Wheel Dogs

Wheel dogs are the power-pullers closest to the sled. Traditionally, they are the biggest, strongest dogs. In Jack London's Call of the Wild, Buck is a Wheel Dog. A force to be reckoned with and a strong puller. Usually, Malamutes are used as Wheel Dogs. They're the big, fluffy version of a husky. A lot of freight sleds used Malamutes to pull across the tundra. However, Wheel dogs are not necessarily known for their speed. On a traditional sled, the fastest dogs are harnessed up front, while the closer they get to the sled, the slower the dogs. This makes sense since the big, strong dogs tend to be slower. It's hard to get 100 pounds moving quickly while pulling 800 pounds.
In the past few decades, however, this has changed. The biggest dogs are no longer placed near the sled. In racing situations, you want speed and agility. When taking corners, the lead dogs swing wide, but by the time the wheel dogs hit a corner, they're in the brush. It requires an agile dog to leap over stumps and sprint through branches without getting tangled with the sled. The large dogs cannot move quick enough and, hence, have been moved to the middle of the team.
This placement for the large dogs is also beneficial in that it distributes the weight throughout the line. In the middle, they can pull smoothly and forcefully. Even more, several mushers set their pace to their biggest dogs. Since your team is only as good as the weakest link, the big dogs have to be excellent athletes to keep up with speeders like lead dogs. By placing the big dogs in the middle, it can keep the rest of the team at an even pace, so everyone stays happy and healthy.

Zion

Osiris

Our big dogs are Zion and Osiris. They are BIG dogs. When they stand on me, their front legs bend at the elbow over my shoulders. They have serious power when they're running. Bill has to frequently tell them to take it easy or else they'll get burned out. These dogs would sprint solo with the 4-wheeler if we let them. They have no concept of too fast or too hard, they just want to go. Maybe someday, I'll see what happens if I let them go....I'll probably end up dragging for 100 miles.