Ok. Need some help/advice regarding Tractor-Trailers on the highway

[matcom]

I have been Googling to no avail. Maybe not using the right terminology.

I have heard the term 'dirty air' and 'air wash' when dealing with the big rigs on the highway. I'm well aware of the wind when one of them passes me but not too sure what I should be looking out for or doing to protect myself around them.

Can someone explain to me what a passing big rig does to the air around me and what if anything I should be doing while being passes/passing one?

You already KNOW you are the best so I'll just look forward to soaking up your knowledge. ;)

[HamstersFromHell]

1. It's been my experience...

Behind one, you reach a point when you're close enough you'll pick up the dead air zone behind the trailer...sorta like drafting in NASCAR. No real worry there, the effect is very minimal. You'll know you're getting close when air buffeting increases...you're passing through the part that's closing behind the trailer.

Passing one, you usually encounter a "wave" (for lack of a better description - think of the stern wave off a boat moving in the water) somewhere near the rear of the trailer...the location changes with trailer configuration and speed...this wave will try to push you outward away from the trailer a little bit. As you go through the wave, you'll hit the low pressure pocket in the side, which will try to pull you in toward the trailer. This is normally stronger than the outward wave you went through previously. The strongest wave will be close to the front of the tractor..the "bow wave" as it were. That will shove you outward...at times, pretty dramatically.

I handle them like driving on grooved pavement...stay loose and go with it, but don't let it sieze control...you may have to do some counter leaning at higher speeds. Really nothing to it as long as you realize it is there and not catching you by suprize.

[ThomWV]

2. The "Bow Wave" is a very good analogy

Just as an observation the 'wave' will hit you just about the time you are even with his front tire. However I don't think that's what people are talking about when they say dirty air, at least its not what I mean by the term.

Hamsterfromhell noted that clear dead air space right behind some trucks (they differ greatly) and you'll find that when you are following too closely. I'm just guessing at the typical distances but here goes, the dead air space, where there is very little turbulence, extends from directly behind the truck back about 50~100 feet. After that you hit the dirty air. I believe what is happening is that the air that has been pushed over, under, and alongside of the truck starts to come back together in that area. This rough area tends to extend back another 100 feet or so. The dirty air will toss you all over the place, it just shakes you all over the place, its not a lot but enough to be unnerving. By contrast when you pass by the 'bow wave' at the front of the truck its a lot like being hit by a gust of wind from the side - which is exactly what it is I suppose. What I mean is that it is a one time event, it'll blow the bike away from the truck what feels like 4 feet and then bounce you immediately back to where you were. For me the trick is simply to pass trucks with authority. You know, zoom, zoom, zoom; get it done, get it over with, motor on up the road. More speed often means more stability.

Let me followup on something above while I'm here. All trucks don't do it, give you dirty air that is. I'm not sure why some trucks create air currents that toss you all over the place but I can tell you that they don't all do it. Surprisingly its not something that you can easily predict from the shape or type of truck. You think a long van with a cab-over would blow you around like a tornado and a dead-heading flatbed behind a conventional tractor would produce smooth air, but it doesn't always work like that. I don't want to say its random, because I know better than that, but you really can't tell which trucks will move you and which ones can be passed without much of any tossing around - so always be prepared.

Hampster' also give great advice when he says they are to be approached much like bridge drain grating; loosen up and go with the flow. I just like to add that while you should loosen up you should also add power and blow right past them rather than ease by and be blown all over the place by them.

[Robb]

3. Like riding in the afternoon in Colorado

Wind can be surprisingly insistent. :D

Just remember it can't put you anyplace you really don't want to go. You're in control. :thumbsup: