Thanks for all the helpful discussion. And I guess this brings up a 'low level' issue that had not occurred to me before. I am guessing that most folks don't have a bike stand set up permanently so they just go in the garage to set up a new computer or GPS on their bike. This requires that you spin the rear wheel and cranks to 'wake up the sensor'.

So the question is 'how long does the sensor stay awake' - or how long to do have to figure out which buttons to push before you have to spin again?

The best answer is probably to spin them often while the pairing is being done. But it is a valid question, I would think.

From all that I can tell my Bontrager Trip 300 will 'stay awake' more than 10 minutes. I judge this by assuming that a reading of '0' means that it got data representing zero. A reading of a 'dash' means no data.

But there is an interesting characteristic here. When go out to my bike first thing in the morning, move nothing, and wake up the head, the head will try to connect. After 15 or so seconds it will go into ride mode showing no input (dashes for speed and cadence). If I wake up only one sensor (spin the cranks, not the wheel) both sensors appear to now be awake. I say that because I will get a zero reading for both speed and cadence.

I was not expecting this. But since the speed/cadence sensor is a single physical unit, it would appear to me that there is (most likely) only one sender that can send speed or cadence information (but not both simultaneously). If there are separate senders for speed and cadence the head must know that it is not connected to one of them, but for some reason chooses to interpret not connected as zero.

Or maybe there is a device profile for a dual device where a single connection can contain either or both speed/cadence info. Just curious if anyone knows. I do know that my Bontrager updates speed more often than cadence - or that is what it seems like. Maybe that is not exactly the case since you can go from very high to zero cadence in no time. I am hoping to avoid that experiment in the speed domain :cry:

dave

ps. Now that I think about it there is another option. There could be two senders but, in an integrated unit, waking up one wakes up the other.

Correct. There is a profile for a single device that transmits both cadence magnet passes and wheel magnet passes. The Bongtrager integrated node device and Garmin GSC10 are examples. The sensors only report each time a magnet has passed. The receiving device counts these and divides by time to calculate and display a rate.

Thanks - very helpful.

Any chance that you know if (or not) the Bontrager sensor info will be accepted by a Garmin 800 edge? it sounds like the answer is YES, but you never know.

Thanks.

dave

Never say never ;) You can look up exactly which displays will work with your sensor: THIS IS ANT - Directory
And yes, the Edge 800 is listed.

Works fine.

I run a 800 and Bontrager Node 2.1 off of the Bontrager sensor.

The 'pairing bit' is not a requirement of pairing a device. scott967 has it right. On a head unit you only search for new devices when in the searching screen, and will usually pair with whatever sensor is found (no need to use pairing bit) as the sensor is happy for anyone to receive its data. Some head units however, restrict you to only finding sensors that you have said are trying to pair (which makes it much easier to deal with having other people with sensors around while trying to pair a new head unit/sensor combo), and so add the filter for the pairing bit being set.


If I remember correctly, the reset button is a way to test the sensor magnets are detected. After you press it the LED flashes when a magnet pass is detected.
Plus, it also sets the pairing bit, so head units that require it will pair.

You aren't quite getting what I was saying.

Particular head units might only connect to sensors with the bit set but things work quite-well without doing that.

Thus, it's really an option (not a requirement). It's not essential to make things work.

On the other hand, the head unit is required to be in a temporary pairing-mode (things would not really work at all without that).

What head units require the sensor to be in pairing mode?

The Garmins (the most-popular head units, by far) don't. Nor do the Bontrager head units.

It's clear that requiring a bit pair-mode bit from the sensor isn't a real requirement (it's an artificial requirement).