Oct 15 2004
For years I have known that riding close behind a moving vehicle, such as a lorry or a bus, allows you to get caught in the slipstream of the vehicle and be pulled along by it. This means that you can cycle very fast (30+MPH) with very little effort. The trouble is that you need to be right behind the vehicle and it only works and is beneficial if the vehicle is travelling at a constant speed for at least 1-200 meters.
But I now have a new theory that I have been trying to test recently whilst cycling into work (I’ve been off the roads for 2 months because of a speeding offence). The theory is that large vehicles also create a bow-wave effect (like a boat) that it is possible to be pushed along by. If this theory is correct then it has a number of immediate advantages over slipstream riding.
- You don’t need to be right behind the vehicle (if the vehicle stops you don’t ride into the back of it!!!)
- It doesn’t matter if the vehicle stops, you just cycle on to the next vehicle that is moving.
- It is possible to catch the bow-wave at low speeds (15mph?)
I have found this bow-wave effect to be most useful where there is a cycle path running along side the road and the vehicles on the road are in a traffic jam type situation that would be completely unsuitable for slipstreaming.
Obviously this is still just a theory that requires more experimenting. I still don’t know how close to the vehicle you have to be to take advantage of the bow-wave (I’ve generally been about 2 foot from the side of the vehicle) and I have a feeling I wont find out until next summer (as I back to riding my motorbike on Sunday).