So I bought a new bike at the end of last summer. I didnt really ride it a whole lot then it got cold. The little I did ride it though I noticed that my rear tire slipped when making turns. I thought maybe the tires sucked so I bought some new ones. The ones that came on it were 23's I bought some 26's. I figured some extra surface area couldnt hurt. That didnt work.

My back tire will slide out from behind me when I make a turn, at pretty much any speed unless I'm making the most gradual turn even. Also, sometimes when I'm pedaling fairly hard I also notice that my rear wheel slips too. I've never had anything like this happen to me before. I've ridden a lot of friends bikes and this doesnt occur on theirs either.

Also, my crank makes a wonderful creaking sound, only when my right foot begins its upstroke. If I spin the back wheel off the ground, no noise. Only when I'm pedaling with force, and only on that one side, in that specific point in pedaling.

tl;dr Rear wheel slips, crank creeks