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Discussion Starter · #1 ·
32 years mountain biking, wrenching on my bikes for 25+ years, former master mechanic.
But this has me stumped.

2018 Trek Top Fuel, boost, 1x 11 drivetrain, XT shifter, SLX clutch derailleur.
Driveline is perfect. Shifts great.
High limit, low limit and b-tension are properly set.

Occasionally, the the rear wheel is removed for transport or whatever. I'll disengage the clutch, remove the axle and pull the rear wheel.

Sometimes when I put the wheel back on, shifting is trashed. There is severe drag on the drivetrain, regardless of clutch engagement, and the shift detents are completely misaligned.
It won't shift into the two smallest cogs, and it overshifts to the largest cog, dropping the chain into the spokes.

I'll pull the wheel and put it back on once or twice, and it is completely normal.
W.T.F!

I thought the wheel wasn't aligned, but that doesn't seem possible with the through axle.
I'm thinking it may have something to do with the clutch (will clean, lube and adjust today), but that doesn't make sense either, as it only limits forward motion.

Help me Obi Wan Bikeobi, you're my only hope!

Bob
 

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Maybe the shift cable housing is getting hung up somewhere? That could prevent the chain from dropping in the smaller cogs but I'm not sure how it could cause severe drag. Definitely an odd problem.

If the chain is going over the biggest cog and into the spokes the low limit screw must not be adjusted right.
 

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I haven't run into this but things I'd look at are: Hub: hub axle not broken, bearings good, end caps good/tight (some are threaded), freehub/cassette (Tight, cassette or freehub not moving axially, bearings good). Frame: ABP pivots torqued and working correctly (the hanger is integral to the right one), shift cable is not hanging up somewhere.
 

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Another thought, maybe the free hub body is somehow becoming disengaged and bumped out to the right a little? That could cause all three issues, binding, not dropping to the outside cogs and going over the top of the inside one.
 

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If not a problem with the hub itself (loose endcaps or something similar), I bet the hub doesn't sit properly into the derailleur hanger slot, catching the edge of the groove.

To have this problem, your initial ("proper") setup should be made with the hub not pushed into the slot. And then, when you remove and re-assemble the wheel, you might manage to put it correctly sometimes, moving the derailleur closer to the cogs. Check for such problem.
Grey Composite material Metal Circle Steel
 

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I've had a similar issue ONCE that I could never explain.

Bike was set up great. Pulled the rear wheel for one reason or another in the workstand. Reinstalled it a few min later and had weird drag and misalignment issues of the drivetrain. Pulled the wheel back out, reinstalled, and it was fine. Didn't touch anything else. I didn't even shove it in a box for travel (I've bent derailleur hangers when traveling with my bike in a box before).
 

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32 years mountain biking, wrenching on my bikes for 25+ years, former master mechanic.
But this has me stumped.

2018 Trek Top Fuel, boost, 1x 11 drivetrain, XT shifter, SLX clutch derailleur.
Driveline is perfect. Shifts great.
High limit, low limit and b-tension are properly set.

Occasionally, the the rear wheel is removed for transport or whatever. I'll disengage the clutch, remove the axle and pull the rear wheel.

Sometimes when I put the wheel back on, shifting is trashed. There is severe drag on the drivetrain, regardless of clutch engagement, and the shift detents are completely misaligned.
It won't shift into the two smallest cogs, and it overshifts to the largest cog, dropping the chain into the spokes.

I'll pull the wheel and put it back on once or twice, and it is completely normal.
W.T.F!

I thought the wheel wasn't aligned, but that doesn't seem possible with the through axle.
I'm thinking it may have something to do with the clutch (will clean, lube and adjust today), but that doesn't make sense either, as it only limits forward motion.

Help me Obi Wan Bikeobi, you're my only hope!

Bob
To eliminate the clutch from your check list, just turn the clutch off. The cage will move freely.

Doesn't sound like a clutch thing though, not if you can't get down to the lowest cogs.

Are the dropout dirty -not allowing the wheel to set properly?
 

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Discussion Starter · #8 ·
I think Marsa and others are on to something.

The wheel may be seating slightly off, somehow.
Interestingly, it happened with 2 different wheels (one new and the other low mileage: Trek/Bontrager, and DT Swiss hubs), which makes me think that it could have something to do with the slot.
You would think that if the wheel is straight enough for the axle to pass through and thread, there wouldn't be an issue.

Edited: I just noticed Lone Rager mentioned the pivots--great catch!
Hmm...Trek's dropouts house suspension pivots (ABP)...maybe I will check to make sure they are ok.

I will check all the items mentioned, and let folks you know if i find something definitive. Might help someone else.

Thanks a bunch,


Bob
 

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I remember I had this problem (although not that severe) on my previous RM Instinct alloy. I never found the reason; but I'd usually take the wheel off and on again, and it would usually work. Weird thing was that the position of the skewer was off too, although my hub caps were pressure instead of threaded.
 

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Discussion Starter · #10 ·
I had it shifting beautifully on the stand. Started from scratch, reset high and low limits, b tension and cable tension.
Didn't ride it over the weekend, instead riding my old GT I-Drive Team for the 2nd time this year (old 3x9 shifted perfectly, PRd the 7.3 mile trail! I thought 29ers were superior to 26ers?).

Yesterday, I pedalled the Trek up the hill beside my house and noticed the drivetrain sounded noisy. Sure enough, shifting was again terribly misaligned! It would not shift to the highest 2 cogs, and dropped into the spokes.
I lifted the chain out of the spokes while upshifting a couple clicks and turning the crank backwards, which placed the chain back on the cassette.

I put the bike on my bike rack, prepared to completely redo the drivetrain setup.
The shifting was perfect. WTF?

I took it for a spin and still perfect.
Rode it today, and PRd the same trail as above but reverse direction.

I will inspect the hub, cassette, etc, but I'm thinking it is the ABP pivot. All was fine until the cassette/hub was placed under tension and the rear suspension cycled while riding up the hill.
I have no flipping idea how it self corrected.

What is mind numbing is just how far out of alignment the shifting becomes. I can understand imprecise shifting, maybe some noise...but being off by 2 cogs?

I'll tinker with it a bit, but may contact my shop to see if they have any info.

Many thanks,
Bob
 

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When the clutch is off and the wheel is removed, make sure that the cable housing ferrules aren't hanging up somewhere when you reinstall the wheel. That would cause the poor shifting, but wouldn't have it overshift off the cassette (unless your limit screw is really off).
Just another thought/suggestion
 

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Discussion Starter · #12 ·
Thanks Jason, all help is welcome.
Something MUST be misaligned, because the limit screws will not allow shifting into the spokes--it simply cannot happen unless something is crooked.

Gotta do some sleuthing...

Bob
 

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I hope I don't cloudy up things too much. If I remember right, Trek's have Split pivot. Wonder if there is anything going on with that pivot area that gets affected when removing and reinstalling the wheel? Is is possible the bolts holding the derailleur hanger is loose that can cause shifting when reinstalling the wheel? Or debris is getting in between the end cap of the axle and the drop out area? Sorry, I wish I had better explanations of potential "It has to be this or that". Good luck. I hope you are able to find the culprit.

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I hope I don't cloudy up things too much. If I remember right, Trek's have Split pivot. Wonder if there is anything going on with that pivot area that gets affected when removing and reinstalling the wheel? Is is possible the bolts holding the derailleur hanger is loose that can cause shifting when reinstalling the wheel? Or debris is getting in between the end cap of the axle and the drop out area? Sorry, I wish I had better explanations of potential "It has to be this or that". Good luck. I hope you are able to find the culprit.

View attachment 1268301
trek somehow managed to get around DW's Split Pivot patent and call theirs ABP without licensing anything. They're strikingly similar, but not identical.

The mystery drivetrain issue I had that was resolved by removing and replacing the wheel occurred on a hardtail, so it's impossible for the rear suspension to be even a part of the culprit in my case. I'm not sure how similar my issue and OP's issue are, though. Mine definitely hasn't repeated, so I haven't been able to engage in further diagnosis.
 

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loose cassette? Could also be a loosening hub. Not sure on your particular hub, but my stock novatecs had a threaded hub tensioner and it slowly worked loose when i would remove wheel. It would slightly move the cassette alignment and it led to all kinds of shifting issues that i made worse trying to adjust it on the trail.
 
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