Originally Posted by Abneycat

It is possible, but the power consumption for those speeds is quite immense. Crystalyte "5 series" motors for instance can nearly made to reach such speed, but they require extremely high capacity batteries which will be consumed quite quickly. The system weight, cost and complexity increases greatly as speed needs do. Legal issues also arise, and the ability of the bicycle to be enjoyed *as* a bicycle decrease.

Motors like the 5 series are massively heavy, and not enjoyable to pedal about.

Practically, it makes more sense to go 20-25mph as mentioned by some other users. The investment and hassle is much less severe, systems can be made to meet those standards fairly readily.

For instance, even my rather mundane setup of a Crystalyte 408, 36/20 controller, 48/10.5 li-polymer battery will meet your range needs at around 25mph. Thats not a heavy investment, and the bicycle remains light enough to be enjoyed. It will soon be either a BMC 400w or a BMC Thunderbolt 600w, which will make it even lighter and easier to enjoy as a bicycle.