Speed difference between Wahoo Element Bilt and Zwift

General Discussion
1

I have my MTB 29" set up on Zwift seen difference in speed on my Element Bolt vs Zwift its quite substantial.

How can i correct this

2

You can’t. Just ignore what your Wahoo is telling you. It’s only keeping track of your rear wheel speed and does not know about the in-game variables in Zwift. The speed and distance will hardly ever match.

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3

Thanks appreciate the feedback i see zwift has no allowance for 29" wheel what do i set the wheel size to

4

Hi @Wayne_Busch

Welcome to the forum.

You can select a 700c wheel, a 29" is basically the same as a 700c road bike wheel. Lots of people use wide road tires on 29" bikes.

@dirk is correct, you Wahoo don’t know if you are going uphill or downhill or if you are in a draft or not.

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5

Thanks Gerrie

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6

Not sure I agree with this… this is what the resistance feature is for… if I am going uphill, there is substantially more resistance than if I am going downhill, so in this case, the speeds should match. If the trainer knows how big my wheel is, then the speed on a Kickr Snap, for example, should match exactly. This is why it’s a smart trainer, and not a set of rollers…

7

Hi @Rob_Leach and welcome to the forums!

The Wahoo Bolt won’t have all the information that Zwift is using to determine your speed such as in-game bike and wheel choice, drafting, power ups, road surface (dirt slows you down on Zwift), etc…

It is much more complex than wheel speed.

8

How does it not have this information… all of this should feed the resistance that the trainer is receiving from Zwift, no? If Zwift knows the circumference of my wheel, and provides resistance based on gravel, incline, wind, draft, then the speeds should match, otherwise, Zwift isn’t calculating this correctly and as a result, not providing the correct resistance.

I have trouble looking at my Bolt telling me that I am spinning at 14mph and Zwift telling me that I am doing 4mph…

9

The only info the Bolt is getting is from the Kickr, not from Zwift. Zwift takes the power that is reported from the Kickr and applies it to the virtual world. The Bolt takes the power reported from the Kickr and applies it to the wheel circumference to determine a speed. Zwift is not sending info to the Bolt.

then turn off the Bolt :wink:

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10

hahaha. Point made… I will turn it off.

To the other point… here’s where Information is coming from…

Bike > Kickr > Zwift > Kickr > Bike > Bolt. If true, things should match a bit more, no?

11

No things will not match. The bolt has it own “simulation” formulas that calculate speed from power produced or just wheel speed, we don’t know what the bolt take into account.

But Zwift is fairly accurate comparing to IRL rides.

12

I find Zwift is a bit faster than IRL, especially if you are in an event with double draft. Plus no wind to contend with, no pot holes to dodge, much less coasting, no stop signs, no traffic/pedestrians, etc…

13

But that is not apples to apples.

IRL on a calm day on a flat trail compared to riding alone on Zwift it is in the ballpark. I must say Zwift has better bikes than my bike.

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14

true, I also work harder indoors I think, but don’t have a power meter on my bike to compare outdoors.

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15

Really appreciate all the input here… Thanks for helping me understand a bit more.

Cheers!

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