[WR304]

Looking at your pictures I think I’d remove the Wolftooth road link and use a longer chain length, so that the 38 tooth with 10-51 cassette is fully usable throughout its range.

One test to do as well is to put it on the 38 x 51 tooth combination, and then spin the cranks backwards repeatedly to see if the chain will fall off when back pedalling. The double chainring will affect the chainline, as the chainring won’t be in quite the same place as a dedicated 1x crankset chainring, so it’s worth checking to avoid any surprises mid ride.

For the small inner chainring having a sagging overly long chain on those smallest rear sprockets (in order for the chain length to run acceptably on the 38x51) would be ok to have. It’s not a combination you’ll use, and also when you sit on the bike with the suspension compressed a bit that will pull the chain tighter when riding so it won’t be as slack in use.

 

[WR304]

On my last 2x drivetrain bike I had 38/ 26 tooth front chainrings with a 10-42 11 speed cassette.

For the front shifting on that setup I was always careful to change down from the outer 38 tooth ring to the inner 26 tooth ring when I was still 3 sprockets away from the largest rear sprocket. I’d stay in the 38x42 if I was sure I could make the hill in that gear but otherwise I’d get my front shifting done well in advance so I was never caught out trying to do a front down shift mid climb.

Trying to shift between the 38 and 26 tooth chainrings under load with maximum chain tension and chain angle was the most likely thing to drop the chain on that bike. The straighter the rear chainline was before doing a front shift the less likely the chain was to drop.

On your bike you have a greater jump in gear range again so might need to do the same when riding to keep the chain on as well.

 

[WR304]

How about replacing the stock B tension screw of the rear derailleur with a longer length screw from a hardware store? That will give you a greater range of adjustment.

 

[WR304]

Thanks. Good idea. I just ordered two of the 16T versions of this one at $12.99 each. I'll try replacing just the lower wheel first. I just hope the narrow-wide tooth profile will work with the Shimano XT chain. I read at Wolf Tooth that the Shimano 12-speed chain isn't compatible with narrow wide chainrings. I guess I could switch over to a Sram NX chain. Hope it will shift ok.

Amazon.com : stone Rear Derailleur Pulleys Wheels 10T 12 T 14T 16T Suitable Mountain Bike Road Bike Adult Bicycle Trekking Bike(10T Hollow) : Sports & Outdoors

Amazon.com : stone Rear Derailleur Pulleys Wheels 10T 12 T 14T 16T Suitable Mountain Bike Road Bike Adult Bicycle Trekking Bike(10T Hollow) : Sports & Outdoors

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You can use a metal file to file down the wide teeth of the narrow - wide jockey wheels if needed to make sure they will work with the Shimano chain. Those alloy jockey wheels should work ok then.