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I've stripped down and rebuilt my old Specialized MTB. About 5 years ago I turned it into a 1x10.
I've put in a new narrow/wide front chain ring (32T, as was the old one, and a new Shimano chain).
Thought I'd indexed everything perfectly on the stand, but after a test drive, gears 1-9 are working beautifully, but gear 10 feels like it's making a horrible jump under load (it doesn't seem as bad when you're at a higher speed).
There's practically no tension on the H screw when it's shifted into 10, so don't think that's restricting it, but is that a sign that something else is wrong?
Chain was measured big to big, and worked out the same length as the old one that came off.
Is it a case of undoing the gear cable and starting again? I've tried the barrel adjustment at the shifter end and can't seem to find a combination that makes it happy. Been through a bunch of online guides, the B screw is set at an 8mm gap.
Don't think it's chainline related as it didn't have the issue previously (used to be unhappy in the middle gears, hence wanting to strip down and try again).
Cheers
Sounds like your small sprocket is worn and won't like the new chain. You could use the original chain or replace the cassette/sprocket.
It was previously unhappy in some gears and now it's only one?
I'd start (as always) with a mech hanger alignment tool.
Have you removed the cable from the mech? Could you have possibly put it back around the pinch bolt the wrong way perhaps?
This happened to... ahem... a friend of mine recently and it messes up the indexing.
I'd suggest it's not that happy with the chainline. Gear 10 being the smallest ? Check the chain isn't rubbing on anything, and the limit screw allows the jockey to sit in line with the sprocket.
New chain and chainring but old cassette? I'm with Bax on this
Thanks for all the replies. The pinch bolt was loosened but not twisted; I replaced the gear cable a couple of years ago but didn't go through the rigmarole of adjusting L and H screws and the like again, at the time. Whereas this time, I did.
Gear 10 is the smallest but I'm 99% sure it pedalled fine in the top gear before, and I've got a small handful of Strava rides where I'd hit the (not so) dizzying heights of 25mph on it. Equally, Strava suggests I've only done ~500 miles since the conversion, so you'd hope an SLX cassette would last at least that long, but will have a go with the previous chain as well for comparison first.
I'll have a look at the mech hanger too, thank you.
Stick the old chain back on, see what happens. If it's fine on the 11t then, it's the sprocket not accepting a new chain. You may be able to get some more life out of the cassette with the old chain then if the new chainring will take it.
Reporting back - Deraileur hanger has a flat edge on the rear, which when offered up to a straight edge, is absolutely flat. I know that's not a cast iron guarantee but with 9 of 10 gears being fine, it seems OK.
I'll try and re-set up the deraileur and cable again first, but assuming that yields nothing, will try the old chain at that exact point to see if it resolves the issue. Annoyingly the Shimano chain didn't come with a quick link so will have to break that off and source another pin.
Just to try and expand on my explanation, it seemed to be wanting to jump back to gear 9, every full rotation, but only under heavy load. That does sort of suggest an issue with one of the teeth on the 11t doesn't it?
What happens when you back off the screw to bring the mech outwards slightly? Try it with the cable undone, then reposition the mech so you can eliminate that as a cause. Is the final sprocket definitely fitted flush?
Disconnect the gear cable, go and ride the bike and report what happens.
I've just undone and redone the casette to be sure, it's seated properly on the HG hub, and the lockring done up to 40nm.
When I backed off the H screw earlier, in 10th gear, it was already at the point of applying no resistance (if that makes sense). Which would then suggest the chainline isn't great, but as I said above, I'm sure I've had this bike up under heavy pedalling in the top gear before.
Simon - will try that before fiddling with the deraileur again.
Where is it sitting visually in relation to the sprocket with the cable undone?
Deraileur hanger has a flat edge on the rear, which when offered up to a straight edge, is absolutely flat
? which way are you checking its straight, for/aft, front/rear... or in/out, DS/NDS, it needs to sit at 90deg to the axle.... do what SimonDBarnes says and the chain should sit in the smallest cog
Cable a wee bit tight?
Thanks all, I tried the suggestion to remove the cable, which then gave me an opportunity to adjust the H screw with a chain fitted to ensure there was no interference.
Same issue with the clunk.
I've then chucked on the 10 speed SRAM cassette from my spare/road wheels for my CX bike, and the issue goes away, so sadly, as Bax + Andrew diagnosed seems it's a simple worn 11t.
Unfortunately it looks like cassette prices are through the roof. If I 'downgrade' to Deore, it looks like I can get a 10 speed 11-36 one for £40, but was hoping to sell the bike so that's going to massively eat into it. Could put the old chain back on but then I'm making it someone else's problem in a couple of hundred miles aren't I? Are the microSHIFT ones good enough?
Thanks for all the help
What are you 'downgrading' from? Deore cassettes are fine, probably better than Microshift (which will also be fine just a bit heavier). Those cheap Airbike ones are fine too. If I was buying a second hand bike that is over five years old I don't think I'd care in the slightest what cassette it had on it as long as it worked.
Was an SLX cassette so on paper slightly better than Deore, but to put into context, my email from Evans at the time shows the SLX cassette was only £23.99 brand new!
But didn't realise the 11ts were available separately anyway. Happy days, thank you for the links
Just to check on the link I gave, says only compatible with XT for some reason. I always thought they were identical in shape, so might be worth hunting around for an SLX equivalent or double-checking.
For 7 quid I’d be trying that MH
I just paid SJS nearly 20 quid for two flat mount caliper bolts (once postage is included), so this is small beer in comparison!
Thanks again Martin, I stuck those details into eBay.
If it helps anyone else in the future, a helpful seller on eBay advised that if it's stamped bj/bl it will still work. I guess because the 11 and 13t have an inbuilt spacer, they'll work across a variety of cassette tiers.
For £12.99 managed to get a brand new Shimano 11t and 13t - https://www.ebay.co.uk/itm/194174848564?var=494266399422
Don't like to leave a thread half-finished so just to confirm, having fitted the replacement XT 11t and 13t, and reindexing, it's working great again now even under heavy load. A couple of teeth on the 11t had worn down, must have just been more use in those gears.
😊👍