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Hi all,
Just to warn anyone short on time or patience... this is a bit of an essay....... 😆
I own a 2007 Commencal mini dh. As I have another bike and lived abroad for a couple years without my bike, it hasnt seen too much action over the years but I do plan on changing this. Anyways.
Its fitted with a Sram nine speed cassete which is mounted on a Hope am-4 hub (new hub due to problems with commencal hub *shock*). The cassette looks brand new when you give it a clean, no signs of any wear and the hub is pretty much new. The original X9 which to be frank I was never convinced by bent during shifting (hanger snapped and was replaced) so I replaced it with an x7 using the original lines and x7 shifter, I checked the movement of the line loads of times with the line in hand and it feels smooth enough, definetly not ceased and I did try to grease it a little.
My problem is the shifting, Im not mechanically shy and I just cant get it to set up properly, I have watched countless videos on this and other derailleurs but its just being a little *&$%£. I understand the principle that the cable has to be set to a certain tension and the shifter will move at pre-determined increments. Once tension is bang on, using the screw on the shifter it should be fine...?
Basically, I have set it up around 10 times (release cable, chain off, starting from scratch) over the past few months, and it just wont work and im following the correct steps.
The symptoms are such that when I set it up and its shifting fine through all gears at a steady rate, I then take it out for a cycle and in various gears it will try and slip out of the gear as if its not set up properly. This happens on both the downshift and upshift on either extreme of the cassette but ONLY[u] when I try to give it some welly and put pressure on the drivetrain.... Sometimes I may set it up and cycle somewhere and it will be fine, and by time Im on the way back it will be out. I have fitted another new hanger and everything looks pretty straight. So it does shift but when cycling hard it tries to skip to next gear. It REALLY knocks my confidence in the bike..... and is pretty annoying after the money spent etc.
So basically I was just wondering if theres anything blatantly obvious I have missed, because I am just about knocking on Shimano's door due to this. Any suggestions or constructive comments/humour is welcome, thanks all.
Have you set the high/low adjustments properly? Bent hanger?
Your shock/pivot bushes are worn and the lateral movement is killing your shifting.
Also, check the B position screw. Could be too far off the cogs.
Also, have you lubed the cable? could be dragging.
Also, check your outer cable for potential draginess.
Also, check you're there's enough links in the chain.
Bring it round if you're ever in South Manclandshire.
Bring beer.
Gears seem to be set up right and work when the bike is in the workshop but jump when under heavy load immediately points to one or both of the chain or cassette being worn out, or at least not matched to each other in terms of wear.
You didn't get a 10s X7 rear mech?
Thanks for the prompt replies lads. Its a 9 speed shifter and 9 speed cassette. The hanger is brand new. The chain is new and the cassette has had so little use I cant see how it could possibly be worn and shows no visual signs of it.
High low adjustments are set pretty much perfect from what I can see, with cable undone it seems fine.
I hadnt thought of the pivot bushes, I will look into it though I really cant see after so little riding how they could be dried out or worn.
B position screw was set as per sram's directions, roughly 8mm when on top sprocket so I dont think its that either.
I lubed the cable but I reckon I could strip it down properly and clean then lube..... will be my next step I reckon.
I might try and find cheap or borrow a cassette if that doesnt work.
I sized the chain as per srams recommendations.... thats one bit I wasnt sure about but it seems fine, chain device is still bit noisy but thats probably not related 😆
Manclandshire? Anywhere near Renfrewshire? New one on me... Beer is rather nice though isnt it.
Overall Im not bothered at all about speed of shifting as I really want to use the bike for am etc only. Just want precise shifting that doesnt hop about the place and a strong deraileur. Il look at the cassette a bit more closely though, maybe it was duff out of the box... and reckon I will replace the cables to eliminate that, start with the cheapest and easiest first i suppose.....
227miles from Renfrewshire to Myhouseshire. If you're not coming down, just send the beer in the post.
This problem is always easiest to diagnose with someone else there to ride along behind you watching the chain, although if it's quite predictable you might manage to do it yourself by looking down if you can find a big enough area to try without risk of riding into something.
If it's the gear adjustment or play in pivots or similar it'll be jumping sideways as if it was trying to change gear, if it's the cassette it'll not move sideways, it just rises up a little and jumps forward a tooth.
Sorry, I'm bored of smashing SRAM mechs with hammers. Go Shitmano.
Sorry hoops, went down the post office earlier and they said some junk about not sending liquids yada yada so I shall have to drink it instead 😥
Thanks robin, wasnt aware of that I will try look at it myself, if you hear of a hit and run on a passing seagull... it wasnt me...
I think il do the smashing so, think your right. Will wait till I get a bit of use out of this one though, will put up and shut up in mean time. Thanks all
IMHO - what worked here is as follows (process arrived at after my sram went mental and wouldn't shift under pressure)
Put front mech in middle ring (or larger ring if twin, not triple)
Put rear mech in highest gear (smallest cog)
Release cable tension at rear mech ( undo Allen bolt)
High and low were originally set as was b-tension screw. If not set, adjust high to ensure jockey wheels line up with smallest cog
Ensure shifter adjuster is approx 4 quarter turns unscrewed
Reattach cable at mech ( finger tight tension - just pull it by hand)
With bike upside down cycle thru gears adjusting tension at shifter by quarter turn (usually one or two turns unscrewed) to get smooth shifting
Shift to lowest gear and adjust low screw to line jockey wheel up with biggest cog
Shift to highest gear and Adjust b- tension screw to move jockey wheel to within few mm of smallest cog. May need to move to 2nd cog to help with this.
Then ride. It sorted mine out fine. If its still not shifting properly then check hanger alignment, lateral movement in swingarm, bottom bracket play, try a new mech / shifter, lube cable, go single speed
Is it a 9s mech? Or 10s?
A video of it in the stand might be worth a try.
your outer cable between the top tube and swing arm may be fractionaly to short. which will ghost shift when you pedal
New chain, old cassette. Despite you saying the cassette is unworn, I'll bet thats the issue. Wear is hard to spot. The best wayt to measure cassette is to measure the chain that spent its whole life on there (ie the chain you removed) if its past 0.75 then it will be hard to get good shifting.
Its a 9s mech and shift, I misplaced the old chain moving houses etc so I cant measure it unfortunately but thanks for suggesting.
Thanks tmb, I think I pretty much did all of that but I adjusted the b screw on the largest cog rather than smallest so I shall try that and some lube on the cable before looking at cassette...
If the above doesnt work toys Il be getting a new cassette and chain 😯
Thanks all 😀
I struggle with long sentences
BUT - has anyone mentioned checking you have the cable the correct side of the bolt that secures it? If it goes round the wrong side this can change the leverage and mess up indexing.
I had X7 on my Carerra Fury. It work faultlessly on the stand. But as soon I got near a trail it started skipping all over the place. I read somewhere that this was a common problem with X7 and that the solution was to upgrade the shifters and rear mech to X9.
I replaced the whole lot with Shimano SLX and sold the SRAM stuff on ebay. Not had to adjust the gears in over a year now.
Ive got X5 on my old commuter which works well, but it's 8speed.