I had a similar experience with the front of a pair of. R501s: after just a few weeks the front was running really roughly, But after stripping, cleaning and re-greasing the hub, it has run smoothly all winter. No problems at all with the rear wheel. For ~£70, they do a good job as winter wheels.I have had R501's the bearings are cup and cone and the front wheel seized after 1500 miles use. I freed it cleaned and regreased it and it has been ok, but they require a bit more maintenance than a sealed bearing wheel. They are quite light for a wheel at that price point. If you can I would stick with the wheels you have get a slightly better wheelset like Mavic Aksiums, Fulcrums or PlanetX Al 30's when the stock wheels die or funds allow.