Originally Posted by
ghettocruiser
Install 700x25C tires, flip the stem and lock out the fork.
Still slower, but not much.
MTB road gearing issues are over-rated. My biggest gripe is actually the width of a MTB crankset.
Agreed. If you're pretty strong, it won't be an issue unless the group is seriously hammering. Ya, you're not as aero. That won't matter in a big group, because you're constantly drafting. Gearing is only an issue if you're over 30 mph, and that isn't often. Hang around at the back and be careful not to let any gaps form. You'll probably be OK.
25c tires might not work depending on your wheel width. 32c or 35c tires will be fine and you'll be just as fast.
There's a guy that shows up to our club rides with a MTB bike every once in a while. He has no problem hanging on, but then again, he's 'Strong like bull'. YMMV.