To minimise the visibility problems and pick up a little speed as well I went back to trying to pick up tows from the lorries. If you could sit 60 - 70 meters back a lot of the spray had dissipated and as you were going at the same speed as most of the trucks very few came past so cutting down on the number of bow waves of spray I had to endure every time a lorry overtook. Over the next couple of hours I picked up, benefited from and lost probably thirty or forty tows and I became quite good at anticipating what would work and what wouldn't. You could forget cars. They came past too quickly and were too small to create much effect. It must be all the effort the factories have put in to cut fuel consumption by reducing drag and I can report that it seems to work. Most cars slipped past with hardly a ripple. Vans, even the largest ones, were much the same. Generally, white van man had his Doc Martens jammed into the shagpile and came past far too quickly for me to be able to benefit. They also seemed to want to change lane every few seconds, something the ardent towist absolutely must resist doing. If you're being towed you stay in the slow lane. I'll explain the reason for that in a minute.
The best tows came, not from the big slab sided trucks, but from bulk liquid carriers such as petrol tankers or milk delivery lorries. It took me while to notice this and even now I'm not sure why but the intensity of the wake at the back was definitely stronger. They were also easier to stay behind because, fully laden, they tended to be slightly slower both on the level and more importantly, on the hills. Once in the wake of a big truck you could sit there, reduce the throttle opening quite considerably and relax a little. There was some side to side buffeting from the vorticies but generally it was a pool of relative calm. I would normally aim to sit about 60 meters back so I could see round the truck but the effect was there much further back and noticeable (although not usable) back to around 200 meters. Occasionally I would be sitting there quite happily behind a truck and suddenly it was like I'd put the brakes on. The tow had vanished but seemingly nothing had changed. I'd have to drop to third gear and start all over again. It took me a while to work out what was happening.
When I did work it out I think I graduated into the "aerodynamic towing level two" class. The basic principle behind following a truck is that the frontal area of the lorry punches a hole through the air. The displaced air doesn't immediately fill in behind though, it takes a little time (and because the truck is moving, distance) before it all settles down (about 300 meters in my estimation) although the intensity diminishes the further back you go. There would be areas of fast moving air and areas of slow moving air and, by the seat of my pants, I'd try and position the bike in one of the "anti-nodes" of slow air. That was all well and good and worked effectively on an ideal day when the truck was moving through still air. On the journey to Wiesbaden though it wasn't still air, there was quite a strong wind coming in from the right hand side. Parts of the autobahn were protected from this, when we went through a cutting for example or by trees or buildings and the air behind the trucks would behave predictably. But if you suddenly came out into the open the side wind would blow the wake from the truck to the left - into the next lane and I would suddenly find myself having to deal with the bike's full 55mph ground speed. That's when you felt like the brakes had gone on. Within a couple of seconds I'd be too far back and too slow to be able to do anything beyond start over.
By the time the afternoon had passed I'd formulated a set of rules for truck towing. Firstly, if I wasn't doing 50mph when a truck came past I'd never make up the speed. The truck also had to pull in fairly quickly after coming past as well so it worked best with some other traffic around. With light traffic almost all of the truck drivers took quite a while to pull back in out of courtesy but by then they were too far ahead. You needed a strong initial surge to gain the extra 5mph and you'd only get that close in. Once up to speed you could slowly drop back to a safe distance and stay there but the bike didn't have the acceleration to make the speed up before the truck was out of range. Once in the tow you had to watch out for things that would disrupt the aerodynamics. The commonest was a car pulling into the gap forcing you to drop back but the next commonest was the previously mentioned side wind issue. You could anticipate it to an extent by looking a few hundred meters ahead to see what was coming and maybe moving in a bit closer or moving to the left hand edge of the lane but a strong side wind would blow the effect completely into the next lane and out of reach.
It was easy after being towed for a few miles to be lulled into a false sense of security. The bike was doing this all on its own, it really could keep up 55mph. So when the truck you were following suddenly indicated it was going to pull out and overtake it was natural to go with it. I very quickly learnt not to do that. You'd go out with it and slowly start to go past whatever it was you were overtaking - usually another slightly slower truck. All would be well until the truck you were following got far enough ahead to pull in - usually just as I was level with the front of the slower truck. I'd then suddenly lose the tow and find that I didn't have enough power to get past. Inevitably there would be a long queue of cars behind me at this point and my only way out would be to gradually slow down and pull in behind. That was a seriously dangerous position to be in - particularly on a 70's tech "seize in an instant" two stroke. I very quickly concluded that if my tow truck pulled out to overtake, just let it go. By the time I got to the Wiesbaden turn off I had formulated a complete set of rules for aerodynamic assistance on the motorway. Firstly, don't worry too much if it doesn't seem to be working, not every truck is suitable. 2. The sooner the truck pulls in the better (subject to not hitting you!). Some of the truck drivers welcomed being told they were far enough ahead - by a flash of indicators for example. 3. Once up to speed behind the truck, drop back. You don't need to tailgate, the effect works quite a way back. 4. If you start going up a hill generally the bike slows down faster than the truck so anticipate it by closing up slightly as the hill starts. 5. Don't follow the truck blindly. If he turns off, let him go (obviously) but, most importantly, if he pulls out to overtake let him go. 6. If you lose the tow for whatever reason just accept it. Some tows can go on for some considerable distance but most of them would only be for a mile or two. There's a lot of trucks around and another one will be along shortly. 7. A general point. For safety reasons I'd rather be behind a truck and doing roughly the same speed than be in front and slower. The consequences of something going wrong with the bike in front of a lorry are much more serious than if you were 50-60 meters behind. I had a rear tyre blowout in front of a truck on the motorway in Belgium many years ago and I was lucky to survive.
Overnighting in Wiesbaden
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