racing question

Some of it is exposure for their sponsors as they tend to get more TV time in a breakaway.

Another part is that every once in a while, it works!

It actually worked a couple days ago when Toms SKUJINS did a breakaway and rode out front by himself for over an hour.  He held on, won the stage as well as acquired the yellow jersey (the overall lead).  He has maintained it for a couple days since then.

While a very tough way to win a race some riders do not have the team support or the sprinters legs to pull off a win.  The big teams have very specific roles for their riders and team strategy is critical.  If you don't have that support you have no choice but to occasionally take a chance and hope that a breakaway holds.  Not unlike running events, a guy who knows he will be outkicked will press early, push the pace, and hope the strong kickers will blowup.  A lot tougher in a bike race because your sprinter is going to be protected through the race and positioned by the efforts of others.

There are many reasons why a breakaway occurs in ever pro race.

Depending on the profile of the stage, the breakaway is sometimes the only chance certain riders have to win.  Think of it this way, you either get in the breakaway and have a 1% chance of winning, or you stay in the pack and have a 0.00001% chance of winning because you can't sprint (on a flat stage), or you can't climb with the best/most explosive climbers.

As already mentioned, some riders do it for exposure for their team.  On certain stages, we know there are only a handful of people that may win...so what about the other 150-190 riders in the race?  Do we just not talk about them or pay any attention to them for the 2-4 hours of TV coverage?  At a certain point, even the TV commentators need something else to talk about, so they talk about the guys in the breakaway, their story, past results, etc, etc.  If the breakaway guys didn't get any publicity before they get caught...then many pro cycling sponsors would back out and you would only be left with maybe 4-5 of the big teams.

Sometimes the breakaway does have a good chance to stay away.  This usually happens in longer stage races where the overall contenders know the men in the breakaway don't pose a threat to their overall standings.  So take the Giro for example.  Some riders will purposely finish far back in some stages and throw away overall time...say 30 minutes behind the overall leaders.  This not only saves energy, but in the following days, if a bunch of similar riders get into a breakaway, the peloton may not be motivated to chase them down.  Why waste a ton of energy reeling in a breakaway if it doesn't conflict with your team's main goals...which is to beat the other GC rivals?  In stage 5 of the Giro, a guy who was far down in the standings was able to win from the breakaway for precisely that reason.  The GC contenders almost caught him, but it was not their goal.  

And lastly, one of the main reasons breakaways form is because the peloton wants them to.  Over a 100ish mile race, you don't want to be on pins and needles racing the redline the entire way.  That's a good way for everyone to burn out and crashes start happening more often.  If you ever watch the middle part of a pro race, you'll notice that the peloton is basically cruising along at a moderate pace.  This is because they want the breakaway to build a solid lead on them.  The breakaway doesn't build a 10 minute lead because they are absolutely drilling it for 4 hours...it's because the peloton backs off.  If the lead is big...then it prevents other riders in the peloton from bridging across to the breakaway which causes chaos.  Thus everyone just relaxes and rides safe from the time the breakaway forms...to maybe about 30-40 miles left in the race where they'll start picking it back up.  Racing hard for 30-40 miles is a lot better than racing hard for 100 miles...especially during a long stage race where the peloton slows down to safely grab their mussete bags (for food) or pull over for "nature breaks."

This is also why you see the peloton try to catch the breakaway at the last possible moment.  If they catch them with 20 miles to go...then other riders will start to get ideas that they can win the race if they get into a late breakaway...and more chaos ensues.

I learned a very valuable lesson about this when I was a fairly new racer on a local team whose title sponsor was a bike shop. It was a criterium (many-lap race over a short course -- usually less than a mile -- for a certain amount of time with a big sprint at the end), and fairly early on I got in a 2-man break. We stayed out for most of the race until the last lap when the real sprinters came up and we were swallowed up, finishing mid-pack.

I'd won a couple of "primes" (pronounced "preems") while out on that break, and when I came in after to collect my loot, the shop owner came up to me.

"Dave, GREAT race!"

"Uh, Stan, we got caught with a lap to go. We didn't even place."

"No, but the whole crowd heard MY name every lap you came around in that break."

Yep, sometimes it's about the sponsors.

Also, being in the break, if it gains enough time to become a threat to the top placers on general classification (GC), it then forces those teams to expend energy chasing the break down to protect their leader.