Spindown on Kickr Snap before each ride?

Is it imperative to do a spindown on a KickR Snap before each ride? The quick start guide for my new KickR Snap trainer says to do a spindown before each ride in the Wahoo app. The spin down test in the app says to ride for at least 10 minutes before performing the spindown but there are going to be days that I’m crunched for time and I won’t have an extra 10+ extra minutes. I know this sounds like an excuse to not do a spindown but somedays I’ll be lucky just to have the time for the workout itself.

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Imperative? No.

But…, if you want the most accurate and consistent numbers while training then yes.

I built this in as a ritual prior to every single ride when I had my snap and the wattage was always within a handful of watts when tested against 2 separate power meters on 2 separate bikes.

  1. Inflate tire to exact same pressure.
  2. Turn knob to the the exact same number of turns
  3. Do an easy spin for exactly 10 minutes
  4. Perform a spindown calibration using the wahoo fitness app.

I just made it part of my routine. If I had an hour long workout I had an hour and 10 minute workout :slight_smile:

Again though, imperative, no. It really depends on how much ocd you’ve got :stuck_out_tongue_winking_eye:

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Yep. Gen.Coutts has it. Basically, with a wheel-on trainer a significant part of your power goes fighting the friction/resistance of the tire on the drum. This is variable depending on the force against the drum, tire pressure, and tire temperature. You do that 10 minute spin to warm up the tire. The spin-down then measures that friction/resistance so it can add it to the power measurement. Another thing this friction does is set the minimum resistance you can get. A direct drive trainer doesn’t have all this friction so can go to lower resistances, and what parasitic resistance they do have is much smaller and less variable. Some even self calibrate. I have a Saris Hammer, which doesn’t self calibrate, but when I do spin downs the cal value has basically been the same for the past few years.

You could always test it for yourself - do say 20 minutes of a workout without calibrating, then do the spin down then do the same 20 minute section and see if it feels easier/harder/no different.

Assuming you do all the usual stuff of same tyre pressure, same tension in knob, spin down reasonably regularly I’m guessing you would probably notice very little difference pre and post spin down. At least that was my experience on the ancient wheel-on Tacx trainer I had before getting my Kickr Core and the Snap is a much better trainer than my old Tacx!