Originally Posted by
carleton
Basically, 15-30 minutes before each event, the rider is required to bring his/her bike to Bike Check. There an official measures the dimensions and checks the weight to make sure that it is legal. Then the bike is quarantined until the race starts and you are marked off the list as having been checked. The bike is put on a bike rack where you can't go fiddle with it...unless you bring it back through Bike Check again.
For mass start events at elite nats it's common for them to just weigh them as you get on the track. They don't usually check dimensions for mass start. When I was riding an old steel pinarello the official just lifted it up and laughed and sent me onto the track.
I've heard similar stories of bikes not being 15 lbs and having large allen wrenches taped to the tubing to make weight. I've even heard of one athlete installing SRM Power Meter cranks (which are heavier than normal cranks) but not using the computer just to make the bike weigh enough. This usually only happens with the x-small bikes (48-52cm) for the ladies.
I once asked a small elite woman about her power (after noticing the SRM when we were sitting around the infield) because I had been doing numbers on power vs. predicted mass start test time. She shrugged and said she'd never hooked it up and just used it for the weight.