This week the Gates Belt Drive has gone back on the Surly Belt Check. The chain drive has been replaced. I also replaced the studded tires with my summer commuting tires, Schwalbe Marathon Plus 700 x 35c. The studs were 700 x 40c. I have to say the 35's look super skinny compared to the studded 40's. Since this bike was built up for the first time for winter travel last November, it is the first time I've ridden it without studded tires on.
For those that have followed my experiment with retrofitting a Gates Belt Drive to a Surly, you know that I had some major issues with the belt coming off the rear sprocket when any amount of snow got in there. For that reason I had to go to a chain drive for the winter. Now that winter is over, the belt is back.
One issue I had when building up the bike was getting the belt aligned properly. There is very little margin for error and the belt line has to be perfectly straight or the belt travels to the side and can come off. My local bike shop helped with getting the belt aligned. It took two different cranks and several different BB axle lengths to get it right. Once we got it aligned properly, there was very little space between the front sprocket and the chain stay. There was so little clearance, only a piece of paper would fit between them. But it cleared the stay. Once I started riding it last fall, the frame or crankarms flexed enough that the sprocket made contact with the stays and took a little bit of paint off. But only when I was climbing out of the saddle.
In an attempt to fix this, I stopped at the LBS Sunday and picked up two 1mm BB spacers. You can see them on the drive side above. I installed them between the BB shell and the outer BB cup. I took it for test drive this evening and the belt did not drift to the side of the sprockets at all. And now I have 2mm more space between my front sprocket and chain stay. That should be enough to keep them from rubbing.
I am so excited to have the belt back on and to continue with this experiment.
And there is hope that I may still get it to work for the winter. Read this post from Old Spokes Home about a possible fix from Gates . I contacted Gates a few weeks ago to see if I could get a prototype cog. They answered and said they had no more prototypes, but it should go into production the end of this month and be available from QBP soon after that. If the summer goes well, I might have to give the new sprocket a try for next winter.