Wahoo Climb while in ERG mode

Would it be possible to send the gradient data to the smart trainer while maintaining ERG resistance? Currently I cannot have a working Wahoo Climb while in an ERG workout. The trainer does not send the data to the Climb. Does that mean that it’s not getting any from Zwift or something else? :man_shrugging:t4:

Hey Selino, the Climb reacts to the resistance change in those modes based on gradient or environment. The Climb simulates environmental obstacles. ERG mode resistance change is based on watts and cadence so there’s no real world “simulation” really.

It would be really nice if in ERG the kickr climb followed Zwift elevation, while allowing us to do structured power based workouts.


Agree. It would be nice for the climb to react in ERG mode if nothing else to move your weight and sitz bones around in the saddle.


+1 I would really appreciate if gradient data were included in workout/ERG mode for Wahoo Kickr/Climb, regardless of the fixed resistance in ERG.

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I think “Terrain” should be a third option during workouts (in addition to ERG and Incline) on the companion app whereby the slope data is sent and changes the resistance (and Climb slope) like a free ride. Even if you don’t have a Climb this is a useful setting because it replicates doing a workout outside.

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@Chip_Brunk: how would that work. what if your workout call for a 2 min vo2 max effort (400w) but you are going down a hill, you wont have enough resistance on your wheel to produce that kind of power.

Check out my feature request for more on this https://forums.zwift.com/t/add-terrain-mode-option-to-workouts-especially-great-for-kickr-climb/14694?u=chip_brunk but I’d do my hard intervals when climbng just like I do structured workouts outdoors. Between the Workout “Pause” button and the ability to turn around with the arrow key/button it would be pretty easy to control but does require you know a little about the course you are riding.

I do not understand. Why can’t the Kickr adjust the resistance while the Climb changes the grade?

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Good question and I’d like to understand too. Anybody knows that?

Gradient is sent to the wahoo kickr and the trainer calculates the resistance using that number. The kickr then sends the gradient to the Climb. So there’s just a single number being sent. If you change that number with ERG then it’s also changed for the Climb. There’s no way for the Kickr to know that the gradient is 8% if the resistance is set to 250w because it’s using one method for both. The method of sending the resistance and the gradient would have to be refactored for this feature request to be fulfilled.

I just have a long conversation with Zwift support about this topic. Like one user was asking, why can’t the resistance and grade be separated. I understand it’s might not be a true real world feel during workout. For example, my target wattage is 80 Watts yet, the grade is at 10%. Or the targe watt is 200W while I am down hill. I don’t need the resistance to simulate the grade. They can be independent. Just want to have an option to have the Wahoo Climb to simulate terrain.


But they are not, that is not how the ANT+ or BlueTooth protocol work. Zwift just send data to the Kickr as a standard protocol. The Kicker will then control the climb. So this request should go to Wahoo so that the kickr send garde info to the Climb while in ERG mode.
Zwift only control the kickr it does not know if you have a climb or not. That is why you can’t use the climb with any other smart trainer.

The below information came from John at Zwift support team.

To begin with, the KICKR CLIMB does not directly connect to Zwift it only receives information from the Wahoo KICKR. Which means that Zwift has no direct control of the CLIMB.


Now in SIM mode (any ride that does not have a target wattage) Zwift sends information about the grade of the terrain that your riding on to your trainer, which in turn tells the CLIMB that it is going up or down hill.

This grade information that Zwift sends your KICKR is also what tells it what resistance level to set to represent that hill.

Now in workout ride (rides that have target wattages) Zwift sends specific resistance information to the KICKR based on your Target Wattage and your current Cadence.

Since Zwift doesn’t send information about the terrain in a Workout, the KICKR has no grade change to give the CLIMB. Which is why in workouts your CLIMB doesn’t funtion.

Base the the above information, Zwift doesn’t send terrain information to the Kickr during workout mode, therefore, the Kickr has not grade information to send to the Climb. Does this sound it a feature Zwift can fix?

Can you help me understand why that’s the case? I am making an educated guess and thinking that Zwift uses FTMS to communicate with Wahoo since this is a common open standard. In the Bluetooth specification I see two independent op codes:


Code 0x03 “Set Target Inclination” in section
Code 0x04 “Set Target Resistance Level”

Why can’t Zwift send both codes serially? Would the Wahoo interpret each in a way that they would overwrite each other?

I don’t know, I am not a zwift programmer.

Because wahoo has designed the climb to communicate with the smart trainer. As far as the climb is concerned, zwift doesnt exist. Same for zwift, the climb does not exist. Both recognize the Kickr smart trainer, which acts as the brains in the entire system. Zwift sends gradient to the trainer, and then the trainer sends gradient to the climb.


I understand that but according to Wahoo Support, Zwift does not send grade information when in ERG mode, only raw resistance values. If this is indeed true then Zwift would first have to start sending both values to the trainer so that it can in turn forward it to the climb.

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The question then becomes can the Kickr line of trainers take those two values and know exactly what to do with them without screwing it up (aka can the trainer get that information and not be competing, causing you to enter and exit erg mode on gradients). Zwift would also need to ensure that any trainer that isnt a wahoo would either be recognized and excluded/handle two pieces of conflicting information.

If all of this is possible, the other question zwift has to ask is how many users does this impact? With the current price of the climb, and the Favre it’s only open to wahoo trainers off a certain generation it might not be worth the time.

Yeah, I agree with everything you said. Those are the right questions and maybe it’s not worth it by the numbers if it’s hard but I think it’s worth doing an initial exploration. Time box it to a day or two. Might not affect a lot of people but those that it does affect it would benefit tons.

I think I’ll probably return the Climb. I am not sure without support for structured workouts who the Climb is for. People who are serious enough about indoor training to splurge on it but don’t do workouts?