Mythbusters: Is a bike greener than a car?
 

Was watching the boob tube and caught a commercial for a new episode of Mythbusters with something interesting... It looked like some sort of streamlined motorcycle.

Looked it up, it's an episode called Bikes and Bazookas:
Preview: Mythbusters-bikes-and-bullets
There's some footage of their streamlined bike on that link.

The premise seems to be testing whether cars or bikes produce lower emissions (I presume this is a question because bikes have better mpg but less pollution controls). Looks like they put it to an "ultimate" test by streamlining a bike.

However, to me it seems they add a TON of frontal area in the process. I've never seen a bike on the salt flats that looked like their creation...

Of course, no results at this point. Ya gotta wait for the episode to air later this month.

Cool. Too bad he had the window open, greatly increasing drag and putting more stress on the engine.

The bike also does look pretty big. Why not just put a rear fairing on?

Right. It didn't need to be anything close to that wide. Drag = cdA and they greatly increased the A.

If you're willing to ride in a hunkered down crotch rocket position, why not use clips-ons and get narrower?

Regardless of Mythbusters, even if a particular bike model and car model got identical fe, the bike used about 1/5 the materials to make, especially oil-based plastics. There's a lot of emissions in manufacture and disposal too.

Sure, the thing lacks refinement. The mirrors are enclosed increasing the width, the all clear panels make it a hot house in the summer, and the rear hatch is awkward. Still it will likely improve mpg by 30% or more. The best part is that the concept of a full faired motorcycle will get a much wider audience. An all weather 250cc motorcycle that gets 150 mpg for around $5000 USD may prove very attractive to commuters.

BMW sort of tried that with the C1. Of course, including the young woman wouldn't have hurt sales.

http://s39.radikal.ru/i086/1108/b3/702cc4593d65.jpg

Honda CBR250R might be much better
 

I would be intersted to see them revisit the car vs bike myth using the Honda CBR250R. The best bike they had came back with 56 mpgUS so they put a giant streamliner fairing on it and got it up to 71. The CBR averages 71 on fuelly right off the showroom floor and has an O2 sensor and a big exhaust (big catalyst?) so it might be cleaner than their best test bike. I get 87 mpgUS all summer long on my 64mph commute. They put the emphasis on CO, HC, and NOx, disregarding the fact that the bikes used less gas and put out less CO2. In the end, they just told everybody to stick with their car. I hope one day they will try it again with the $4000 Honda.

There are, but sooner or later they're trumped by rubber use. A bike usually goes through something like three to six times more rubber than a car. IIRC it's something like an extra ~150-300 lbs per 100k miles, which is equivalent to the same weight in plastic or about three times that weight in steel.

For a bike that goes through tires in a reasonable amount of time, say ~15k-20k per set, the comparison isn't too bad because it only reaches the embodied energy of the car after a few hundred thousand miles, but a sport bike that goes through those tires in half the time or less will add the energy equivalent of a half ton of steel every ~100k or so.

The major consideration should be fuel consumption which can be much less with a motorcycle. Especially for around town errands where there will be no comparison between car and bike. The entire continents of India and South East Asia get by entirely with small two wheelers that get 130mpgUS. My 250 is considered a luxury model there. I commute on the highway so need the better bike but still get 87.

QUOTE=darcane;261151]The premise seems to be testing whether cars or bikes produce lower emissions (I presume this is a question because bikes have better mpg but less pollution controls). Looks like they put it to an "ultimate" test by streamlining a bike.[/QUOTE]

Mythbusters can be fun to watch once in a great while, but their science is often deeply flawed, and half the stuff they do can be answered without the theater and within a minute on the web.

Bikes emit far more criteria emissions than cars, because they are allowed to do so. (There are not as many bikes; it's harder to clean up a high-specific-output-engine; some of the manufacturers are small and would be burdened; etc.) Ironically, the fastest bikes now owe part of their speed to technologies that came from the implementation of emission controls in cars.

It used to be true to say "A Jet Ski emits more pollution in and hour of operation that a Volvo emits in an entire year." The differences in emission standards are narrowing, but a 50cc scooter is allowed to emit on the order of 10 - 50 times as much (measured in grams per mile) as a 7 series BMW. All cars have to meet one regulation; bikes have three levels, with bigger bikes required to emit less (even though they obviously burn more fuel).

So if you streamline a bike to get 150 mpg, The bike will still emit more criteria emissions than any car... even the very biggest, heaviest gas guzzlers.

However, CO2 is now considered a "pollutant" but is not regulated. In this sense, a 150 mpg motorcycle emits one third the CO2 of a Prius. (CO2 is not only conveniently tied to MPG, it is actually the thing measured in EPA dyno tests to indicate fuel burned.) (I used to use a pipette when I ran motorcycle dynos in the dark ages.) CO2 is probably more important these days. The criteria emissions are easy to deal with -- they are all but eliminated in cars (and bikes could be equally clean if we wanted to make them so). But CO2 is nearly impossible to deal with -- none of the sequestration methods seem to be likely to work well.

So today, knowing what we do, it is probably better to get 150 mpg in a streamlined bike than to get 50 mpg in a Prius with one person in it. Doesn't really mater what the criteria emissions are, unless bikes get to be a significant part of the whole.

The Montracer gets 53 mpg at a constant 75 mph, and emits fra more criteria emissions than a Prius in the process. This is about equivalent to 53 mpg in an EPA highway fuel test cycle. So getting 150 mpg in a streamlined motorcycle is more than a no-brainer -- and some claims are not measured in accordance with the EPA test cycle.

Having built a tiny enclosed motorcycle, I can say it is not easy to get over 100 (real) mpg in anything that most people will want to ride.

BSFC remains a challenge, as the Monotracer shows. If you have produced a bike that requires only 10 hp to maintain 75, then a 100 hp bike engine is far too large, and engine operating efficiency might be 8%. Make the engine 10 hp, and then acceleration is rotten (and top speed is 75) -- but you've bumped the engine efficiency back up to 25%.

No free lunches today.

I've never had a bike rust out and have to be scrapped.

Bike tires contain far less materials than car tires, in average sizes.

Since I don't have a crotch rocket, my bikes' tire life isn't that dismal.

The premise of the discussion is which is greener. Not which emits less criteria. Fuel consumption must now be ranked much higher in the criteria as we will soon (a few more generations) run out. Then it won't matter how clean things are as there won't be any personal ownership of internal combustion engines.

This is somewhat related and interesting repost:

Emissions Test: Car vs. Truck vs. Leaf Blower

Cliffs: 0.03L leaf blower is way dirtier than 6.2L 411hp truck.

On the subject of bike ownership cost... I sold my last bike like 2 years ago, but even at 50mpg, it was arguably more expensive and more hassle to operate than a 30mpg car. It could eat a rear tire in no time flat, eat brake pads, and is very maintenance intensive.
Chain clean + lube every 400 miles.
Solid lifters that need to be adjusted.
$50-100 gloves wearing out after only 10k miles.
Helmet visor replacements.
More expensive and more frequent oil changes.
Fork rebuilds every 2 years or so.
Etc.

Mine was definitely not greener than a car as it had zero emissions controls.

I'm looking at about 9,000 miles out of a rear tire for my CBR250R. 27,000 for the front? It still looks brand new with 6,000 miles on them. Even 50mpg should be seen as much greener than 30 despite NOx levels. And now finally, there are motorcycles that are affordable and aspire to achieve much higher mpg.

I agree that now, resource depletion and CO2 emissions are more important than NOx, etc.

And I likewise agree that it is great to see bikes like yours. In fact, it was the mention of your bike here that made me look into the 250 and its variants, and announce (in jest) to my wife that I was going to buy one like yours, the $12,000 racer and the $28,000 racer. To get the $28,000 down to essentially half the weight of yours must have required quite a bit of unobtanium. I raced when two-stroke Yamahas ruled, so I looked up their power levels, expecting them to be lower -- but surprisingly they were actually a little more powerful, with 50 some hp from a TZ1.

We raced a 350 four Honda for a couple seasons, and could, in endurance races, soundly trounce everything on the track: 500s 750's and 1000cc bikes. The only things we could routinely pass on straightaways were the "tricked out" American V twins. For me, nothing beats a small bike.

It would be interesting to see what a 2011 CBR250R produces as far as tailpipe emissions. It has FI and a cat, not sure about the O2 sensor but I would assume it is a feedback system. Compared to a CV type carburetor I would bet the emissions are comparable to a car, not another bike without the same system. If they are comparable as a percentage, then they would be much lower in volume.

regards
Mech

I just checked and the CBR does have an 02 sensor. It has a check engine light, just like OBD cars so it would be fairly safe to assume it produces the same emissions as a percentage of exhaust volume, which would be considerably lower than just about any car on the road.

regards
Mech

Does anyone know where I can borrow a portable emissions logger or recommend a suitable motorcycle dyno to check the stock emissions of the CBR. The cat is fairly large for a motorcycle and the O2 sensor runs in closed loop.

You're talking about regular maintenance on your bike. How about your car, it doesn't cost to maintain?
I've had bikes for 10 years and i could easily get 10000 miles on a set of tires, unless you're buying soft racing tires.
Gloves every 10k miles? c'mon now

So we can see that cars/truck have better emissions but the question should be:
If i use a bike for a summer and travel 10000 miles. I would use 200 gallons of fuel (at 50mpg) would the bike polute more than if i used that Ford Raptor on the same 10000 miles and wasted 666 gallons of fuel (at 15 mpg)

I found my gloves on the road yesterday, a gust of wind blew the trunk open on the Harley in front of me. Tried to catch him and let him know, but after a mile, I turned around and went back and picked them up. Head ski gloves, about $35 on the web.

Free and brand new ;).

regards
Mech

10-15k miles on a set of mediocre tires on a bike. Even "sticky" street tires on a car last ~20k. All seasons usually in the 40-60k range, and pretty easy to find stuff that goes 80k. Aggressive brake pads on my car again last many times the life of motorcycle pads - and they cost about the same amount. My car doesn't have any solid lifters to inspect an shim at 6000mile intervals. I don't have to lube the chain, etc.

Point is, many things that are common maintenance on a bike don't exist on a car. For the rest, the maintenance intervals are WAY further apart than they are on a bike. Look at how many cars you can buy new that will go more than 50k miles while only needing a couple of oil changes and an air filter. Even at 100k you only add in spark plugs, brakes, and tires. By the time you reach this point with many bikes, you are looking at new rings, bearings, or a complete rebuild.

How many miles do you get out of a set? Sure, four tire on my cat at ~22lbs each is ~90lbs, but they'll also do ~100k miles, and I've never heard of people routinely getting 30+k miles out of two 15lb motorcycle tires. 10-15k average seems to be what the longer lasting tires are at, which is still two to three times the rubber a car uses. Crotch rockets are even worse.

How did we end up talking about tires? A minimal concern next to thousands of gallons of gas and CO2. An 80mpg bike is much greener than a 40mpg car. Get one and start riding it to replace the use of your car whenever possible. And, fuel efficiency and motorcycles are two words that have only recently been considered together outside of India and Southeast Asia where the average bike gets 120mpg at 35mph and sells for $1600. Bike companies could do much better if they thought anyone wanted it. Honda could re wrap the CBR250R with a recumbent seating position and aero body work to sell a 100mpg all weather (above freezing) highway commuter with a trunk for $6000 if they thought anyone would buy it. Vote for it with your wallet. Buy a CBR250R. Ride it everywhere, all the time. A rolling billboard toward sustainability. And spread the word that we want even better fuel economy from better bodywork on two and three wheelers and maybe someday one of the big companies will sell one affordably. RIP Aptera. Their styling would have been a quantum leap forward.
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ps. car tires last for 35,000 miles as a high average. I work at a car dealership.
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The tire talk started because of the talk about the difference in embodied energy. Initially it's pretty big, but as the miles rack up and a motorcycle goes through more tires the gap closes. An 80mpg bike does have half the carbon emissions of a 40mpg car, and it also tends to have similar or greater emissions aside from carbon.

On the subject of tires, I can see a dealership cutting corners and going with el cheapo tires, but plenty of tires in the U.S. come with 80k to 100k mile treadlife warranties and will last for that long, or less if the owners abuse them. I don't see any bike tires with 30k lifespans.

Sorry. This is not the case at all. You are getting hooked in by the treadwear adds. The tire companies are banking on the fact that you will loose the receipt or forget. 35,000 miles is tops on all kinds of cars. OEM tires and replacements. SUV's get 25,000. I see thousands of cars come through my shop per year for 28 years.
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Anyway it takes 28 gallons of oil to make 4 tires that will be used to burn 875 gallons of gas in a car to go 35,000 miles. 56 gallons (or less since they are half the size) to make 8 tires ( I won't use even 3 in the front but whatever) to burn 440 gallons of gas to cover 35,000 miles on the bike. The bike still wins by a factor of 2. Bringing tires into this discussion is a complete non issue.

Well, sure :-) But where do you find an 80 mpg bike? (I mean an actual bike that you wouldn't be afraid to take on the interstate, not a Vespa-like scooter.) I've had a number of bikes over the years, from a 350cc Honda back in the '70s to the most recent 850cc Suzuki. As far as I can remember, none got much better than 50 mpg. On the other hand, I'm now driving a car that gets over 70 mpg.

Wrong. The rear tires on my Insight are at close to 60K miles, and look nearly new. (I replaced the old ones, which may or may not have been original, at around 90K.) 35K is about what I get on the fronts, though.

In my experience the bulk of bikes get in the 50 mpg range. But James, you are aware that getting better fe in your car than on your bike falls into the exception-to-the-rule category?

Re: tires: I don't recall putting on/getting a bike with new tires and wearing them out, then replacing them, so that I know how many miles they went. I've replaced shot tires but they were worn when I got them. I just can't answer the question of how many miles I get from bike tires.

The lifetime mpgUS of my 2011 Honda CBR250R is over 80. And that will improve with the new gearing. In the summer I am over 87 mpg at 65mph. If you are getting 70 in your Insight, your average speed must be pretty slow. The CBR will break 90mpg at those speeds right off the show room floor. For $4000! I used to get 63mpg in my Insight over the same commute. Now only 59. Time for some new injectors? Tire life was never more than 35,000 with the excellent Bridgestones that are made for it.

I'll believe it when I see it, or proof of it. My experience is contrary to what you're stating, but maybe I'm just lucky. I've had sets of tires rated for a 40k/50k miles treadlife warranty last that (Or a little less if I didn't rotate them) and I've had tires rated for 80k last 60k before a defect in the steel belts ruined them (They were later rated for 40k because of this). In terms of tread they were fine and would have lasted if not for the weird deformation. I currently have a set rated for 85k and 100k on two cars, so as usual time will tell.

Like I said before, I'm not talking about total lifecycle energy usage, I was just talking about the difference in embodied energy, which narrows when considering rubber use. This comment was in response to Frank's comment about embodied energy, not total energy use.

FWIW, I changed the OE Potenzas (hardly economy tires) on my Subaru at 54k. They would have gone a lot farther but I didn't wan't to start the winter on them as they were. And yes, I was tearing it up all the time back then.

If you're going to count tire usage as a minus for bikes, remember that they only use two at a time.

Man. I gotta get me some of these magic tires. My 2009 fit that my daughter drives made it to 43,000. Including two winters on snows! The summers may have had 30,000 miles on them. One was worn. Three may have had another 5,000. It will get new summers in the spring. I just asked through the whole shop and not one single person here has seen any set of tires go past 35,000 miles.

Great point. It is a shame that the makers of the monotracer did not go that way with their design. The new breed of more fuel efficent cars seem to all have smaller engines capable of greater highend power. Sounds like a motorcycle engine to me. Of course the car engins are much more sophisticated.

Go look on Tire Rack. Here's a tire for the Fit that has a 65K mile warranty. First one I clicked on.

Goodyear Assurance Fuel Max

There are plenty to be found with 80k warranties. I have personally driven tires well beyond 35k before.

Treadwear warranties are completely bogus as an indicator of expected real world tire life. You know that. They are hoping you will lose the receipt or forget. 35,000 is a high average. But it has nothing to do with the topic of lifetime fuel consumption. It's silly to keep polluting this thread with a question of tire life. Tires are completely insignificant compared to fuel usage.

My aunt bought a new Cadillac in 1965, the original tires wore out at 6000 miles. She asked me which tires were the best for long wear. I told her Michelin X. She replaced the tires 13 years later because she was worried about dry rot. They would still easily pass state inspection for tread wear.

My Civic VX was purchased in March of 2008 with 27,492 miles on the odometer. It was totalled and sat in an Insurance company training center for about 13 years before it was shipped to me with the rear end smashed.

I started driving the VX in April of 2008, still on the original Bridgestone tires that were made in March of 1993 (date coded on the tires). I drove it another 10,000 miles on those 15 year old tires. One trip in June 2008 I averaged 68 MPG in the VX, 300 miles on 4.627 gallons of fuel, same pump, same station, same day, with two passengers weighing just under 500 pounds.

I changed the tires because I was worried about a blowout messing up the bodywork and the fresh paint job. Changed the 15 year old timing belt at 35k miles so I wouldn't have to worry about it breaking an messing up an engine I could never replace. I can virtually guarantee you it was the only VX that was on the road in 2008 with the original tires.

When I replaced the Bridgestone RE92s on my Insight I saw no change in mileage. When I changed the Bridgestones on the VX to Michelins, my average mileage dropped by 7 MPG. I measured the tread depth on the Michelins at 25k miles and it was still 90% of the depth when new. I think the tread depth on the Michelins was almost twice what it was on the RE92s, probably a very significant factor as far as rolling resistance and tread wear. I wish I could have bought the same tires for the VX that were OE but they had long since stopped making them.

regards
Mech

I must be another of those extra-lucky magic tire people. ;)

The OEM Michelins on my Odyssey lasted 60k.
The replacement FuelMax's are now at 33k and maybe halfway worn.
My Civic has Michelin Destiny's at 41k and still legal but getting low.

Tires are really a non-issue when talking about lifetime 4-wheel vehicle costs. Back on the subject, how about a car getting 74 mpg? Sure, a bike would use less fuel, but there's not a lot there to conserve at this point.

We must have abrasive roads where I live.:)
Original MXV, MXV4, MXV4 green, Conti CH95 same tire for 15 years and the best wet performance/ price. Bridgestone RE92 a little better. 1000's of cars. Never once over 40,000 miles. Median closer to 32,000.
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What car gets 74mpg lifetime on a highway commute?