Cor they're a pack of grumps.

Carbon fibre frames aren't necessary, for anyone really, but if you can afford them, they're nice in a carbony sort of way.

I reckon you'd be wasting your money though for that riding - you'd never use any potential performance gains and so you'd be paying for image only.

25 miles is a long ride for legs that aren't conditioned to it. Cycling uses different muscles to walking and running so even a fit jogger would struggle to leap onto a bike for the first time in years and do 25 miles - his cardio system would do it but his legs would mutiny. So you'll need to build up to those distances ... and build up to the hills too. The more you ride, the better and besides, it's so much fun, why wouldn't you ride more?

Triple crankset is the way to go. You don't 'need' a granny gear until you hit a slope that you just can't get up. Guess what, in my area, there are lots of those. A granny just makes life a lot easier and if you find you're not using it, don't buy one next time. It doesn't cost anything to have it on the bike, just for 'when'.

Drop bars are good, but if you're only an occasional rider, maybe a flat bar bike with bar ends might suit you more thanks to a more comfortable riding position. I personally would go for drops, but I'm a bit more 'full on' with my riding.

Is your son going to want to go mountain biking or on dirt tracks? If so, don't overlook a mountain bike. Very versatile and with slicks, not a lot slower on the road.

Richard