Anyone know how to work out Power:Weight ratios?

[SilverFish]

I'm trying to figure out the Power:Weight ratio of the 2004 GS.

I dont really know how to do this. So far I have:

Power=98Bhp (est)
Weight=219Kg (est, wet)
..
98/219
..
0.4474

But this result is fairly meaningless on its own. Is there an Industry Standard for this?

My thoughts are that the increase in HP and reduction in weight should make a dramatic change in bike performance. Common sense I know, but I would like to see how it rates against other bikes.

Thanks,

Mike

 

[Roge]

Its very often expressed in bhp/ton.
However the ration that you have worked out does make sense if you are using it as a comparison with other bikes with light high powered sports bikes having a ratio which is moving nearer to 1.0.

Some of the Westfield type cars have something like 700bhp/ton!! ie 300bhp and <500kg in weight hence the accelerate like a bike.

 

[Rob Farmer]

I believe Power to weight ratios only give an indication of a vehicles acceleration from stop. You really need to take into account the riders weight as well.

I've got a mate who weighs 26 stone, with a 12 stone wife, and is always complaining that is bike really should accelerate better than is does. Since he used to be a wrestler I tend to make make feeble comments like "it's probably duff fuel".

 

[The Mechanic]

Why bother?

Panniers on, off?
Big screen, little screen.
Wind pressure.
Atmospheric pressure.
Full tank of fuel, nearly empty.
REMUS and Y piece with Carlos Fandango go faster black box.

Power to weight ratio's are all academic in the real world, you'll either buy a new model BMW or not and it won't be the power to weight ratio that makes your buying decision either. If that was the sole important factor then we'd all be riding Speedway Bikes running on methanol. 65-70 bhp and sod all else to speak of, apart from buttock clenching acceleration and NO BRAKES!

As an exercise try working out the power to weight ratio for a Honda CR 450 or a Gas Gas 250 Trials bike.

Beemers are big and heavy, the new incarnation will be nothing exceptional in the weight stakes. Probably everyone will hang on a while to see what goes wrong before committing to actually owning one.

 

[Ming]

It certainly aint there strong point now is it ???


and lets by honest who gives a flying f*** when it comes down to it ??

 

[Vern]

The only time the power to weight ratio is important, is when you're on the grid, ready to dump the clutch, that's it. Has all this bolox come from the press all of a sudden, more car park talk now tyres are so last year.

 

[Howard Millichap]

Power=98Bhp (est)
Weight=219Kg (est, wet)
..
98/219
..
0.4474

Not a GS then. That would be 84/235. i.e. even worse!! 0.3574.

An R1 is around 1.0 i.e. 170bhp/170kgs.

Just goes to show how slow these GS things are.

 

[kitchenpete]

SI Units

OK, still fairly meaningless and still nothing to do with why we chose the bike, but you have to be consistent in using metric or imperial measurements.

The R1150GS quoted 85 bhp is also known as 62.5kW, which at least is in SI units (standard metric units, e.g. metres, kilograms, joules, candela!).

228 kg dry weight (well, different tank sizes would make comparisons useless).

The figure for power to weight would therefore be 62.5/228 = 0.274 kW/kg

Sorry to return to my scientific days, but now I'm a pedantic Forensic Accountant, so using/explaining the right numbers is how I make my living!

 

[JTalbut]

Re: SI Units

The figure for power to weight would therefore be 62.5/228 = 0.274 kW/kg

If you're going to be pedantic about it you could have finished it off:
= 0.274W/g
And a Watt is a derived unit...

 

[Howard Millichap]

Re: SI Units

228 kg dry weight
The figure for power to weight would therefore be 62.5/228 = 0.274 kW/kg

So you ride your bike with no oil or brake fluid etc. in it.
Good luck mate. You won't get very far. And if you do, you won't be able to stop.