I love the simplicity of a single speed, and with the recent addition of a fat bike to the stable that came with a poor drive train, I thought I would go that route, at least for a while. One thing I don't like about SS is that the gears are fairly tall for what I ride, tight, enduro, trials, kinda stuff and the lowest chainring you can get is like a 36 for a SS while the lowest cog is around 20 which is too high for some of the hills I ride. However, when I hit the connector roads I am way low, so I am going to cheat. Single 20 cog in back and a 2 speed 22/34 in front and leaving the front derailleur. This tensioner allows for that, no problem and I still have a sort of SS..... maybe thats what I'll call it, SSS! Anyways, now I have a high/low range SS, and it is darn near perfect. Only problem, you have to make sure the rear cog aligns perfect with the teeth of the tensioner. Its also typical Shimano quality, very well made. Don't but the Alfine gear for it unless you know what it is, its for a special hub even though it fits a regular cassette. I broke one first ride.

Used on a single speed ebike. It is very smooth. I wanted quality and it definitely is. I have it on a 750 watt 30 amp custom ebike setup. The bike literally pulls a wheelie. The peak watts is somewhere around 1200 watts. This Shimano tensioner is simple but strong. Paired it with a Shimano freewheel. Well worth the money. Follow the diagram on installation instructions.

First and foremost the shipping was fast and tracking was on point. The idea with this tensioner is to line the pully with the rear cog. Don't worry about your front sprocket having a perfect line. Your chain won't jump off. All I had to do was reposition my spacers and cog to line up with the tensioner pully. Didn't even have to use the washers that were provided. About the Alfine tensioner. This is a good quality strong spring tensioner that will hold your chain steady and strong.

Only works with Shimano nexus or alfine or 7-12 speed hubs. It worked for my cassette, but it is in a fixed position so it won't work with freewheels, only cassettes or alfine hubs. Make sure to get a cassette spacer set

Fit perfectly on my old Diamond Back for converting to a Nuvinci hub. You basically end up with a rear derailer, so if you're going single speed to get rid of that, this isn't for you.

It's nice on the Nuvinci hub, because I could leave the front derailer on with a two speed road crank set, and get more range from the internally geared hub.

It makes chain adjustments easy by just using shims to space it. It set mine to the middle between my upper and lower front gears, and it tracks both with no issues.