You are twenty minutes into a Saturday loop, stopped at a junction you did not expect, poking a phone screen with a wet glove while the battery slides toward orange.
The bolt is home, the clamp feels tight, and you still watch the screen nod at every seam in the tarmac. Or you drop off a kerb and the computer is face-down in the grass behind you.
Six in the morning, and the phone is clamped to the stem before you have even clipped in. By the cafe stop the screen has dimmed in the sun, the battery is down a third, and there is weather stacking up over the ridge.
You and a friend roll out together, ride the same loop, stop at the same café — and the two computers on your bars disagree about how far you just went. Neither of you took a detour. It happens often enough that Strava keeps a help page devoted to the question.
Search for a wireless bike computer and you get three machines that barely belong in the same category: a head unit listening to a magnet sensor near the fork, a GPS unit that needs nothing on the wheel, and a round display that is really a second screen for the phone in your pocket.
Three lanes of wet interstate, traffic bunched up, spray coming off every truck. You check the mirror, see nothing, start to move over — and the car sitting exactly in the gap your mirror does not cover leans on its horn.
You have read enough close-call threads to want blind-spot radar on the bike, and now you are staring at two very different price tags: a screen at around $400 with the radar baked in, or a box at around $80 that bolts onto the cockpit you already ride.
A driver pulls out of a side road, clips your front wheel, and swears blind you were speeding. Two weeks later your inbox has a claim that splits the blame fifty-fifty, your premium is creeping up at renewal, and you have nothing but your own word to fight it.
You get home from a ride where a driver swerved into your lane, screen-recorded the clip to send to your insurer, and hit play expecting to hear the car's horn and your own shout — and instead it is a wall of wind.
You tip into a downhill hairpin, stab two quick downshifts to set your entry speed, and feel the rear tyre skip and chatter underneath you as the engine fights the wheel — that stomach-drop half-second where the back end steps out and suddenly you're managing a slide you never asked for.