These are the new custom stealth dirt bikes made for covert ops
When the U.S. military is looking for a custom bike, they look to DARPA. This time, they needed a stealthy dirt bike that could handle rough terrain... and maybe a few other tasks SEALs and Green Berets might need during an operation.
The differences are where it gets interesting. The Nightmare weighs 400 pounds while Silent Hawk weighs 350. Those extra 50 pounds go toward generating additional horsepower for the Nightmare's all-wheel drive. Silent Hawk was built with a battery pack that has a higher density and active cooling system to keep lithium-ion batteries from exploding.
The two bikes can also provide power to external devices, including medical equipment, blue force trackers, and communications gear.
Bikes — especially dirt bikes — aren't new to the military. Veterans and active duty bike enthusiasts have been building their own custom bikes for years. It's a huge community. One retired Marine Corps First Sergeant even founded a vocational therapy non-profit centered on building custom dirt bikes. It's called Warrior Built.
Dirt bikes and motorcycles are also a reliable means of communication in large-scale combat. It was used as recently as the Millennium Challenge Exercise, where a Marine General was able to take on an entire carrier group maintaining comms using messengers on dirt bikes.