Chain skipping on 11t..

ashes_mtb

Has preferences
Having some issues with the chain skipping when back pedalling in the smallest cog.

Setup is 11 speed SLX, 11-42 cog. Boost 29er. Using middle position of a Shimano triple crankset with Wolftooth NW ring. Chainline measured around 49-50mm.

B-screw looks good. Only an issue in small cog and it looks like the chain is catching the next cog and trying to climb up.

Tried adjusting the limit screw further outboard, but doesn’t fix it.

Any ideas?

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ozzybmx

taking a shit with my boobs out
Is it a new chain on an old cassette ?

Shimano is not the best when back-pedalling anyway... dont back pedal.
 

ozzybmx

taking a shit with my boobs out
I knew there was a detail I left out..

Both were installed new together. No chain “stretch” showing on the gauge and everything looks in good order to the eye.
If you look at the angle of the chain... just don't back-pedal.

Shimano has had skipping issues when back pedalling since 11spd.

#1 son had dropped his chain on a few races 2-3 times and it was only when we went riding together I seen he was doing a 1.5 rotation correction where it would be a 0.25/0.15 on a downhill rutty section correction... I lost my shit with him, fucking show boating, thinking he's shit hot cool with a few back pedal rotations in front of a crowd... costing him a place and blaming my gear setup.

Problem sorted... in my house :D
 

ashes_mtb

Has preferences
If you look at the angle of the chain... just don't back-pedal.

Shimano has had skipping issues when back pedalling since 11spd.

#1 son had dropped his chain on a few races 2-3 times and it was only when we went riding together I seen he was doing a 1.5 rotation correction where it would be a 0.25/0.15 on a downhill rutty section correction... I lost my shit with him, fucking show boating, thinking he's shit hot cool with a few back pedal rotations in front of a crowd... costing him a place and blaming my gear setup.

Problem sorted... in my house :D
I only back pedal when it’s in the work stage I swear!

If it’s normal I’ll move on. It rides fine so I was just being a pedant about setup.
 

The Duckmeister

Has a juicy midrange
Limit screw has zero effect over the cassette when backpedalling, because the derailleur is downstream of the misalignment. Ex-triple crankset will almost certainly be non-boost, so that will increase the chainline deflection from mid-ring position to small sprocket, and that will affect backpedalling. You could overcorrect by putting the ring in the big position, then you'll have the backpedalling peoblem on the big sprockets.

Short version: don't backpedal on the cassette extremes.
 

ashes_mtb

Has preferences
Limit screw has zero effect over the cassette when backpedalling, because the derailleur is downstream of the misalignment. Ex-triple crankset will almost certainly be non-boost, so that will increase the chainline deflection from mid-ring position to small sprocket, and that will affect backpedalling. You could overcorrect by putting the ring in the big position, then you'll have the backpedalling peoblem on the big sprockets.

Short version: don't backpedal on the cassette extremes.
Non-boost chainline did cross my mind. I might look to get some new cranks down the track - are the standard m7100 ones with 52mm chainline the best bet for 11 & 12 speed boost, or are the 7120 55mm chainline version better? Shimano seems to suggest both are boost compatible.
 

The Duckmeister

Has a juicy midrange
Shimano's component numbering has got a bit illogical recently, but the 55mm chainline is what you want to pair with a boost back end. The appropriate crank variant should have a -B suffix to the model number.
 

Daniel Hale

She fid, he fid, I fidn't
Short version: don't backpedal on the cassette extremes.
i see all manner of peeps on FB complaining about this issue constantly -the gravel crew were whinging about grx back-pedalling -W?TF are people throwing their bikes onto work stands and back-pedalling the shite out of them??? then whinging -one guy told me he back-pedals when riding his mtb -, not just a tiny bit but a half rotation of crank??
 

moorey

call me Mia
i see all manner of peeps on FB complaining about this issue constantly -the gravel crew were whinging about grx back-pedalling -W?TF are people throwing their bikes onto work stands and back-pedalling the shite out of them??? then whinging -one guy told me he back-pedals when riding his mtb -, not just a tiny bit but a half rotation of crank??
Gravel riders. Explains everything.
 

Mattyp

Cows go boing
-one guy told me he back-pedals when riding his mtb -, not just a tiny bit but a half rotation of crank??
Was he faster than you on the descents?
It can be good to switch which foot is back when you're coming down a steep windy chute.
 

sebbyreddan

Likes Dirt
Looks like there may be a few bent teeth in the next cog up. This may be catching when back pedalling, looks like your RD keeps it far enough away to stop it catching when forward pedalling.
 

The Duckmeister

Has a juicy midrange
Looks like there may be a few bent teeth in the next cog up. This may be catching when back pedalling, looks like your RD keeps it far enough away to stop it catching when forward pedalling.
More likely they're bevelled to aid shifting. They're staggered in a way that gives the illusion of being bent. Plus they're shaped to work when pedalling the right way.
 

Daniel Hale

She fid, he fid, I fidn't
Without a helmet...Ive seen it.
insert that stooped gif of the guy holding up his finger

but yep you’re right, at the speed i ascend helmet not really necessary...besides it messes up the hair, marcel kittel has nothing on me -even have this for hair doping -#bioacceleration technology
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