Jim’s Tech Talk
By Jim Langley
I’m letting reader Phillip Young steer the Tech Talk sled this week because he took the time to share what seems to me to be an ingenious tip – and even provided photos. His hack is a new one to me, too.
It concerns how to get those annoying under-pavement red light sensors to detect your carbon wheel-equipped bicycle. I’m sure you’ve experienced intersections that seem to completely ignore you and your two-wheeler. And, I think it’s gotten worse when you’re on a carbon frame with carbon wheels. You sit there hoping a car or a metal bicycle will come along to trip the light.
Phil has what sounds like a better idea. Read on and then please comment and let everyone know what you think. If you have some red light tripping tips and tricks it would be great for everyone to learn about them.
For example, I know some riders lean their bikes so they’re almost flat on the ground to try to get something to trip the sensor faster. And, if there’s a pole with a walk button, hitting that button is a way to get the light to go green, too – though it’s not always safe to get to that pole.
Here’s Phil’s trick. He wrote:
“Would you please pass this traffic light safety tip along to the RBR readers with carbon rim wheels?
Carbon rim bicycle wheels usually do not trigger traffic signal light sensor coils buried in the pavement and this can be a safety issue. The non-conducting carbon rims do not change the magnet field around sensor coils, so the traffic light doesn’t change for you. (Aluminum rim bicycle wheels usually do trigger traffic signal lights if the wheel is positioned parallel to and directly over the pavement sensor coils.)
If the traffic signal light doesn’t trip in your travel direction and you have waited for 2 or 3 minutes, you may be inclined to run the red traffic signal light dodging traffic at your peril. [Editor’s note: I believe it’s legal to do this in most of the USA.]
How I Modified My Carbon Wheels
My carbon rim bicycle wheels would not trigger traffic light sensor coils buried in the pavement until aluminum foil tape was applied to the rim circumference with some foil tape overlap.
I Added 3M adhesive backed aluminum foil tape cut about the width of rim tape where the normal cloth rim tape goes. Please see my photos. The adhesive backed aluminum foil tape sticks well to the carbon rim material and weighs almost nothing. This should work on all carbon rims using inner tubes.
Push the aluminum foil tape down against the rim to get full contact and adhesion. Install the normal cloth rim tape on top of the aluminum foil tape. The foil tape also offers additional support to the rim tape over the rim spoke holes.
The rim with aluminum foil tape now reliably triggers traffic light sensor coils. The bicycle wheel rim with aluminum foil should be positioned parallel to and directly over the sensor coils buried in the pavement rewarding you with a green light.
May your travels be safe and green lights always be with you!”
Thanks very much for sharing, Phil!
Ride total: 10,036
Jim Langley is RBR’s Technical Editor. A pro mechanic & cycling writer for more than 40 years, he’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Tune in to Jim’s popular YouTube channel for wheel building & bike repair how-to’s. Jim’s also known for his cycling streak that ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.