There are two schools of thought when it comes to laundry while travelin' on two wheels. There is the method JAC and I use... and then there is the Waffle Stomp Boogie.
In the interest of equal time... I shall share both.
Method 1: JAC and I do not believe in carrying around dirty socks and undies. We wear them, throw 'em away, and buy more. The further into your trip you get.. the more room in your bags for other stuff you may have collected. That's just an added bonus though... the main benefit is not smelling up the whole of God's Creation while drivin' down the road. Simple.. easy.
Method 2: The Waffle Stomp Boogie. Here we require a favorite old song... so... all together now... in the Key of G:
Russel Up a Dog Turd
Daddy Shot a Bear
Shot him up the Bunghole
and I don't care!
The Wash Cycle
The Rinse Cycle
The Dry Cycle
*Note: Combining these two methods is not expressly forbidden... ommiting the song however is.