Wireless computer 'jumping' at traffic lights?

[oyster]

Why on earth do I sometimes approach a set of traffic lights with the computer reading a certain trip distance and then find as I pass the lights the distance often adds to itself itself miraculously? This morning crossing one paerticular junction my computer told me I'd covered nearly a kilometre in about 30 seconds (if only I could!)

Is there some super magnetic field emitted by the lights?

If so, why can't it be utilised to stop RLJ'ers? In a sort of wacky races style. (oibviously carbon bikes would sail past!).

[WinstonWolf]

Could be the sensors under the road on the approach?

[upsidedownmark]

More likely because you're stopping with the magnet right next to the sensor, jiggling around, and as you do so, generating spurious signals. The computer is only counting the number of times the magnet passes. it doesn't know if you just jiggle back and forward a bit..

[budgie smuggler]

Railway crossings make my bike computer go haywire. Often gain a few KM while sitting still! Assume it is RF interference, maybe the same on a set of traffic lights?

[oyster]

Answering my own question but I suspect it's the under-tarmace induction loop sensors causing the problem. This morning I went across the same junction, stopped behind the road sensor and had no issues. Then moved the bike over the sensor and the distance setting went bananas.

[WinstonWolf]

:smug: