This week I seemed to develop issues with changing from the small to the big ring on my road bike (50-34 10-spd). At first, I thought it was because my ankle band had failed and I had snagged my trousers in the front mech, possibly knocking it out of position, as after I did this I couldn't shift from the big to the small ring. I did try to adjust the low limit screw which helped but then had problems with overshifting and dropping the chain when changing up to the big ring. I also had problems changing up from the bottom gear on the cassette which I resolved by putting a new chain on, as I found out the chain was worn. I can now change gear smoothly at the back but am still having problems at the front. I have managed to adjust things so that I can change down but I am still throwing the chain when changing up at the front. Trouble is I can get it to work when I am testing indoors, but doesn't work out on the road (very annoying). My thought is that the big ring is worn however it would surprise me that this would wear quite this quick as I understand the wear rate of a cog should decrease with increasing number of teeth. I have attached a couple of side-on photos of the front ring, one of which shows the meshing of the chain and chainring part way through a change, and was wondering if anyone could confirm whether or not the big ring is worn from these photos. Any advice would be much appreciated.