The 15 mph problem

1Watch

The same path, seven hours apart

Same rider, same machine, same throttle position, same path. Only one thing in that shot changed, and it is the only thing that was ever going to.

2The idea

The number, and where it sits

Many multi-use paths carry a 15 mph speed limit. Look at that against what is under you: a Class 1 or Class 2 assists to 20, a Class 3 to 28. The path limit sits below the speed your machine treats as ordinary cruising.

Which means you do not drift up to a path limit. You have to come down to it. On a pedal bike, 15 mph on the flat is work and you feel it. With a motor it is nothing at all, so nothing about the ride tells you when you have gone past it.

3The idea

The sign is the ceiling, not the instruction

The guidance is one sentence long, and it is the important one in this lesson: regardless of the speed limit, adjust your speed based on conditions. The posted number is the most you may ever do there. It is not a speed the path is promising to be safe at.

Ride Illinois puts numbers on it for towns: about 15 mph on busy paths, about 20 on quieter ones. Read that the way it is meant — the same path is two different speeds on two different afternoons, and the sign at the entrance cannot tell them apart.

4The idea

What counts as conditions

How many people are on it. How much width you have to go round them with. How far ahead you can see — a bend, a bridge, a dip, low sun straight down the path. Whether the surface is wet, gritty or covered in leaves. Whether it is the hour when everybody walks.

Any one of those on its own is a reason to be slower than the sign. None of them are visible from the entrance, which is why path speed is something you keep setting all the way along rather than something you choose once.

5Look

Two numbers, one path

Both of those numbers are real and only one of them is about the path. The display is telling you what the motor is doing. The sign is telling you what the surface can carry.

6Find them

Which of these mean go slower than the sign?

Tap the ones that count.

7The idea

Path speed is a stopping distance in disguise

You have already measured your own stop. On a path the thing you have to stop for is not a car, it is a person who has taken one step sideways without looking, four metres in front of you. That is all the distance the situation is going to give you.

So the honest version of path speed is the speed you can stop from inside the clear space you can actually see. Work it backwards from the gap in front of you rather than forwards from the number on the sign.

8Decide

Your local path has no speed limit posted anywhere on it.

9Say it

The line that replaces the number

It is the version that survives a path with no sign on it, and the one that still works when the path fills up behind you halfway along.

10Do it

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