Originally Posted by BlazingPedals

Yes, many bents have a single pair of rear stays, not a triangle. These include all stick bike bents, and many carbon bents. Of course, there's still the issue of every single model having a different chain/belt length, even among the ones that don't move the boom to adjust for leg length. Bottom line is, don't expect belts for bents until someone comes out with adjustable belts.