My axle slipped in the drop outs while riding so I had to walk the bike home and adjust the axle and tighten it down really well and then start my ride again, I got to spend a little more time outdoors this morning and I was only 20 minutes late or so. I may need to look into some tensioners, I guess I am getting stronger but it did happen at a take off from a stop, I think when I tensioned my chain this morning I didn't tighten the nuts down enough because I was still sleepy.