Other Options for Bent SLX M7100 Rear Deraileur

[JayMartin]

Hello,
I bent the outside cage on my SLX M7100 SGS rear deraileur. The two wheels are no longer aligned, making indexing super finicky. I have some questions about options:

Would a M7000 cage fit? I can’t find cage parts for my M7100.

If I’m faced with replacing the rear derailleur, would you recommend replacing with the same component? Or what upgrade would you recommend?

Thanks,

Jay

 

[Bones]

Can you not just straighten it? It doesn't have to be perfect as mine looks a right mess but still works ok.

 

[steve_sordy]

@JayMartin I have bent my rear mech arm several times. Each time I straightened it the best I could and then put it back on the bike. Stand over the mech and cycle through the gears, look for the jockey wheel alignment with each other and the cassette. If they are out of alignment, it is more important that the upper jockey wheel is in alignment with the cassette. If necessary, have another go at straightening the mech arm. It may just require twisting. Be aware where the twisting force is going, so hold the top of the mech arm and twist the bottom bit, use tools if you have to do so. Make sure that the two plates that form the mech arm are open enough where the chain enters to allow it to do so without rubbing.

You may end up with a mech that is pretty damn good but is out of alignment with the bike and causing shifting problems. In which case you may need to bend the mech hanger. For that you really need a mech hanger alignment tool. They can be expensive (£10-£85)*, but the job is very quick to do, so bike shops don't charge much for hanger alignment. The last LBS charged me £10 for mech hanger alignment, but that was about three years ago.

I have completely snapped the original XT mech right through the clutch body, so I had to replace it with whatever mech I could get, an SLX one. Yesterday I discovered that one of the teeth on the lower jockey wheel had snapped off. I thought I would replace the broken SLX jockey wheel with one of the XT jockey wheels. Don't bother, it doesn't fit! When I tightened the axle screw, the wheel would not rotate. Back off enough to allow rotation and the screw is too loose to stop in. (By the way, the XT jockey wheel has a proper ball bearing, whereas the SLX is a bush).

I refitted the broken jockey wheel and it still worked perfectly on today's wet and gritty ride.

I now have a spare SLX M7100 mech, just in case.

*later edit

 

[JayMartin]

I can try to straighten it. Do you agree that is what would make indexing tough. I can get the small gears dialed in, but then the big ones want to just slightly grab the chain to go up even more. An 1/8 of a turn with the barrel connector can almost get it out but not completely. Or am missing something else?
Thanks for the comments,
Jay

 

[steve_sordy]

I can try to straighten it. Do you agree that is what would make indexing tough. I can get the small gears dialed in, but then the big ones want to just slightly grab the chain to go up even more. An 1/8 of a turn with the barrel connector can almost get it out but not completely. Or am missing something else?
Thanks for the comments,
Jay

That sounds like you need to realign the mech hanger. Usually, when my mech-fu fails me, it is time for either a new cable or mech hanger realignment. I usually know which it is given the history of my bike.

 

[JayMartin]

Okay, I straightened the cage out and the indexing is clean at both ends. In the long run, I should probably pick up a hanger alignment tool (brand recommendations?).
Thanks all,
Jay

 

[Loe Rider]

I picked up one of the generic ones off Amazon for £18. Works a treat.

 

[steve_sordy]

I bought the Parktool one several years ago. YIKES they are now £85!!!!

The LifeLine Pro looks good for £32. But I see that Ali Express do one for £10.03 provided you live in an area they will deliver to.

Just found this: "Best ...hanger alignment tool......"

The best derailleur hanger alignment tool: 9 tested - CyclingTips

Once thought to be only for workshop use, a hanger gauge is now a commonly needed tool to achieve perfect shifting.

cyclingtips.com

 

[JayMartin]

I went ahead and ordered a Park Tool. I'll be interested to learn whether any of the indexing problem was from the hanger being bent or all from the cage being bent. Also, I heard back from a vendor that the M7000 cage will fit.
Thanks again,
Jay