What am I even looking for?!?

[KnottedYet]

Or a touring bike.

Touring bikes are way sexy, too. They tend to be a lot more stable (less squirrelly) than cyclocross. You can load the heck out of them and still sail along.

If you can get to a shop that sells Surly, compare a Surly Long Haul Trucker (touring) with a Surly Cross Check (cyclocross). Give each a good ride and take them over some gravel, grass, and dirt. Same brand, same frame materials; so the comparison might more clear than if you mixed brands and frame materials.

Besides, it's another excuse to ride more bikes!

Surly Long Haul Trucker: http://surlybikes.com/bikes/long_haul_trucker_complete/

[WindingRoad]

A very cool bike I like is the Giant Seek. It's technically a commuter bike but has a big fat slick tire on it. Rides like the wind and pretty light weight.

Initially I thought trail bike for you because of your back; that's a mountain bike with dual suspension. The drawback is they tend to be pretty heavy because of the extra 'stuff' but because they ride so smooth I thought that might be good for not jolting your back around on rough off road courses. I know they make carbon one's too that are a lot light but they are a bit pricey, however it sounds like you have a pretty kickin' road bike so maybe you should go try one out?

I love that road bike you have, I rode it at the LBS here and it was like butta'. It's quick feeling but very forgiving to the body, great design by Cannondale on that one.

[ACiveE]

Touring bikes are way sexy, too. They tend to be a lot more stable (less squirrelly) than cyclocross. You can load the heck out of them and still sail along.

If you can get to a shop that sells Surly, compare a Surly Long Haul Trucker (touring) with a Surly Cross Check (cyclocross). Give each a good ride and take them over some gravel, grass, and dirt. Same brand, same frame materials; so the comparison might more clear than if you mixed brands and frame materials.

Besides, it's another excuse to ride more bikes!

Surly Long Haul Trucker: http://surlybikes.com/bikes/long_haul_trucker_complete/

Can you explain what you mean by squirrelly?

[KnottedYet]

More or less responsive.

If having a bike respond to your every command (intentional or not) feels wrong, you might say it feels twitchy or squirrelly.

My best example is with kayaks. I love the longish (17 foot) touring kayaks. I can't stand the chubby short puttering kayaks because they feel sluggish. Racing kayaks (long and very narrow) scare the ever lovin' cr@p out of me because they respond to every dang move I make and I seriously feel like I am gonna flip 'em over. Too squirrelly for me, but someone who loves racing kayaks is going to feel like my favorite touring kayak is sluggish and not responsive enough. It took a lot of kayak rentals for me to figure out what I liked best.

Ride lots of bikes, the more the better, and on lots of surfaces. You'll notice which bikes feel like they were made for you and which feel like you're engaged in a wrestling match.

Tire size makes a big difference, too, so also make notes of which tires you like on which surfaces during your test rides. I have no problem riding 23-25s on fresh gravel, but prefer 32s. So if I found a bike that felt marvelous in every way but wasn't quite up to snuff on gravel, I'd ask the shop to change out the tires before I gave up on the bike.

[lauraelmore1033]

You can definitely ride trails with a cyclocross bike, but as I recently discovered doing the "Stinky Spoke" ride, certain areas of steep, (somewhat, but not too technical) single track, or thick gravel will give you trouble. If you don't mind hopping off the bike and hoofin' it through those spots, you can certainly still have a lot of fun with your MB buds. I did, however, scour craig's list afterwards for an "entry level" MB, and am finding that having the proper bike for the conditions is MUCH more satisfying.

[ACiveE]

You can definitely ride trails with a cyclocross bike, but as I recently discovered doing the "Stinky Spoke" ride, certain areas of steep, (somewhat, but not too technical) single track, or thick gravel will give you trouble. If you don't mind hopping off the bike and hoofin' it through those spots, you can certainly still have a lot of fun with your MB buds. I did, however, scour craig's list afterwards for an "entry level" MB, and am finding that having the proper bike for the conditions is MUCH more satisfying.

I've attached a generic photo from the internet... would a cyclocross be able to handle this? This is what a lot of the trails around me look like. I have been browsing craigslist but it seems like you need to be *very* savy... not quite where I am yet!

[lauraelmore1033]

Definitely looks do-able, I'd say.

[moderncyclista]

I'd go cyclo-cross bike. It would be lighter on average than a mountain bike. Which is one of your concerns right? With back probs. and flights of stairs to climb. Lots of manufacturers make them - one thing - if you are short, most cyclocross bikes don't come in a small enough size. I think Surly's CrossCheck is the exception. If you are not, you don't have to worry.

Trek makes the XO-1 and XO-2 www.trekbikes.com, Specialized makes the TriCross www.specializedbikes.com, Jamis makes some fine bikes - Nova Race, Nova Pro, and SuperNova www.jamisbikes.com, and the other suggestions are great too!

Do your research. That is the best advice I can give you. Go to your Local Bike Shop (LBS for short on the boards) and ask questions. Do not go to a dept. store - steer clear of cheap. Quality does matter in bicycles. Or, if your budget is big go custom. You have lots of options. Happy bike-shopping to you.