Following Distances

Question: How close can you tailgate someone, and getaway without hitting them in the rear if they slam on the brakes?

Many motorcyclists and car drivers lapse into the habit of following vehicles too closely.  So we’ve done some math for you, to explain exactly how close is too close….

  1. A car in front, travelling at 60 mph suddenly brakes.  It’ll take 4 second to come to a stop if it is braking at 0.68g (the same as the highway code, and roughly where ABS kicks in).
  2. The motorcyclist behind reacts in 0.68 seconds (same as the highway code), but brakes at 0.5g (about the most you can get away with before locking up), ABS on a motorbike comes in around 0.6g.
  3. Motorcyclist takes 5.467 seconds to brake, plus the 0.68 seconds in reaction time.  Total time = 6.147 seconds. Therefore;
  4. Motorcyclist needs to be at least 57 metres behind the car when it hits its brake to avoid running in the rear.

If you react in .68 seconds, any closer than 16.6 metres means you’ll hit the car before you even get your fingers to the brake lever!

So, what if you think you can do better?

  1. A car in front, travelling at 60 mph suddenly brakes.  It’ll take 4 second to come to a stop if it is braking at 0.68g (the same as the highway code, and roughly where ABS kicks in).
  2. The motorcyclist behind reacts in 0.4 seconds (about the same as Sebastian Vettel or Jenson Button), but brakes at 0.68g (your ABS will kick in long before you get to this force, or your wheels will now be billowing smoke).
  3. Motorcyclist needs to be at least 10.7 metres behind the car when it hits its brake to avoid running in the rear.

If you think you can brake at 0.68g and have reaction times of 0.4 seconds…Good luck!  We’ve not met anyone yet who has, and very much doubt we will.

You need time to react, and you need time to stop.  If you can judge how far 57 metres is whilst riding then best of luck, alternatively have a look at this article for how to keep safe.