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Drafting Semi's...Does anyone do it?(20 posts)

Drafting Semi's...Does anyone do it?Kristin
Jun 13, 2002 5:44 AM
No, not on a bike. In a car. After discovering pacelines and this wonderful think called a slipstream, I inadvertently discovered that Semi's have a huge pocket behind them that I can slip my car right into. I've gained up to 5 MPG doing this. But then, there is the question of ethics. I'm guessing its, 1) illegal and 2) impolite. But oh that gas milage!!

Okay, for the truck drivers out there...do people ever sit on your wheel? How does that make you feel? Is it offensive to you when people do that?
Been there, done that.Len J
Jun 13, 2002 5:52 AM
Milage is great but.......

1.) remember, you can't see what's in front of the truck. To really take advantage of this, you need to be real close. One lapse of concentration can be pretty serious.

2.) It's illegal to follow too closely.

Be safe.

Len
I'm pretty careful about it. My rules:Kristin
Jun 13, 2002 6:18 AM
1) Choose someone with a full load. There stopping distance is longer so I following at 1 car length still gives me plenty of stopping time.

2) Mix it up. Don't sit on a wheel too long. As soon as I have to "shake it off" or feel sleepy, I drive on my own for a while, then find another truck.

3) Be respectful. A squirrely truck driver usually is saying, "get off." Once I'm detected, most drivers will pull to the right to take a look at who's there. What they do next tells all. If they slow down lots or begin pulling often to the left or right, its probably an indication to move on.

4) Help out. Trucks are big and slow, and drivers take advantage of that. In traffic jams, if I'm behind a truck and he wants to change lanes, I help out. (Oh, for anyone who doesn't know...flashing your headlights twice tells a driver you're letting him in.)

5) Wave. They're usually aware that I'm back there. When I get off and drive past, I usually wave to say thanks.
you mean in a car?DougSloan
Jun 13, 2002 6:30 AM
I thought you meant on a bike. Sure, up to about 45 mph, then it gets sort of hard.

I would not do it. It's tailgating. Sure, you'll be able to stop faster then the truck, but it bugs the crap out of them. They really hate it when you do it on a motorcycle. Been there. But when it's cold out, it really helps.

If they start swinging the trailer around to see you in their mirrors, that likely means they don't like it.

Doug
drafting semi on bike world recordDougSloan
Jun 13, 2002 6:56 AM
Michael Secrest, Phoenix, AZ
26 Apr 90 drafting 18-wheel truck Motor Speedway, AZ 1216.81 miles in 24 hours / 50.70 mph average

http://www.ultracycling.com/standings/timedrecords.html
Wow, that puts things in perspectiveKristin
Jun 13, 2002 7:16 AM
It would take me 3 days to drive 1200 miles. How does someone turn pedals for 24 hours?
It ain't worth it, honey-rideslikeagirl
Jun 13, 2002 7:33 AM
I'm actually shocked that you would do such a thing. Tailgaters happen to be my pet-peeve, tho.

One car length between you, at any speed over 10mph is just dumb. Everything I've ever heard says to keep one car length for every 10 mph - so, that's 5 car lengths at 50 mph.

Think about that big truck (or a car for that matter) blowing a tire or having to swerve to avoid something you can't see cuz you're plastered to his butt - 20 ft doesn't buy you any reaction time.

I don't car how much gas you save - it ain't worth it.
Hmmmm...Kristin
Jun 13, 2002 8:01 AM
Now we have each have laid bare the others pet peeves. I personally hate being called "honey."

With regard to tailgating...I don't do it unless in extreme traffic. I don't know where you live, but I can't always avoid tailgaiting here. (And I dislike being tailgated too.) However, I will try to cut past my pet peeve and sincerely note your opinion. Its not invalid--though I wish you hadn't called me honey.
careful ladyFender
Jun 13, 2002 8:24 AM
I wouldn't like to see you plastered onto a semi one day. actually I have a little story about drafting of other vehicles.
Upon leavinf from a 125mile race in San Felipe, Baja, Mexico, we stopped for gas at the towns only station. They had a long wainting long, say 25min, so we decided to stop at the half way point between San Felipe and Mexicali, the next city, which was at mile 65. When we reached the midway point and pulled into the gas station, they where completely dried out. NO GAS!!!! Our tank had less than an 1/8th.. and we still had 70 miles to go. So we see this RV drive by and we where on its bumper. Even though we could only drive at 55mph, it still gave us an extra 10 miles before the car turned off because it was out of gas. Long story short, we asked this lady who lived by the side of the road for gas and after half an hour of convincing she sold us 1 gallon for nearly 5 bucks!!! that got us into the next station 12 miles down the road.
Jeez-rideslikeagirl
Jun 13, 2002 8:38 AM
Believe me, it didn't come outta my fingers the way it woulda come out of the mouth of one of those truckers you draft. And certainly not with the tone of a sassy waitress as she smacks her gum at you.

I shant ever use a term of endearment towards you again.
how 'bout "sweetie"?DougSloan
Jun 13, 2002 9:13 AM
or toots? girrrrlfrend? sugar?

Then there's always "Francis" -- "Anyone calls me Francis. I'll kill ya."

Just kidding!

Doug
I believe "pumpkin" is the proper form of address. (nm)Sintesi
Jun 14, 2002 5:06 AM
Why, why, why ......nn23
Jun 13, 2002 10:30 AM
...would anyone want to do that?

It raises my blood pressure if someone tailgates me on a 3 lane freeway at night when its just the two of us for half a either direction. I feel like hitting on my brakes so the tailgating car rear ends me. It will be impossible to prove that it was deliberate, they will be declared at fault, and their insurance will go thru the roof. Man.. what a sadist ;)

As for me drafting a semi, never. You just can't see around them, which is
a] Not safe
b] Spoils the view - not just on the on the front but also on the sides as you can't afford to take your eyes off the semi's brake lights.

Oops.... just re-read your post and found the answer.. 5 MPG savings

Lets see... 12,500 miles a year at 25mpg = 500 Gallons v/s 417 gallons for 30 mpg. Savings of 83 gallons or $133 if gas costs $1.60. In real life you will not be drafting all the time but say 25% of the time so savings is more to the tune of $33.

You really think its worth it ? Just enjoy the drive instead and relax. Look out the windows at the fields, and enjoy the radio. I'm assuming you dont draft in traffic snarls and stop-go traffic.
or get a Volkswagon TDI and get 49 mpg nmDougSloan
Jun 13, 2002 10:34 AM
Don't do it!4bykn
Jun 13, 2002 1:31 PM
It isnt safe! Often the driver can't see directly behind him. And have you ever seen those slabs of tread alongside the highways? Those are the result of semi tires blowing out. Twenty-plus pounds of hard rubber at highway speeds will do major damage to your car (did you ever get that new one, by the way), and it could go right through your windshield. Also, even though you are wide awake, the trucker could be drifting off and you wouldnt know it 'til he slams into a bridge abuttment. It isn't worth saving a few bucks in gas for the risk involved(just my opinion, of course).
Drafted a Bronco once...cory
Jun 14, 2002 8:29 AM
Years ago when I was young and feisty, a guy ran a red light and nearly killed me. No kidding, if I hadn't been looking right at him and had my hands on the brakes, I'd be dead now.
I was so pissed I tried to follow him, but it was on an arterial street and he pulled away. A guy in a Bronco with a Yakima rack saw the whole thing, and he motioned me in behind him. We chased the guy several blocks, at speeds up to 48mph. Finally caught him at a light, and I hammered on his window and said, "GASP, pant-pant-pant-hooWAAAW-gasp-pant-pant." I couldn't get out one word. Then the light changed and he drove away. He's probably still talking about the crazy cyclist who tried to attack him.
Drafted a Bronco once...DougSloan
Jun 14, 2002 8:36 AM
see, that's why you need that 53x11 gearing. :-)
Was it white? Was Al Cowlings driving it?mr_spin
Jun 14, 2002 9:04 AM
If you had been in Los Angeles, your chase would have been covered live on all the networks. As a native, longtime, but now former resident, I can safely say that TV news in LA is so car chase happy, I'm surprised they don't stage them on a slow news day.
That's classicKristin
Jun 14, 2002 10:07 AM
Thanks for sharing. I get what everyone is saying about drafting trucks being a brainless activity~~unless your on a bike, and then it becomes cool. I just got kinda giddy when I averaged 33 MPG on a road trip, in a car that was EPA rated for 30 HWY MPG brand new. Anyway, all points made were good and I will refrain. 'Specially in my new beauty--I pick it up tonight...will post a pic later!!!
Drafted a UPS truck on my bicycleMr Good
Jun 20, 2002 7:33 PM
...while going north on 3rd street in SF. Thought I was pretty cool, spinning along at 40-some MPH, effortlessly, in the big ring. But to follow the truck I had to stay in the middle of the road, where I don't usually ride, so I didn't know that there were old trolly tracks still embedded in the pavement. My wheels fell right into the track slot at 40 mph and I had a very nice wreck--lost some skin, but learned a lesson. (I don't know if those tracks are still there since they built the new ballpark for the giants.)