Huh? HTF that happening?

Pufftmw

I've got a Polar HRM with coded bandy thing, so when I wanted a speedo for my bike, thought I would get a Polar CS100b so that I could get heart rate onto it as well. Followed instructions and installed it and it seems to work fine.

Problem I've got is the recorded journey mileage. Last night I rode home & it was 6.6 (via Jamaica/Lower Rd etc) and in theory, coming back in this morning and it should be the same more or less. At Mansell St I noticed it was 6.3 so expected it to be 6.6 when I got to the office, but no, it was 7.2!

This has happened a couple of times, the worst being 8 miles for a 7 mile journey! The timing aspect is fine, the max speed is not something stupid, 50% of the time the distance is spot on, the rest not. Has been lower as well. I'm reasonably confident the wheel diameter is set correctly.

Any mechanincal/logical reasons or is it just maybe a faulty unit?

MonkeyMonster

Have you got a led light near the unit? The electrical spark produced when the led is activated can produce interference with the HRM units.

Pufftmw

Nope - no lights on this morning. I keep my LEDs on constant not flashing as well. Camera was operating though.

The HRM was fine, it was the trip meter that's all to buggery. It's a wireless set up but the sender is right at the top of the fork leg win the receiver/speedo on the riser bar.

cee

Pufftmw wrote:

Nope - no lights on this morning. I keep my LEDs on constant not flashing as well. Camera was operating though.

The HRM was fine, it was the trip meter that's all to buggery. It's a wireless set up but the sender is right at the top of the fork leg win the receiver/speedo on the riser bar.

While it doesn't seem to have been the problem....

LED's are never constantly 'on'.

they flicker on and off, just so fast that we can't detect it with our eyes....

They are actually 'off' more than they are 'on'...which is partly why the fare so well in power consumption.

EKE_38BPM

Speedos are more accurate when the magnet and sensor are nearer to the axle than the edge of the wheel as the magnet passes the sensor more slowly and gives the sensor more chance of registering it as it goes past.
Or more accurately, the sensor is less likely to 'miss' the magnet going past.