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transmission ratio?

3317853
over 3 years ago

i!

i have a edge 830 and a elite direto smart trainer

when use the direto with zwift app, all seems ok

but when i connect the garmin also,

the speed on garmin is way high!

in settin of wheel circumference and transmission drive ratio , what value i have to set?

  • +1 over 3 years ago

    Divide your wheel circumference by 12.1 and put the result as the wheel size in the Direto sensor settings on your Edge.  That will fix it.

  • 0 over 3 years ago in reply to Wongataa

    Does this actually make the Garmin-reported speed match the speed in Zwift though? My understanding is that it will not.

    My understanding is that Zwift does not actually use the "speed" reported by smart trainers, it only uses the power, and then the simulation calculates speed based on a variety of factors (gradient, draft, rider size/weight, etc). So there is no actual direct link between the smart trainer's reported speed and the speed shown in Zwift.

    If so, then using any single fixed ratio to "correct" the speed shown on the Garmin will never match the Zwift speed at all times. It may get it closer, on average, but I think there will still be a lot of variation as simulation conditions change.

  • 0 over 3 years ago in reply to Kyle J

    I don't think it will match Zwift as you say Zwift does it's own calculations.  It will match what you would see with a speed sensor/GPS on the road when pedalling at a certain rate in a certain gear.

  • 0 over 3 years ago in reply to Wongataa

    Ah ok, I see what you're saying.

    On mine (a Tacx Neo 2T), the speed Garmin gets from the trainer is always a lot lower than the Zwift speed (Zwift is stupid fast). It's like 30% lower or so, so I ignore it. I suppose though there might be some cases (or other trainer apps) where it's useful info.

  • 0 over 3 years ago

    yes the speed of zwift isn’a “fixed tatio” of wheel speed .

    it’s calculated on the parameter reported in posts before,

    but before the correction of right wheel speed, the edge speed was really out ……200mph .

    now is more realistic

  • 0 over 3 years ago

    This Garmin Support page explains "Garmin" reported speed on a Smart Trainer as compared to the "Virtual" speed reported by most Apps (including the (Garmin) Tacx Training App) , https://support.garmin.com/en-US/?faq=M0wRO9OkFb9PrFlWgNfJn9

    For me the Tacx Training App is much closer to what I would get on an outdoor ride for up hill, down hill and on the flat whereas the Garmin is very optimistic regarding my up hill effort and pessimistic to very pessimistic for flat to down hill. The "ride experience" is much better with the App. The Garmin could be a lot better if it used the same algorithm as the Tacx App. The resistance  effort for a flat grade is much higher with the Garmin controlling the Trainer than with the Tacx App and this continues for negative grades

  • 0 over 3 years ago in reply to 3317853

    Wow I like that speed!! :D

  • 0 over 3 years ago in reply to L.Rouge

    Because of this, I recently started using the Fit File Repair Tool to merge the speed data from zwift (plus elevation and location) into my Garmin data. It replaces whatever Garmin recorded. It works for other virtual ride apps too.

    It's probably meaningless in the big picture, I just do it so all of the data is consistent and reflects the virtual ride. And also because pandemic boredom so a lotttt of free time

    Anyhow just mentioning it here because it's an option if someone wants to replace the Garmin speed with the data from the virtual ride so they match.