Wahoo Kickr Bike and Zwift Workouts

General Discussion
#1

I just acquired a Wahoo Kickr Bike as an upgrade from the Snap. I am very happy with the Bike, except that it feels very different when used during Workouts. The transitions of power between segments are very awkward.

While using the Snap, the transitions felt very smooth as you could use your inertia to lean into the segments with increased power, and, slowly ease down when the power decreased.

With the Bike, it feels as if there is no inertia. When the power goes up, the brake just seems to grab the wheel and immediately slow your cadence. When the power goes down, the brake releases and your cadence awkwardly jumps until you slow yourself down.

Are there any settings I am missing that might help me improve the Workouts experience? I really enjoy the Workouts and Training Plans and am not sure I should keep the KICKR Bike if this is the best Workout experience I can expect.

#2

CT, I have a Kickr Bike, too, and really enjoy it.

Concerning your question, are you referring to workouts in ERG mode? The reason I ask is that the machine is trying to keep your power delivery pinned to the target value. Since power = force x velocity, you will have to deliver more or less force depending upon the cadence that you are pedaling to keep the power constant. This isn’t a bad training technique since it forces you to maintain smooth pedaling technique. However, if you slow your pedaling, the amount of force required on the pedals will get VERY large!

Of course, you can turn off ERG mode, either by doing a group ride/free ride/race on Zwift or by explicitly turning it off using the menu option on screen or in the companion app. With ERG mode off, you should feel the smooth inertial of the Kickr Bike flywheel.

Finally, if you want to smooth out the hills in Zwift, you can adjust the trainer difficulty in Zwift. Think of that setting as an inertia knob on the climbs. I personally don’t like doing that and set it to 100% (Max) setting.

#3

Thanks for the response. I understand what you wrote and how the power and cadence interact while holding a steady power target in any given interval on Zwift Workouts.

My concern really has to do with the changes from one interval to the next. More specifically, if I am riding an interval at say 150 watts, which is followed by a power sprint interval at 400 watts, the transition between those intervals is very awkward. It would be like free riding on Zwift at a gradient of 0% and then suddenly hitting a 12% gradient without moving through any gradients in between.

This transition is much smoother on the Snap. I am hoping that I can figure something out to improve the experience.

Would it make any sense to turn ERG off while riding in Workouts?

#4

OK, I understand your issue a bit better. First off, I would NOT turn off ERG mode. That’s the whole enchilada when doing prescribed levels of effort defined by power. As for the ramp-up or ramp-down between intervals, I don’t have much to add. I did a Threshold workout this morning with intervals, and usually I get mentally prepared as I see the banner for the next change in power. When it is a big jump in power, I typically up my cadence above 90 rpm, which seems to help with the transition. If cadence is lower, I find that the transition can be a bigger shock. Sorry I can’t offer any other help.

#5

Yep. The problem happens when the prescribed cadence for the interval is 110 at 400 watts and you are coming form an interval at 200 watts and a 90 cadence.

When you start ramping up the cadence above 90, the resistance decreases to keep you at 200 watts, which exacerbates the awkwardness when you immediately find yourself with a massive change in resistance as you continue to work your way up to 110 cadence and 400 watts.

I am not sure if this is something that Zwift can help with to make the power jumps more gradual, or, whether Wahoo needs to adjust how rapidly the braking can be applied to the flywheel.

#6

I’ve had a chance to do some more riding in both Workout mode and Free Ride and reached some conclusions.

ERG Mode does work fine with the KICKR Bike in Workout Mode, except when there are short hard sprint intervals.

If I am doing a HIIT workout with these types of intervals, it is best to turn ERG Modes off for those intervals.

ERG is easy enough to toggle off and on that there is no problem turning it off and manually shifting to meet the Watt targets for short (i.e., 30 seconds or less) sprints and then just toggle ERG back on to help produce a steady Watt output for longer intervals.

#7

CT, my solution to this problem is to keep an eye on the intervals, be aware when a rapid power increase is coming, and start ramping up the cadence some 4-7 seconds ahead of time. If you bring your cadence up to 95-105 by the moment of transition, you will be able to withstand the rapid power change. Try it! 200 watt to 400 watt works fine with this method.

The second factor which helps is to set power smoothing to 3 seconds in two locations: one in Zwift, the second in Wahoo app on your phone, on your Kickr Bike page. I have the impression that when power smoothing is on, especially on the bike itself (i.e., set up through Wahoo app), the transition from low to high power and from high to low takes a little time and is easier to handle.