Most Economical Motorway Speed?

[Spiderman]

Calling all sciency, geeky, mathy, smart type of people....

Following on from fuel economy and tyre economy i've always wondered what is really the best speed for fuel economy on a motorway on an SV.
I've always wondered what it might be.

I was told by a very knowledgeable man once that when the fuel was low I should not worry too much about my top speed when getting home as it was hard accelaration that ate the fuel, not a high top speed.

Some of you who are knowledgeable about these things must be able to do some kind of calcualtion and come up with the definative economical speed surley

Extra points for showing your working out of course and the winner gets, erm, the satisfaction of knowing;
A) you're well smart
B) we all will ride at your calculated speed from now on and be saving the planet a bit by not filling up as much.

[Viney]

Isnt it meant to be 56mph?

The most economical speed is the lowest speed for drag. For the sence of practicality, the lowest speedin the highest gear without laboring the engine. I wouldn't go much slower than 60 on safety grounds. Trucks are not used to overtaking motorbikers!

[Spiderman]

Originally Posted by Viney

Isnt it meant to be 56mph?

I'm sure thats for cars and based on very old technology, isnt it

Surley for a modern fuel efficient bike with fuel injection and electronics controlling things to a degree this cant be the right figure can it?

Maybe it is, i dunno but i'm hoping someone does and can explain why too.

[Brettus]

I think it does get technical, that was the general rule of thumb but I'd imagine its relative to gearing and revs.
I agree with the hard acceleration and braking though, (braking less so) but it means you wasted the fuel to get you to the speed you are scrubbing off.
Will be interested to see if someone does come up with a decent answer though, I've often wondered what it was, well usually when I'm on a motorway with the fuel light flashing

[jamesterror]

Originally Posted by Viney

Isnt it meant to be 56mph?

I read somewhere 56mph is the speed engines tend to run most efficiently at, think thats the reason for the NSL in America? .. as well as saving on fuel use (1970's). Whether thats correct I don't know.

[Quiff Wichard]

131.8

You're welcome

[ophic]

Originally Posted by ricky_t

The most economical speed is the lowest speed for drag. For the sence of practicality, the lowest speedin the highest gear without laboring the engine. I wouldn't go much slower than 60 on safety grounds. Trucks are not used to overtaking motorbikers!

+1 unless the engine has some weird drinking characteristics at low revs.

eg My car will pull top gear at 35mph but its more efficient at 50.

I was once told that you get the best fuel economy when the engine is at peak torque. I've no idea if this is correct. Does anybody know?

The most economical speed for any vehicle would be where the engine produces the most torque, which in most cases is around 3200rpm in cars, which in general, depending on type of car, is between 55 and 70mph, so hence why most people take 60 to be a good general rule of thumb.

On the SV I just keep to 60 as it's a lovely and rounded 4500rpm.