[Michael Beard]

Roughly 1-5/8", but that can change depending on what stage beam height is required to come up with the right measurement on the track or sanctioning body's rollout wheel. Ironically, having the same physical rollout distance can result in wildly different reaction times, depending on the timing system. I'm not exactly certain why, but certain timing systems have certain characteristics... probably the type of photocells used, or their sensitivity settings.