Well, at the speeds you ride, you would want a fairly fat tired bike. 1.5 – 2.0” slick tire. Any tire over 35mm would probably do you good – that points toward a hybrid.
For you, fit is the most important thing. That can go a long way to address the aches you have. I would get a professional bike fit – it may be worth its weight in gold. I ended up going to a bike store that did a bike fit for me – took the basic measurements, and then fit the frame, stem, and seat height from there. Fit is important for everyone, more so for you.
When buying a frame, the most important measurement for me is the effective top tube length. This is going to set your cockpit size, and everything else can be adjusted from there. You really need to know the cockpit size that works best for you. So, don’t worry about standardization, look at the geometry chart and start with effective top tube length.
You are going to be happy with a hybrid with fairly relaxed geometry and fairly upright positioning.
“Performance hybrids at your friendly neighborhood local bike shops… Checkout the Jamis Coda Comp, the Giant Escape 1, the Trek 7.4FX, and the Raleigh Cadent 3..” ---Good advice!
The return policy, fitting, maintenance and tune ups may make it worthwhile to get it and your local shop.
I want to get a road bike for commuting. I'd prefer not to spend more than $800....
I want relaxed geometry. I know a lot of people swear by the positions of conventional road bikes, but it doesn't work for me--I don't mind a reasonable forward lean at the waist, but I get a ton of pain if I have to actually bend my spine to reach the bars (I have scoliosis and some other problems). Even some "hybrid" bikes kill my spine if they're not altered in some way to get the handlebars up high.
If the bike has a threadless stem, then I will use one of those stem risers to bring up the handlebars. if it has a threaded stem, I need one that can go up pretty high.
I feel a lot of pressure at most bike shops to get a bike that has a much more aerodynamic position than I'm comfortable with, so I want to have some idea of some entry level road bike models that have a relaxed geometry (or can be inexpensively altered to that end) before I actually go into the shops to start looking around.
Recommendations are much appreciated.
Are you within reach of an REI store? Check out the Novara Safari, on sale right now for about $800 out the door....