Strange thing with fuel economy....

[Antarius]

Something odd I noticed, and perhaps you all have noticed the same?

When I commute at 65-70mph, around 3800rpm for 100 miles -- steady throttle, being easy on it, I average around 63-67mpg depending on how much fuel I put in (hard to put the exact same amount in each time).

When I'm riding backroads, granted at lower speed, but doing a lot more hard acceleration, a lot higher RPM's and a lot more shifting, I'm getting significantly better mileage out of the bike, usually just over 70.

Literally when I'm commuting during my work and being careful to keep RPM's below 4000 and around 65mph, I go at a max 180-ish miles, and usually more like 170 before the fuel light starts blinking at me and then I go get fuel.

When I ride backroads, with much more stop-go, much less steady throttle position and a lot higher RPM's as I'm riding tight and fast roads.... I go an easy 190+ miles before the light goes on.

I thought it'd be the other way around...

 

[Naked_Duc]

Wind resistance (drag) is a big factor for adventure/dual sport bikes that tend to be less aerodynamic. So, generally speaking, the faster you go on the freeway, there would be more wind resistance for the engine to overcome. In fact, wind resistance grows exponentially to speed increase.

Going 70MPG consistently on the freeway would be like non-stop accelerating hard in the backroads. Increase your hwy speed to 75 and you might see your MPG drop another 5MPG.

 

[Old Can Ride]

Something odd I noticed, and perhaps you all have noticed the same?

When I commute at 65-70mph, around 3800rpm for 100 miles -- steady throttle, being easy on it, I average around 63-67mpg depending on how much fuel I put in (hard to put the exact same amount in each time).

When I'm riding backroads, granted at lower speed, but doing a lot more hard acceleration, a lot higher RPM's and a lot more shifting, I'm getting significantly better mileage out of the bike, usually just over 70.

Literally when I'm commuting during my work and being careful to keep RPM's below 4000 and around 65mph, I go at a max 180-ish miles, and usually more like 170 before the fuel light starts blinking at me and then I go get fuel.

When I ride backroads, with much more stop-go, much less steady throttle position and a lot higher RPM's as I'm riding tight and fast roads.... I go an easy 190+ miles before the light goes on.

I thought it'd be the other way around...

Your bike just knows that you enjoy the back roads a lot more than the go to work roads. The bike just likes the back roads more also. So, bike gives you bonus factor for enjoying the back roads, its about the ride not the commute.

 

[Antarius]

Your bike just knows that you enjoy the back roads a lot more than the go to work roads. The bike just likes the back roads more also. So, bike gives you bonus factor for enjoying the back roads, its about the ride not the commute.

Aint that the truth.

Unfortunately for the bike I bought it for the sole purpose of commuting. Luckily for the bike (and me!), I also use it to ride around the backroads for FUN, haha.

 

[Antarius]

Wind resistance (drag) is a big factor for adventure/dual sport bikes that tend to be less aerodynamic. So, generally speaking, the faster you go on the freeway, there would be more wind resistance for the engine to overcome. In fact, wind resistance grows exponentially to speed increase.

Going 70MPG consistently on the freeway would be like non-stop accelerating hard in the backroads. Increase your hwy speed to 75 and you might see your MPG drop another 5MPG.

You're probably spot on here. When I ride 75-80 my fuel economy drops significantly, to the 55-58 range.

 

[Mr_Krabs]

Bikes are not like cars. They're a lot lighter so constant acceleration cycles doesn't burn nearly as much gas. A=F/M is a linear equation. So our bikes being 1/4 the weight of a car means accelerating will theoretically be 4 times more efficient than a car. Say your car gets 20 mpg city, cut the weight 3/4 and you should theoretically get 80 mpg. That's nearly concurrent with most people's experience.

Now here's where it gets muddy. Motorcycles are terribly unaerodynamic with drag coefficients (Cd) of .6 to 1.0. Whereas most cars are usually less than .5 specially these days many cars like the Prius can get .29. So even though most motorcycles are small they present a lot of drag for their size. The simplified equation for drag is D=1/2 * Cd *v^2*A. The V squared part is the killer. So as velocity increases you get a really big increase in drag. So even though a motorcycle weighs very little and presents a frontal area about 1/3 that of an aerodynamic car the fact that it has a drag coefficient 2 times higher or more can mean a small motorcycle can require just as much power to drive freeway speeds as a car. Yes they're that unaerodynamic. Which is why a small car can get upwards of 50 mpg highway and our bikes only can manage 65-70 at similar speeds.

That's what really trips most people up, on the freeway weight is nearly meaningless when it comes to mpg. It's all about aerodynamics at that point.

 

[Naked_Duc]

Fortunately for my MPG, traffic here is pretty horrible. During rush hour, I'd be luck to get up to 60MPH, which helps out at the pump.

 

[Antarius]

Fortunately for my MPG, traffic here is pretty horrible. During rush hour, I'd be luck to get up to 60MPH, which helps out at the pump.

Haha! I guess lane splitting isn't legal there? Here I'll do 65 the entire time for the full hour+ of my commute.

 

[Backroads]

I've noticed the same thing. Fortunately about half of my commute is Backroads. (Just like my name!!!)
And whenever traffic is bad (for instance when the Bay Bridge is closed) my mileage shoots through the roof.

BTW, Antarius, was that you I saw today getting off the Richmond Bridge and going towards San Rafael? Around 5:45? It was my 2nd NC sighting!

 

[Antarius]

I wasnt on the bridge but I was on 101-south passing 580 at about 5:45 today. Usually in a black/grey aerostitch.

I've noticed the same thing. Fortunately about half of my commute is Backroads. (Just like my name!!!)
And whenever traffic is bad (for instance when the Bay Bridge is closed) my mileage shoots through the roof.

BTW, Antarius, was that you I saw today getting off the Richmond Bridge and going towards San Rafael? Around 5:45? It was my 2nd NC sighting!

 

[happy]

When you are travelling on a smooth level road, the fuel gauge (float or something) comes on earlier because the fuel is stable.

When you are hitting rough roads and winding ones, the fuel gets tossed around, giving the float the impression that the tank is fuller than it really is.
When you calm down and let the fuel sit down, the fuel light will come on.

It's logic.

 

[Antarius]

When I fill up and put 2.9 gallons in when the light comes on and one time I go 190
Miles and the other I go 175, it's not fuel sloshing around, it's that I've used less...

 

[SergeantChuck]

I haven't done any trail riding but have done a lot of highway riding. Someone above state and if you but your speed up to 75mph you would see a difference and they are exactly right. I have played around with this just to see what the difference would be. My 30 mile driver is half backroads and half interstate. If I drive 70mph on the highway I am sure to get between 70.1 - 70.6mpg. If I bump my speed up to 75mph on the highway I am generally down to 68.7mpg. I have tested this on about five tanks now. I thought about trying the other side of 70mph but I don't want to get ran over on the interstates around Little Rock. Needless to say, I pretty happy with 68mpg so I drive 75mph.

 

[anglachel]

Bikes are not like cars. They're a lot lighter so constant acceleration cycles doesn't burn nearly as much gas. A=F/M is a linear equation. So our bikes being 1/4 the weight of a car means accelerating will theoretically be 4 times more efficient than a car. Say your car gets 20 mpg city, cut the weight 3/4 and you should theoretically get 80 mpg. That's nearly concurrent with most people's experience.

Now here's where it gets muddy. Motorcycles are terribly unaerodynamic with drag coefficients (Cd) of .6 to 1.0. Whereas most cars are usually less than .5 specially these days many cars like the Prius can get .29. So even though most motorcycles are small they present a lot of drag for their size. The simplified equation for drag is D=1/2 * Cd *v^2*A. The V squared part is the killer. So as velocity increases you get a really big increase in drag. So even though a motorcycle weighs very little and presents a frontal area about 1/3 that of an aerodynamic car the fact that it has a drag coefficient 2 times higher or more can mean a small motorcycle can require just as much power to drive freeway speeds as a car. Yes they're that unaerodynamic. Which is why a small car can get upwards of 50 mpg highway and our bikes only can manage 65-70 at similar speeds.

That's what really trips most people up, on the freeway weight is nearly meaningless when it comes to mpg. It's all about aerodynamics at that point.

Last weekend I found a nice flat straight road, so I tested some aerodynamics, starting out sitting up straight, I locked my wrist in place on the throttle (grabbed the bar end with my pinky and put my index finger resting on the brake lever so I'd notice if I rolled on or off any) then I leaned way down on top of the frunk and got behind the stock windscreen (I still had a camelbak on so my back wasn't terribly aerodynamic even at this point).

Once I was down behind the windscreen I watched as my locked in 50 mph on the speedo ticked up... after about a minute I was doing 55 without giving the bike any more gas...

10% bump in speed isn't bad for using roughly the same amount of fuel.

If that 10% bump carried through to MPG that'd be a jump from 75mpg to almost 83 mpg. When going fast aerodynamics is where it is at, when going slow weight (or stopping and starting) it's all about weight.

 

[SergeantChuck]

Plus the fact that most of us add weight. That has a factor too. Radiator covers, skid plate, saddle bags and trunks. The more you add the more weight you add. Some items even cause more wind drag. Taller windscreens and hand guards. Cause and effect. It will take it toll on fuel economy. Great thing is I am still getting over 65mpg. Can't beat that!!!

 

[VE258]

yes, i've noticed that too and mention it in some other thread about mpg.

 

[dlee6413]

I have the Madstad screen and soft luggage and most of my daily 125 mile commute to work is at highway speeds (70-80 mph). I just started using fuelly but got 70mpg out of my last tankfull. Love my NC!

 

[SergeantChuck]

I have the Madstad screen and soft luggage and most of my daily 125 mile commute to work is at highway speeds (70-80 mph). I just started using fuelly but got 70mpg out of my last tankfull. Love my NC!

125 mile a day. Jeez. I'm assuming 60 miles each way. Still a long ride. Still it is better than sitting in a car.

 

[mathdl]

I take the back roads whenever I can, some 1st and 2nd gear 2track, gravel roads and have a short, many stop commute at less than 45mph and agree that as long as you spend little time above 65mph, you'll get better than 70mpg.
You math folks need to leave the equations at work and just enjoy the ride. Which reminds me, I think my boss wants me to get some work done on the other computer now.

 

[Nortwestrider]

I get my best MPG offroad!!.
I'm always hovering around 2,500-2,800 rpm's offroad and get 72-76mpg.


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