Thanks for the replies. I must say I generally don’t calibrate the Kickr Snap every time I ride as it’s 10 minutes faffing plus the iPhone Wahoo Fitness app gets confused and often can’t see the speed on my Kickr. At that point I generally have to add it back in again, that is delete it and add it back.
Also I am slack and only turn the Knob 1 3/4 turns. I always felt 2 turns was just too tight, at my power level it was never going to slip.
Also I hate pumping up the tyre so I only do this every week or two.
Last calibrate I did was via the Zwift app and it gives you no feedback on ramps time, temp etc. Firmware was up to date.
Anyway I reasoned the power would just be a few Watts to high or low, no issue as I don’t race these days.
This is all by way of excuses, hopefully this helps someone else…
So, I pumped the trye up hard to the recommended 100psi or so.
I turned the knob a full two turns.
I found my trusty old Galaxy S4 had the Wahoo Utility App on it. I did a few Spindowns while I was warming up. I was getting times of just over 15 seconds for the Spindowns, so I tightened the Knob a bit more, like a few degrees until down to 15 seconds.
After 10 minutes I did 2 more Spindowns and ended up with 14.9 seconds, 19.3 Deg C and 0.703 braking factor (yes Android app has braking factor). After my 30 minute ride I did another spindown, 15.3 secs, 28.2 DegC and 0.703 braking again (that seems a little odd to me, all my braking factors were bang on identical). There doesn’t appear to be an advanced Spindown anymore, unless it is hidden in yet another Wahoo app.
The result of all of this anyway was a completely changed ride experience, I have more power than before on the flat and it doesn’t all vanish when I go uphill, more effort uphill now results in more power. I have however lost some power going downhill, but that always seemed wrong. Also I think the Kickr Snap flywheel feels a lot cooler at the end of a ride (another indication it was robbing power).
So yes, being spot on with the Spindown, Knob tightness, 10 mins warmup, tyre pressure will do the trick. As long as the knob is put back to the same position for the next ride or two the calibration seems fine. I think it would spoil it if I did another spindown at present, unless via Android app. I have no confidence in the Zwift Spindown because it doesn’t show me the numbers.
Sorry for the long story but hopefully this will save someone else from grief or give them what they need to figure out what is going on.
The Spindown it seems is needed to determine much power the Kickr reports on the flat and equally importantly to adjust the resistance downhill and uphill.
If you have 10 minutes to faff before a ride you can get it spot on. If you are slack like me find something that doesn’t need this (wheel off). Anyway its spot on now.
Thanks for reading this!
PS - running on Apple TV 4k. Very good mostly, although tonight it wouldn’t pick up the Kickr Snap or Wahoo Tickr. Had to turn off everything, a restart of the ATV didn’t fix it.