I started cycling a little under 290 (the highest I specifically saw on a scale was 287). I took up cycling simply as a way of getting around and covering more ground so I could continue my hobby of geocaching.
The great thing about geocaching is that it gives you a reason to go somewhere. Even if the "somewhere" isn't necessarily interesting, it got me out and about. Not only that it got me covering longer and longer distances without specifically thinking about what I was doing, until it just happened that I found myself 10+ miles from home and realising that I just had to ride it on the basis there wasn't much other option.
For the longest time I didn't actually lose any weight at all but everyone said they thought I had. Then despite not losing weight I found my 44" waist jeans that had been a bit tight were loose so I bought some 42" waist jeans to replace them. Now I'm down nearly 40 pounds, my 42" jeans are too loose so I need to buy some more, and the belt I loved as a teenager but couldn't wear for years because I was too fat now fits me again. Admittedly I need to wear it on the loosest hole there is but the point is I can wear it at all.
It always used to be hard to buy smart trousers because most places around where I live either stop at 42" waists or charge silly money. It's great to be able to buy clothes without realising I'm too fat for anything in the shop. It's also great that clothes last longer - previously where my legs rubbed together I'd wear through the thighs of a pair of trousers within 3-4 months, now they last longer I don't mind spending more on them.
There's also the general improvement in confidence, although that's more associated with increased fitness and riding experience than specifically the reduction in size and weight. It was always a bit embarrassing when I first started riding, having a gleaming black fancy mountain bike but still being passed by just about anyone else on two wheels. Now it's fairly rare for anyone except the serious roadies to pass me.