All depends-on the type of bike-and how much technology has advanced since I bought it, and use. My mtn.bike is very old (I've replaced just about everything on it at one time or another), but isn't ridden much now (lack of the type of off-road riding I used to do around PA), and it's still in excellent shape, tho a bit heavy. If I rode off-road more and was seriously into mtn.biking, I'd replace it, as components are better now and a lighter weight would be appreciated. The LeMond road bike-I'll probably never part with it. Though not the newest in tech, it's fine and this bike just flat out works for me. It was the first "real" decent road bike I owned, and I still prefer it over newer bikes I've ridden. It's not a sentimental bond, can't describe what it is, it just plain out fits my riding!