Shimano Shadow plus works with 9 speed drive train
As most of you know, Shimano is claiming all the shadow + derailleurs are strictly 10 speed. I am one of those who refuse to 'downgrade' to a 10 speed, sorry but I'd would rather spend the couple hundred $ on something more practical. Besides I discovered it's possible to create a 2X9 9 speed drive train with a greater gear ratio compared to 10 speed. 22/36 up front, 11-34 in back. But that's for another discussion..
Somewhere on MTB, someone posted a 'hack' to make it work with 9 speed, In short the hack consists of a 1/4" spacer where the shifter cable is bolted to the derailleur. Spacing the cable out changes the pull rate so it approximates a 9 speed version. Most importantly however the shifter must be a SRAM coupled with the the Shimano shadow + Again, this effects the pull rate.
I recently installed a Zee short cage expecting to do the above hack, but found out it wasn't necessary. Coupled with a Sram shifter, the Zee shifting works fine without mods. So good news to those runniing a single up front and want to eliminate chain slap. BTW, I already had a chain retention device, but the Zee is far more effective. No more chain slap into spokes. Yay.