Half way thru my ride this afternoon, my chain starts jumping around in the smallest rear cog in both middle and big front rings. It started a few minutes after getting a whole load of bracken snagged in there. Gave it an “on-trail” clean but couldn’t solve the skipping. Not sure if the teeth are worn (cassette about 9-12 months old) or if there is something else I should be checking.

Appreciate this is a v basic question but I am a mechanical numpty. Any ideas that I should check before visiting LBS?

Rear mech out of alignment? (maybe when removing said bracken)

If it started all of a sudden like- the bracken thing may have bent or twisted your mech hanger. Or mech. Or theres bracken under a limit screw. Or ….

Thanks guys, yes rear mech alignment was my second thought (happened before). I have folk coming round soon so need to have another look in the morning. I guess if it’s only the one cog (in he past bent hanger was 2-3 cogs), it should be an easy tweak? As the lBS said before a bit of cold bending!!!

Just watched the park tool video – don’t have one of their alignment gauges so may need to be careful in the morning!!

Bllx!! not just a simple “manipulation” of the hanger then. Sad to have insufficient skills to sort this out 😳 looks like a little trip to LBS

I bought one of these to do the job last week.
http://www.bike-discount.de/shop/k839/a9183/derailleur-hanger-adjustment-tool.html?mfid=295
If you use it twice, it’s paid for itself.

Worked a treat. Align vertically, then horizontally. Take it easy and do a little at a time (no ham fisting!), checking after each ‘manipulation’.

Popped into LBS (not normal one as it is a Sunday) and couldn’t find anything wrong. Fine in the stand but after a little tweaking only slight skip in the big ring but more occassionally when ridden down the road. Not sure what the answer is. Unsurprisingly, the LBS went for the default new cassette option. Not sure that is correct given that it is now only happening more occassionally in big ring and not in middle ring any more. Sigh…..

My guess [from experience]of the same thing is you have a worn chain,its only a guess but i had the same problem,new chain problem sorted

Thanks, but we checked the chain and it’s ok!

So far tried – clean the bike (!), check alignment/hanger etc, check limiting screws, check chain, check cables, check teeth on cog.

There is “some” slight wear on the cogs/teeth and I have ridden a lot this summer, but not as much as normal when the chain starts to skip.

denials more than a river in egypt.

if it looks worn and it sounds worn – its probably worn.

have you another wheel to try as my guess is also it is worn.

An eye test IME is useless for telling if this is the case or not hence i try another casette

Ialso try the same wheel in the other bike to be sure

Yes, probably worn in the end. But will have another clean and a quick ride to see if it is any better first. I thought with the dry summer that cassettes would last a bit longer this year. Having said that I have ridden a lot.

At least, if the pro mechanics couldn’t spot the problem, I dont feel such a numpty!!!

But no, I dont have another cassette/wheel. If there is still a problem later, I will take the LBS’ word for it!!! 😉

perhaps you were going faster or riding flatter routes so using the little cog more?

or have you become a bodged 1×10 convert recently and now use your little cog more because the range is shite;)

check you dont have a stiff link in the chain.