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Problem calculating speed while training on smart trainer

I have neo 2t and forerunner 945 and I would like to use them for indoor training.
The trainer calculates the speed based on the power and maintains a constant power even when I change the bike cadence. This is exactly what happens on a flat road, speed depends on power and not on cadence.

The watch calculates the speed based on the cadence only and therefore a ridiculous situation is created when I am at very low power and high cadence the speed that the watch compute is very high and when I am at very high power and low cadence the speed is much lower. This opposite from what happens in real world outdoor cycling and also from the speed that the smart trainer calculates.
As a result I can not use the watch for indoor training and I lose important metrics like training load and effect (I use the data form tacx).

Garmin, please add to forerunner 945 an option for indoor cycling to collect the speed form the smart trainer!

Thanks, Gideon

0 mcalista over 3 years ago

1. You are sitting in your pain cave and have gone nowhere on your trainer. Therefore your speed is zero. Seriously, speed is an irrelevant metric when it comes to indoor training

2. On a flat road, speed does depend very much on cadence - and also what gear you are in. The neo is no different. The reported speed from the trainer is based on how fast the axle is spinning. Put it in a high gear, and turn it at 90 rpm, and it will report a high speed. Put it in a low gear and spin at the same 90 rpm, and it will report a low speed. The reported speed coming from the watch IS coming from your trainer.

3. As a consequence, no, trainer speed and head unit speed will not match speeds reported from virtual training environments (Zwift, Rouvy, etc). But as from point 1, speed is an irrelevant metric for indoor training. But if this bothers you, change gears as you ride. A bit like the real world really.

0 Dr Phil over 3 years ago

nachshonrider said:
Garmin, please add to forerunner 945 an option for indoor cycling to collect the speed form the smart trainer

This can already be done. Well I can choose to gather speed/cadence from my Tacx Vortex Smart on my 945. However, as already noted speed is not of any value when cycling indoors; or outdoors for that matter. Power is the important metric. And it is power that is used to compute training load etc when cycling indoors with a smart trainer. Speed is irrelevant.

0 NickMN over 3 years ago

I understand the desire to track distance in your weekly/monthly/annual , as well as power & time for indoor workouts - but also as outlined it has little bearing on reality because every ride can have a large difference in speed vs effort. If you usually ride solo in mostly flat or rolling hills it is pretty easy to go by speed outdoors for things like avg speed and distance. So when indoor even with my dumb fluid trainer and wheel speed sensor... it is usually pretty darn close! Easy ride 16-18mph... throw in some good long intervals and I avg 19-21mph. Compare that to my rides now with power and connected with RGT Cycling app... still pretty close in speed/distance.

If I ride gravel virtually it slows me, if I climb vontoux or something the distance is way off !! If I am doing a flatter route and do a bit of drafting on RGT then my distance is also off (higher!) due to the increased speeds at lower watts. Sometimes I edit my Garmin distance to match RGT, sometimes I don't, sometimes I meet in the middle. My goal is just to have something to look at in my running/biking totals - usually I use time, but sometimes distances are nice also.

Easy fix, Just edit activity plug in a distance for activity that roughly matches your intensity and past outdoor ride's speeds.