The Zee short cage problem

Shimano has recently issued the new Zee line of parts. Essentially, Zee is just SLX for downhill and gravity bikes. Zee is a very nice line of parts and essentially makes up for the problems with the Saint line of parts – cost and weight. Don’t get me wrong. Saint is awesome. I use many of the parts regardless of the huge cost. Saint is perfect for honest hard hitting DH but many users who need 57mm drivetrains aren’t really pushing hard enough or are heavy enough to need this. Zee fixes that. Truly, Zee is SLX. It just has a different paint scheme.

So, now we have an affordable and light short cage rear derailleur from Shimano to add to the mix. Given my recent study of drivetrains and my desire to try the (26″) 26/24:12-30 gearing on my trail hardtail, I thought that this would be a perfect part to set this drivetrain apart.

I procured the part, put it on the bike… and it didn’t work. It wasn’t able to take up the slack. I was bummed. I went to work that day feeling like a failure but not understanding why.

I didn’t stop thinking about what went wrong throughout the day. Why didn’t it work? A short cage road derailleur would have done better or even worked here, there’s not much difference between this drivetrain and a road drivetrain. I decided to look deeper.

It seemed that the derailleur was over wrapping the gears and was sitting too far forward. Maxing out the b-tension didn’t help much at all. I had a SLX derailleur to compare and then I saw it. While the derailleurs are identical in every way, there is one part that changes. The Bracket Axle Unit! On the Zee derailleur it is marked ‘DH’. Similar to the old Saint shim for wide or narrow range gearing I figured that this part changes for that. The SLX unit had a bracket with a different shape. I simply swapped them.


This morning while prepping this blog post, I found that Shimano intends this to be the case.

Shimnao Zee RD-M640 (SS) – Tech Doc : Parts List
Shimano SLX RD-M765 (GS) – Tech Doc : Parts List
Shimano SLX FD-M676-D – Tech Docs : Parts List

ZEE Options:
Shimano #Y5Y598060 – Bracket Axle Unit for downhill mode (28t)
Shimano #Y50Y98010 – Bracket Axle Unit for freeride mode (36T)

SLX Options:
Shimano Y50Y98010 – Bracket Axle Unit (for normal type)


Two details that I want to share.

Initailly, I mis routed the cable for the SLX FD-M676-D Front derailleur. It seemed so elegant.

Here is the proper routing.

Now – this is PURE GOLD for bicycle mechanics everywhere. Look at the crimping on the cable end in the picture of the incorrect routing.. It’s different isn’t it? Typically, a bicycle mechanic learns that the cable end is triple crimped with the light use of diagonal cutters. My technique is different and much much better as it works better, looks better, and doesn’t provide any ways of weakening the system by actually cutting the end. Below is a picture of the tool. A Craftsman #45177 (45666) mini round nose pliers. These are typically found in jewelry making outlets. If I were to be a pimp, I’d order up the Wiha #32633 160mm round nose pliers although I do like the precision of the mini plyers..