Power loss in zPower

(David Lusty) #1

Hi all, I’m using a Tacx Booster set to level 2 as per requirements. Today I did the sprint in Watopia and to my surprise the power went down as I pedalled harder. It seems to be that above 110 rpm the power dies off fairly predictably. I don’t have a power meter to check against so I guess my question is - does the trainer resistance tail off at this high speed? I’m in top gear at the time so pretty high speed wheel movement. As I said it’s predictable in the app so it’s either a weird power curve for the trainer or a weird trainer. Unfortunately no other levels are available otherwise I’d just pop it up to 3 or 4 on the trainer and use a lower gear to put out the power.

Thanks all

(David Lusty) #2

Just in case anyone stumbles across this and has the same issue, I opened a support ticket and it turns out that Level 2 on a Booster doesn’t go any higher on power. At the time of writing there are no other levels for this trainer and Zwift don’t currently have the resources to add more (but said they hope to in future).

(Andreas Maninakis) #3

As a user for the same trainer, I came across the same issue. It would be nice to select the difficulty setting in the set-up screen.

(Malachy MacCarthy) #4

Also using the Booster.  First ride so I just set it to level 4 and then on hills I set it to 6 or 7, I just assumed that would be how it works!  But then my avatar only does 5kmph going uphill.  I’d assumed that they’d have all of the power curves for each setting.  Tacx and Zwift should get together on this, it can’t be too hard to do?

(Thomas Fritscher) #5

Is second the need for a different booster setting. Maybe just let us choose between 3 and 7 or something. 

… And Malachy, what you are asking is hard since there is no way Zwift can know about your Booster setting …

(Malachy MacCarthy) #6

Sorry I wasn’t clear, what I’d like is for the Zwift course to suggest me a resistance level for the Booster as the course gradient changes.  Then if you follow that they do know your setting and there is a power curve for each setting so they should be able to calc the zPower.  It just doesn’t make sense to keep the trainer on one level at all times as it isn’t a good workout plan to have no variety on resistance.

(Thomas Fritscher) #7

Hi Malachy, I don’t think this is necessary. I keep my Booster at level 4 which is enough for me from regeneration to slow cadence power workout. The resistance is done by shifting the bikes gears. Changing the Booster setting mid workout seems clumsy and (unless you do it at the exact time every time) you loose the ability to compare workouts.

(Lukas Durand) #8

Hi there,

New to Zwift, also using the Booster, but I do not have a powermeter. Set it to “2” as described, but the power numbers in Zwift seem way too high. If you look at the curves on the Tacx website (https://www.tacx.com/de/products/trainers/booster), the power numbers seem to be those of setting “3”. Have changes been made recently?

(Daniel Ullmann) #9


I do not understand, why Zwift does not include an option to select the trainer resistance. Since Tacx publishes the power curve (approximately) this should really be no problem! It’s really annoying that wattages above ~380W are not “available”…

(Harmen Faber) #10

I’ve got the same issue with my Tacx Booster. Is there a way to tweak this by playing with my weight?

like this: https://drive.google.com/open?id=0B7B-iHM-DqJ-MWttVHpNSDY3Um8