...to run alongside my muppet puncture thread, I have a chain question. We had a bike mechanic on our India trip, who took great delight in cycling alongside me and telling me I was in the wrong pair of gears (big and big etc). He seemed to think I should be able to look down and see if I was in the middle cog both at the front and the back. First of all, should I be aiming to have the chain in the middle cog at the front whenever I'm not going uphill or downhill? Secondly, how on EARTH can I tell what cog I'm in on the back derailleur? I nearly hit a sacred cow trying to check, I just can't see it whilst I'm cycling. Finally...can someone talk me through this chain and cog malarky? I've always just gaily sat in whichever gear I found most comfortable - it was a shock to find there's a science about it and I have no idea what to do. Thank you!