Shimano

Alfine CT-S500 Chain Tensioner, Black

I admittedly am not using this for its intended purpose, which is severely specific (running internally geared hubs on vertical dropouts, I think?), so I can't comment on that. I wanted to run my single pivot full suspension mountain bike as a singlespeed, and the Alfine looked like it would fit the bill (basically a derailleur with no shifting). All I can say is that it does not work for my particular application (Cannondale Prophet) as I skip like crazy as soon as I start to mash. I think the issue is the minimal chainwrap it allows on the cog as it pulls the chain pretty low, much like a derailleur. I tried dropping a link and got the same result on today's ride. Also, the Alfine's design allows only 5 mm of side to side adjustment for chainline, which didn't help me as I hoped it would and I ended up with a chainline that was about 1/8" out of whack. I'm going to end up dropping the ridiculous coin on a Yess ETR-D, which I hope will remedy the situation. I've grown to despise gears and love mashing to the point of failure, so I will find a solution eventually!