The Visible Reserve

I’d like to address an issue unheard of by some and often overlooked by most; it’s called the Visible Reserve. It is the visible distance in which you can safely and successfully avoid incident or accident.

At any given speed, a certain minimum distance is needed to stop a specific motorcycle. If you expect to avoid that pedestrian, or the stationary truck just around the next blind turn, your speed must be limited to your stopping distance. For example, let’s say your bike is capable of coming to a stop from 100 km/h in 35m. If you can’t see any further ahead than 35m, your speed shouldn’t be any faster than 100 km/h.

Of course in real world situations, it also takes 0.5 seconds or so to react, and another 1 second of progressive front brake squeezing to full braking capacity. At 100 km/h, 1.5 seconds will eat up an extra 40m. OH SNAP! That means that your actual stopping distance from 100 km/h is more like 75m! If your visible reserve is only 40m, your speed should really be no more than perhaps 60 to 80 km/h. Now let’s not bring ABS into these calculations yet, we all know that ABS is primarily intended to help prevent the loss of control and not to, in some magical way, make the brakes more effective at stopping in a shorter distance. Our article on ABS or Not ABS will shed some light on that issue.

At this speed, can I come to a controlled stop before I get to that car?

While riding, very few of us can accurately judge distance in metres, or car lengths. The road surface goes by in a blur, too quickly to make a mental measurement of distance. The trick is to make time measurements by using reference points. Choose a fixed object like a lamppost or telephone pole, and count the seconds it takes you to get there. Count out loud, one-thousand-and-one, one-thousand-and-two… By taking an actual measurement of your visible reserve and comparing it to your speed, you can make calculated decisions on how far you are pushing the bubble. Our article on Braking Explained will also be of great help!

I’ll offer some guidelines:

SPEED MIN. VISIBLE RESERVE
60 – 80 km/h 4 sec.
80 – 100 km/h 5 sec.
100 – 120 km/h 6 sec.
120 – 130 km/h 7 sec.

Give these numbers a try, and see if you agree with the minimums. If these minimums make you a little nervous, add a second. If reflexes are really quick and you can make consistent hard stops without losing control, drop a second.

The point is that you get to a method of assessing honestly (without ignorance or arrogance) how your speed stacks up to you and your bike’s stopping performance. If you consistently find that you are entering fearful situations at speeds too fast to stop or even react to within your minimum visible reserve, the message should be obvious: get on the brakes and slow down quickly whenever the visible reserve closes up on you.

Better yet, get trained by an expert!

Hein Jonker

Founder of the Motorcycle Safety Institute of South Africa Editor in Chief of Bike Talk South Africa Chief Instructor of Bike Talk Motorcycle Rider Academy Motorcycle Safety & Skills Expert for Arrive Alive South Africa

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