Gradually, classes became "authentic" with reasonable pedal speeds — about 60 to 100 revolutions per minute — and guided imagery.
Pulses of electrons are injected at energies of a few hundred kiloelectron volts (that is, speeds about half that of light).
It works with both PCs and Macs and can transfer data at U.S.B. 2.0 speeds, about 480 megabits a second, depending on network capacity.
Their built-in radios connect with what's called the GSM-GPRS cellphone network, which supplies relatively fast Internet speeds (about the same as a desktop dial-up modem).
Sprint Nextel, the nation's third-largest cellular carrier with 51.7 million subscribers, said it would use WiMax, a technology promoted by Intel, in building a high-speed wireless data network with connection speeds about five times those currently available.
"Although these days," he tells me on a crackly phone line, as he speeds about some part of the country or other, "my job is much more about protection than promotion.
