Nope it should be just the way it is, why would you think that.....?
No chain idler roller I've ever seen had anything but straight sides and the ones I make are grooved to work with 3 different chain widths which are all commonly used on our china girl builds as well as custom builds. The way I make them is by far the best design for what these are made for.
I sent you a PM with details of what I have made up and the cost, the T8F chain will work just fine with the rollers I have grooved, the chain will be much narrower than the groove but that is just fine, alignment is less critical that way and that is why I groove all of them out to .630" so that T8F all the way up to 410 chain will work in them.
Map
If you ever need one just holler, I have several made up and I have some different colors, I normally include an axle bolt, three flat washers, one standard nut, one nyloc nut, the roller, twoo high quality bearings and the bearing spacer installed which prevents the bearings from locking down when the nut is tightened.
$12 and free shipping anywhere in the lower 48 US states.
$10 for Roller, bearings and spacer only if the bolt, nuts and washers aren't needed.
All I charge is a couple bucks for my time and a couple bucks of it are to cover packaging and shipping.
