Dr. Stupid, Another Day

Today's another day!!

"Dr. Stupid, I'm not made of cash and I don't want to sell my sister
just yet, can I use my road bike or mountain bike for Cross? What
about my dad's Hybrid?

Your pal,

Stiney"

Well Stiney,

You might try raiding your folks "secret" drawer, or nose around in
your sisters bedroom, or just sell some of your Beanie Babies.
If that fails then by all means you can race/play Cross on one of
those other bikes.

For the more Cross "experience" I would go with your road bike, unless
it's one of those fancy-schmancy ones w/ very little tyre clearance.
An old steel plain-Jane road frame works best. They general have
clearance for a 28-30c tyre, they "give" a bit, and they can be had
for cheap.
Put some lower gears up front.
With a traditional 130mm bolt-circle crank you can run a 38 and you'll
really not need anything larger than a 46.
If you're lucky enough to have a compact 110mm bolt-circle crank then
you can run a 34 which is very sweet and a 46.
Run what ever shifters you got; them lever-swingie-things, or on the
down-tube, or get "real" and use those Bar-Cons your Uncle left you in
the will.
Maybe go and check out some used old road bikes, heard Vlad at
PositiveSpin might have some.

If you *have* to use the MTB then you're gonna want to get ride of
some ballast, like that suspension fork. Also those big fluffy tyres
can hit the road, put on some 1.5s or smaller, they'll be fine. If
you're going to race and it's on of them there USCF ordeals you'll
have to huck the bar-ends too, those wacky officials don't like the
"poke somebody in the butt" devices.

Dad's Hybrid would probably work well, as they generally come w/
somewhat skinny 700c tyres. It'll be a little upright, but you can
fix that w/ a hammer or wrench. It'll also probably have lots of
gears, but since it's Dad's I'd just leave them alone and run what you
brung.
Get ride of the handlebar bag, the rack, and the orange flag though.

On any of these rides your saddle position should be the same as it
always is. You do measure and check that right? Good.
Your reach can be the same or shorter and the bar drop can be the same
or a bit less.
Other than that, the motor needs to be in the same place.

Now get out there, stop w/ your excuses Stiney, and don't forget my danish,

DrS.