Motorcycling: Group Rides: Safety in Acceleration

I used to belong to a motorcycle club that did a lot of group rides. Quite often you hear comments in group rides, that the leader is going too fast or too slow. And strangely enough it may happen in the very same ride from people in different positions in the group. The fact is, it is not the leader of the ride causing these conditions. It is inherent to group rides, and it is caused by the laws of physics.

I don't want this to be complicated, and basically it is simple, but requires a little background. First, a review of the distance to be maintained between motorcycles. It should be a 2 second gap to the motorcycle directly in front (in the same wheel track), which actually means the faster you are travelling, the greater the distance. This blog is about how best to maintain that spacing without having to reach ridiculous speeds.

If several motorcycles are riding together, with the speed varying from time to time, there will be a lag between the time the leader begins to accelerate, and the next motorcycle begins to accelerate. It may be half a second or 5 seconds, depending on the following rider. You can then add that lag to each rider in succession, because it is cumulative, so with five riders it may be a total of 20 seconds lag from the first to the last.

If the front bike begins to accelerate, it will by definition begin increasing its speed. When the following motorcycles begin to accelerate, they also begin increasing their speed, and as long as both are accelerating at about the same rate, the first motorcycle will always be travelling at a higher speed. As long as the front motorcycle is travelling at a higher rate of speed, the distance between the first and the next bike will be increasing. The increasing distance is also cumulative, to the point where the distance between bike 1 and bike 5 is a kilometer or more.

And eventually, the following riders want to close the gap, and so they speed up a little. Eventually they will catch up, but they may have to reach some quite high speeds to do it quickly.

What can be done about this entire process, which is variously referred to as the accordion, the whip, or the slinky? The lead rider should maintain a constant speed, but of course this is not always possible in traffic. Another question often asked is, should the lead rider ride at a slower speed to minimise the effect? I don't think it actually minimises the effect at all, and I have tried this myself and found the accordion effect apparently works just as much at low speeds. There is also a negative side effect of slowing down, and that is creating a jam of cars behind, which will lead to some cars tailgating and trying to overtake a long groups, which end up forcing their way into the line of motorcycles.

One answer is to keep the group at five or less, if possible. Another solution is for every rider in the group to accelerate harder than normal when following another rider. Many riders think it is dangerous to accelerate hard in a group. I just want to correct this misconception. Speed is dangerous, yes. Not acceleration. That's because speed takes time to bring down and involves momentum. Acceleration can be eliminated instantly by simply turning the throttle off. So in my opinion it is safer to accelerate hard and maintain a position, than to accelerate slowly, lose distance, then have to increase speed to close the gap. In the end, what we need to worry about is differences in speed leading to accidents, and not hard acceleration.

I adopt a policy that the lead rider sets the speed, the following riders set the distance. When I am in the lead, I sometimes want the the following rider to close the gap, but slowing down never seems to work. All it does is make the following rider slow down too. So when I'm the leader, I just set the pace and let the following bike decide how far behind they want to be. When I'm the follower, I try to maintain to correct spacing, and never "push" the rider ahead to go faster.

Just a few more ideas, to keep the group together without going so slow as to create a hazard. If I am in the lead, I try to slow down ahead of traffic lights, rather than speed up to get through. And I stop longer at stop signs to wait for people to catch up, and to find a safer opportunity to pull out. If the lead rider loses sight of the last rider, you need to wait at the next turn or intersection to make sure everybody is together. I also try to avoid overtaking other vehicles, unless I know everybody in the group can handle it.

I also want to mention that in my opinion, the worst type of traffic control for groups is a merge sign onto a two lane road. This is where the group can get split up easily so if possible I try to avoid them.