Indoor Cycling activity ->Calibrate->get a number but still have too many miles?

I'll make a stab at this, but I'm flying blind as there isn't much to go on and I don't use Sufferfest, although I do use Zwift and a Tacx Neo smart trainer or Assioma Duo pedals. 

By the sound of it you're calibrating a power meter, since you are instructed to unclip. I have no idea what the number is that you've mentioned. It sounds rather like a wheel circumference, and quite a large one at that (Tacx Neo is 2133), which would exaggerate speed and hence distance. When I calibrate my pedals with the watch (not done it for months so my memory might be faulty) I don't recall seeing a number produced as a result, just an OK. 

Basically, Sufferfest will (if anything like Zwift) be using your power data to calculate speed /distance based on simulated gradient and rider/bike weight, possibly other things like height too. The watch is calculating speed and distance from the wheel speed, actual or simulated depending on your trainer setup. So Sufferfest is using power to calculate speed /distance while the watch is using wheel rotations x circumference. Two completely different inputs. Two different outputs. 

If you're doing a workout on erg mode then the relationship between power and wheel speed could be pretty much anything, with no correlation at all. In the absence of more information I suspect a difference in distance is absolutely too be expected. How much of a difference depends very much on your actual setup, which you have not described. 

For example, suppose you are doing a workout in erg mode and producing 200W. You could pick very low gearing and high resistance as though hill climbing. Your wheel speed will be slow, just as when climbing in real life, and your distance covered will be short. Alternatively you could be in top gear, with light resistance, as though riding on the flat or even a slight decent. Your wheel speed will be high and your distance exaggerated, which is what the watch sees. If your wheel circumference is wrongly set in the watch that will throw things out further.

If I've got this backwards then sorry, but it's all a bit of guesswork on my part, based on experience of my own setup, which is obviously not the same as yours. 

You're not calibrating the distance, you're calibrating the power. You can't relate distance travelled indoors to wheel revolutions on a smart trainer, sorry.

eezytiger said:

Tacx Neo is 2133

Do you have consistent datas using this wheel size with Tacx Neo? 

I have different data's form the app and Garmin devices like Edge 1000 and 935. I have more problem using power trainings. 

The data is consistent, but distance and speed recorded by the watch doesn't match the distance and speed recorded in Zwift. Nor should it be expected to. This is what I was trying to explain above. Have a look here....

zwiftinsider.com/.../

For example, let's say I pedal at 80 RPM with the same gear and the same resistance for 1 hour at 225W and the watch shows 20 miles at 20 MPH. If I connected 100 watches and head units they'd all show the same data, based on number of wheel revolutions x wheel circumference. They'd also show the same power for the hour.

But in Zwift my speed will vary depending on gradient, my weight, drag from my height, my choice of bike and wheels, whether I am drafting a single rider, a huge pack, or nobody. Zwift speed is likely to be faster than the watch speed if I have draft. On the flat, without draft, it might match more closely, but if I choose TT bike with disc wheel set up I'm going to be faster than if I pick a mountain bike for the same course. If I train with erg mode or reduce gradient reality then there is even less hope of matching the watch speed/distance to the software.

It is meaningless to care about matching speeds because the watch knows nothing of the simulated world in the training software.

Also, to be certain that you have consistency between head units you need to make sure that wheel size calibration matches on all devices - set manually. Disable auto calibration for speed and also disable autopause.

As previous posters indicated, VR apps tend to do their own speed measurements. This is how Sufferfest does it: support.thesufferfest.com/.../360000519475-Virtual-Speed-Understanding-Speed-And-Distance-Calculations

Your Garmin picks up the speed reported by your trainer hardware, which is different.

eezytiger said:

But in Zwift my speed will vary depending on gradient, my weight, drag from my height, my choice of bike and wheels, whether I am drafting a single rider, a huge pack, or nobody

Thanks for the explanation, you confirmed what I thought. 

But... when I tried the Neo with the Edge 1000 I hoped  that was different because the Edge series is using  ANT+ FE-C and see the Neo as a smart trainer and not only as a speed sensor like the Fenix. 

Ok, during swift activity this not have sense but... during power based trainings (Erg mode) why not  calculate virtual speed to have more realistic datas? 

I do not care of speed and distance while I am doing a ERG mode training but all statistics about total distance of one year or similar loose sense if some activity have not consistent datas. 

Another way, probably easier, could be to sync Tacx website/app to Garmin Connect. This allow us to have data's calculated from Tacx Training App that are more realistic in my opinion. 

I will try with my new Edge 830 to see if something changed compared to 1000 but I do not think so. 

Smart trainer only means that the software can control the resistance of the trainer, or the power in erg mode. The trainer is not told and does not transmit the simulated speed of the software. It has no interest in that data as it has no influence on what the trainer should be doing. It is just a brake that you push against. 

FWIW I use my watch to monitor and measure *me* and my physical performance and condition. For that to happen it needs good heart rate data, FTP, power, zones, HRV etc.. It has all these things 24x7. For that purpose things like speed and distance for cycling do not matter. They don't impact on my physical assessment. TSS does. If I push 300W for an hour up Alpe du Zwift, covering just 8 miles, or 300W for an hour on Tempus Fugit and cover 25 miles it makes no difference to my training load, my FTP, my VO2max etc.. I really don't care what distance the watch records because it doesn't matter to me.

However, for annual mileage and so on I use Strava to record data out of Zwift or from my head unit (Wahoo Elemnt) when I ride outdoors. That's where I do care about how far and fast I went, segment times, elevation gain and so on, plus how many miles I've covered on which pieces of kit.

If you depend on your Garmin Connect account for the totality of information I can understand the frustration. I guess you could discard the activities recorded by the watch or head unit and replace them with the fit files from the simulation software. That would at least give you the simulated speed and distance in your records, but possibly at the expense of other metrics.