[sbierwagen]

Look up-thread. You have to thread the belt through the frame. You either need a special frame with a gap in it, or a belt that can be split.

[dsfyu404ed]

I read that part. That doesn't explain why they chose that oddball cogged belt instead of a commonly available belt profile (cogged or otherwise) for which pulleys are available off the shelf (or cheaply built to order) and belts are dirt cheap.