The thing about giving advice to another cyclist is interesting as well. I find that the best way to deal with this, is don't, unless someone asks you directly. It's better to go down the 'actions speak louder than words' route. For example, last weekend I was riding up in the Surrey Hills, and I passed a couple of guys who looked like they were having a hard time on Leith Hill. I made a mental note of what they were doing, and their bikes, and why they were probably finding it harder than they should, but said nothing and carried on to the top of the hill, before a brief stop. The 'strugglers' appeared as I was about to depart, and came over to me. One of them asked what set up I was using on my bike, so I told him, the other one asked for my opinion as to if there was anything that he could do or change to make the hills easier. I gave him my opinion, about how I would set the bike up, to make it easier, and his mate agreed, and pointed out, that what I'd said should help, is what he'd told his mate the previous day. That's a nice way to do it, just telling someone that they've set their bike up wrong, or their doing something wrong, without backing it up is just going to irritate most people.