Because belt drives are a relatively new technology in the bicycle world, adjusting belt tension remains a bit of a mystery, with even some local bike shops not knowing much about it. Fortunately, with the proper tool and the tension specification from the manufacturer in hand, it’s a simple process that anyone can do in a few minutes.
The Gates tension testing tool looks similar to the tension testing tools you may have seen for automobiles (it looks nearly identical to the tool used for Micro V-belts). Using it couldn’t be easier. You simply place your finger in the rubber strap, place the tool on the belt equidistant from the front and rear sprockets, then press the tool against the belt until it clicks. Once it clicks, the leading edge of the arm indicates the belt tension. Gates is recommending 50-60 lbs. for an Alfine 8-speed IGH, but you’ll want to check the tension specifications for your particular drivetrain. I found it best to test a few times, rotating the crank a quarter turn each time, then averaging the results.
If the tension is outside the recommended range for your drivetrain, you’ll need to adjust the tension. On the Norco Ceres shown in the photo, it’s simply a matter of loosening the allen bolts that lock the sliding dropouts in place (4 total, 2 on each side) and making small, equal adjustments on each side until the tension is within spec. Once the tension is set and the wheel is in alignment, tighten the 4 allen bolts and you’re done. The first time I tried, the entire process took less than 10 minutes. It’ll be even quicker the next time around. Of course, the method for adjusting tension varies from bike to bike, so you’ll want to check with the manufacturer on the specific method for your bike.
These new technologies can be a little intimidating, but I’m living proof that an old dog can learn new tricks (honestly, I love this stuff; it’s a blast learning new techniques and expanding my skills as a home mechanic). There’s no reason to fear change, and if a new technology appeals to you, I wouldn’t let learning a new maintenance routine keep you from diving in head first!