Zee M640 SS cage derailleur with 11-40t cassette

Retrorockit

Old School Hero
Why the M640 Zee SS cage? It's a DH rated part. No plastic. The clutch cover and lever are both metal. The SS cage helps keep it up away form curbs and things on 26" bikes. This test confirms it works with up to 40t cassettes in 1x setup.
Also 10-11 speed Shimano comes out at the same cable pull as SRAM 1:1 shifter. So using those shifters 7,8,9,10,11 speeds can be done with this. Including gripshifters and even vintage 1/2 pipes.
The bike is a 2004 XC Softtail MTB. I converted it ti 1x11 as part of a front Freewheel conversion ( whole separate story) and the SLX derailleur hanging down was driving me nuts (as do all vintage 26" bikes with SGS long cage derailleurs).
The SLX can run up to a 51t cassette (I've done it).
The M540 comes in 2 versions DH for 11-28 cassette, and Freeride (FR) version with a different hanger extension for 11-36t cassettes. I bought the DH before I knew about the FR, so I got the FR hanger extension also.
I pulled off the SLX, and with the FR hanger it bolted right up, and adjusted in with the stock B screw. I didn't have to cut the chain either. It was already the right length going around the big cog. Now in the top gear it should be running just the way Shimano intended. But I didn't like the way it only wrapped less than 1/2 way aroung the 11t cog. If I don't like the way Shimano does something I tend to fix it. So I got the DH hanger and stuck it in there. The guide pulley was still some distance below the 11t cog, but it wrapped around to the front further for some improvement. But now it did need a slightly longer B screw. I pulled one out of a Deore I had sittting around and that was enough.
I didn't measure the SLX, But I do have an XTR M960 mid cage on another 26" bike with the same size tires. The XTR has 6" ground clearance in the worst gear, the Zee has 7".
I've seen claims the M640 can run an 11-42t cassette. I think the FR version could probsbly do that.
 
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