(no subject)

[arethinn]

The battery powered LED headlight on my bicycle emits interference that prevents the nearby wireless bike computer (odometer/speedometer) from receiving its signal from the wheel sensor. Both have to be mounted on the handlebars and there isn't room to move them further apart. Nor can the wheel sensor be moved closer to the computer. Does anyone know how I might go about shielding the headlight so this doesn't happen?

(edited to clarify the nature of the equipment involved)

Comments

not a cyclist -

[psybelle]

Does the headlight run from power generated by biking, or is it strictly battery (with "external" charging)? If it runs off of bike power, the interference may be coming from the electricity generation system, rather than the headlight itself... (easy test of this is to have the bike stationary, turn on the headlight and see if the odometer loses signal (assuming that it *will* register 0 mph while not moving).

Barring that, is there room to move the wheel sensor around a bit?

Re: not a cyclist -

[psybelle]

more info over here - https://kentsbike.blogspot.com/2011/03/wireless-cycle-computers-and.html

And, yeah, foil shielding might cut down on the RF

Re: not a cyclist -

[arethinn]

I wonder if they literally mean household aluminum foil. I thought of trying that, just for larfs, but my dad (who was a radio antenna engineer for decades, so not just armchair speculating) thought that would not likely work and started spouting off about something made of nickel, I think it was, that didn't sound very practical.

Re: not a cyclist -

[psybelle]

Is the wheel sensor wired to the computer or is that wireless? If it's wireless, I'm out of ideas; if it's wired - I can't imagine the interference from the LED being very strong, so a layer or two of the heavier foil might do it (and I have some old copper transformer wire from my dad's stash, if you want to build a proper Faraday Cage for it)...

Re: not a cyclist -

[arethinn]

It's wireless. Apparently the signal strength on such things is pretty low and that's why it doesn't take much interference to wreck it.

My old one was wired, but very old (like, 1990) and when I started riding again in 2016 I found that it didn't behave properly anymore -- picking up random speeds (even with the light off, so it wasn't that), acting as though I had removed the battery entirely when I pressed the button to reset the trip odometer like something was making contact inside that shouldn't be, etc. I figured something might have gone with with either the pickup, or the wire, or the unit itself and decided to replace it.

Re: not a cyclist -

[psybelle]

It's still probably worth trying to shield the headlight... and if you don't like the look of the aluminum foil, you might be able to find steel or copper screening somewhere (and, if possible, ground that to the frame of the bike or run a wire out to the handle grips - humans make a reasonable ground for that weak a signal/charge)

Re: not a cyclist -

[arethinn]

No, the light has an internal battery.

It's definitely coming from the light, which I determined in exactly the way you suggest - turn it on, it drops to 0 mph. The sensor cannot be moved either as it's already as high on the wheel fork as it can go without hitting the brake caliper. (Even if it could be moved, there's no way I could get it closer to the receiver than the light is, since it has to be next to the wheel to pick up from the magnet clipped to the spoke.)

[foxgrrl]

I think that you would need to attach any shield to ground for it to really work... on a moving bicycle your gound it going to be floating... so... um maybe if you connect the low voltage side of the two devices together. (Or the sensor's low voltage side to the handlebars.) Does the odometer use Zigbee or something?

This is mostly pure speculation.

I'm guessing that the light is a white LED, a Lithium ION battery, and a noisy square wave generator to flash the LED at some multiples of 1000HZ to adjust the brightness? Maybe a USB plug to charge, which means there's a chip in there to talk to the USB power supply to get anything more then 5V when charing.

Could you wear a headlamp?