Motorcycle Suspension 1

[HSNIC]

I asked this question a week ago in the Automotive Engineering field to no avail. 'Might as well try it here.

I am analyzing the effects from vehicles, and vice versa, on a multispan bridge deck that has been plagued by long term creep. As a result, the deck has taken the shape of a sinusoidal wave. One of the vehicles is a 600# motorcycle and rider system. What would be a good k value (#/in) for the motorcycle?

 

[GregLocock]

The one you measure in the carpark with a tape measure and a known rider's mass.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[BrianPetersen]

Are you looking for the effective spring rate of the suspension?

Stock fork springs in my 2004 Kawasaki ZX10R are 0.925 kg/mm spring rate, and if you are looking for the effective spring rate at the wheel, double that because there are two fork springs. This bike weighs about 200 kg "on the road" plus the rider. About half the bike's mass and a third of the rider's mass rides on the front wheel. The rear suspension isn't so simple because of the shock linkage, but the relationship between the "at the wheel" spring rate and the mass riding on the rear wheel is in the same range as the front. All of this is very typical of modern sport bike suspensions.

That bridge sounds unpleasant to ride across ...

 

[JStephen]

I suppose you have some additional springiness from the tires- perhaps negligible.