Twistgrip

[1][2] Motorcycle Consumer News design columnist Glynn Kerr said that pioneering this technology was a point in favor of the Roper's precedence as the first motorcycle, in response to Cycle World Technical Editor Kevin Cameron's position that the 1885 Daimler Reitwagen was more deserving because it used the more successful technology, internal combustion rather than steam.

[2] The design drawings of the Reitwagen depicted a twist grip speed control, also applying the brake when turned one way, but when turned the other way, it would have tensioned the belt drive's idler pulley, applying power to the rear wheel in the manner of a clutch.

[3] Glenn Curtiss, unlikely to have been aware of the prior uses of the twist grip, used it in his 1904 motorcycle land-speed record machine, and is sometimes credited as the inventor of the device.

[4] Whether Curtiss, Gottlieb Daimler, or Roper were the true inventors, the 1904 Indian would be the earliest use of the device on a production motorcycle.

[4] Motorcycle throttles are spring-loaded to cut the engine power back to idling when the twistgrip is released.