Author Topic: Ultimate MPG road bike?  (Read 1046 times)

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Ultimate MPG road bike?
« on: July 16, 2017, 05:03:21 am »
My C10 is likely to be my last bike, but when I think about why I started riding it is really economy that I was after.  I'm wondering what current model or yet-to-be-built design would have the comfort of a Concours with the maximum economy?  I'm going to specify that it should have enough power to maintain the speed limit on interstate grades. (My 250cc cruiser couldn't keep up with the semi-trucks on I84 between Newburgh and Port Jervis).
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Offline Diz

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Re: Ultimate MPG road bike?
« Reply #1 on: July 16, 2017, 08:19:02 am »
Pretty broad range on comfort vs. economy as opposed to a purpose driven model like a cruiser or adventure bike. Honda's 270* parallel twin is pretty economical although the bikes it is installed in are not known for comfort. Africa Twin may be an exception, perhaps an owner will chime in. I'm hoping Honda will expand their lineup to include a 75 HP in their parallel twin equipped bikes. But if there was a motorcycle that ran car tires and still handled like a bike; that would be a pretty good savings right there.

Offline jettawreck

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Re: Ultimate MPG road bike?
« Reply #2 on: July 16, 2017, 12:30:43 pm »
It's sort of sad, but most every bike I care to own/ride gets less fuel mileage than my VW TDIs.  52+ mpg lifetime average(s) and sometimes pull a 55+ tank. And they are a lot more comfy when it's wet or cold.
« Last Edit: July 16, 2017, 05:36:47 pm by jettawreck »
Snowmobiles, I have a bunch.
Motorcycles-I haven't had anything except dirtbikes 30 years ago, so this will be all new to me.
2005 C10 with Rifle w/s, SISF Exhaust sprocket, overflow tubes, 2 minute jet mod. (SOLD)
2004 Honda ST1300-the current mule.

Offline Ranger Jim

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Re: Ultimate MPG road bike?
« Reply #3 on: July 16, 2017, 01:01:25 pm »
My Versys 650 will deliver mpg in the low 50s when ridden in the 60-70 mph range. Push it up to 75-80 mph and the fuel economy dives for the upper 30s. I suspect this is mostly due to aerodynamic inefficiency.  Both numbers are still better than my cars though.  :motonoises:
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Re: Ultimate MPG road bike?
« Reply #4 on: July 17, 2017, 06:02:19 am »
I assumed modern VWs were autobahn capable but I don't know what their performance is like.  Meanwhile I was wondering if a smaller or otherwise more efficient engine could improve economy.  Initial cost and maintenance are also part of the economy equation and I also believe fewer, lighter parts must be cheaper somehow if not in cash or fuel terms.  So the problem with cars is not just the mpg, you have to bring tires etc into the figures (maybe glass and windshield wipers etc, higher insurance, whatever).  So even an air cooled twin might score higher than expected if it was low maintenance.
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Offline Diz

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Re: Ultimate MPG road bike?
« Reply #5 on: July 17, 2017, 08:57:29 am »
the honda parallel twin gets 65-85 MPG It was falsely said to be 1/2 the Honda Fit engine. Designed for a bike, rev limiter at 6500, engine produces lots of torque with only 49 HP 8000 mile intervals for service Was getting in the high 70s, low 80s with MPG Put a top box on and the bike still gets in the high 60s. The BMW F700GS averaged for me in the high 60s, lower 70s with MPG, lost 10 MPG with a top box. It had 73 HP but it was a BMW.....

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Re: Ultimate MPG road bike?
« Reply #6 on: July 17, 2017, 12:47:56 pm »
The CB500 looks nice for this question.
I was/am reading (at my own intermittent pace) a book written by a guy who designed boats for Yamaha and did a lot of work with fairings on the crew rowboats in a long-ago Olympic trial.  Basically they gained a good % of speed by putting smooth backpack type things on the oarsman, reducing drag in the process.  They also put wing-like fairings on the oars in an experiment for more % gained.  So maybe a bike with full or beyond-full fairings could do better at high speed, and maybe that's part of why a VW is so competitive in direct mpg.
As I recall from riding in convertibles and boats with windshields, the air curls behind the windshield like a breaking wave and blows on the passengers from behind.  If I was willing to go beyond the norms for fairings, would  a wind shell add a lot of mpg or just make for excitement in a crosswind?
Or, is the savings even significant being that I can ride at 40-42 mpg today without doing anything? 
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Offline Warwgn

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Re: Ultimate MPG road bike?
« Reply #7 on: July 18, 2017, 09:55:41 pm »
The old Kawasaki Voyager 1200's consistently got around 50MPG, I would say those would be a good one. In fact I think I will pick one up in the future when it is ready to find me and ask to be bought.

Offline Jim M.

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Re: Ultimate MPG road bike?
« Reply #8 on: July 20, 2017, 04:18:59 pm »
Test ride a maxi-scooter. They get great mileage. Yamaha, BMW and Suzuki make very nice touring capable scoots. You'd be surprised at how much storage is available. The wife has a Yamaha Majesty 400 and loves it. I've had it north of 80mph and it's still very stable. The 65-70 mpg ain't bad either. I'm 6'2" and the Majesty is a bit short on leg room, but still it's great fun to ride. I'd probably really enjoy the Suzuki 650 Bergman.

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Re: Ultimate MPG road bike?
« Reply #9 on: July 21, 2017, 02:13:59 pm »
Does the "girl's bicycle" design on a scooter / Bergman really make sense?  In the spirit of the OP, suppose the scooter specs were applied to a conventional frame?  I'd expect something better.  But things don't always make sense, like when a ship with a big wart on its nose gets better economy than a sleek pointy nose ship. (Maybe SG will post with a pic to liven up the thread  >:D )
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Offline Diz

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Re: Ultimate MPG road bike?
« Reply #10 on: July 22, 2017, 11:30:49 am »
no pic to liven up the thread but an observation about over sizing a fairing or windshield. My C-14's  MPG instrumentation consistently says the economy is better with the windshield in the lowest position. I don't believe my position riding the bike has superior aerodynamics so am quite curious as to why the bike is recording better fuel economy when my body has more exposure.

Offline jettawreck

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Re: Ultimate MPG road bike?
« Reply #11 on: July 23, 2017, 12:30:26 am »
no pic to liven up the thread but an observation about over sizing a fairing or windshield. My C-14's  MPG instrumentation consistently says the economy is better with the windshield in the lowest position. I don't believe my position riding the bike has superior aerodynamics so am quite curious as to why the bike is recording better fuel economy when my body has more exposure.

Not so much the frontal area as the "drag" created behind the screen. Perhaps, I think. Maybe.
I get better mileage with the Honda ST1300 when riding with a passenger and also notice quite a reduction in back pressure. Coincidence? Not sure, just my theory.
Snowmobiles, I have a bunch.
Motorcycles-I haven't had anything except dirtbikes 30 years ago, so this will be all new to me.
2005 C10 with Rifle w/s, SISF Exhaust sprocket, overflow tubes, 2 minute jet mod. (SOLD)
2004 Honda ST1300-the current mule.

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Re: Ultimate MPG road bike?
« Reply #12 on: July 23, 2017, 07:36:06 am »
An old saw of yacht design was "V on root L" as I recall where it means the speed of two yachts should be compared when divided by the square root of their length.  The longer one is expected to have a speed advantage when everything else is scaled up identical.  When I was shopping for cars I surprised that a sedan model had better mileage than a miniwagon even though the sedan was heavier and had a bigger engine.  That's a reason why I wonder if a longer fairing with a top & sides could get much better mpg.  No experience or reading to back up the thought.
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Offline Diz

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Re: Ultimate MPG road bike?
« Reply #13 on: July 23, 2017, 08:57:33 am »
Maybe this will lead you to an answer. They originally had a BMW boxer engine but did not surpass the bike with MPG. Last I heard the company developed an all electric Montracer that beat all competition in Los Angeles for range. Competition did not include a Tesla product.

https://www.youtube.com/watch?v=wJ1sn1BDJyQ

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Re: Ultimate MPG road bike?
« Reply #14 on: July 23, 2017, 12:26:13 pm »
An old saw of yacht design was "V on root L" as I recall where it means the speed of two yachts should be compared when divided by the square root of their length.  The longer one is expected to have a speed advantage when everything else is scaled up identical.  When I was shopping for cars I surprised that a sedan model had better mileage than a miniwagon even though the sedan was heavier and had a bigger engine.  That's a reason why I wonder if a longer fairing with a top & sides could get much better mpg.  No experience or reading to back up the thought.

The "miniwagon" has a longer/better shape-until you get to the back end and that's where the "drag" is created. The tall/squared off tail makes for a lot more turbulence than the stepped down cabin/trunk of the sedan and makes for very "dirty" air flow. You don't see aircraft with a chopped off fuselage. The Prius is most common in the hatchback version and is a very aerodynamic shape with the gradual taper off the back. Those spoiler lips are there for a reason also.
But, don't believe those animations of wind tunnel smoke trails. Most of those are simply very low speed presentations for advertising purposes.
Following at even quite reasonable distances such minivans/wagons, suvs, (any larger vehicles) at speed results in a big mileage jump on my on board ScanGauge system. As those larger vehicles pass and get out of range ahead you can watch the readings return to "normal".
Above about 50 mph for every 10 mph increase fuel mileage drops roughly 5%.
« Last Edit: July 24, 2017, 02:33:20 am by jettawreck »
Snowmobiles, I have a bunch.
Motorcycles-I haven't had anything except dirtbikes 30 years ago, so this will be all new to me.
2005 C10 with Rifle w/s, SISF Exhaust sprocket, overflow tubes, 2 minute jet mod. (SOLD)
2004 Honda ST1300-the current mule.

Offline Toller

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Re: Ultimate MPG road bike?
« Reply #15 on: July 23, 2017, 09:12:15 pm »
[snip]  I'm going to specify that it should have enough power to maintain the speed limit on interstate grades.

Does the NC700X meet this qualification? Have never ridden one.
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Re: Ultimate MPG road bike?
« Reply #16 on: July 24, 2017, 03:19:33 pm »
I think a 400cc bike could carry me uphill at the speed limit on an interstate.  I'm suree a 700 could.
Maybe I should have said microwagon.  I had a Suzuki Aerio and compared it to the bigger  Suzuki sedan.  Sedan had the better figures IIRC.
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