wheel keeps coming loose
in the last month i have had to tighten the cone on my rear wheel twice now. it has never come loose before but i have also recently fitted a pannier rack and when fully loaded it can be quite heavy although to offset this a little i have also lost around 2 stone which should make up for this. its on my mtb commuter and there should be a link in the sig bit below. i would take some close ups but it doesn't seem worth it as i can see no obvious problems. in the previous two years of owning the bike i have had no problems whatsoever so i'm just wondering if wheels have much of an expected "life" and if so should i start looking for some new ones. i do clean them up and regrease them every now and again and the bearings still seem ok to me. any ideas what causes it?