Hi there,
So I’ve taken the plunge with an xt shadow plus mech which was running lovely on my first ride but has developed a strange thing after the second – when running in the smallest cog the cage is not fully tensioning the chain. It’s not a problem in any of the other gears and it appears to do it with the clutch both engaged and disengaged. It feels like it just won’t return to its fully compact state (if that makes sense!)

Has anyone had anything similar? Or could anyone suggest what I can try to rectify the situation?

Thanks in advance

Do you mean that the bottom run of chain is slack? Just sounds to me like the chain is too long

I do indeed and that was my first thought. However the chain length is big ring to big ring plus a couple of links (single ring at the front)
It’s more like the mech just isn’t fully closing up

That big ring + a bit is only a rule of thumb. I’d try taking a link out and seeing how it goes. As long as you don’t get it so short in big/big that you’ll damage things you’ll be fine.

Cheers for the advice. Tbh the chain is about as short as I’d want to go, the mech is pretty well stretched out – not too far! In the big cog already

Hmm, ok. Will the cage move back far enough to tension the chain if you move it by hand?

It will indeed. It sort of feels like there is a lot of resistance to it tho. This is the same with the clutch on or off, I have even tried removing the clutch mechanism altogether!

I just get the feeling it’s probably something really stupid I have got wrong!

Yes, got the same problem.

But it’s on a six week old spicy so the whole shooting match has gone back to the shop. Will repost when I know more…

Couple of things :

When removing the rear wheel did you move the “clutch” lever/switch to the off position?, if not then you have possibly borked the clutch mechanism.

You can adjust the level of tension in the clutch mechanism, do a google and you’ll find the info on the shimano tech docs site.

Rear mech B tension screw, the rear upper jockey wheel should be under the rear cassette and as close as possible without actually interfering with it.

That sounds a bit odd. There shouldn’t be anything that would stop it. It might be the spring in the pivot for the cage that has moved out of its proper place (it has pegs that house in a hole a bit like an old canti brake spring) meaning the cage won’t spring through its proper travel arc. Usually shows itself by the cage springing forward rather than back though.

Hmmm ok is that an eAsy fix? Thanks the b tension screw is set properly,

Soma funk when you say borked the clutch – does that mean knackered completely or rebuildable?

Thank you for all the suggestions/ help

It’s relatively easy to sort. Not complicated but can be a bit fiddly. You just need to undo the circlip in the pivot and it should all be obvious.

Cool that’s great I’ll have a look at that tomorrow. Thanks again for all your suggestions!

Shimano Tech Document for XT M786 Shadow Plus Mech

How To Adjust Clutch Mech

Had the exact same problem with mine. Bought new from a big Irish retailer, set up fine, pedalled twice around the locker room (it’s big) and realised was having the same problem. Have sent it back to them as I didn’t want to take it apart and bork it some more!

Check your lower jockey wheel
Had same with mine, turned out to be the jockey wheel not sat central in the cage, causing chain to slip off and back on it
Replaced jockey with a cheap alloy one from eBay, been fine since
I wrote a thread on it – http://singletrackworld.com/forum/topic/shadow-rear-mech-jockey-wheel-problems

Hmm- didn’t notice any probs with the jockeys- mine was straight out of the box and on about 15 minutes..
Had googled it and some folk had had similar issues with yhe clutch being the problem..
I didn’t want to cause any damage and poss invalidate the warranty so sent it straight back to that large Irish retailer I mentioned. Hopefully it’s an easy fix and I csn get it back ASAP! Haven’t had a ride since before Christmas and am itching to get up to Cathkin!

Allthpal mine is also from a large Irish retailer. I guess my suspicion is that I the clutch was knackered would it not just act like a normal mech when I switch it off (and have even removed the clutch)
Ill Have another look at it and see if I can get it sorted.
Thanks for all the assistance. Ill post any findings!

Will keep an eye out on here minky, will also post up when I have some news.

just heard that the mech has gone to madison. hope it will be back for the weekend
😐

Hmmm, that doesn’t sound good if its a problem with the mech rather than setup – I was hoping to ride on thursday!

Hmm- sent mine back on Friday so guessing its gonna be a few days before I even hear anything!

Mine was from bike discount.de
The jockey being off centre dropped chain between jockey and cage, the chain would still move but extra resistance overcame the clutch and the whole thing jammed causing chain to come off
I sent just the jockey pulley back and it was replaced as faulty (but after I’d already bought an alloy one)

Ok, Ive got it fixed! what sorted it was looking at the cage tension spring or P spring. I’m not sure if it had come out or not but there was a choice of positions on the cage for it locate in. I repositioned the spring in the position that gave the most tension and everything seems to be fine now. (although ive only done about an hour this eve)
It wasn’t difficult to do and i reckon is worth having a crack at if you run into trouble!

Cheers for all the help!

Oh well. Have already sent mine away..

Mine chain seem slightly slack in the smallest cog also.. (Shimano Zee)
Largest ring chains very tight, (can’t really take more links out),
Might have a look tomorrow at Somafunk’s Link see if it’s the same for the Zee as the XT..

Samjgeorge that’s exactly the situation I had!

Interesting, I recently noticed the same with my XT Shadow, rather than +, when I fitted a new chainset.

It got scratched a bit by a rock in a crash last year so I just figured I must have damaged it then. A side effect has been that the sometimes slack chain has taken some of the rubber off the tyre sidewall exposing some of the threads.

Exactly the same issue with mine, 3rd ride out today suddenly started feeling really stiff then i snapped the chain – turns out the bottom jockey wheel had seized solid ffs

Mine decided to snap and bend and twist itself all out of shape last night whilst riding an inoffensive though muddy South Downs bridleway. Looks like the back half of the not-really-a-parallelogram snapped between the high/low screws, the top pin holding front half of it to the carrier then bent out of shape, and then I think the cage got stuck in the cassette and got bent. Despite everyone’s best efforts to ghetto singlespeed it, I had my first taste of cyclocross getting back to the carpark… That’s a short-cage Zee by the way, so I’m 99% certain it’s faulty, a DH/free mech should be way tougher than that.

just heard that madison are replacing the mech as mine was buggered. YAY!

no stock for another 7(working) days BOOO!!

i wonder what failure rate the shadow + has had??

Just got bike back. LBS swapped out mech from stock bike to get be mobile again ASAP. Top guys, well pleased.

Email today from large Irish retailer. Replacement mech being sent out tomorrow after the the old one was sent back to the distributer- I too also wonder how many have broken?

I’m worried about fitting mine now!

I have had an XT mid-cage one for almost 2 months and its been faultless so far. 😀

I wish that I could say the same for the (non-Shimano) brakes on the bike!!! 😡

I wish that I could say the same for the (Shimano)brakes on my bike 🙁

New mech received today- hoping to fit it tomorrow and get a ride in ASAP!

loverofminkys – Member
Ok, Ive got it fixed! what sorted it was looking at the cage tension spring or P spring. I’m not sure if it had come out or not but there was a choice of positions on the cage for it locate in. I repositioned the spring in the position that gave the most tension and everything seems to be fine now. (although ive only done about an hour this eve)
It wasn’t difficult to do and i reckon is worth having a crack at if you run into trouble!

Thanks, this basically sorted my clutchless XT Shadow, although I also cleaned and greased mine which definitely helped it rotate freely too. I suspect this aspect to be equally applicable to Shadow + even if your mech has been replaced or serviced, because I’d imagine bad weather conditions and blasting the mech with a hose to clean it will lead to the same problem reoccuring.

Just some notes on my experience. Most importantly, if when you put it back together the cage is springing forward rather than back, you haven’t wound the spring forward past the cage stop. If you undo the cage stop pin and manipulate the mech linkage you can rotate the cage forward through 1 full turn without fouling. Then simply screw the cage stop pin back in and you’ll find that the cage now springs back as you’d expect.

The clutchless Shadow has what appears to be a single grubscrew in the front body of mech parallel to the plain of the cage. Undo it anticlockwise fully and it reveals itself as a post that extends into a groove in the axle that is attached to the cage. This allows you to pull the cage off the mech.

I had just wanted to shift the pin of the spring into the higher tension locator hole, but the wound spring means it doesn’t just slide off until you pull the cage almost off the mech. When you free the spring from the cage locator hole the spring will unwind itself unless you wedge it with something. This is probably fortunate because it gives you an opportunity to clean the cage axle – mine had that kind of slightly sticky dark dry film. Considering how minimal the seal is, and that it seems to leave a slight gap anyway, I’m not surprised people are having problems in UK weather conditions. Most of the time it’s dry and dusty here and I’ve still experienced a problem. Perhaps they used to better sealed or the tolerances weren’t up to scratch at some point.

I cleaned the cage axle, greased it lightly, reinserted the spring back into the mech fixing it into the internal locator hole, then inserted the spring into the rearmost locator hole on the cage, pushed it home, undid the cage stop pin, rotated the cage 1 turn forward to rewind the spring, screwed the cage stop pin back in, and voila, my chain was no longer slack.

This made a massive difference, because before starting I had found that my chain was so slack, despite making it 1 link shorter than the big-to-big rule, that it was hanging down on the top as well as the bottom in the three smallest cogs.

Great thread this… I will have all the parts for a dream build at the end of the month including an XTR + rear mech… will have a look at it before fitting now.

Cheers

My post on THIS thread links to the official doc that clearly states it needs maintenance. It’s worth a gander if you own one and have (obviously) lost the printed version that accompanies the product…