Right - recently took off my old chain for a deep cleaning & discovered a couple of cracked links, so I launched it right in the bin & bought a new one (KMC X10 - decathlon branded) upon fitting & shortening it using the large/large +2 method I subsequently discovered that the cassette was now past the point of receiving a new chain as it skipped on pretty much all gears, except when using the bottom 2 cogs, so that went in the spares box & I invested in a new Tiagra cassette in the same flavour ratio, fitted that & stood back to gaze at the shiny newness of it all.
Then I went out for a test spin (20 miles to work) & to my annoyance found the chain still skipped when in the small front ring & using the bottom 3 or 4 cogs on the new cassette under load, not a big deal, so I whipped off another link thinking i'd been over-cautious with my shortening - this helped a bit, but when out of the saddle on climbs (again, small ring at front) using the 3rd or 4th bottom cogs on the cassette it still jumps occasionally.
So I shortened it again - result is the chain now won't shift into the top 2 cogs when using the big ring up front without the mech cage hitting the cassette due to the chain tension (b-screw has little effect here, anyway it was fine before) and the shitting thing is still skipping under load in the same cogs it was previously...
I vaguely remember something about KMC chains being slated a few years back, is it the chain or is it me? Rest of the drive is Sram Apex 36/46 & 12-28
Cheers,
J
KMC chains are fine, I bet its your chain rings. How many miles have they done? Will it shift in the smaller ring?
You know the solution is that you need a new bike right?
How long did you ride the new chain on the old cassette for? Aspin round the garden is fine but worn cassettes wear new chains down very fast in my experience
your indexing ok? jockey wheels ok? chain/cassette fitted ok? theres no real reason why it shouldn't work. rather than removing links fine tune the b tension screw can sometimes help.
The obvious answer is that the small chainring is worn. Chains don't usually slip because the chain's too loose unless it's literally hanging loose with the mech swung fully back.
Or, how long did you ride the new chain on the old cassette? Unlikely but it would eventually 'stretch' to match the old cassette.
yup probably chainring i'm afraid
I'd check the jockey wheels
Stiff link? Check all the chain links are moving freely, give the whole chain a good side to side flex at each link.
Chainring, did this myself a couple of weeks ago, thought I was being proactive, went for a ride, chainrings were past it, they look ok to the eye as well, you can't always tell by looking.
Replace chain / cassette / rings as one when they start to skip, otherwise you just buy them, well one at a time like you are doing 😉
Hi all,
Cheers for the responses - the chainrings have probably seen 3k (ish) miles & now I have proper look at them, they are looking a bit worn so I guess it could be that, but everything still shifts lovely - i've been pretty impressed with the Sram kit actually as I ran this right through one winter one year with nary a tweak required...
Anyway - when I replaced the chain prior to changing the cassette it seen probably 40 miles using only the 46 front & the bottom 2 cogs on the old one, which looked literally like new, my commute is pretty flat & i like spinning rather than mashing so I usually only really ride across the middle 5/6 cogs... wife had left for work already with the car & I decided to man up and mash the bigger gears for a change... perhaps "mash" is the operative word here
That new bike might be a shout 😳
It's not a directional chain that's on the wrong way is it?
Some types of quck link (like the KMC) ones if fitted the wrong way cause jumping but that's usually once per revolution and only on the smallest cog of the cassette (on Shimano XT anyway).
Are you using a mixing link or a pin type (like shimano)?
Check the link seated properly. If its the pin type, it may be pushed too far forward as catching the shifting ramps.
Check your cassette lock-ring is tight, I had a spacer break and disappear leaving the cassette loose with a slight wobble, only skipped under higher powers so all seemed fine on the bike stand.
It's a KMC quick link - tried turning it round just in case but made no difference... Actually, I've not tried the cassette locking tightness yet although this exact thing happened to me at Glentress one day after a hasty cassette swap & I couldn't work out what the hell it was - another thing to try before I set it on fire & break out the credit card 😆
The bike's due a proper strip down & rebuild - if I can cobble it through until October-ish I'll strip it & get the frame blasted & powder coated to cover all the scratches and do everything properly... Well, at least replace the cables, BB & chainrings... and the bars & tape... and headset in fact... 😐