Interesting change to bike while away.

AK_jnr

So I went away for a couple of weeks and before going I gave the bike a clean.
Before leaving the bike was running well, gears perfectly indexed.

I hopped back on today and the bike was jumping sprockets all over the place! Any idea why?!
Im not worried about how to index as I can happily do that but just interested why it happened? The house has been empty so it hasnt been knocked or anything.

The only change from before is that its a new chain so the bike clean got rid of the factory wax. Apart from that its been sat inside the house waiting for me. Lol.

Cheers.

AK_jnr

Good point, ill have to check that.

svetty

Assuming all is adjusted correctly I'd plump for a worn cassette.

keef66

Need to know if it's the chain skipping forwards over the cassette, or if it's hopping sideways from one sprocket to the next.

If it was fine before you went away my money would be on stiff link(s) in the chain too...

JesseD

Knock the mech out of index whilst cleaning?

AK_jnr

I spose its possible but I cant remember knocking it.
Its hopping sideways Keef in the middle of the cassette.

I indexed the gears which I thought had sorted it until it did it a couple of times.

I did get my nan to pop in while I was away so maybe she knocked it over lol.

fenix

Ghosts.

AK_jnr

Haha must of been!
I had some 5 min intervals today and it was fine. Problem with me is because ive only been confident to service my whole bike the last year I'm still wary of sprinting 100% until I know the indexing is spot on. I dont quite trust myself fully yet!

AK_jnr

Little update. The hanger was slightly loose which I thought would be the problem. Still wasnt indexing properly.
Changed the cable and outers and still not happy with the indexing so im going for it needing a new cassette like mentioned above. I have no idea how cleaning brought the issue to light though!
It was new at the middle of Jan and has done 2150 miles since. Its been pretty much all dry miles as I was in Spain for most of it. Isnt that quite soon?

svetty

AK_jnr wrote:

Little update. The hanger was slightly loose which I thought would be the problem. Still wasnt indexing properly.
Changed the cable and outers and still not happy with the indexing so im going for it needing a new cassette like mentioned above. I have no idea how cleaning brought the issue to light though!
It was new at the middle of Jan and has done 2150 miles since. Its been pretty much all dry miles as I was in Spain for most of it. Isnt that quite soon?

I understood from your first post that you'd fitted a new chain? Assuming the problem does turn out to be a worn cassette (which given your total mileage since fitting it does seem somewhat improbable TBH) the principle would be that the old chain, having become worn, has been used for long enough in a worn state to create premature wear on the cassette. Was the chain also changed in mid Jan or did you run the new cassette with a chain that already had some wear?

AK_jnr

Yeah I fitted a new chain a few weeks ago and I used a worn chain with the new cassette. I was of the impression you could get through a few chains before replacing the cassette. Woops. I'll chalk this one up as experience. Ha.

svetty

AK_jnr wrote:

Yeah I fitted a new chain a few weeks ago and I used a worn chain with the new cassette. I was of the impression you could get through a few chains before replacing the cassette. Woops. I'll chalk this one up as experience. Ha.

It depends how worn the chain becomes - the more wear in the chain, the faster it wears the cassette. I'm still somewhat sceptical that this really is your problem here given that you say that you have done a moderate amount of mostly dry (and presumably therefore cleanish) miles.

AK_jnr

Well that annoying. I wrote out a long reply and deleted it by mistake! Lol.
You were right it wasnt the cassette.
So its not the cable or chain either.

Sitting on the turbo to get a better look the RD is changing fine down (if thats right. I mean to easier gears) but going the other way the RD moves partially then needs a second click which throws it slightly too far hence the skipping. No amount of indexing is sorting it.

Ive found my old RD to try tomorrow. Thats all I can think of now?! Nightmare.

keef66

Has the hanger alignment been checked?

Did you replace all the cables, inners and outers?

When my 5600 equipped bike exhibits that kind of nonsense I'm immediately suspicious that the cable's fraying inside the shifter; it's done it 3 times so far. If the cable's OK I then check the hanger is straight. It often looks OK to the naked eye but is significantly out according to the alignment tool.

slowbike

My bikes have exactly the same issue and I think I've isolated the cause to be friction under the bottom bracket - this is where the gear cable is exposed and runs over a plastic moulding. I've tried new cables and it doesn't help.

I worked out this was where the problem was by plucking the gear cable above and below that point before and after gear change - the tension isn't uniform between gear changes - above the BB can be nearly slack on shifting down which suggests that the rear mech isn't strong enough to pull the cable past that friction point. Similarly, shifting back up again the cable above the BB has to be over taught to get it to shift up a cog....
I keep meaning to try putting a bit of outer around the cable under the BB to see if that solves it.. haven't got a round tuit though.

AK_jnr

Ah thats a good point. I will check that.
Well i know the reason I took my old RD off in the first place... it was broken lol so I couldnt try that one. Gave me a chance to take the current one off for a good clean. Seems better on the stand but will have to test again on the turbo later.

Yeah I replaced outers and inners. The only thing I havent checked is the hanger. If it hasnt been sorted tonight, I will have to take it to the LBS to check that.