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Not matter how hard i try i cannot get my rear derailleur setup.
The problem is when i shift to the second largest cog it always wants to shift up into the the largest one. When actually shift into the largest cog everything is fine.
I've watched all the videos and had multiple attempts, the only way i can prevent the jumping is to slacken off the tension to the point that shifting off the smallest cog becomes a problem.
As far as i can tell i've got the limit screws set perfectly and all the other changes are crisp.
I haven't touched the b-screw as I don't really know what it does! Could that be a problem?
It's a new chain, new cables, i'm wondering whether to try a new cassette!
I did recently get some new shifters (on here) which were a big upgrade from my old ones (new ones deore xt, old ones altus) but i've tried putting the old shifters back on and the problem is still there (i think it always was tbh even before the new shifters).
It's a nine speed setup with all shimano gear so although it's not all the same groupset i thought it should be compatible?
Help!
Is the hanger perfectly straight? You can get a tool to check and realign.
I would check the hanger alignment. It only needs to be slightly out to mess things up. Could also be a bent rear mech (less likely in my limited experience).
You can buy a tool to check it from the usual places, or make one if you have a long straight piece of steel with a hole at both ends.
Thanks 🙂
I did buy a rear hangar as a spare recently. Is it worth banging that on just to see if it sorts it? Can they be put on misaligned or is it a case of if it's not straight it's bent?!
Just be aware that there's no guarantee that a new one is straight either - but 9sp is generally much more forgiving of small alignment issues than 11 or 12 speed. Is it a wide range 9sp cassette or a normal 11-32/34 size?
It's 11-36. Why would the new one not be straight, are they often subject to manufacturing defaults?
I've just had a look at the old one and tbh it "looks" perfectly straight but not sure how to test other than by eye. I don't remember it being knocked but it's entirely possible.
As always I recommend buying and using a mech hanger alignment too. There's no guarantee that a new hanger is perfectly aligned, not that the fit between hanger and frame is perfect (indeed, the dropouts may not be perfect either).
Don't underestimate the impact of worn jockey wheels too. If the upper pulley wheel develops too much side-to-side play in the bearing/bush, it can properly screw up your shifting because the chain isn't moved far enough when the mech moves. I've had this happen a few times, even when the teeth on the actual jockey wheel are fine and have loads of wear left in them.
Not sure I'm ready to splurge on an alignment tool. I'll either live with it or take it to lbs! Thanks for the advice.
Maybe worth finding out what the LBS will charge first?
A basic ZTTO tool is showing for under 20 quid at AE
https://www.aliexpress.com/item/4000630948367.html
But if/when you go for one I'd suggest the Lifeline as a good starting point, currently 40 quid.
https://www.chainreactioncycles.com/lifeline-pro-gear-hanger-alignment-tool/rp-prod122319
Even after checking the mech hanger alignment,it's also worth checking if the cage plates between the jockey wheels are slightly twisted.
Oh, and some mech hangers really are made of cheese,you can move them with a hard stare 😉
i had some similar issue a while back - I screwed the gear cable the wrong way round. I screwed it straight when in fact it should have loop around the screw using the groove provided.
I had some excellent help on here recently with an almost identical set of changed components and similar issues with jumping.
Mine was the other end of the cassette but transpired it was just that the 13t and 11t teeth were worn down, the derailleur and hanger weren't the issue. Swapped those two cogs out for new Shimano items and it shifted beautifully.
All other advice on the thread seems spot on but it's a costly bit of troubleshooting to eliminate things. If you've access to another cassette (even temporarily, as in my case) got to be worth a try in case that penultimate cog is worn?
i had some similar issue a while back – I screwed the gear cable the wrong way round. I screwed it straight when in fact it should have loop around the screw using the groove provided.
This. I've been doing this long enough that I should know better, but I recently had persistent indexing issues and despite the way that I had routed the wire around the mech pinch bolt looking the most obvious, it was actually the other way and once changed, my shifting was spot on.
Try that.
It's worth trying the new mech hanger but they only have to be ever so slightly bent/twisted to make quite a difference over the distance that a tool allows you to check.
It might be useful to see if there is any difference though.