draft while driving?
#2
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From: Seattle, WA
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#3
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From: Long Island NY
Bikes: 2009 Specialized Allez
I tried to pull behind a 18 wheeler and had my hand out my window in front of my windshield to see if I could feel a difference after changing lanes. I couldn't really tell though.
#5
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From: Santa Barbara, CA
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I do find when driving home from a crit I tend to drive like I'm still in the crit. Following close, looking for holes, moving up the field, etc...
#7
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From: Warshington DC
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IIRC there was an episode of Mythbusters about this. You have to be reaaaaaaaaaally close to the back of an 18 wheeler before you get any benefits from it.
#8
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From: Santa Barbara, Ca
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if you need a tow to make a pass for position, then yes. on public roads it would tend to be a pretty bad idea, an actual draft would probably be illegal.
the hypermiler trend is adding to people who follow way to close on the streets. i drive a smaller car so sometimes i sit back behind a big truck, or at the end of a train of cars. you have to be really close to be in a clean hole so you better be able to out brake whatever is in front of you, and even at that if there ever is any sort of accident having followed so close may play a role in determining responisbility for any part of the accident.
the only time a draft would be benificial in racing would be to use it to accelerate faster than the person in front of you so you could pass them without slowing them down.
the hypermiler trend is adding to people who follow way to close on the streets. i drive a smaller car so sometimes i sit back behind a big truck, or at the end of a train of cars. you have to be really close to be in a clean hole so you better be able to out brake whatever is in front of you, and even at that if there ever is any sort of accident having followed so close may play a role in determining responisbility for any part of the accident.
the only time a draft would be benificial in racing would be to use it to accelerate faster than the person in front of you so you could pass them without slowing them down.
#9
Are you referring to the illegal activity of tailgating?? No, absolutely not. My life and vehicle are worth too much to me for that.
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#10
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#11
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^Machka is serious.
I used to do it behind trucks in my subcompact. I could pick up 15-20km/hr if I had a stiff headwind and/or lots of stuff on the roof.
But I no longer drive and far prefer bike drafting now.
I used to do it behind trucks in my subcompact. I could pick up 15-20km/hr if I had a stiff headwind and/or lots of stuff on the roof.
But I no longer drive and far prefer bike drafting now.
#12
I'm very serious. I do not understand people who tailgate. It makes absolutely no sense to me whatsoever. A tailgater has to be an incredibly trusting and naive person.
What if a dog runs out in front of me, and I have to suddenly brake to avoid hitting it? The tailgater would have to have lightening-quick reflexes in order to avoid running into me, and if he/she did run into me, he/she would be at fault. What if a ladder shoots off the truck in front of me, and I need to swerve to avoid it. The tailgater wouldn't see it coming until it's too late. Just to name a couple possible scenarios.
The ladder thing did happen, and since I was not tailgating, I was thankfully able to swerve to avoid it. There was no one tailgating me at that moment either, but there easily could have been ... there usually was in central Alberta.
Tailgating has to be one of the most stupid, pointless things a driver can do.
What if a dog runs out in front of me, and I have to suddenly brake to avoid hitting it? The tailgater would have to have lightening-quick reflexes in order to avoid running into me, and if he/she did run into me, he/she would be at fault. What if a ladder shoots off the truck in front of me, and I need to swerve to avoid it. The tailgater wouldn't see it coming until it's too late. Just to name a couple possible scenarios.
The ladder thing did happen, and since I was not tailgating, I was thankfully able to swerve to avoid it. There was no one tailgating me at that moment either, but there easily could have been ... there usually was in central Alberta.
Tailgating has to be one of the most stupid, pointless things a driver can do.
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#14
#16
Still can't climb
Joined: Sep 2006
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From: Limey in Taiwan
tailgaters need to have some sense beaten into them
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#17
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From: Tariffville, CT
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+1 on tailgating.
Tailgating is unnecessary. It can be very dangerous, and the follower is liable almost regardless of what the lead car does. Even if the brake lights on the lead car don't work, the tailgater can be cited for following too closely (because if you were following further away, you'd have time to figure out that all the brakelights on the car in front weren't working).
This is especially true when someone in a car that stops well is followed by someone in one that doesn't. Think SUV or minivan drafting a Porsche. Porsche driver sees something, reacts. If the Porsche driver slammed on his brakes (went around a bend at 60 mph, big accident blocking road), a typical SUV will go about 40-50 feet through the Porsche before stopping, and that's if they both braked in unison. In reality it takes half a second to brake, so figure another 30-50 feet.
I consider myself a "safer" driver. I take nominal risks. For example, when driving in open traffic (i.e. not too many cars around), I'll leave a 2 second gap. If traffic is kind of stuff at speed, i.e. no real passing going on, I'll still leave a 2 second gap. I can't get anywhere, neither can anyone else. So I just sit. It's like being in the middle of the field in a race/ride. What are you going to do, shove people to move up?
If the volume is a bit heavier, a 2 second gap invites others to cut me off. So I reduce it to about 1 second. I find this to be somewhat automatic on my part, but if I check the time/gap, it's about a second. This is kind of like when you're near the front of the field but things aren't critical, so you just want to maintain position, not aggressively defend it.
If volume is extremely heavy, I'll close it up to, say, 1-3 car lengths. Anything more invites cut-offs and other risky moves. By slightly increasing the risk I take, I hope to reduce the risks others take. However, if someone still insists on moving in, I'll let them, and ease accordingly. On the way to the track in NH a Prius (plate = COFFEE1) was driving extremely aggressively on the MA/NH border. He essentially moved over from a stopped lane to a moving lane (my lane) when there was *less* than a car length between me and the guy in front (we were moving at about 10-15 mph). He angled in pretty hard and his rear bumper hadn't entered my lane before there was no gap left. I eased and let him in (well, I had to). Later I passed him as he maneuvered back into the other lane and it slowed drastically. Tip: if you do need to drive aggressively, do it in a "normal" car, not something with a vanity plate
My wife and I were astounded by the extremely aggressive driving exhibited here in the Simsbury area. Folks regularly follow so closely you can't see their headlights (SUV/truck) or license plate (car). I'm talking maybe 5-10 feet, less than a car length, less than even a car wheelbase, at 35-45 mph. I feel like I'm watching NASCAR.
We also noticed folks pulling out into fast moving (40-45 mph) traffic when a 1-2 second gap existed.
(Folks also consider 20-30 mph a "stop" at a stop sign - yes, this is in a car, and this is with traffic close to the intersection - and turn on red is ALWAYS done regardless of any signage in the area saying the latter.)
We have now named these driving techniques the "Simsbury Follow", "Simsbury Pullout", and the "Simsbury Stop". We haven't named the "right on red" one.
After saying all that on tailgating, drafting is a different story. I learned, in my less careful youth, that you could pick up 6 mph on a heavily laden Honda CRX (4 bikes, 4 extra sets of wheels on roof, 2 racers + 2 weeks of gear inside) when approaching an 18 wheeler from as far away as 100-120 yards. I know this because we drove for many hours with the foot on the floor, the car's power maxed out, and we observed this phenomena when passing those rigs.
I also have an mpg indicator in one of my cars. I am not necessarily a hypermiler (less hyper, more antsy?), but I've noticed that I can bump up my mileage a bit by drafting. Not drafting like Breaking Away drafting, but by following half a second to a second behind a truck. I'll resist passing trucks when they're close to my speed, esp if on a downhill, and go find another one on the next big uphill. For a long time I literally drafted, but then the thoughts of a brick being picked up by a pair of tires (this happens apparently) started to wear on me, and now I draft further back. Even further back I can see about a 1 mpg gain in mileage (based on what happens when I have nothing to "draft").
Sticking a hand out the window won't really illustrate things, but if you listen for the wind noise changing, that is the sign you're drafting. It'll sound like you're in a shelter, not in the open. Like the sheltered side of a dune at a beach. Roll down the window a touch to better hear/feel the wind. You'll hear the same noise when drafting riders while riding.
Having said that, drafting is not really the end all. It makes MUCH more of a difference to coast in neutral when possible than to draft. For example, I can coast in neutral (retaining all power assists and lights) at 70-80 mph (standard travel speed on the Mass Pike), and on certain sections I actually have to brake to stay under, say, 85 mph. A hypermiler will turn the engine off, but I don't feel comfortable doing that. I'll increase my mileage from 27 to 29-30 by doing this.
The best thing is a steady stream of traffic going the same speed. It may be annoying to go "only" 70 in a 65, but if all three lanes are doing this, you automatically get a draft. I can get 33-35 mpg in situations like this, without "drafting" per se, just following traffic, and my car is rated 21/26.
I feel that skills necessary in the field apply to driving in traffic and vice versa. Not skills. Judgment.
cdr
Tailgating is unnecessary. It can be very dangerous, and the follower is liable almost regardless of what the lead car does. Even if the brake lights on the lead car don't work, the tailgater can be cited for following too closely (because if you were following further away, you'd have time to figure out that all the brakelights on the car in front weren't working).
This is especially true when someone in a car that stops well is followed by someone in one that doesn't. Think SUV or minivan drafting a Porsche. Porsche driver sees something, reacts. If the Porsche driver slammed on his brakes (went around a bend at 60 mph, big accident blocking road), a typical SUV will go about 40-50 feet through the Porsche before stopping, and that's if they both braked in unison. In reality it takes half a second to brake, so figure another 30-50 feet.
I consider myself a "safer" driver. I take nominal risks. For example, when driving in open traffic (i.e. not too many cars around), I'll leave a 2 second gap. If traffic is kind of stuff at speed, i.e. no real passing going on, I'll still leave a 2 second gap. I can't get anywhere, neither can anyone else. So I just sit. It's like being in the middle of the field in a race/ride. What are you going to do, shove people to move up?
If the volume is a bit heavier, a 2 second gap invites others to cut me off. So I reduce it to about 1 second. I find this to be somewhat automatic on my part, but if I check the time/gap, it's about a second. This is kind of like when you're near the front of the field but things aren't critical, so you just want to maintain position, not aggressively defend it.
If volume is extremely heavy, I'll close it up to, say, 1-3 car lengths. Anything more invites cut-offs and other risky moves. By slightly increasing the risk I take, I hope to reduce the risks others take. However, if someone still insists on moving in, I'll let them, and ease accordingly. On the way to the track in NH a Prius (plate = COFFEE1) was driving extremely aggressively on the MA/NH border. He essentially moved over from a stopped lane to a moving lane (my lane) when there was *less* than a car length between me and the guy in front (we were moving at about 10-15 mph). He angled in pretty hard and his rear bumper hadn't entered my lane before there was no gap left. I eased and let him in (well, I had to). Later I passed him as he maneuvered back into the other lane and it slowed drastically. Tip: if you do need to drive aggressively, do it in a "normal" car, not something with a vanity plate

My wife and I were astounded by the extremely aggressive driving exhibited here in the Simsbury area. Folks regularly follow so closely you can't see their headlights (SUV/truck) or license plate (car). I'm talking maybe 5-10 feet, less than a car length, less than even a car wheelbase, at 35-45 mph. I feel like I'm watching NASCAR.
We also noticed folks pulling out into fast moving (40-45 mph) traffic when a 1-2 second gap existed.
(Folks also consider 20-30 mph a "stop" at a stop sign - yes, this is in a car, and this is with traffic close to the intersection - and turn on red is ALWAYS done regardless of any signage in the area saying the latter.)
We have now named these driving techniques the "Simsbury Follow", "Simsbury Pullout", and the "Simsbury Stop". We haven't named the "right on red" one.
After saying all that on tailgating, drafting is a different story. I learned, in my less careful youth, that you could pick up 6 mph on a heavily laden Honda CRX (4 bikes, 4 extra sets of wheels on roof, 2 racers + 2 weeks of gear inside) when approaching an 18 wheeler from as far away as 100-120 yards. I know this because we drove for many hours with the foot on the floor, the car's power maxed out, and we observed this phenomena when passing those rigs.
I also have an mpg indicator in one of my cars. I am not necessarily a hypermiler (less hyper, more antsy?), but I've noticed that I can bump up my mileage a bit by drafting. Not drafting like Breaking Away drafting, but by following half a second to a second behind a truck. I'll resist passing trucks when they're close to my speed, esp if on a downhill, and go find another one on the next big uphill. For a long time I literally drafted, but then the thoughts of a brick being picked up by a pair of tires (this happens apparently) started to wear on me, and now I draft further back. Even further back I can see about a 1 mpg gain in mileage (based on what happens when I have nothing to "draft").
Sticking a hand out the window won't really illustrate things, but if you listen for the wind noise changing, that is the sign you're drafting. It'll sound like you're in a shelter, not in the open. Like the sheltered side of a dune at a beach. Roll down the window a touch to better hear/feel the wind. You'll hear the same noise when drafting riders while riding.
Having said that, drafting is not really the end all. It makes MUCH more of a difference to coast in neutral when possible than to draft. For example, I can coast in neutral (retaining all power assists and lights) at 70-80 mph (standard travel speed on the Mass Pike), and on certain sections I actually have to brake to stay under, say, 85 mph. A hypermiler will turn the engine off, but I don't feel comfortable doing that. I'll increase my mileage from 27 to 29-30 by doing this.
The best thing is a steady stream of traffic going the same speed. It may be annoying to go "only" 70 in a 65, but if all three lanes are doing this, you automatically get a draft. I can get 33-35 mpg in situations like this, without "drafting" per se, just following traffic, and my car is rated 21/26.
I feel that skills necessary in the field apply to driving in traffic and vice versa. Not skills. Judgment.
cdr
#18
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Joined: May 2009
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From: Tampa
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Had someone in a toyota drafting me on the interstate last week with plenty of places to go by safely (6 lane highway)... the guy was so close, I literally couldn't see his car in any of my mirrors. After about a mile of that I realized what he was doing and had enough. I did the right thing and slowed down to force him to pass... he didn't. Mr. prius then found out that certain vehicles with certain programming modifications can turn day into night as a tailgating deterrent.
#19
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From: Ann Arbor, MI
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Had someone in a toyota drafting me on the interstate last week with plenty of places to go by safely (6 lane highway)... the guy was so close, I literally couldn't see his car in any of my mirrors. After about a mile of that I realized what he was doing and had enough. I did the right thing and slowed down to force him to pass... he didn't. Mr. prius then found out that certain vehicles with certain programming modifications can turn day into night as a tailgating deterrent.
#20
Bike ≠ Car ≠ Ped.

Joined: Jul 2007
Posts: 13,863
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From: Washington, DC
Bikes: Some bikes. Hell, they're all the same, ain't they?
I was once driving in our old Ford Granada, had the cruise control set, and was gradually coming up to the back of a semi truck. I moved over to pass, and the headwind was enough to push the car back (bad aerodynamics, mediocre power, plus a dumb cruise controller meant that it didn't downshift for more oomph to push through the wind). I did this loop for three or four times before overriding the cruise and putting my foot into it to pass.
I've tried to get some benefit from drafting, at least as much as I could while keeping a reasonable distance. I listen for the wind around the car -- if it's choppy, it means I'm still in the turbulence behind the truck, which although it's not as good as being "in the pocket", is still better than being in clear air.
I wish conditions allowed for NASCAR-quality drafting, but they just don't.
The best driving mileage I've ever gotten was when taking 50-mph secondary highways. Even with the rolling hills and slowing for towns every 15-20 miles, the car did at least 5-8 mpg better than usual.
I've tried to get some benefit from drafting, at least as much as I could while keeping a reasonable distance. I listen for the wind around the car -- if it's choppy, it means I'm still in the turbulence behind the truck, which although it's not as good as being "in the pocket", is still better than being in clear air.
I wish conditions allowed for NASCAR-quality drafting, but they just don't.
The best driving mileage I've ever gotten was when taking 50-mph secondary highways. Even with the rolling hills and slowing for towns every 15-20 miles, the car did at least 5-8 mpg better than usual.
#21
My wife and I were astounded by the extremely aggressive driving exhibited here in the Simsbury area. Folks regularly follow so closely you can't see their headlights (SUV/truck) or license plate (car). I'm talking maybe 5-10 feet, less than a car length, less than even a car wheelbase, at 35-45 mph. I feel like I'm watching NASCAR.
Hwy 2 is a highway with two lanes in each direction so these monstrosities could easily have passed me. I couldn't figure out why on earth they wouldn't. Sometimes I'd have to slow way down before they'd finally go roaring past me.
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#22
<----- I usually have 3 friends go with me wherever I drive and when we get in the range of 2 miles we pick up the pace and in the last 500m I pull out of their slipstream and sprint to wherever I am going. It saves on gas I think.
#23
I've tried to get some benefit from drafting, at least as much as I could while keeping a reasonable distance. I listen for the wind around the car -- if it's choppy, it means I'm still in the turbulence behind the truck, which although it's not as good as being "in the pocket", is still better than being in clear air.
I experimented with hypermiling earlier this summer, but I only ended up saving a few bucks per week, which wasn't really worth the effort. Unfortunately many of the most effective techniques are dangerous. You'll save more money by minimizing your driving and not driving like a jackass.
Last edited by mihlbach; 08-10-09 at 07:32 AM.




