Indexing

[thunderlips76]

Recently had to replace a shifter. As this is beyond me I took it to the LBS. Shifters sold as a pair and new bar tape. £300 later I pick up my bike new bar tape shifters and new cables fitted. Gears started to skip first ride out and climbing out of the saddle the chain suddenly shifted four sprockets up making my headbutt my stem. Gears all over the place by the time I got home. Decided to drop it back in the shop. Re-indexed, no charge, mechanic even test rode it. “Yeah it’s all good now”. First ride out gears skipping, shift three slickers at once under load. What’s going off here. Sad thing is gear shift are smooth on the stand but skip when putting power through the pedals. I’m terrified on every climb as out of saddle sprinting could lead to an off. Am I better off taking it to another shop. Seems like indexing should be a basic thing.

 

[Chief Broom]

Ive had my gears jumping around when i forgot to put the spacer on behind the cassette, the gears changed fine when inverted...
Has the cassette been replaced or taken off? if not it isnt that!

 

[Gunk]

Sounds like incompetence, when ever I set up a bike I always ride it, they behave totally differently under load than they do on a stand

 

[thunderlips76]

Ive had my gears jumping around when i forgot to put the spacer on behind the cassette, the gears changed fine when inverted...
Has the cassette been replaced or taken off? if not it isnt that!

Yeah I have put a new cassette on, but it’s identical to the one I took off. Same spacers and everything.

 

[Mike_P]

Plenty of guidance on line
If as bad as that you have nothing to lose having a go yourself

i.e. https://www.tredz.co.uk/help-advice/product-help/how-to/maintenance/index-your-gears

 

[Big John]

New chain too?

 

[thunderlips76]

New chain too?

Yep

 

[DCLane]

Yep

Daft question; is the derailleur not adjusting properly because it's clogged? That's a possibility that may not show up on a stand.

The other is that the chain may be too long. Again that doesn't always show up on a stand.

 

[screenman]

It never ceases to amaze me how many cycle mechanics do not check rear mech alignment, it should be one of the first steps in setting up the indexing.

 

[thunderlips76]

Pretty much sorted it myself. Chain been a bit too long might be a thing.