Blackspire Single ring roller kit with hardware - red

I bought this as a tensioner for my Schwinn Tango tandem bike for the front chain. It has a flat-ish metal piece that has a slot in it for the tensioner and the old tensioner crumbled into dust.First, this roller only has a single bearing on the outside. This is not a problem, but there is no way you would know that from the picture since it looks like a hollowed out skate wheel and skate wheels have two bearings. Second, the end of the axle bolt is flush with the red roller material, making it bad to mount to a flat surface since the rubber would rub against the flat surface when tight.I ended up having to find a very specific washer to space it out a small amount. The washer I used came from one side of the spherical washers from a normal cable operated brake pad. With this little washer (with the small side out) I got the space I needed for the roller to move freely. Once spaced out, it worked great.If the manufacturer had provided just a little longer axle bolt, like 2mm longer, I would have been golden from the get go. Alternately, making the roller just slightly thinner would be the same thing. This is why I say that the tolerances are bad. I don't know why the axle is the same exact size as the roller, but unless you have a positive difference in length from the axle length to roller thickness, tightening down the roller makes it stop rolling.