This idea might be of interest to other owners of bikes with Shimano Sora hubs.
For a while I have been dis-satisfied with the sealing design of these hubs. Basically this comprises a specially designed cone that has a groove around its circumference, into which are fitted two plastic washers. Shimano describe this as improved sealing on their website. Presumably the idea is that the washers fill the gap between the cone and the hub body. Unfortunately this is only partially sucessful, they are not a great fit. In wet conditions, the bearing is soon filled with an emulsion of grease and water which squeezes out past the seals, and later a rusty mess develops.
So, I decided to experiment, to see if the sealing could be improved. Since the cones are provided with a handy groove, I cut some old inner tube to make sealing washers that fit snugly in the gap between the cone and hub. It was a little tricky to get the size just right: inside diameter so that the seal squeezes over the cone and holds on in the gap, outside diameter (more critical) large enough to fill the cone-hub gap without being too tight. This does add a little friction to the bearing, but I am assuming that the rubber will eventually conform to its surroundings - this is an experiment after all and is much cheaper than having new wheels built around more expensive hubs. The modified wheel spins freely enough
After fitting the new seals, cleaning and re-packing the front hub with plenty of grease I rode today without any problems. There was certainly no sign of grease squeezing from the bearing. The real test will be some rain, but we won't have to wait long for that, it is summer here in the UK!
If there is any interest, I will keep this thread updated.