I was changing a tube on my front wheel today when I gave it a spin round, as you do. It hardly managed a quarter of a revolution. When I dismantled the axle and bearings to see what was going on, I found that the grease in one side had turned black while that on the other remained a sort of amber colour. Neither set of bearings was easy to move, although none appear to be damaged after removing and cleaning. The grease itself was very stiff. What has happened? Has the grease broken down? I wondered about the temperature (it was below zero last night) but that wheel has been down to -9C in the last two winters without any problem. Whatever it is, it might go some way to explain the effort I've had to put in on recent rides - and it might not!
Any ideas, please?
