Very frustrated with power

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1

I’ve posted a few times about this and have yet to get reasonable resolution.  I’ve now done some experimentation and have determined that it is definitely a problem with Zwift, not with my trainers.

 

Here’s the problem.

I own a total of 3 Tacx Bushido Smart trainers.  They’re great units and very convenient as well as powerful.  My son and I ride side by side on Zwift using these trainers.  Prior to that, I was using a CompuTrainer.

 

With Zwift, it always feels like we’re pedaling uphill or through molasses.  Neither of us can get our bikes past the 2nd cog (25t) on the rear with a cranks in the big ring - even down hill!

It always feels like we’re climbing a 3-5% hill no matter what, until the big hills really come and then we can barely move the rear wheels.

Furthermore, in real world climbs, I can easily hold above 300 watts for upwards of 20 minutes.  On Zwift, I can’t sustain 220 for more than a minute or two.  And that’s likely because it ALWAYS pushes against us.  Not a little, but a lot.  

When we encounter downhill sections, there’s still no relief on the brake unit on any one of our units.

On the real roads, using a couple different power meters, I can sprint to 1050 watts (I’m 145 lbs, so that’s not terrible - not awesome, but not terrible).  In Zwift, the highest I can hit is 650 watts.  When I shift my bike up a few gears to go for a sprint and really start putting power into the pedals, the bike feels like I’m pedaling through almost dry concrete with my wheels submerged 1’ deep!

 

We tried TrainerRoad last night and for the first time since we started using the trainers with apps other than OEM, we actually felt what the trainer SHOULD feel like.  In “slope” mode, there were times where we could actually get into the 52/11 and push the bike!  Power on the PM, on the Garmin, and on the trainer all reflected what it feels like in the real world!  I could get into my 52/14 and hold 350 watts for extended periods!

I’m happy to post a video showing the exact problems I’ve had, but at this point, I’m so frustrated with Zwift, I’m ready to just switch to TrainerRoad instead!

Here’s the other pertinent data:

Current firmware on trainers
Using iPad and PC versions of Zwift
10 minute spindown calibration performed
Using both/either the Tacx as well as Stages PMs

 

Help me…this is really frustrating and has made me choose to barely use Zwift at all this winter!

2

Thank you for  posting this issue.

We do have very similar situation. For this winter I bought second Kickr Snap just for me to ride with my partner together. I was so excited and sure it will help me to ride more than last winter since ride together is sure more enjoyable.

Opposite is true - after few rides with my partner  I better “sit in sofa”. There is the reason - my partner start ride usually earlier than me. In moment I enjoy his ride for first minutes everything ( watts and speed) looks good but after few minutes my power shows  numbers I’m never able to hold in real ride and - what is worst- I do not feel I work so hard in that moment. ( up to me - it shows double value and if I stop to pedal - my watts are for several minut around 70.)  

  On opposite side my partner ( who is much much better) his watts value is in the same moment getting on very low level even he push so hard and he is not able to keep tempo with me!!! so in the end - we do NOT ride together what was reason to buy second KICKER.

We try several set ups, this and that - NOTHING help to solve the problem!!! 

Trust me - this unrealistic situation is very, very annoying and really brought me to the question do I really need to use Zwift???

Thank you for any advice and help.

Sona 

3

Wheel-on trainers (like the kickr snap and bushido) are never going to be as accurate with power as an actual power meter. A few things that your posts did not mention- have you done the advances spin down? messed around with the wheel tension?

I use the kickr snap and when i’m not pulling power from my power meter I have to do a spin down after i’ve been riding a bit and often mess with the wheel roller tension to get things working well. Issues like this aren’t really with Zwift- they are more with the way your trainer is interpreting the information Zwift is sending it. 

4

I have a Wahoo SNAP and notice the tension on the wheel is quite sensitive with power.   The resistance can be too high especially if the Spindown calibration is done at a lower tension.   So its important to always tension the tire the same amount.  I now have numbered the knob so I can dial exactly the same number of turns.   So you be able to experiment with calibrating and then backing off wheel tension to fine tune the resistance.  

5

Christian - 

I don’t question their accuracy.  In fact, I have 2 power meters and can compare their accuracy just fine.  Power is not the problem.  The problem is there is always excess tension on the wheel, so as you point out, it’s the information being sent from Zwift to the trainer.  And since it works just fine on all other platforms, this is a problem with Zwift.

Also, in my post, I did mention that I did spindown calibration (which checks wheel tension).  

Again, this is not about power being read wrong.  It’s about the slope data being sent from Zwift incorrectly.  On downhill sections, I can’t move up the cassette indicating that no negative percentage grade is being sent.  On flat sections, I can’t move up the cassette because tension is way too high.  

 

David - 

I appreciate the reply.  Thank you.  In this case, again, it’s not about calibration (which I do every time) or wheel tension.  As I mentioned in my original post, I have tested this on other platforms and have zero problems.  It’s not off by a little bit and it has nothing to do with the power numbers.  It has to do with the fact that every ride, regardless of slope, it feels like I’m climbing a long, steep hill the whole time.  

 

Other platforms I’ve used:

Tacx 
TrainerRoad
KinoMap
BKool (gradients are terrible, but the road feel is way better)
CycleOps

Zwift is the only platform with this issue.  It’s not a wheel tension issue.

6

I have exactly the same issue on my Tacx Bushido. When riding using the Tacx app on my iPhone I can stay easily in the big ring.

However in zwift it seems I have to use the small ring a lot more… only when doing max effort I can really use the big ring…

 

Could this be due to mobile link app?

Has any progress been made on the above?

 

 

 

7

Same here, I also ride a Bushido and have issues with riding the big ring. I have to ride small gears or I get exhausted after 20minutes…

Tom, have you found the solution? 

Is iT a set up problem?

8

Yes, I bought myself a Elite Direto…ftp increased with 20 watts
No issues with big ring anymore and pedal stroke is a lot smoother.

Get yourself an upgrade if you ride frequently :slight_smile:

9

I have same problem when i try and use zwift at the same time as my wife. I’m on a Wahoo Kickr snap and she’s on a Tacx Genius. Wattage seems appropriate to effort if i use train on my own however when riding together the given effort/resistance is much higher for a given wattage output on the screen. Consequently i can’t keep up with her and when doing workouts in ERG I keep ending up in the spiral of death on exercises that i’m able to complete without a problem at other times. I’ve performed numerous spin downs without success.