Scott
Well done with this. This is what I have done to prove that treadmill belt is not running at the advertised treadmill set speed.
I’m going to apologise for the length of my reply but I hope, like you have done, that if I can help others to set up a Runn it is worth the time writing this.
I have also contacted Runn to discuss why they have a ‘calibrate your Runn’ option if their Runn very accurately measures the belt speed. They are very confident that their Runn is accurately calibrated and does not need calibrating. They say the option to calibrate your Runn to your treadmill (or any speed you desire) is for those people who would like their Runn and their treadmill to report the same speed, irrespective of whether that is actually the real belt speed.
I have measured my belt length and carried out very similar calculations to your own to check belt speed at three speeds, slow, medium and slightly faster (but in no way considered fast!). When I, eventually, calculated the belt speed correctly i actually found that it very closely matched what the Runn was reporting.
So as you have written some nice easy to follow instructions for new users or anyone struggling to set up their Runn may I suggest the addition of a couple of extra steps.
5a. Set your belt speed to the Slow speed you have calculated it to be and check what the Runn ConfigureZ app says the treadmill belt is running at. Up the treadmill speed to what you know the medium speed to be and check Runn ConfigureZ app speed reading then do again same for fast speed. (This is similar to what you are describing in your step 6 but at step 6 you are already starting to talk about calibrating your Runn, I believe my steps 5a and 5b might save you having to calibrate at all)
5b. If your calculated belt speeds are not closely (0.1-0.2 kmh or 0.1 mph) matched by the Runn may I suggest a recheck of the belt speed calculations again before moving to step 6. (Now move to step 6 if you really believe you need to calibrate your Runn)
I believe these two additional steps may persuade users that there is no need to move to your step 6 to recalibrate their Runn as it is accurate.
I add these two points from experience as I initially got my set up procedure and belt speed calculations wrong.
I may also add that counting more than 100 revolutions, say 200 or 300, leads to a slightly more accurate belt speed although obviously takes longer.
For those wanting a slightly different belt speed calculation option I decided to find out how many revolutions of the belt was 1km and time how long it took to do exactly 1km at various speeds.
So in my case
- belt length was 322.5cm or 3.225m
- 1km / belt length —- 1000 / 3.225 = 310.08 revolutions = 1km
- 310 revolutions took (say for easy maths sake and my medium run speed) 360 seconds —- 3600 seconds / 360 = 10.0kmh
I am very happy with my Runn, I believe it accurately reports the true belt speed at all belt speeds (without the need to calibrate at all). It tracks my cadence well although doesn’t register cadence at walking speeds but think I have set it up too far towards the back of the treadmill and might at some point try moving it closer to where my feet hit the belt.
There are questions on other forum threads as to whether testing belt speeds and counting revolutions should take place with you running on the treadmill or not. In my experience the treadmill belt does move at very slightly different speeds depending whether you are on it or not.
Does this mean you should calculate belt speed whilst running on the treadmill. Absolutely no need to. Why - because the Runn doesn’t know whether you are on it or not. All it is required to do is measure the belt speed. Does the belt speed slow down when you run on it -Yes(*1 see below). Does the Runn identify the drop in speed - Yes(*1)
If you want proof here is a test you can take. For H&S sake I recommend only doing this test if you are experienced with stepping off a treadmill on to the side ‘running boards’ whilst the treadmill is moving.
Set up and enter Zwift Run.
Raise the treadmill to a comfortable running speed in my case 6.0mph.
Run for 30 seconds - does Zwift/your avatar continue to report 6.0mph, hopefully yes.
Without touching the treadmill speed setting button, hold onto the treadmill handles and step off the treadmill onto the side ‘running boards’.
Does your Zwift Avatar start to run at a faster speed.
Yes in my case it now runs at 6.1mph.
Proof that the Runn has identified that the belt is moving faster now you are not on it. IMHO proof that the Runn is accurately engineered to calculate belt speed irrespective of whether you are on it or not.
Note 1* - I suspect, but have no proof, that the better quality top end treadmills with more powerful motors will have a smaller deviation in speed when you are on it or not. I also suspect, with no proof, that a much lighter runner will have less impact on belt speed deviation than a very heavy runner.
Once again I hope this helps someone else get their head around the NPE Runn setup.