I'd estimate that my bikes have traveled more than 45,000 miles on the front of bus bike racks over the past 3 years, most at highway speeds. in that time i've had ZERO negative experiences. no bent rims, no fenders f'd, no lights falling off, no bike falling off, nothing.

The bike is largely held on the rack by gravity. the wheels sit in a cradle that prevents the bike from sliding around. the support arm goes over the front wheel to prevent the bike from falling over. the support arm provides tension that keeps the bike from bouncing out of the rack. it's a brilliant design. putting the bike on the rack takes no more than 15 seconds on your first try. it's easy, and it's designed to be so.

the bike racks themselves are rated for 250 pounds of static weight. they're actually spec'd so that a maintenance worker can stand on them in a pinch. over the past few months i've been putting my loaded touring rig (30# bike + 30# gear) on the rack daily and have had no problems. the racks also accept tires from 20" to 29" (this includes 700C and 27").

fenders are the Achilles heel of bike racks. "OFFICIALLY" the bike rack manufacturers recommend against using fenders on your bike, but you can make it work easily. if you're in a pinch you can get away with putting the support arm over the fender without causing damage to the fender or risking your bike falling off the rack. my experience over time is that day-in and day-out support arm pressure on the front fender causes additional wear-and-tear to the fender, especially around the fork crown mount (no damage to the fork though, just fender). i've tried two different solutions that are both acceptable: if you have enough room, try sliding the support arm under the front fender. if not, you can simply hack-saw the front fender off ahead of the fork crown. it reduces the effectiveness of the fender minimally but it definitely makes the setup work much better on the bus rack.

my bike normally has panniers, lights, water bottles, and a pump on it. transit agencies recommend users remove all of these accessories from the bike when it's on the rack. i don't. in theory, if your water bottle (light, panniers, etc...) doesn't fall off when you ride it's not going to fall off on the bus rack. in practice nothing falls off.

finally, if you use canti or v-brakes, the end of the support arm (shaped like a hook) inevitably rests right on the brake boss, or just above it. the arm is designed with a plastic cap on the end to prevent the bare aluminum arm from scraping the s#!t out of your canti brake arm. that cap falls off the rack after the first 10 miles of service. all my front right canti brake arms have been scratched to hell. you have to pay to play though, right?