MythBusters - Drafting a Semi

[Snax]

Reminds me of drafting a garbage truck this last week on my motored bike. I think the driver was expecting to just pass by me, not have me tucked firmly in his wake at 35 mph.

I don't make a habit of that and it was really the first time I did it on the motored bike. It scares the crap out of me for obvious reasons.

[theholycow]

Wow...you are really committed to it, if you're willing to draft a garbage truck.

[slurp812]

Originally Posted by ziddey

drafting semis... good way to say bye bye to your windshield.

i was maybe 5 carlengths behind a semi today and still managed to destroy my windshield this afternoon.

I had a rock from a dump truck hit my windshield. No damage, but I wasn't drafting. Trucks are a fact of highway driving. It can happen without even drafting as well. Drafting of course increases this risk.

[Snax]

Well one of the reasons I no longer ride a regular motorcycle is because of trucks and crap flying off of them. I only got nailed once directly, but it was about a 1 foot long splinter of scrap lumber that hit me directly in the chest. I saw it lift right off the flat bed it was on and come right at me. There was absolutely no way to avoid it. Fortunately it was neither sharp enough nor heavy enough to even cause any pain, but it left me even less complacent about such things.

I also worked as an auto liability investigator and heard plenty of tails of objects from trucks damaging cars - including a 50 lb electric motor that rolled off of one, and down the lane to ultimately bash into the front end of another car going the same direction. Obviously, to a motorcyclist, that would be a very bad thing to face!

Drafting too close limits your options to deal with such hazards.

[theholycow]

Oh, don't get me started on unsecured loads. I've witnessed too many accidents caused by blown-off loads, including one very spectacular fatal one. I do recommend that (unless you're on a motorcycle) you just head straight for whatever random road debris has surprised you, rather than swerving to avoid it. In my observation, the swerve causes far more damage on average, since far too often it results in a collision, spin-out, or rollover...and the debris is usually something pretty harmless, like a 2x4 that even a lowered Civic could roll over, or a bouncing empty rubbermaid garbage barrel.

[R.I.D.E.]

I have had a large rock hit the windshield and shatter it, almost coming through on a test drive of a customers car. It came off a tire from a vehicle travelling in the opposite direction. I paid for the glass replacement out of my pocket.

I had to completely stop in a 45 MPH divided 4 lane road to avoid a falling pine tree that covered all 4 lanes, and missed a school bus by 5 feet. Had to move the pieces of tree to continue down the road.

I swerved once to dodge a tire and wheel that came off a car going in the opposite driection. It had been hit by another car already and launched 40 feet into the air.

I watched a 64 Rambler station wagon once loose its right front tire, wheel and brake drum. The driver kept going down the road and stopped at a light. The car was balanced so the suspension where the missing wheel was located never hit the ground, until the driver stepped on the brakes (early Ramblers had dual systems before it was legally required). The driver turned left and drove away.

I had a friend whose brother was run over on a Kawasaki 900, by a woman in a Dodge Dart. The police followed the trail of body parts and motorcycle parts to the womans driveway. She told them she never knew she hit anything.

I had another friend whose Chevy van hit a deer, the deer came through the windshield. They had to open the side door and let the still living deer out of the van.

I know a cop who saw a guy fall off a motorcylce for no apparent reason. When he stopped and asked the guy what had happened, the bike driver told him a big bug had hit him square in the chest. When he showed the cop the mark where the bug had hit him the cop issued no ticket to the driver.

I try to avoild driving at night!

regards
gary

[slurp812]

Originally Posted by civic94

that test is tested at 55 mph, and i rarely see semi's going that slow. besides, going 55 mph in most cars get very good mileage, anything after 55 is getting more and more worse


if they tested it at 70 mph, it would of been a bigger difference

I live in Ohio, they are really tough on big trucks here. Just ask any trucker. Most trucks NEVER exceed 60 mph around here. So I often draft a 55mph truck. Other states I've driven in are not that way. Indianan for example, trucks do ~70 on he turnpike all day long...

[Project84]

I draft every time I'm on the interstate. I've seen as high as 46.7mpg on a trip from Cleveland to Cincinnati drafting about 200 miles of the 250 mile trip and using a HAI.

My gas log tells the story...

HAI remains my only true mod, and it's crude and not as effective as it could be. The suggested temp is around 180*F at full speed, which I've never attained. (only in stop and go traffic actually)

I draft at about 1 truck length back, just a hair off center and use my headlights so they can always see the gleem of me behind them. If you draft in this manner, at least what I've seen, the semi drivers won't mind a single bit that you're back there. My tank average on the way back from Cleveland this time was 39.8mpg when I arrived in Cincinnati. Currently adding city mileage to this tank, but I'm going to fillup short of a full tank so I can record the good mileage!

If you're determined enough, you can listen closeley as you move within correct drafting range and hear that wind noise is substantially less, turbulance is much less, and at 1 truck length back, you're safe from getting pulled over from tailgating and Semi drivers are now doing about 60mph in my area, so they keep you at a perfect speed.

[GasSavers_GasUser]

I have had 2 broken windshields from trucks and one was from a truck coming in the opposite direction going around a curve on a 2 lane road. And one time something came off a truck in the other lane on a 3 lane highway at highway speed and bounced on the road in front of me. It was pieces of tire. Also had a semi jacknife up ahead of me in an ice storm once. Luckily there was nobody there. Good thing he didn't hit anybody. I stay far far far away from trucks on the road.

Just my experience.

[Snax]

Well said Dave.

I actually follow the suggested 2-second rule when drafting. It's fun being able to tell people we get over 38 mpg in our minivan.