Talk:Top Gear

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In the UK, Top gear is the highest ratio gear. Is this another UK/US difference? Biscuittin (talk) 09:36, 5 January 2008 (UTC)

Speaking as a British petrolhead, in the UK the "top gear" is the lowest ratio gear as well. The ratio of a first gear is generally around 4:1, the top gear (5th, 6th, 7th or 8th depending on which car you drive) is around 0.7:1. The ratio is input revs to output revs, thus anything below 1:1 is an overdrive gear, anything above 1:1 is underdriven. It is a little confused, as when one drives a 4x4 we talk about a "low-range" gear for driving at low-speed up a steep gradient. This low refers to the SPEED range, not the RATIO. Thus, when we select a low-rage mode in a Land Rover, we are selecting a low-speed gear range with a high gear ratio. It's easier to understand if you grab some Lego Technic and try combining different cogs!!! —Preceding unsigned comment added by 81.107.182.109 (talk) 18:27, 30 March 2008 (UTC)

That's right, the gear ratio measures the relative size of the gears that are being meshed. First gear is a high gear ratio, because the speed of the transmission output is necessarily low compared to the engine speed, and the gap narrows as the output speed rises and you cycle through the gears, and in overdrive the transmission's output exceeds the speed of the engine. Each successive gear of the transmission is larger and thus can hold more kinetic energy at the same RPM, while the engine input is unchanged. Chaparral2J (talk) 11:45, 3 May 2008 (UTC)