Originally Posted by jkw
Sorry, I'm rushing out and don't have time for a complete post, but i think a CYCLOCROSS bike would suit all your needs. Drop bars, almost roadbike, but with a much more forgiving riding position and tires that will be able to take you off the road.
If you intend to do downhill mountain biking, then disregard, otherwise...
If you want only one bike, to do the road, commute and eventually go off road on moutains and so, without jumps and such, probably a cyclocross bike is the one you need.
A cyclo-cross bike is a bike with road geometry, drop bars, a little more relaxed and with clearance for wide tyres.
You could have one cyclo-cross bike and 3 sets of wheels.
- one set 700x23c to 700x25c to do sports-oriented road riding.
- one set 700x35c to 700x40c knobly tyres for off-road
- one set ~700x32c-700x42c for commuting/touring.
or skip the touring/racing pair and have just one set of slick 700x28c for road and one knobly 700x35c for off-road.
You could have also removable fenders, so you can use them when commuting and removing them for the sport.
- A Cyclo-Cross bike has Canti-Lever brakes, for a wider tyre clearance, but these breaks are less powerful than standard road or MTB V-Brakes, anyway they can stop you, but you need to apply more force on the brake levers.
- A Cyclo-Cross bike doesn't have suspension, so downhill or jumps are probably not possible
- A Cyclo-Cross bike has drop handlebars, that could be somewhat less comfortable for touring/commuting ( however I much prefer them than flat bars)
- A Cyclo-Cross bike has a gearing in-between road and touring. This could be an advantage more than a disadvantage however.
Check out this generic pictures of cyclo-cross bikes
... and this is mine