Posts Tagged ‘Tension’
Belt Tensioning

One of the most exciting and unique parts of the Trek District besides it’s amazing good looks is the fact that it features the Gates Belt Drive. There have been quite a few people, including myself, wondering just how you go about getting the tension and tracking set right and how it’s affected by having to take a wheel off. I had a chance to ask Trek some questions, and here is what I found out.
TD: I think the biggest question that people have is just how the belt tensioning and alignment work. I know that belt drives require a fair amount of tension to avoid slipping, and the alignment is pretty critical. Is it something that is easily done, does pulling the wheel off to fix a flat totally screw up the alignment?
TREK: The belt is tensioned at the rear dropouts, which attach to the frame via two bolts and slide horizontally. The drop outs are each one piece, but when the wheel is taken off and the drop outs are completely removed, the belt can be removed and replaced via a slit between the chain stay and seat stay on the drive side. There isn’t any lateral adjustment because the chain line is set by the BB spindle length and it’s nearly impossible to successfully have the wheel installed with the dropouts bolted in different positions, and since the drop outs themselves are not horizontal, the wheel is easy to install correctly. It’s not a quick release system, but installing and removing the wheel takes very little effort.
TD: As far as tensioning the belt, I was half expecting some sort of set screw like some of the horizon drop out bikes have. Without set screws, how do you have fine adjustment over the belt tracking and tension. It seems like it’s not a very refined method? Or am I just making it sound harder than it really is.
TREK: Since you’re actually moving the dropouts themselves, and not the wheel in the drop out, it’s much easier to set tension and position. I would say the sliding drop out system is easier to set than setting a wheel into the correct position of a traditional horizontal or semi-horizontal drop out. It is essentially impossible to set the wheel into the frame without the correct lateral spacing between the stays. All one has to do is pull back on the wheel till the belt is tight while the drop out retaining bolts are loose, tighten the bolts, then ride.