Road frame shopping for a bad back

To distract myself from the boredom of no exercise, I'm looking into getting a road bike for when I can ride again. I love my Bike Friday NWT, but it's build for distance, not speed.

I've never owned a road bike. So I don't know my riding preferences or frame size (aside from what charts suggest). A mechanic at an LBS mentioned that lower back issues might preclude riding bikes with more aggressive geometries. However, I do want to go fast. No comfort road bikes for me. (No recumbents either, although they can certainly be fast). I like the look of the Cannondale CAAD9 frame, for instance, but have no idea how one can tell without extensive test riding (currently out of the question) whether it'll work for me.

Who would know about these things? Bike shops? Sports-medicine specialists? I've asked my doctors and physical therapists, but none of them are bicyclists and I haven't learned anything. I have time -- I can't ride anytime soon, but I want to start planning so I can keep my eye on the classifieds. :)

You should go to a reputable fitter to get pre-fit to find out what bike geometry will work best for you. The fitter should have some kind of "fitting bike" they can adjust to do things like change the top tube length, bar height, stem length, etc. That way they can adjust the bike close to the bike you want to purchase. Here's an example of a couple of fitting bikes:

http://www.next-fit.com/fitbike.html
http://www.cartecaybikes.com/fitmaster-machine/

Since you don't already own a road bike this will help determine the correct size for you. Beyond just measuring your height of your crotch and various other measurements. For lower back issue I think the most important measurement is the head tube height of the frame. The taller the head tube, the less strain you are putting on your lower back/core. With a taller head tube, it gives you more options to lower and raise your stem/handlebar height. Without compromising the safety of your fork. Most forks have a maximum height which they can be cut above the head tube & head set. I don't know what your height is but I would look at frames that have a taller head tube. You will still be just as fast, but you will be able to get the bars at the right height. And if you start out a bit above where you need to be, you can bring the bars down over time as your flexibility and strength improve. A frame like this would be a Cervelo RS or Parlee Z5 (tall frame size). Maybe these are outside of your budget, but the fitter should be able to figure out the best frame size and head tube height. Then you can shop around which means these specifications. When you see someone with their stem flipped up which is not uncommon or bad, but this generally means the frame maybe a bit small for them, their flexibility/core strength needs to be better or their fork is cut too low.

As someone who has lower back pain, having a bit taller head tube helps so I can not only ride on the hoods comfortably but ride in the drops comfortably too. I like to race, and do very hilly rides with lots of descending. Which puts me in the drops a lot and if I am too low I can get lower back pain. A CAAD9 is a very nice frame, just make sure you get a proper fit prior to buying the bike and then take it back to the same fitter for the final adjustment. And make sure the bike shop doesn't cut your steerer tube too short on your bike.

Parity, thank you!!! This is really helpful and exactly the type of information I was looking for. I have just been referred to a recommended fitter who is also a physical therapist who specializes in fitting people with back issues. (Jackpot!) Getting pre-fit seems like the perfect solution. I'm also glad to hear a taller head tube won't necessarily make me slower. I'm on the shorter side (5'3"), so I don't know how that will affect my choices.

I notice that both of the frames you mention are compact frames (though, yep, beyond my budget). Do you think a compact frame is the way to go, in general?

Again, thank you so much!