My kids are riding with M640 Zee wide ratio mechs, which claim they can handle up to a 36t cassette. Does anyone know if that’s realistic or how much bigger a cassette I can use? The sunrace 10-speed 11-42 looks mighty tempting.

I had one running on 11-42. Longer B screw. Depends on frame/hanger design.

Great, thanks. Might experiment with the 11-42 on my wheels. Where does one buy longer B-screws?

40T is overstretched without a longer b screw, trust me I know, I learnt the hard way as it exploded and had to singlespeed home.

Noted! 🙂

zee +40t wouldnt work on my single pivot empire due to chain growth.

zee + 42T worked fine on the HT.

so it depends on teh frame n stuff.

36t is a realistic limit for Zee, in my experience. The new Deore mech is cheap if you want to go larger.

Ah yes, the M6000-GS. 10-speed, 42t top, and clutch. Now the boy is on 26″ wheels having a tiny mech is less of a concern.

Mine works on a 42 with normal b screw, full sus frame and shifting is pretty good.

ZEE is for sending, leave the flappy long chain at home

I have a similar experience to kelvin, in that I couldn’t get the zee to work with anything bigger than 36. Switched the cage for a oneup RadR cage and now works happily with a 42. They’re like hens teeth to get hold of these days though.