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Chainring shifting issues - best option?
I was having some shifting problems a while back going from middle to inner chain ring (the shift would be very slow or would have to be accompanied by a shift on the cassette to make the chain jump down). The LBS filed the teeth on the chainrings a little and this improved a lot. However, the problem has started to return. If I am in the middle ring and shift to the lower ring it will just rub on the deraileur cage until I shift up and down the cassette and then it will shift down the chainring.
The front deraileur has been adjusted by the LBS, they suggested that the next option would be to put new chainrings, chain and cassette on - going all out Shimano and this would solve the problem.
My current setup is:
Scott Genius RC10;
FD Shimano XTR (M960-E);
Chainrings Raceface;
Cranks Truvativ Stylo Team;
RD SRAM X0;
Cassette SRAM PG-990;
Chain SRAM PC-991
All of it is in good service and doesn't appear to be very worn.
LBS suggested that mixing SRAM and Shimano and Raceface works ok when everything is new, but will cause problems when things wear a little.
Where should I go next, should I try XT Chainrings and see if this helps, should I go XT rings / cassette / chain, so I go SRAM rings with my current cassette / chain? Or is there something else to try?
Thanks
Jonny
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front derailleurs on full suspension bikes are often a PITA. On new bikes I dont think i have ever come across a front deraileur setup optimally. My guess is the cage is too far from the chainring, but also on some bike a little toe in can help with throwing the chain down to the little bit easier, then reset hi and lo stops. check cable for cleanliness etc.
Fundamentally the lbs wont be setting the deraileur while the suspension is sagged with a rider on the bike - they will be setting it in a stand, with full height - a situation that is never replicated on the trail. watch some youtube videos on setting up, learn whats what and why, then sit on the bike, mark your sag point, then use a tie down strap to hold the suspension at that point, now adjust it.
There are so many variables witha cycling suspension that i think this is the only way to have a chance of getting it right - every lbs i've been too, returns playing up gears to me, saying all adjusted and fixed - but it never is once out on the real trail with a rider on board mashing pedals the whole thing does exactly as it did before - its why mtbers have to become their own mechanic.
if it was perfect once and now isnt, try and think what changed -ie if you took off the derailleur, the cables have been rerouted etc. but failing to go down should be a deraileur prob
Adjusting the lower limit screw out a bit to give the cage more pressure against the chain?
Cleaning the derailluer and then lubing the spring and pivot points?
Checking the cable to ensure that there is slack when it is in the lowest chainring position?
Checking the cable outers are free from dirt and lubed - dry ceramic lube works a treat here or Squirt lube - magic product.
A personaly favourite of mine - cause it happened to me - the small chainring was back to front and it was offset ever so slightly when the wrong way around - chain kept falling in between middle and small and shifting was shite.
Derailluer alignment - making sure it matches up precisely with the chain rings?
Derailluer height adjustmemt - too low and the inwardly bulge part of the cage won't hit the chain like it should.
Loose BB which makes the chainrings go out of alignment with the derailluer?
All those from my experience trying to fix the same issue with an older bike.
What fixed it?
This: http://burkescycles.blogspot.com.au/2011/02/staf...
Thanks for this guys - I'll look into the above as a start. I know the E type FD's can be harder to tune, so maybe I'll look on the Shimano site and try to get a good tuning guide for it first off.
Has anyone else had Shimano / SRAM / Raceface compatability as things start to wear - or this just an LBS excuse and rationale to get $500 out of me a new drivechain!
I cannot see how compatibility for a middle to granny ring shift could occur through wear- the other way is dependant on the ramps on the middle ring, jamming in between could be a compatibility problem, but not failing to jump down. LBS just cant figure it out because they arent approaching it the right way, so a whole new setup they are hoping will get it fixed.
as to dangermans point above about distance between chanrings, i once replaced a shimano 9 speed 32 ring with another 9 speed 32, and would you believe that a hollowtech I offset is different to a hollowtech II - that meant a deore LX front ring couldnt replace an slx/xt front ring from the same year??? 3 shops, 3 rings, all quality mountain bike shops, and none knew of this - but i cant see how wear can cause this same effect i had - but if you have recently changed rings thats a whole new ballgame.
Hi. I have Stylo cranks and rings, running on an XTR derailleur, Shimano ? cassette and chain. Shifting was rather iffy ... until I replaced the middle chainring, the chain and the cassette.
With the same mix ... Stylo ring, Shimano ...etc. Nowruns perfect. Turns out the drivetrain was worn (!). So for me it wasn't a comparability issue, it was just some shot components.
FYI; I'm running an 8-speed set up, so perhaps compatibility could be different with your set-up. Doubt it though; these 'compatible' parts are designed to work together, and come out of precision-engineering factories.
Also, the cost for me was well below $500. Kept the granny and large chainring, the cranks,the BB, ... Cost was about $220 all up for only the parts that were needed, and that included paying for servicing the bike.
I've one question, what are you doing riding around in the granny ring?
Despite the claims, I've found matching up SRAM 9-speed shifters and Shimano FDs to be less than seamless.
With all-Shimano gruppo (2010 XT dual-control), you just need to set the derailleur end point adjustment to line up over the required cog or chainring with the cable off, pull the cable as tight as you can before torquing down the clamp bolt, remove just enough of the remaining slack with the tension adjuster on the shifter so that the derailleur still sits on the limit screw but moves as soon as you put pressure on the shift lever, and you're good for the entire range at either end.
With SRAM shifters (at least with X-7 and X-9 that I've tried) that are supposedly compatible with Shimano LX/SLX front derailleurs, you still set the end point with the screws, but find I need to leave some slack in the cable or it overshifts middle and big chainrings horribly. So my strategy there is to set the FD cage on the middle ring, and adjust the lower limit end point screw to stop the cage dropping the chain off Granny and the upper limit to stop the cage throwing it off the outside of the dog.
With the stay out of the granny ring sentiments!
It's called cadence, mate! Keep those pistons flying. It's all the rage you know.
Thanks for the input. Shifters are SRAM X9
Everything has been working perfectly, and I haven't changed anything (other than a new link in the chain when the old powerlink broke).
I'll try a good clean up this weekend and realigning the FD. I haven't looked too closely yet, but I assume there is less adjustment possible with a BB mounted FD than a clamp on style FD?
As for staying out of granny ring ... I had thought of switching to a 2x10 setup, but the cost of chainrings, cassette, chain, shifters, FD and RD is a little prohibative at the moment
And cadence - thats the key isn't it!! I bought a road bike to 'train' on during the week and commute around 6 months ago, and since doing more road riding, I've come to realise how important cadence and correct gear selection are over just pounding harder on the pedals on inclines!
Spent a few hours yesterday cleaning the bike and adjusting the FD.
It seems to be shifting well now, however it catches slightly in the small chain ring when on the smallest two cogs on the rear, but if I adjust this then it catches on the top chian ring on the same cassette cogs. It's only a small rub, so think I will live with it
Thanks for the advice!
Jonny
You shouldn't be selecting small/small, it's called cross chaining and is bad, bad, bad. It puts stresses on the drivetrain that it wasn't built to take and will likely always result in some rubbing and you're much more likely to snap your chain. Big chain ring should be used for the smaller cogs, middle for the middle cogs and small chaining ring for the larger cogs.
Yes, that's the conclusion I came to too - I was trying to get the alignment as good as possible in the workshop, but I know that on the trails I'd only ever use around 18 of the 27 gears for the above reason.
Another thing to check is the spacers on the bottom bracket bearings if you have outboard bearings. They are about 2mm thick so if you swap one from one side of the bottom bracket to the other you can sometimes get the chainrings to line up with the rear cassette better. A small change in the alignment can make a big difference. Use a straight edge to check for excessive offset.