Do I need to reindex?

[Billy_Rosewood]

So I've had the gravel bike a few months but probably haven't yet done 100miles on it..

That being said, shifting has (already?) become problematic, as well as dissapointing as the grx800 (with 600 shifters) gearset is supposed to be decent?

The issue is more problematic when dropping to lower cogs, either on the crank or the cassette. Sometimes I'll click down and nothing. Then click down again and it might either shift once and stay there or shift twice but with the second shift delayed.

Highly annoying. And not the smooth experience I was expecting.

[Harpoon]

Mechanical or electronic shifting (I presume there's a choice in GRX)?

[bobbo89]

If cable then I'd assume a bit of cable stretch and so just a tweak of the barrel adjusters might sort it.

If not and you're running Di2 then I've no idea...

[Billy_Rosewood]

Cable, not di2.. I did think perhaps it's a bit of slack as the cable was new and is "settling"? Is it normal at this sort of mileage?

I'll have a search on YouTube on how to reindex

[bobbo89]

Mileage doesn't really matter when it comes to cable stretch as you can do loads of miles on the flat and not shift much or do less miles and be up and down them all the time.

[anonymous-user]

Billy_Rosewood said:

Cable, not di2.. I did think perhaps it's a bit of slack as the cable was new and is "settling"? Is it normal at this sort of mileage?

I'll have a search on YouTube on how to reindex

Perfectly normal. Even if you'd done no miles, the cable is still under tension and they tend to stretch more when new. Just give it a tune up on the barrel adjuster and it'll sort it.

[CatMatt7]

You might have a bent rear mech hangar - possibly worth having this checked (and straightened, if needed) by your LBS

[Crippo]

Do you mean going into smaller cogs or smaller gears as the low gears are the large ones on the rear and people often interchange the term gears with cogs and they mean the opposite things.

However, it sounds like you mean smaller cogs so trying to shift into a higher gear…..in this case it sounds like your bike has cheap cables with loads of stiction. This will account for the delayed and slow shifting. Put some quality cables on and the problem will disappear. Also while at it check nothing is snagged and the cables have as clean and kink free routing as possible.

If you disconnect your cables you can manual;y manipulate the mechs and you’ll probably find the springs in them pretty strong and as you let go they will shift very easily to the small cogs. That proves the point about the sticky cables…..many bike brands use cheap acables yo cut costs

[Maracus]

Crippo said:

Do you mean going into smaller cogs or smaller gears as the low gears are the large ones on the rear and people often interchange the term gears with cogs and they mean the opposite things.

However, it sounds like you mean smaller cogs so trying to shift into a higher gear…..in this case it sounds like your bike has cheap cables with loads of stiction. This will account for the delayed and slow shifting. Put some quality cables on and the problem will disappear. Also while at it check nothing is snagged and the cables have as clean and kink free routing as possible.

If you disconnect your cables you can manual;y manipulate the mechs and you’ll probably find the springs in them pretty strong and as you let go they will shift very easily to the small cogs. That proves the point about the sticky cables…..many bike brands use cheap acables yo cut costs

This was going to be my answer. My previous CX bike had a similar issue, loads of dirt, etc had gotten into the last piece of cable to the rear derailleur and the cable wouldn't slacken to drop down.

[Billy_Rosewood]

The issue seems more prevaillant when shifting up/going to small cogs, but having just tested the bike when suspended, I can repro the issue going both up and down. Seems to be worse from around the middle of the cassette and up the gears (toward the smallest cog).

Based on that I think its an ever so small amount of slack in the cable. The dereilluer hasn't taken a smack or anything and the cable seems to move OK through the sleeve.

Will have a look later today or this weekend.

Thanks all!

Edit: had some time just now, added a little tension to the rear dereailler (I think) which seemed to line it up a little better.. seems to have stopped the mis-shifting when testing in the air. Will take it out for a ride at some point to see if its any better under load. Imagine it will be though.

Edited by Billy_Rosewood on Thursday 7th September 14:42