So I’m trying to figure out a more “permanent” solution to my budget (currently only $45!!!) wide range 1x drivetrain on this old Scott.
The issues (as far as I can tell) is that the b-limit is unable to go far enough to give the necessary spacing in the 42t ring.
Right now, I’ve only been able to make it work by adding a nut to the bottom of the fully extended b-limit screw to add extra spacing to the b-limit.
Does anyone have a better way to make this work? Thank you!
by Cantaloupsareswell
7 Comments
If I remember this all correctly, try putting the b screw from the other side, if that doesn’t work, look for a goatlink to give you better shifting
No matter what you do with a RD-M772 (?) to *clear* a 42T cog, you’re going to suffer poor chain wrap on the small cogs. It was not only intended for a 34T (36T?) max cog, but with a parallelogram shape that doesn’t ramp very much compared to modern RDs.
How are you shifting? An original SL-M770 shifter or similar?
Pretty sure it works the same with 9 speed, it’s made to do exactly what you’re looking for, and fits into your budget – [https://www.wolftoothcomponents.com/products/goatlink](https://www.wolftoothcomponents.com/products/goatlink)
Good luck. I tried getting my RD-M772 working with an 11-40T cassette, and ended up getting a longer 4mm screw to replace the original B tension screw. It worked but I was never thrilled with how it shifted so I changed to an 11-36T cassette and it shifted flawlessly on that. It would probably work fine with one of the 11-38T Microshift 9-speed cassettes as well.
You may have it “working” with the modified b-screw cranked way in, and a goat link might even work better, but 11-42T is so far outside of what it was designed for, I doubt it’ll ever work perfectly.
That may be fine for you. Personally, if I am running an XT level component I want it to operate as smooth as silk, even if it’s vintage.
I can’t say for sure it will get you to 42T, but I used an [extra-long, aftermarket B-tension screw to get this Deore derailleur](https://imgur.com/gallery/rd-m592-with-ritchey-rocket-index-adjusting-barrel-extra-long-b-tension-screw-98GqCdI) to shift pretty comfortably up to 38T on [this bike](https://imgur.com/gallery/bridgestone-mb-3-rebuild-bgzQbFZ). The cassette is a SunRace 9SPD 11-38.
As some of the others have said, the derailleur was never designed to stretch this far. Modern derailleurs will work much better and shift easier and more smoothly. You run the risk of the derailleur failing to shift under pressure while stomping uphill.
Easiest way to do it without all manner of hackery is a goat link.