Routes how do speed & gradient work

Hi, I’m new to Zwift. Did a couple of experimental rides and the a FTP test. Today I followed a route London Pretzel. It consisted of a few laps round central London and then a couple of climbs in the Surrey Hills. My question concerns the speed and gradient when following a route. I’m spinning along trying to keep cadence reasonable and power lowish under control. One minute I’m spinning along at 20 mph or more, the next 10 mph or less. On the bike it feels no different, same cadence, same power, same resistance. What’s changed in Zwift is the gradient which has suddenly increased. The feel on the bike has not changed but Zwift has halved my speed. How does Zwift calculate my virtual speed? I don’t have a speed censor nor a power meter.

Hi @David_Shaw2 and welcome to the Forums.
Check out this thread: How Does Zwift Determine My Speed?


What sort or trainer do you have?

Elite Directo XR

Make sure you have the Controllable device paired, as well as Power and Cadence from the trainer.

It sounds like you don’t have Controllable paired, and if so then that would explain why you don’t feel the pedalling resistance change with the gradient.

What’s the Controlable? The Trainer is paired to Zwift by Bluetooth. The power readings seem pretty accurate. My FTP test result was pretty much what I was expecting

Thanks. In other words Zwift does a calculation to estimate what my speed would be given various variables such as power, gradient, weight?

I haven’t tried a training programme ride yet. My understanding is that if I do Zwift will control the resistance to generate the programme power regardless of which gear I ride in in the bike. I believe from what I’ve read it’s best to select small chain ring and a larger cog?

Sorry, David, I’ve just started a 3-hour ride :sweat_smile: so can’t help more right now.
Suffice to say, if you have a Direto XR (which includes a power meter and controllable brake), you have everything you’ll need to have an optimum experience on Zwift. Ride On!

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It’s generally recommended to do an ERG mode workout (the default for a workout) in the small chainring and the middle of the rear cassette. Maintain a steady cadence and let the trainer adjust. Don’t change gears or try to “chase” the power by changing cadence. It feels really odd at first but you’ll soon get used to it. Again, you need the Controllable device paired for this to work.

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Ok, yes the controllable is connected. My question was about following a route not a programme

Once the smart trainer is connected as both power source and controllable, when riding a route you should experience something similar to real life when riding up gradients in Zwift compared to the flats: much less momentum and progressively more resistance as the gradient increases.

Zwift uses your weight, height, gender, and the virtual bike/wheels that you have selected, plus the road surface (tarmac / gravel / dirt) to determine your speed in the game for a given power/cadence.

If you haven’t already been there, Reference Archives - Zwift Insider is a wonderful source of information.

ur going up a hill.
ur not increasing ur power.
hence u slow down (just like outdoors).

if you have a dumb trainer just change into a harder gear to simulate an increase in resistance :wink:
if you have a smart trainer and it’s not working despite being connected as a “controllable”, check you haven’t turned “trainer difficulty” to 0% (slider bar all the way to the left) in settings bcos this disables resistance changes. stick it back in the middle to feel the difference.
p.s. resistance changes due to gradient are disabled in workouts because the workout programme overrides it.

Thanks Ben. I’ve realised what the issue is. Though I connected my trainer via Bluetooth I didn’t know that in addition I had to pair it as a controllable. I’ve now done that, and will test it out later on a training programme.

just make sure you try it in a free ride and not a workout programme if you want to feel the resistance change on gradients…! (watopia hilly route is a good short test route)

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