Originally Posted by
dddd
I've actually done most of my riding on the Miyata using 29mm-wide tires labeled "27X1-1/4".
Cheap gum walls, and based on my body weight of 155lb, I run the pressure at 60psi, enough to fend off rocky terrain at modest speeds.
A 28mm Continental will measure about 26mm after the first couple of days inflated on a road rim. I would run such a tire (preferably a Gatorskin for sidewall protection) at about 72psi, and depending on the trail surface and your willingness to hone your skills, you might be able to do some extensive adventuring.
I've used ordinary road bikes with 23mm tires offroad as well, but at that size and (90psi), it is perhaps more challenging at times than would be ideal. But you do get used to such things and can learn to limit your travels as appropriate.
A road bike with a low gear of 34X28t will be enough for some pretty steep climbing considering the limits on traction you will encounter, and your existing offroad skills will allow your learning curve to progress rapidly.
Keep an eye on your rear rim's lateral runout and stay on top of any needed spoke tensioning and trueing. It will be strong if the spokes are kept uniformly tight.
I try to do most of my off-roading on the way up a hill or mountain, with the downhill parts taken on the road if possible. I am thus able to avoid the longest, bumpy fire-road descents which encourage unsafe speed.
27X1-1/4" tires should be nominally 32mm wide - I would guess the 3mm difference is pretty standard deviation from the labeled size. Anyhow, 27X1-1/4 and the very similar 700X32C sizes are great for riding rough surfaces, and then when pumped up to 90 or 100 psi will roll as fast as a good racing tire.
Originally Posted by
pashlit
I wonder what tires you run on that bike? I just looked at my CAAD and it has pretty low brake clearance. So, I am not sure if I ll be able to fit cyclocross tire on it.
Also, I like doing aggressive riding, so I am not really interesting in touring steel type bikes or hybrids. Not going carbon either. I am happy with CAAD, granted I got an incredible deal when I bought it. I love my mountain bike also. But I just cant keep 3 bikes right now.
May be I should sell my CAAD and buy a dedicated cyclocross and a set of road wheels, but, again, its gonna be a true road bike either LOL. I like doing long 50-100 miles trips and love being in aerobars.
You are mistaken about the ability of a CX bike to be used as a road bike. A decent CX bike with 25 or 28mm wide tired pumped up hard will feel exactly like a road racing bike - except for the ability to do the absolute tightest corners at high speeds, as a CX bike will have a slightly longer wheelbase and might make criterium racing a bit tricky. But you can easily slap aerobars on and do a 100 miler with absolutely no loss in performance compared to a road bike.
So to sum up:
modified road bike != CX bike;
modified CX bike = road bike