Gears jumping

davegilly · 22-06-2021 8:58pm #1

Dropped the bike into Rothar in Phibsborough (where I bought bike) to have the gears looked at as going from big to small and vice versa on front derailleur was starting to get more difficult and it was due a service as well.

Anyway got bike back today. Went out for a spin this evening and the gears are worse now than when I took it in. Front cogs are fine but it's jumping all over the place on the back gears, hopping between two gears when pedaling. I live about 45 mins from Phibsborough and have no notion of going back again, your man in there was pig ignorant as well.

Is this something I can fix easily at home do you think? Any advice on what I need to adjust? Gears 1 & 10 are the only ones that seem to be fine, the rest just hop over and back or completely skip a gear.

hesker · 22-06-2021 9:37pm

This is the perfect opportunity for you to learn how to do this yourself. Tons of videos on YouTube. Park Tools do good quality ones. It’s quite straight forward really.

I could explain a step by step approach but it’s all already online. Start with that and ask specific questions if you can’t grasp something.

Your first objective is to get it tuned. If it’s still not right you may have worn components or a misalignment. But start with the basics first.

nicksnikita · 22-06-2021 10:09pm

Good advice above...
Best case - rear derailleur cable tension needs to be adjusted.

If that doesn’t solve it, a hanger realignment (maybe not so simple to do at home) or some new components (chain and or cassette) may be required.

davegilly · 22-06-2021 10:28pm

The bike is only 9 months old so I presume or at least I hope nothing has worn out already??

I'll have a look at Park Tools. Thanks for your help

[Deleted User] · 22-06-2021 11:07pm

Wear can be an issue but unlikely at 9 months if you've kept it reasonably clean and not done huge mileage in ****e weather and not cleaned it afterwards.

Did it get a first service after bedding in 200km / 6 weeks?

davegilly · 23-06-2021 8:41am

Enfilade wrote: »

Did it get a first service after bedding in 200km / 6 weeks?

No, this was the first service due to COVID and no travelling/shop closed etc.

I did wash the bike when dirty and lube reasonably regularly, every couple of months.

fat bloke · 23-06-2021 9:17am

I'd be the first to admit that I'm thick as a plank when it comes to mechanicals but even I managed to decrypt the mysteries of the rear derailleur. It's well worth watching any of the vids telling you to reset and microadjust the indexation. The limit screws are probably fine, all's you need the first time is an allen key and from then on just the barrel adjuster.

In fact with the bike so new and so few miles on it, you could just use the barrel adjuster to sort it. - Best to put the bike in a stand so you can raise the rear wheel and turn the pedals. Put the chain on the lowest /smallest sprocket in the back. Click up one index on your lever (which may or may not result in an actual gear change). Turn the barrel adjuster until the chain actually changes to the next sprocket and does so cleanly and runs with minimal clicking. -The theory is that if the indexing is correct under minimal load going from 10 to 9, then it'll be similarly correct for 9 to 8, 8 to 7, 7 to 6 etc etc etc.

davegilly · 23-06-2021 8:55pm

So I played around with the barrel adjuster this evening and no amount of modification could get it to shift cleanly.

Gears 1-3 and 7-10 are mostly fine, it's 4,5&6 that are either skipping when shifting or jumping over and back from one gear to another when pedalling.

Back to the bike shop I presume?

hesker · 24-06-2021 10:16am

Put it in gear 6 and adjust until it is smooth. Then see how other gears perform.

lissard · 24-06-2021 10:21am

Here's a video to show exactly how to properly index gears https://youtu.be/UkZxPIZ1ngY.

To be honest it refects really badly on your mechanic that it came back out of whack. I'd definitely be moving my business.

Paul Kiernan · 24-06-2021 11:00am

davegilly wrote: »

So I played around with the barrel adjuster this evening and no amount of modification could get it to shift cleanly.

Gears 1-3 and 7-10 are mostly fine, it's 4,5&6 that are either skipping when shifting or jumping over and back from one gear to another when pedalling.

Back to the bike shop I presume?

This is completely consistent with a worn out cassette. As yours is very unlikely to be worn out after 9 months is it possible that the bike shop accidentally mixed up your nearly new cassette with an old worn out one they meant to throw in the bin?

letape · 24-06-2021 12:36pm

Paul Kiernan wrote: »

This is completely consistent with a worn out cassette. As yours is very unlikely to be worn out after 9 months is it possible that the bike shop accidentally mixed up your nearly new cassette with an old worn out one they meant to throw in the bin?

I think it’s more consistent with a bent or kinked cable or alignment issue. The shop wouldn’t have had a need to remove the cassette!

davegilly · 24-06-2021 6:19pm

So I have it working now, all gears working but still a little noise when in middle gears but not too bad. Bent the derailleur slightly and played around with barrel cable.

Doesn't look overly complicated to do in the future so I think I'll buy a derailleur alignment tool and do this myself in future. Kids bikes are constantly out of alignment as well. Thanks everyone for your help.

secman · 24-06-2021 6:53pm

As it happens my indexing was all over the shop on my spin this morning, called into CSS as it's only around the corner from me, fair play to Sue as she had a look and made a few adjustments. Still jumpy on way around to house. Called back into her and dropped bike in, suspect its cable and the cable housing at the RD. Hopefully get it back tomorrow. There's currently a waiting list for repairs, so delighted with that.

Gears jumping

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