Originally Posted by kokodeselavy
This is most popular among old-school riders (you may have noticed a little seatbag under Voigt's saddle, for instance) but now the bags are fabricated from carbon fiber and contain titanium shavings.
The bag under his seat contains a transmitter that provides things like heart rates.
When Phil says "throwing out the sandbags", he's just saying that the sandbagging is over and the rider is going to now get serious.