my wife's bike has just been upgraded. we went from an old suntour chainset, had it for years, with a shimano m542 hollowtech 2 version.
Now she is unhappy.
I can't get the front mech (an older xt version) to get the full three ring range, either granny ring or the big ring but not both at the same time.
Is this the main symptom of a 9 speed chainset and a 7/8 speed mech?
confused here, any help?
Have you reset the limit screws? If not, wind them all the way out and see where that leaves you.
[b]BE VERY CAREFUL!![/b]
there are [b]three[/b] limit screws, the high limit, the low limit and the parallel limit. Its the parallel limit screw that you need to watch out for as even the smallest fraction of a turn adjusts the very fabric of the space time continuum, Sadly there is no standardized position (often it is installed in the place of the low or high limit screw) nor would it have any identification markings . The only way of telling if you have adjusted the parallel (dimension) adjustment screw is that everything that used to work has now been plunged into malfunctioning disarray and you will personally be experiencing feelings of confusion, desperation, anxiety, impotence, panic accompanied by a tendency to walk in circles. Sadly once the Parallel screw has been adjusted this can also alter its very position swapping with ether or both the high and low adjustment screws. The only proven method to rectify any incorrect parallel adjustment is a bit of a sit down with a cup of tea accompanied by a large slice of "try again later". 😀
mr Nutt: from the very depths of my soul, thank you.
I'll fetch some cake and have a quite sit for a bit till things return to normal.
happy to help 😉
Park tools website has step by step guides for this sort of thing. Mostly with front mechs it's limit screws and cable tension
The range of movement of the old mech is probably not big enough.HT11's are wider than chainsets without outboard bearings.
front mechs are the the work of satan!
the concept of the parallel limit screw is consistent with string theory where 11dimensional strings fold up and are unobservable in our universe, so that's all good.
and all mech cables consist of exactly 11 wound wire "strings", I know, Steven Hawkins told me.
If you're able to get either the small or big ring then it's unlikely to be a limit screw problem. If the mech cage is parallel to the chainrings, this leaves cable tension, cage height(approx 2mm above outer ring required), or an incompatible mech(this can be in a few forms i.e. standard drive for old 48t outer has a longer and less radiused cage. Some earlier mechs won't cope with new wider chainlines, reaching their limits before shifting is achieved, and 7sp mechs have a wider gap between the cage plates so may need to move further to achieve the shift,something that can't really be done in both directions with an indexed system.)
Sounds like the sort of thing I'm experiencing The mech is likely to be an old XT sort possibly from 7 to 8 vintage. I'l going to get a 9 speed version and run it with her 8 speed system and see if this have any effect.
I've checked and removed all tension from the limit screws. The Front mech in the lower granny setting sits against the seat tube so its fully down as far as it can go. And still it won't get granny anything like quickly, just runs the chain along it's outer plate. I clearly need another. But should I go with a diferent swing version, currently it's a very typical bottom pull top swing, but my epics is top swing bottom pull.
Why can't they all just fit.
I hate front mechs, pretty much anything on my bikes, I can do first time every time and it works,just needs a little fettling. Front mechs drive me up the effing wall.
The Parallel adjustment screw can actually cause the poles to reverse if you are not careful.
That usually happens with new mech/older chainset combo(chainline too narrow for new mech), have you got the BB spacers fitted correctly?
Don't have the mech parallel with chainrings- have it parallel with the chain (in a middling setting)
If you swing that mech back towards the back wheel almost, you'll get into the granny ring
I'll give that a try tomorrow.
There's one last thing to try if it's really struggling to get into the granny.
My bike did this when I'd freshly set it up and it had me stumped for ages, but I ended up swapping the BB spacers around so I had an extra one on the drive side. That cured it despite it being "wrong".
SpokesCycles, that would make sense. If the chainrings are all closer to the seat tube than they used to be, and this is stopping the front mech shifting down into the smallest properly (limit screw letting it rest on the tube), sticking another spacer behind the BB on the driveside should push everything out a bit.
Otherwise, as other people have said, mech height and cable tension are likely culprits...
: P
Can I do that, Isn't there more pressure on the drive side? will a plastic thing be string enough. I might try, much cheaper than a new Front mech.
The difference in pressure is negligible, but if the spacers are fitted properly and the BB is screwed in to the right torque, it shouldn't be a problem - the little plastic spacers are pretty strong and you're not going beyond the design limits of the BB, the manual probably shows various different spacer configurations you could use.
: P