Riding the City
Kerb Height Decides More Than It Should
The vertical step between a road and a path is a small dimension with outsized effects on where riders can go, what they can carry and who is able to ride at all.
Kerbs exist to separate vehicles from pedestrians and to channel water. For riders they act as a set of walls that determine which movements are possible.
A vertical edge is a hazard at a shallow angle
A tyre meeting a kerb straight on can usually be lifted over it. The same tyre meeting it at a shallow angle is deflected sideways instead, and the front wheel is displaced.
This is why kerbs at the edge of a narrow lane are more dangerous than kerbs elsewhere. A rider moving over to give room encounters exactly the shallow angle that causes the deflection.
The height at which this stops mattering is low. A step of a few centimetres is enough to catch a wheel, which is why flush transitions are specified in good designs.
Dropped kerbs decide where a route actually connects
A cycle path beside a road connects to the road only where the kerb is lowered. Between those points the two are parallel but separate systems.
If dropped kerbs are placed only at formal crossings, riders must travel to them and back, adding distance. The path may run past a destination without offering any way to reach it.
Where they are missing entirely, riders improvise. The desire lines worn into verges beside kerbs are a reliable record of connections the design failed to provide.
Loaded bikes have far less clearance than empty ones
A bike carrying shopping or a child cannot be lifted or hopped. The rider must ride the kerb transition, which means it has to be genuinely usable rather than merely negotiable.
Cargo bikes and trailers add a second problem, because their wheels do not follow the front wheel's path. A transition taken at an angle may work for the front and catch the rear.
Handcycles, tricycles and bikes used by riders with limited mobility have the least tolerance of all. A step that an athletic rider ignores can end their journey.
Drainage and kerb design are in tension
Kerbs channel water to gullies, and flush transitions interrupt that channel. Designers therefore resist removing kerbs where drainage would otherwise pond at the edge of the carriageway.
The compromise usually adopted is a chamfered or sloped kerb, which reduces the vertical step while keeping some channelling. It is better than a square edge and worse than a flush one.
Standing water at the edge of the road is itself a cycling problem, since it hides potholes and covers drain covers. Solving drainage badly moves the hazard rather than removing it.
Small dimensions accumulate across a journey
One awkward kerb is a minor irritation. A route with a dozen of them is one that riders describe as tiring without necessarily being able to say why.
Each transition demands attention, a change of line and often a change of speed. The cumulative cost is a journey that feels less like transport and more like an obstacle course.
This is why kerb detailing appears in serious design guidance in a level of detail that seems disproportionate. The details are where the difference between a usable route and a decorative one sits.
Questions readers ask
Why do people ride on the road next to a cycle path?
Usually because the path is slower, gives up priority at every side road, or does not go where they are going. Directness is a real requirement, not a preference.
Why does a new cycle route sometimes seem little used?
Often because it does not yet connect to anything at either end. Network value grows as links join up, so early sections can look disappointing until the gaps close.
