I ordered a Cube Hyde Race bike with Gates belt drive. I live in an area where it rains a lot, and I use my bike year round, so I was sold on the promise of virtually maintenance-free drivetrain.
The bike has a 46 teeth front sprocket (Gates S150 CDN 46T), 22 teeth rear (Gates CDN 22T) and Shimano Alfine 8 hub. If I understand correctly, the maximum gear ratio is 46 / 22 * 1.61 ≈ 3.37, compared to 48 / 11 ≈ 4.36 on my current bike. Probably enough for daily commute, but not for faster rides (I ride with my friends outside of town every now and then).
I tried to find belt drive bikes with higher maximum ratio, but 46/22 (or similar ratio) seems to be the most common. However, it is possible to order front sprockets with higher teeth count: 50, 55, ..., 70, which I will probably end up doing.
Will I need to order a longer belt as well in this case? If so, how do I calculate the correct belt length? There also seem to be 3 different types of belts/sprockets: CDX, CDN and CDC. CDC is obviously different mechanically (does not have the center track), but are CDX and CDN compatible? Can I use CDX front sprocket instead of CDN? Any other things to consider?