Bluetooth vs ANT+

Hi there,

Is it only me that feels harder when I do workouts via BT?

The same workout feels harder when I use my iPad and BT, while it feels so smooth when I do it on my PC via ANT+.

Maybe I am just dreaming :slight_smile:

You’re probably dreaming. With both protocols, the trainer receives a target power, and then adjusts its resistance to maintain that power (assuming you’re in erg mode and not using Power Match). It’s the same trainer reacting to the same command - it has no way of acting differently.

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Since I got me a Kickr I’ve always used Ant+, that is until just recently when I switched to BT. The main thing I noticed is that BT offers a more responsive feel and a smoother ride. I can’t determine if it easier or not but it feels different.

I’m very interested to know if other users report this. I’ve not heard of it before. I’m curious to know the reasons. Maybe @GPLama has some insights?

Yep. I find BLE to be faster for SIM changes with newer trainers (I guess ERG too?). Yet to measure this in any meaningful way. It’s on the cards.


I might try tomorrow’s workout using BLE.

Will be interesting to see @GPLama ’s result.

I will also test this week BT and ANT+ over both desktop and mobile apps.

I don’t have anything to compare but only RPE based result.

A trainer will be slower to react to commands over ANT+ than Bluetooth Low Energy (BLE), just because of how the protocols work.

From what I remember of ANT+ FE-C communication:

  1. The trainer is master. Zwift/TR is slave
  2. Master transmits every 1/4 second (every 250ms)
  3. Slave is only allowed to transmit commands/requests immediately after receiving a message from master

This means that there can be as much of as a 1/4 second delay between slave wanting to change the resistance/target power/grade simulation and it being able to actually send the command. If the message from master is lost due to intereference, there will be an additional 250ms delay with the slave waiting for the next message from master. Same extra 250ms delay happens if the command from slave to master is lost.

So in environments with lots of interference, occasional 1/2 second delays in responsiveness (or even longer) are not that uncommon and even in interference free environments delays up to 250ms are normal.

Don’t remember the BLE specs too well right now, but there is less latency and it handles message loss better, so it should be faster to respond.