Kickr Snap - Random (?) resistance changes
 

Been using mine for about 10 days. I've noticed at times that the resistance changes, seemingly randomly during a ride. Not constantly, but at some point it will become easier for a given speed/cadence (or, put differently, power drops). I don't have it on Erg mode - just the basic level mode (and I'm not changing levels).

Do I have something set wrong? Something odd about the unit?

If you’re pedaling along, without changing cadence, gears, or anything, that does sound strange. What are you using to control the Snap?

I've noticed something similar with my Kickr (not Snap). The resistance sometimes drops when I change from one display page (on my iPad) to another. Very odd ...

iPhone. But, as mentioned, not "controlling" it in any sense because I'm not adjusting resistance during rides. I do a spindown after each ride (or every other), but even so what's odd is it happens part way through the ride.

I'll try to make more mental notes of what else may be happening (data page changes, certain point in ride, etc.)

Hmm, okay, that does sound strange. I don't have any particular insights, but have you used the Wahoo Utility app to do a spindown calibration?

ANT+ or BT?

If ANT+, how far is the dongle from the unit?

I found that using a $3 USB extension cable to move the dongle right under my bottom bracked (and close to the kickr), exterminated lot's of little gremlins... and this smells a lot like the particular flavor of gremlin that it could fix.

BT connection. I have my phone mounted on my handlebars (left side, so a bit more direct to the unit).

I called Wahoo. First question was about the spindown, and he told me that my spindown was taking too long, so the power readings weren't accurate. I asked him how I was to know how long the spindown took or what the right length was, and he told me it should be 10-15 seconds, and mine was over that. I told him that was good to know, but that if such a time is a requirement the app should inform the user that the spindown took too long and the tension needs to be tightened. And that it would also be helpful, but less necessary, for the app to have an indicator for the time the spindown has taken.

FWIW, it's not clear to me why poor calibration on power would lead to jumpy changes in resistance. But I'll give Wahoo CS the benefit of the doubt on this.

I haven't done another spindown yet, but will report back as to whether this solves the issue. (I'd been waiting to report back.)

IME, BT is horribly susceptible to interference. My BT speakers come and go sometimes, and my BT ear buds pick up interference on the train.

I would consider TRYING ANT+. If you have a laptop you can try, it's probably worth trying the $15 ant+ stick from amazon.

I think you're on to something - tonight I noticed it when I switched to a different page of information (iPhone app).

I've been using a Kickr SNAP for over a year now, mostly on Zwift. Early on, I saw that problem but haven't seen it for a long time. Two things seemed to be the cause:

1. Wahoo had a bug, and a software update fixed it. I would think the Customer Support asked you about firmware version but check that you are on the latest version of firmware.

2. Too many things on Bluetooth. I have the SNAP, a cadence sensor and a heart rate monitor routinely connected to an old Mac Powerbook which runs Zwift. If I added a Bluetooth headset, I invariably ran into problems - would see dropouts of cadence or heart rate or power.

A variant on (2) that may be an issue: to use that BT headset, I had to turn on Bluetooth on my cell phone, in addition to BT being active on the Mac Powerbook I use to run Zwift. I noticed once that the HRM had attached to the cellphone, which may have meant it wasn't paired to the Macbook for a while.

Going to a wired headset (and turning of BT on my phone) when I want to do audio solved the problem.

This was also the case for a friend of mine who bought a SNAP over the holidays - he is a cell phone junkie, basically walks around all day like a dork with a BT earpiece and his phone on his hip. Taking that off, turning off BT cured his SNAP blips.

^ which is why I tell everyone I help set up...

I know you think BT is better because it works with your phone... but I'm telling you... just use a laptop and ANT+.

Bluetooth may "work"... but it's just not good enough, reliable enough for this.

Several things to note here. KICKR Snap needs to be calibrated (spin down) every time you ride. As part of this you need to make sure that your tire pressure is at 110psi and that your roller tension is set properly. They have a target spin down time and if you're outside that they want you to increase tension (too long) or reduce tension (too short) in order to have the correct spin down time.

ANT+ vs BT. To me it's all in how you want to control the unit. Sounds like the OP is just controlling resistance with the Wahoo app? If so I'm not sure there's a PC solution that will work for him so BT is his only path. That said if you want stability you can't be changing the app you're using in the middle of a ride. Personally I wouldn't use a smart trainer without some sort of proper controlling application like Zwift or Trainerroad. You're just throwing away the reason you have a smart trainer otherwise IMO.

I've had my Snap for a couple weeks too -- I found I had to air up my tire more, to about 100 psi (700 x 23s right now) and increase the tension - 2.5 turns past contact, and some of these little quirks seem to have disappeared. Also, I warmed the trainer up for about 5 minutes before doing the spindown, which seemed to help. I'm going to invest in a USB extension soon though, sometimes it seems to lose connection here and there for a couple seconds.

Overall though I've been pleased. It's really brought a new dimension to both Trainnerroad and Zwift -- the ERG mode shows no mercy on those intervals -- and since this is my first time riding with semi-accurate power data it's showed me a lot about how strong I'm NOT.

ETA -- oh yeah and when I first fired it up I had too many connections -- BOLT head unit, phone, and computer. I think it got confused. Now I just have the phone on at first, to do the spindown, then I fire up my computer and start Zwift or Trainerroad.

Update - I got a cheap USB extension cable so now my ANT+ dongle is inches away from the SNAP -- but I was still having random moments on Zwift in which my wattage would drop to 0 for a couple seconds even though I was still pedaling and there was resistance.

This wasn't happening on TrainerRoad so I figured it was an internet issue instead of an ANT+ issue, so I turned off my VPN and I think (fingers crossed) that did the trick, on Zwift yesterday I didn't have any random wattage disconnects.

Do you mean it was changing resistance as switched between screens in the Wahoo app (e.g., ERG, resistance screen,kickr level, sim screens)? I noticed that the resistance would reset itself as I went through the different screens listed above, as though it's waiting for a new resistance/power command from whatever screen it's on, but resets it first when you migrate to a new screen.

Yes - exactly. I think the screens can be customized, but anyway my first screen shows speed/cadence/HR/time/power, the second shows time/heart rate/speed, the third has detailed figures on power (avg., 20 sec, 1 min, 5 min etc.) and some other info. It's switching to that third screen that causes the drop in resistance. Last night I waited until near the end of my 'ride' to switch to that screen, and sure enough that's when the resistance dropped. Was good for a cool down.

ETA: I have Wahoo support looking at this issue. They were not previously aware of it, but are testing.

Follow-up:

After a lot of back and forth, testing of various scenarios, Wahoo sent a replacement that doesn't have the problem. They hadn't tried to replicate the issue on the returned unit when I asked, but it seems like there was probably some sort of odd logic board bug.