Hi everyone - I am wrestling with some of the same issues others are seeing with ERG mode and unreliable resistance.
I am on a Kickr Snap 2017. I noticed the following little gem on their support site.
This says spindown no longer works on the 2017 Snap (although it does on prior versions) and that the old method of resistance trial and error is the only way to get accurate power from the unit.
It suggests any of us with a Wahoo Snap 2017 are wasting our time using the spindown capability in Zwift…does anyone else have a view or experience with this please?
cheers
Aaron
I asked Wahoo about this (having a 2017 Snap). My two questions were:
To calibrate a 2017 Kickr Snap should tire pressure be 110 psi per the video or the recommended tire pressure on the sidewall as stated on your site.
…and what’s this about ignoring spindown times and roller adjustment. Do you just pump up the tire and turn the knob twice for calibration??? very confusing
to everyone.
Their very prompt response was:
Thank you for reaching out. You should pump up the tire to 110 PSI before installing on the Snap. As far as ignoring spindown times on the first generation of Snaps there were recommended spindown times but due to improvements in the 2017 the same protocol doesn’t apply. Once you got the tire pumped up and the two full turns once it touches the tire it should be good. I do want to make sure you saw this link about completing spindowns on our support site:
Thank you Steve! I sent Wahoo a ticket as well yesterday and am awaiting a response
I am confused as to whether the whole spindown is a waste of time, or just the advice on the timing. I am also getting more common spindown failures when i try to use the Zwift spindown function, and the power on the Wahoo is running consistently 15% below actual, so an accurate spindown is important if we don’t want to be spending hours twiddling the resistance knob to get things aligned. I’ll post Wahoo’s response when i get it. Cheers A
The spin down time is not applicable to the newer Kickr SNAP '17 which is the trainer I have.
That said, I still use it to gauge the amount of the turn of the blue knob because the recommended 2 turn does not work out too well for me. The Kickr SNAP would underreport the power, by a significant amount compare to my 4iiii crank arm power meter, with all variables taken into account.
To get the power output from the Kickr to an acceptable range, and consistently from ride to ride, I would warm up for 10 mins and get the spindown time somewhere between 13-14 seconds. This takes turning the blue knob 2 1/4 to 2 1/2 turns from tire contact. I’m using the blue Tacx training tire, pressure at 110.
@_Ray_C I’m finding the same thing. I just changed my trainer tire from a Vittoria to a Continental which seems to have much lower rolling resistance. Pressure at 110 psi, 2.25 turns on the SNAP’s knob for both tires. Spindown time increased from 15.2 seconds (Vittoria) to 21.5 seconds (Continental).
According to Wahoo, this should not matter.
According to my legs and lungs, it sure does!
I’d guess that with the longer spindown time the SNAP is under reporting power by ~30 watts.
Wondering if you, or someone else with a SNAP 17 and a crank/pedal/hub power meter could do a comparison and post the results. Adjust the wheel tension to give a spindown time of about 15 seconds, perform a spindown using the Wahoo app, then ride at ~250 watts and compare the readings of the SNAP and the external meter. Then adjust the wheel tension to give a spindown time of about 22 seconds and repeat the test.
Since my post the trainer tire have pretty much feel apart, and I have given up relying on using the SNAP as the power source and use the 4iiii left crank power meter exclusively.
Not having to deal with the spin downs and onerous routines have improved my indoor riding and zwifting experiences.
I am hoping to upgrade to a direct drive trainer eventually.
