Bike sizing

Darkewolfe

I need to go into a bike shop to get fitted for a bike. However, I've been browsing used bikes on craigslist and would like to make an educated guess on road bike size. Are there any 6' guys of average to muscular shape who could tell me what size their bike is? I forget the names of the two sizing groups. A friend suggested I should look for something 54-56". I know there's another, smaller measurement often quoted, is it stand-over height? I'm not expecting to get a lot of use out of a road bicycle, but a friend wants me to take some trips with him. That's why I'm trying not to waste the time of the bike shop guys when I have no intention to actually buy from them, so I was hoping I could make an educated guess for a $150 bike on craigslist.

Darkewolfe

This actually makes me want to bring up another question. If I could both mountain bike and road bike with the same bike, I would be a lot more willing to sink fundage into the project. I am aware that cross bikes exist, but I have to assume that they're just not as good for either activity. What are the major cons to getting a hybrid with the intention to participate in both activities?

EggyToast

You might want to post this in the biking thread in D&D, as there's a lot more bike traffic there. As for size, at 6" you're in-between a 17" and a 19" bike. The measurement is roughly the distance between the top tube and the crankshaft, along the "middle" post in the diamond. Of course, it's not an exact science, and different bikes will give you different geometry and feel different, despite being the "same" size.

I ride a flat bar road bike, which is commonly referred to as a "hybrid," although I think a proper hybrid looks more like a mountainbike in the form of the handlebars. My bike sits me more upright but is still very zippy, with a good body geometry like a nice roadbike.

Do you actually plan to go on trails and in dirt very often? I like the flat bar because I can ride in traffic and feel more comfortable having my head a bit more up, but I still have good leg leverage so I can power through bad spots. I don't think that a hybrid is necessarily worse -- if you're ONLY racing on roads, then a road bike is better; if you're only going over rocky/rooty dirt trails, a mountain bike is better. If you're going over city streets in traffic, potentially over grass in a few spots, or hopping the occasional curb, but generally are on a paved surface, a mix of the two is better than either extreme. Especially because on a hybrid it's trivial to swap out your tires for something smoother or knobbier, depending on your riding preference.

saltiness

Road bikes are generally measured in centimeters and you would probably be looking at a 54, 56 or 58cm bike depending on your specific dimensions and the model of the bike. Mountain bikes are generally measured in inches and you'd be looking at a 17 or 19" bike. Hybrids are sometimes measured like road bikes and sometimes measured like mountain bikes.

A hybrid bike is going to allow you to go on and off-road but it's not going to be as good on road as a road bike or as good off road as a mountain bike.

I would say it depends on your riding style when choosing a hybrid or specific use bike. If you like going fast and want to use the bike for recreation then a road bike or mountain bike might be better. If you're okay with going slower and plan to use the bike for commuting and utility purposes then a hybrid makes more sense.