Gearing Question

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Mark - 29 Oct 2007 23:56 GMT

I was reading through the December issue of Bike earlier - the fuel
challenge section. It's not in front of me now but IIRC one of the testers
said that the bike was doing 24 mph in top at 1500 rpm but 60 mph at 3000
rpm.

I'm no gearing expert but surely twice the revs will give twice the speed in
the same gear everything else being equal?

Mark

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Champ - 30 Oct 2007 00:42 GMT

>I was reading through the December issue of Bike earlier - the fuel
>challenge section. It's not in front of me now but IIRC one of the testers
[quoted text clipped - 3 lines]
>I'm no gearing expert but surely twice the revs will give twice the speed in
>the same gear everything else being equal?

You're right. [1]

At such very low revs (for a bike), tho, it's quite easy to misread by
a few hundred rpm, and also the instrument accuracy (of both) may vary
a bit.

[2] unless you have a very seriously slipping clutch. In this example
even that doesn't make sense unless it's slipping more at 1500 rpm
than 3k. Which it won't

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Champ

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davethedave - 30 Oct 2007 20:06 GMT

>> I was reading through the December issue of Bike earlier - the fuel
>> challenge section. It's not in front of me now but IIRC one of the testers
[quoted text clipped - 13 lines]
> even that doesn't make sense unless it's slipping more at 1500 rpm
> than 3k. Which it won't

An interesting yet somewhat moot point I believe. Why would anyone want
too ride
a bike around at 1500rpm?

Ok hands up all those who bought a bike based on minimal fuel consumption.

Anyone? Really? No one?

OK now hands up those who bought a bike to convert as much fuel as possible
as quickly and efficiently as possible into f.ck rapid forward motion?

Right so that sorts the fuel issue the only gearing we need to worry
about is maybe a couple of teeth off the rear to cure the bike
manufacturers obsession with unattainable(legaly) top speeds and away we
go. :)

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davethedave

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Ofnuts - 31 Oct 2007 00:37 GMT

> Ok hands up all those who bought a bike based on minimal fuel consumption.

*waves*

OK, that wasn't the only criterion, but that wasn't completely ignored
either.

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platypus - 30 Oct 2007 01:01 GMT

> I was reading through the December issue of Bike earlier - the fuel
> challenge section. It's not in front of me now but IIRC one of the
[quoted text clipped - 3 lines]
> I'm no gearing expert but surely twice the revs will give twice the
> speed in the same gear everything else being equal?

Bike staffer in math incompetence shock.

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Bod43@hotmail.co.uk - 30 Oct 2007 03:40 GMT

> > I was reading through the December issue of Bike earlier - the fuel
> > challenge section. It's not in front of me now but IIRC one of the
[quoted text clipped - 5 lines]
>
> Bike staffer in math incompetence shock.

If bike tyres are anything like lawn mower tires then
perhaps tyre growth needs to be taken into account?
http://videos.streetfire.net/video/67ec09a8-98fd-45ce-99bf-989101387428.htm

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The Older Gentleman - 30 Oct 2007 08:15 GMT

> If bike tyres are anything like lawn mower tires then
> perhaps tyre growth needs to be taken into account?

At very high speeds, yes. At 60mph, no.

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Motorcycle Forum / Country Specific / UK Group / October 2007

Gearing Question