I have ridden a bike in the past that was 'automatic' shift...had centrificul (sorry bout the spelling) weights on the wheel that did the shifting. If i remember it was even more than 3 speed. Anyway it was OK for a lazy evening ride when you did not care if you were biking or not. the shifting was pretty good but definately not ideal as it did not always shift when it was time to shift. In other words not for someone who knows gears and shifting.