Gears jumping, after new cassesste, chain & derailleur

canoas

Well.....I just have my bike back from the official Giant shop in London, they replaced the cassette, chain and large chain ring plus new brake cables. This all needed attention, the large ring was as sharp as jaw teeth, after 3 years of London commuting. Anyway......I could hardly ride home which is 15 miles. The gears are jumping like hell, I first saw the KMC chain link wasn't properly tightened, sorted that out thinking that was the problem.....then again, skip, jump and a skip jump! Its not the rear barrel adjuster as the gears are moving nicely up and down and from lower to upper ring vice versa.

Could it be the B-Srew needs tightening? Maybe derailleur is too close to the cog? I haven't checked yet. Any ideas?

Bitterly disappointed after spending £240, expensive! Ultegra derailleur, 105 cassette, KMC chain, and Ultegra 50 ring and cables, jagwire.

spankwilder

If you've managed to ride it a distance from the store with no problems, it's more than likely that the barrel adjuster needs a turn. What gears jump? all? a few? front or rear gears?

tonysp

Possibly the jockey wheels. If all the other parts have been replaced due to being badly worn then I reckon the jockey wheels will be pretty knackered also.

chrisaonabike

What about the gear cable? I had problems last year with poor selection, and jumping after selection. I'd fiddled about with the barrel adjuster to no avail.

Someone here suggested looking for cable fraying where it attaches to the shifter. Sure enough it was all frayed to buggery, introducing slack.

Perfect after replacement,

arlowood

ChrisAOnABike wrote:

What about the gear cable? I had problems last year with poor selection, and jumping after selection. I'd fiddled about with the barrel adjuster to no avail.

Someone here suggested looking for cable fraying where it attaches to the shifter. Sure enough it was all frayed to buggery, introducing slack.

Perfect after replacement,

^^^ +1

Your LBS service summary covered everything crucial except the gear cables. Were they replaced along with the brake cables. If not I strongly suspect that you have some snagging issues along the cable somewhere or at the shifter.

Recently completed a build with all new 105 components. Initial gear changing was great but after about a week I started to experience the problems you describe - chain skipping and clicking on the cassette. Did a re-indexing exercise but that did not cure the problem. Eventually disconnected the gear cable and pulled it part way through at the shifter end. Applied plenty of Teflon lubricant to shifter and inner cable and re-assembled. All now working sweet as a nut.

canoas

had the bike on my stand this afternoon and everything seemed ok in regards to cables, gear shifting etc, then I started slowing down each rotation to figure out why the jockey wheels were jumping, and its the KMC chain master link. The master link looks fine to me, but it seems most rotations the master link makes the noise and jumps in jockey wheel (new derailleur) . First time I've ever used or had KMC, going to take the bike to my local bike shop and see if they can have a quick look free!

arlowood

canoas wrote:

had the bike on my stand this afternoon and everything seemed ok in regards to cables, gear shifting etc, then I started slowing down each rotation to figure out why the jockey wheels were jumping, and its the KMC chain master link. The master link looks fine to me, but it seems most rotations the master link makes the noise and jumps in jockey wheel (new derailleur) . First time I've ever used or had KMC, going to take the bike to my local bike shop and see if they can have a quick look free!

Maybe they fitted a chain for an 8 or 9 speed set up - these are a bit wider than the 10-speed variety (I'm assuming you're running 10-speed). However I would have thought the derailleur tolerances would have coped with the slightly wider chain. Can't hurt to get them to fit another chain or a new master link to sort it out - after all it was their servicing that introduced the problem.

Ouija

Just sounds like the KMC master link is a stiff link. Try removing it and greasing the insides of it, reattach and see if it hinges properly without any resistence.

Bozman

Take the factory grease off and relube the chain or it'll be a quarter/half a turn on your cable adjuster.
I've had it twice in the last 12.months and a mate has had this issue once, both of us had chain slip under load after replacing the chain, cassette and chainset.

canoas

Ouija wrote:

Just sounds like the KMC master link is a stiff link. Try removing it and greasing the insides of it, reattach and see if it hinges properly without any resistence.

Yep that was the problem, was a stiff link. I moved the master link backwards and forwards a number of times, but my local mechanic had to remove and attach again, all fine now shifting like a peach! He remarks "that's KMC for you". He didn't charge me.

I used Campy on my race/road bike, Shimano for commuting. I usually replace my worn chains with Ultegra on my commuter bike.

One thing my local mechanic was not happy with Giant, a shoddy check. Really bad service, wasn't indexed properly either. Not going back to Giant London again! PLEASE NOTE if you live in London or Greater London.