Set the timer to 37 seconds

How to use the online timer

With one hand steadying the bike, stay beside the muddy wheel and rinse the dirt from the mudguard for thirty-seven seconds. That is enough time for a focused pass after a ride along a wet towpath or a gritty British lane, without leaving the water running while attention drifts elsewhere. Watch where the loosened mud flows and keep the spray aimed away from the chain and brake surfaces.

Dirt clinging beneath the mudguard needs continuous attention, even if the countdown tab slips into the background on your phone. Its display may disappear behind another app, but the countdown normally continues; whether its sound is heard can depend on browser and phone settings. Since you remain by the bicycle, use the visible change in the runoff as your guide, then respond when the alert interrupts the rinsing.

Mud washing from the curved inner surface may clear before the alert or remain in a stubborn strip near the stays. When the countdown interrupts you, pause the spray and inspect that area instead of automatically continuing. If the runoff is clear, stop there; if grit remains, loosen it with a brush or cloth before using another brief rinse, which avoids spending the whole interval pushing water over packed dirt.