Throwing your bike
This is not where you toss your bike in disgust after a poor performance. For bike tosses, please refer to Greg Lemond (tossing his road bike in the Tour but I don't have a link yet) or Bjarne Riis (tossing a time trial bike in the Tour). If you insist on throwing your bike, be very careful as it is hard on your back. Lemond's story is amusing now although it was probably pretty frustrating back then. He hurt his finger in a crash and could barely pull the front brake lever. This caused him to brake more with the rear wheel. Eventually, with aggressive braking locking up the rear wheel, the tire blew. With no teammates nearby, he actually tried to fix the tire, or so it seems in photos (he's holding a tool of some sort and the tire is partially off the rim), and in disgust threw either the wheel or the bike off to the side of the road. This hurt his back and he had to nurse that for a bit. I believe he still won the Tour - and I'm pretty sure it was 1990 since he was in the World Championship jersey.
Anyway, back in the present...
I love sprinting. One of the things that amazes me is the number of racers strong enough to get to the line at the front but not knowledgeable enough to throw their bike. It's common to see someone lose 2-3-4 places because of a dismal or missing bike throw. In one particular Tour de Michigan sprint (in Lansing), the field was lined up curb to curb and the front row was going dog slow due to a head wind. But due to the width of the road, no one could pass the front ten riders. As one of about 10 racers stuck in the second row, I alternately pedaled, coasted, braked, and then pedaled again. We were totally stuck behind the front row of racers. At the line I agressively threw my bike forward in between two racers in the front row. My front wheel ended up by their cranks, pedals, and downtubes. My place? 11th. Someone in the same row as me probably got 20th. Big difference.
You may say, "Well I'm not a pro", or "It isn't really important". Okay that's fine. But if you're at the front, you've put in a good race to end up there. It would be good to finish off that effort.
In sprinting, throwing your bike is completely different from a "bike toss". It refers to pushing your bike forward relative to your body. Remember, the rules of cycling state that you finish when the front tire breaks the finish line's vertical plane (Rule 1N1). If you can push the bike forward a bit, you'll finish a little quicker.
The reason why throwing your bike forward works is you weigh a lot more than your bike. For example, if you have a 20 lbs bike and you weigh 160lbs, you weigh eight times the bike. Any movement you make with the bike will be resisted by your body. For example, if you shove the bike forward 8 inches, your body will move back 1 inch. This nets you a 7 inch forward movement. If you're side by side with someone and fighting for every inch, a good bike throw could net you 12-18 inches. This is more than half a wheel, and if you're scrabbling for an inch or two, you really have to take advantage of that 12-18 inches.
Throwing the bike is simple. You start by holding the drops and sprinting out of the saddle. When you are very close to the line (about 10 feet or whenever your feet are parallel to the ground), extend your arms and legs forward. This forces your butt to go behind the seat, almost to the point where you are sitting on your rear tire. Your stomach/chest will almost be on the seat.
You can practice this in slow motion. Use your cycling shoes, your bike - it might on on a easy training ride or while you wait for people to catch up to you after a stoplight or pee-stop. You should be standing up, rocking the bike back and forth like your sprinting. Pick a line (shadow, crack in road, whatever) and make that your goal. As you approach it, extend your arms forward. Your legs will naturally level with one foot forward. If you don't slide your butt off the back of the seat, you won't be able to extend all the way. So slide your butt off the seat till the front wheel is barely weighted. Your forward leg should be virtually straight and your arms should be totally straight. Your stomach/chest will end up on the seat. If you aren't careful, you'll just fall off the back of the bike.
The wrong way to throw your bike is to simply extend your arms without moving your butt off the saddle. All this does is hunch your back. Your bike can't move forward because you're still sitting on it. A similar mistake is to simply stand up without sliding the seat forward. If you simply stand up, you're not pushing your bike forward, you're simply moving your body up.
Revisiting that picture at the beginning of the blog, you'll see that my competitor, Morgan, has moved his body up more than back. This caused his bike to maintain its position relative to his bike/body unit. In contrast, I've move my butt completely off the seat and came close to sitting on the rear wheel. My legs aren't level because I was desperately pedaling as I threw the bike. My arms were so extended I briefly lost my grip on the right side of the bar and careened to the left curb just after the line.
The kicker with that particular sprint is that I was going slower than Morgan right before the line. I was in the process of losing the race when I started my bike throw. I simply threw my bike quickly and used up what momentum I had to shove it forward. I was passed about a foot after the line, but it was okay. The throw was enough to win the sprint, the race, and the Series.