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Re: [ST] Backing it in (was ABS)
- Subject: Re: [ST] Backing it in (was ABS)
- From: Gavin Lawrie <gavin.lawrie@xxxxxxxxx>
- Date: Wed, 12 Oct 2005 10:19:26 +0100
On 11 Oct 2005, at 20:46, Nathan Maher wrote:
> how exactly it serves to benefit the rider in terms of lap times
It can (or should) make laptimes faster, but tyre wear goes up.
The reason it is useful is to do with cornering forces. To get
around a corner a body needs to find a way of providing enough
centrepetal force to stop it carrying on in straight line (Newton
style). The amount of force needed depends upon the weight of the
body (i.e. it is harder work to turn a supertanker than a bike) and
its speed (the faster you want to turn, the greater the force you
apply). One way of doing this on a bike is to use a combination of
gravity and lean angle, but for this to work it relies on the tyres
to provide the pivot point for this system to work. Therefore the
fastest you can go around a corner depends upon the maximum grip the
tyre / road contact can give you. But it is not the only way -
another is to angle the bike relative to the line of the corner and
provide some or all of the necessary cornering force from the drive
off the back wheel. This is particularly important where the road /
tyre grip is low (think how bikes go round corners in speedway).
In the MotoGP context, the tyres are really grippy, and lean angle is
sufficient to provide cornering forces for most people most of the
time. Spinning up the rear tyre (if done properly) is a way to
increase the available cornering force above that available from
simple lean angle - with more force, and no change in bike weight,
cornering speed can be increased and (in theory) lap times reduced.
As you point out, there is a penalty to pay in form of increased tyre
wear - so presumably the best MotoGP riders use this extra speed
thoughtfully etc.
Best regards
Gavin Lawrie
ST'03
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