My post from before has to do with FRS radios. I've learned this since buying some more radios (I have 8 FRS/GMRS radios, used 3 days).
GMRS is the relay station thing where you have a central base and rebroadcast the message at a higher power. Typically this base resides in a chopper. In Philly it could be a really high building. You need a license for GMRS as pointed out above.
FRS is the standard Motorola walkie talkie thing. It's good for a crit, yes, but debatable for a Philly race. I haven't tried "ultimate" range, but it's fine at 1/5 mile outside, fuzzy if you're in a metal frame building at that distance. Batteries do last all day on one charge (7 or 8 AM until 4 PM).
I don't know what radios would be good for Philly.
If you want to borrow the radios I have PM me. I have 3 x $80/
pr, 1 x $70/
pr. You'd need to buy the wire mike/earpiece things. I also have a bucket load of lessor radios (12? 14? FRS only). AAA batteries (3 each, rechargeable or not). A few leftover Motorola walkabouts.
Gotta go.
cdr