Most of my biking is road biking, and I do own a very nice road bike. It's an older Schwinn frame, chromoly (but I don't mind the weight), with the componentry that I've put on over the years. Most of it is older high-end Shimano stuff. That's the bike I use for the really long-distance stuff; the centuries, or the two- and three-day rides that I'll go on a few times a year.

For ordinary riding, especially around city streets, I ride a mountain bike. I like having the range of gears, including, as I get older, the low gears that are easier on my knees. Of course, I can't ride on knobblies on the sidewalks, which brings me to my favorite bike modification: the tires.

I buy Continental, because I like real rubber. It's got a natural propensity to self-seal the small knicks and tears that will wear out a sythetic tire over time. For city riding, I use a good set of road slicks, tires that are bald or nearly bald, and mount them on my mountain bike. I even have a whole second rear wheel, with a higher ratio gear cog, for road riding with the mountain bike. It helps to keep things comfortable.

For off road riding, I use the same bike, but with differential directional tread knobblies. These are tires with rugged tread, and the front and rear are not identical. In addition, the tire needs to be mounted in the correct direction, as the tread only grips properly when it turns in the correction direction. My rear wheel for trail riding has a much smaller gear cog than the road riding wheel.

Too often, we overlook our tires, but that's at our own risk. They're important; after all, they're the contact between you and the road!