Not too technical at all IMHO. More info like this, please Zwift. Thank you!
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this post is great!
any chance you can comment on any of these questions:
- is this for all OS’s? or just iOS?
- are you ONLY addressing “controllable”, or the bluetooth connection to the trainer more generally?
- should i try to upgrade my firmware on my trainer? or is it safer to stay on the older version?
- is this direct-connect bluetooth only? or does it apply to companion app-as-bridge, too?
- your post title says “controllable trainers and treadmills”… but will this affect HRMs or cadence sensors connecting via bluetooth, too?
- are you writing linux drivers for bluetooth so we don’t have to use the companion app to connect? (sorry i couldn’t resist that one)
Hi Jeremy, thanks for taking the time to add some info.
Would this change in language suddenly affect a device?
My situation was as follows
Kickr 17 connected to Apple TV suddenly went from being a great ride experience to a horror story!
Having to pedal hard down hills, coming out of a supertuck on the Innsbruck descent, stationary flywheel needed 400w to get it spinning again… like if you stop in erg mode!
Then the odd bits…. Struggling to pedal on the flats, power at any effort would fall back to around 120w meaning I couldn’t stay in a bunch!
And the really really odd thing was that the power meter on the bike that wasn’t used for Zwift agreed with the kickr!
I did successful advanced spin downs, standard spin downs etc in wahoo app and Zwift with no change! After a week doubting my legs even though I was getting decent outside ride power I changed to a v5 kickr and that’s so far ok …. But still on outdated firmware, I’ve not updated it in case it breaks !
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That sounds like expected behaviour to me, i.e. watts are watts, and both the Kickr and power meter are measuring the same force exerted by your legs.
What’s going wrong in your example is the controllable side of things, i.e. the resistance that is being set on your Kickr.
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Exactly this, it was like riding with a brake on, but no matter how hard I pushed the power reading just fell back to a similar level as if it were in erg.
20 mins slower up Innsbruck than pb despite the same HR
Leg snapper I can usually ride up at 12-13mph I did at 4.7!!! Out of the saddle!!!
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Thanks for the info. More like this pls. 
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is this for all OS’s? or just iOS?
The entire platform (all OS’s)
are you ONLY addressing “controllable”, or the bluetooth connection to the trainer more generally?
This update is primarily FTMS related, however the general improvements section applies to BLE overall.
should i try to upgrade my firmware on my trainer? or is it safer to stay on the older version?
I can’t really answer this as I don’t know the state of firmware. I’d go with what your hardware manufacturer recommends.
is this direct-connect bluetooth only? or does it apply to companion app-as-bridge, too?
The FTMS updates apply to both.
*your post title says “controllable trainers and treadmills”… but will this affect HRMs or cadence sensors connecting via bluetooth, too?
The general fixes may improve reliability across all devices.
are you writing linux drivers for bluetooth so we don’t have to use the companion app to connect? (sorry i couldn’t resist that one)
Nice try.
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Hi Mantis,
I’m curious, could your trainer difficulty setting have changed? Also, have you defined your rider weight in the Wahoo app and Zwift (are they the same)?
Edit - Any other applications connected at the same time?
is this an addition to the client side log file?
awesome thank you!
the reason i ask about the firmware upgrade is that many of us using kickr’s have had to roll back firmware to just before wahoo introduced updates for FTMS. for example, i had to roll back to 4.1.2 on my kickr v5, because the 4.2.1 release made the hill simulation i was feeling on my trainer badly out of sync with what was happening on screen in zwift. the 4.2.1 release notes say they “added bluetooth FTMS support”. lots of folks on this forum have been struggling with this sort of problem and/or “reversed” gradients. in almost all cases, rolling back to a firmware just before “added bluetooth FTMS support” solves the problem.
here’s the release notes i’m referring to:
here’s another post i wrote about the firmware versions for kickrs:
those of us who have contacted wahoo support on this have gotten a response of “that’s probably something happening in zwift software”, but not much response here in the forums until this thread appeared.
your answers appear to be dealing with this problem – i’d love to upgrade my firmware, but 4.1.2 “just works” now. (4.2.5 adds LED sleep mode!)
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Hi Jeremy
I don’t use any other apps, so can’t say for sure.
Weight is set at 70kg ( despite me being 66kg as it’s easier to stay in a bunch on a fast descent) and my TD is about 75/80% and has been for a couple of years prior to these issues that have only recently started.
I did try a test ride in the wahoo app after a spin down and control of the trainer in 10w blocks in Erg mode was possible and while in that app 120w was feeling tough it was immediately after a zwift session that had already got me tired, so not overly conclusive
I changed the trainer for the V5 kickr in desperation and that’s totally different, I’m back being able to sit in with a B pace partner for long durations again instead of being dropped by the C after a couple of minutes.
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@Jeremy.c I have a 2016 kickr like yourself and have to say with the recent changes, the riding experience with gradient changes has gone backwards. For many years,it worked floorlessly, but things have changed where resistance suddenly drops right off. The other night I was riding TdZ stage 3 long route and with the climb going up to the castle there was weird changes when crossing the wooden bridge before the climb ie: jumping up n down. So for me, something is definitely not right with these changes, using an ATV 4K
I’ve had the TD setting at 50% since the day is a started Zwifting, so 5yrs or so
Any luck with looking at the wattbike Atom free ride issue that has been in existence for about 4 years on Apple TV?
Seems to be just being ignored…
There are multiple other issues with ATV and Bluetooth but let’s start easy…
@Jeremy.c Could it be that the less frequent sending of gradient changes, makes the signal more error-prone when riding in a noisy environment? Previously a single lost command would not have a huge impact since you were sending many commands for the same grade, while now lost commands have more impact on the riding. You are probably doing a resend of failed commands. Just an idea 
@Jeremy.c, I found out that sending less commands has the effect that in ERG-mode the first power value is send before the “ride” button is pressed (in a windows environment). So if the user isn’t prepared and isn’t already “riding” the trainer sends 0W and zwift switches to “SIM” before the user is ready to start his workout.
It would be much better to send the first watt value after “ride” was pressed and the user started to ride, so the trainer will receive the first power value and powers up to the given watt value. This will avoid the change to SIM, like it was in the former BLE FTMS implementation.
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I hope this isn’t too technical, but provides you with insight into what/why we are updating our communication protocols
Sorry, but I have no idea what you’re talking about. Can you explain this as if you’re talking to a 5th grader? All I know is that everything was fine before the upgrade and now this connection failure message messes up every ride I do since the update.
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Yup, there is some additional stuff in the log - basically FTMS responds and we’re logging those responses to make sure the protocol is behaving the way we expect.
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The kickr 2016 should not have been affected at all with these changes since it is NOT an FTMS trainer. Sounds like there might be another issues.
BTW, there’s a dip in that bridge where the incline changes rapidly. I notice the same thing on my SB20.
There’s a response mechanism with FTMS, so we know if a message we send was received correctly or not (or at all).
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We fixed the way we talk to FTMS enabled smart trainers.
Do you know which device is disconnecting? Or are your devices connected just fine, but the message is staying on screen?