TLDR: I did not research and bought an XT 11-46 11s cassette for my Deore M5100 RD which I now know is only compatible with 11-51 cassette. Can't adjust the B screw to get the top jockey wheel any closer to the 46t cog, but it is shifting and holding gear, should I just roll with it or replace with XT RD?
Been running a 38t chainring with the 11-51t cassette and Deore M5100 derailleur on my Surly Bridge Club. Been mostly riding trails lately and other than steep climbs, never felt like I was in the correct gear. I got the idea to change my cassette to the XT 11-46t and my chainring to a 32T. This would give me tighter gear spacing for 2nd to 8th and a lower gear at 32×46 vs 38×51. Just would lose top end speed but that's not important to me. I did not realize that the M5100 RD was only compatible with 11-51 until I had things swapped over and making adjustments. The top jockey wheel is as high as it will go but still pretty spaced out from the 46t cog. It is shifting and, from my quick test ride, holding gears. Maybe not as smooth as it should, but still working. Would it be smarter to upgrade my RD and shifter to XT if I can, or would I be okay to leave it as is?
by DeanW13
4 Comments
Is the b tension entirely backed off? In my experience this works ok. I think I had it setup like this on my fat bike until I crunched the derailleur into pieces and all I could find was an m7000.
Wouldn’t it be more affordable to find an 11-51 cassette?
I am running a Deore RD-M5100 with an 11spd 11-46T Sunrace cassette on one of my bikes and an M5100 with an 10spd 11-48T Microshift cassette on the other. Both shifts beautifully. I am not sure why you’re having this issue but it’s not because the largest cog is too small.
https://preview.redd.it/pm9uzzdju1bg1.jpeg?width=4096&format=pjpg&auto=webp&s=e457f45c3804704a999e30f70cb947dfa40275bd
I can’t see the b-screw in your pics, but I do see a very VERY backed out limit screw. Just want to make sure you’re looking at the correct screw. The B-screw is this one back here
https://preview.redd.it/8lruk5dwx1bg1.jpeg?width=800&format=pjpg&auto=webp&s=9488a9f184447368878c8eb4871bfe0ced016614
I’m suspicious of how the derailleur itself is mounted. I’ve never encountered a situation where the derailleur couldn’t come close to the largest cog. Absent b-limit tension, any derailleur would run up into the cog. The b limit is the only thing holding it away from the cogs.