Miles per gallon vs. RPM

[superdiamond]

Commuters unite!

 

I ride daily to and from work (with occasional continuations into the mountains). I have been wondering in these days of gas prices whether there is a reccomended apex for miles per gallon relating to the Economy gear at 3800 RPMs or 5th gear at 4300.

 

And the bigger question I have is: Does my bike like to run at lower RPMs so I get better gas mileage, or does it like to be hotter 4500-5500 RPMs getting less mileage?

 

My goal: To care for my darling and ride her the way she deserves to be ridden.

[smiller]

I have been wondering in these days of gas prices whether there is a reccomended apex for miles per gallon relating to the Economy gear at 3800 RPMs or 5th gear at 4300.

My recommendation would be to simply try it and see.

[velomoto]

+1 on the recommendation to try it... While Beemers are noted to have "low end torque", IMO there is no comparison to the low end torque of a large cruiser. At 3800 RPM the 12RT has ample torque to accelerate, drop the RPM by 1K and the bike isn't going to respond without dropping a gear or two.

 

FWIW I've found that fuel economy is inversely proportional to fun factor - or to put it another way, if I'm havin' fun I'm not getting great mileage!

[steve.foote]

Assuming that your bike is a pre dual-spark 1150, I'd keep the RPM's up. Carbon tends to build up in the compression chambers at low RPM on these bikes.

[ShovelStrokeEd]

Aw hell, just ride the thing. Fuel economy isn't all that big a factor in the cost of riding a motorcycle anyway, despite all the touting. If you ride a lot, tires and other maintenance will quickly overshadow the 1 or 2 mpg savings you'll get by hyper-miling and you'll remove the main reason for having a motorcycle = FUN!!

[skinny_tom (aka boney)]

wondering;

 

if it requires the same amount of energy to move the bike at the same speed, does it seem reasonable that the amount of gas it would consume in either gear would be roughly the same?

[ShovelStrokeEd]

Speed really isn't much of a factor until you are above about 50 mph. Throttle habits have a bunch more to do with it, that, and braking, of course.

 

My Blackbird will just crack 40 mpg if I keep cruising speed at around 70 or so. At my preferred 82-85, it gets around 37. That is 4000 RPM in 6th vs 5000. There are also short bursts to 100 or so, 6000 RPM, as traffic dictates.

 

My new rear wheel bearings have brought back some fuel economy that I had been missing. I'm off to Tucson next week and then home for a week. Think I might change the OEM spark plugs. At 77K miles, it is probably time. Not a trivial exercise on this bike, it takes about 2 hours and requires an extra wrist joint.

[yabadabapal]

Hyper-miling is great for cars but on a motorcycle, I would think that in order to be in a gear ration speed factor, which might save a few cents per mile, you might also be putting yourself into an unsafe performance margin in setting your gear ration speed factor for minimum gas consumption rather than safety and performance.

[Bob Palin]

wondering;

 

if it requires the same amount of energy to move the bike at the same speed, does it seem reasonable that the amount of gas it would consume in either gear would be roughly the same?

Only if the engine is equally efficient at all RPMs.

[Mister Tee]

Hyper-miling is great for cars but on a motorcycle, I would think that in order to be in a gear ration speed factor, which might save a few cents per mile, you might also be putting yourself into an unsafe performance margin in setting your gear ration speed factor for minimum gas consumption rather than safety and performance.

 

I'm not following. How are you compromising on safety?

[Joe Frickin' Friday]

I'm not following. How are you compromising on safety?

 

If you're riding very slowly relative to surrounding traffic, that's one issue.

 

Another potential problem is if you have selected a very tall gear to put the engine in a more efficient (low RPM, high torque) operating point: you may not be able to rapidly summon the horsepower to get out of a troubling situation if you have to downshift twice. If traffic is light this is probably not a big deal.

[Mister Tee]

>If you're riding very slowly relative to surrounding traffic, that's one issue.

 

Agreed.

 

>Another potential problem is if you have selected a very tall gear to put the engine in a more efficient (low RPM, high torque) operating point: you may not be able to rapidly summon the horsepower to get out of a troubling situation if you have to downshift twice. If traffic is light this is probably not a big deal.

 

I'm not sure I would agree that downshifting a couple times is a big deal in a normal riding situation. I might ride a gear or two up if I'm actively lane splitting, but other than that, unless I'm in really dense traffic of varying speed, I'll ride in the highest gear I can without lugging the engine. But that's maybe 1-5 percent of my riding. I certainly wouldn't want to cruise at an artificially high RPM on the freeway or highway for long periods of time.

[hANNAbONE]

Commuters unite!

 

I ride daily to and from work (with occasional continuations into the mountains). I have been wondering in these days of gas prices whether there is a reccomended apex for miles per gallon relating to the Economy gear at 3800 RPMs or 5th gear at 4300.

 

And the bigger question I have is: Does my bike like to run at lower RPMs so I get better gas mileage, or does it like to be hotter 4500-5500 RPMs getting less mileage?

 

My goal: To care for my darling and ride her the way she deserves to be ridden.

 

uH......wHAT bIKE you got...?

[hANNAbONE]

Think I might change the OEM spark plugs. At 77K miles, it is probably time. Not a trivial exercise on this bike, it takes about 2 hours and requires an extra wrist joint.

 

aND a cold one or two..!

[ShovelStrokeEd]

I'm not following. How are you compromising on safety?

 

Diminished acceleration available if in too high a gear at too low an RPM.

 

I rarely ride even my Blackbird below 4000 RPM around town even though it will pull from as low as 1500 RPM in 6th.

[Ken H.]

I'll through out another related strategy that I've been having fun with lately to improve my overall mileage - coasting! It's amazing how far I can travel 'for free' by pulling the clutch sooner as I approach slow down / stop points.

[Boffin]

I'll through out another related strategy that I've been having fun with lately to improve my overall mileage - coasting! It's amazing how far I can travel 'for free' by pulling the clutch sooner as I approach slow down / stop points.

 

Coasting you are burning fuel to let the engine idle. Keep in high gear and shut the trottle and the Motronic shuts off the fuel - ie no fuel burn at all. Better than coasting.

 

Andy

[Mister Tee]

I've noticed that overall, mileage seems to be more of a function of speed than RPM. I seem to get about as good of mileage winding the engine to 7,000 as I power through the twisties, as I do cruising a steady 70 mph on the freeway locked on cruise control.

 

I do however, agree with Ken. People that do vehicle mileage competitions use the technique of moderately accelerating to speed, and allowing the vehicle to coast. Fuel consumption at idle is pretty minimal.

[smiller]

I'll through out another related strategy that I've been having fun with lately to improve my overall mileage - coasting! It's amazing how far I can travel 'for free' by pulling the clutch sooner as I approach slow down / stop points.

 

Coasting you are burning fuel to let the engine idle. Keep in high gear and shut the trottle and the Motronic shuts off the fuel - ie no fuel burn at all. Better than coasting.

But if in gear you have engine braking stealing some of your energy...

[Joe Frickin' Friday]

I'll through out another related strategy that I've been having fun with lately to improve my overall mileage - coasting! It's amazing how far I can travel 'for free' by pulling the clutch sooner as I approach slow down / stop points.

 

Coasting you are burning fuel to let the engine idle. Keep in high gear and shut the trottle and the Motronic shuts off the fuel - ie no fuel burn at all. Better than coasting.

But if in gear you have engine braking stealing some of your energy...

 

A true hypermiler would clutch-in and hit the kill switch. Probably bad for your clutch on a bike - engine at zero RPM, gearbox input shaft at several thousand RPM for an extended period - but on a car you can put it in neutral and just let the clutch out again.

[motoguy128]

Doesn't coasting with the clutch pulled in add unnessesary wear to your throw-out bearing on the clutch?

 

I don't see how slowing down using neutral throttle in a higher gear would use any less fuel than coasting with the clutch pulled in.

[Joe Frickin' Friday]

Doesn't coasting with the clutch pulled in add unnessesary wear to your throw-out bearing on the clutch?

 

It's no worse than loitering at a traffic light with the bike in gear and clutch pulled in. Which is to say, yes, you're using throw-out bearing life, but it's not really awful.

 

I don't see how slowing down using neutral throttle in a higher gear would use any less fuel than coasting with the clutch pulled in.

 

If you're using neutral throttle - that is, you are twisting the throttle to make the engine spin at an RPM to exactly match the gearbox RPM's - then you're using extra fuel to make that happen.

 

If you clutch-in, then the engine is operating only at idle speed.

 

In either case you're not transmitting any power to/from the wheel, but the first case uses more fuel.

 

 

[James Clark]

A true hypermiler would clutch-in and hit the kill switch. Probably bad for your clutch on a bike - engine at zero RPM, gearbox input shaft at several thousand RPM for an extended period - but on a car you can put it in neutral and just let the clutch out again.

 

If you own a bike with EWS, wouldn't that qualify as "living on the edge"?

[yabadabapal]

>If you're riding very slowly relative to surrounding traffic, that's one issue.

 

 

 

>

 

I'm not sure I would agree that downshifting a couple times is a big deal in a normal riding situation. .

 

There is no such thing as a normal riding situation when on a motorcycle. Never. IMHO