investment

 

[wafter]

Cheers both - as per above post, cassette ordered and I'll hopefully be able to fit it a bit later in the week. I'm quietly hoping this might cure the shifting ills too, although that remains to be seen.

As for component age; it seems that everything on the bike was original when I got it (barring the saddle and some accessories). The bike however was a state and I think had been poorly (or not at all) maintained, so it's not outside the bounds of reason that an excessively-used small sprocket with a dirty chain might have expired in a similar amount of mileage to the original-fit rear tyre..

 

[wafter]

For closure, as per this thread the cassette arrived and the skipping turned out to be due to wax buildup from my waxed chain; the original now working perfectly and the new one kept as a spare

 

[C R]

For closure, as per this thread the cassette arrived and the skipping turned out to be due to wax buildup from my waxed chain; the original now working perfectly and the new one kept as a spare

How hard does the wax residue get to cause skipping?

 

[wafter]

How hard does the wax residue get to cause skipping?

Evidently hard enough

As per the link I think it was mostly compacted moly powder; probably eaxcerbated by my experimentation with making the wax mixture itself softer.. so I'll take measures to adjust it next time and see how I get on. Worst case I'm wise to it now and can just give the cassette a brush out every few waxings..

 

[cheys03]

I’m happy for you that the cause is fully understood and learnt from - it’ll never cause you this problem again. Thank you for sharing too so that those of us in a similar situation can make a quick check as needed.