Momentum issue on dips - new island

(S C) #1

Seems to be a momentum issue related to the steep dip sections on the backside of the new course (loving the new course btw). Based on FB comments it may be isolated to individuals using a Kickr. Essentially, at the bottom of the ‘dips’ your rider loses almost all momentum and comes to a near complete stop. Current solution is to power into the dip section - you still lose a great deal of your momentum but the system then kicks in and creates an almost slingshot effect in which your watts skyrocket up with little effort. I haven’t had a chance to see what effect this will have while riding in a larger group, but I imagine it could complicate group dynamics.  Any chance for a fix in the near future?

(Christian Wiedmann [X] 50) #2

Oh good - I was just about to post this. I know that it’s Wahoo that needs to eventually fix this, but the flywheel momentum issue is particularly noticeable on Watopia because of the more extreme changes in grade.

Zwift - is there any chance you would put in some correction for the flywheel energy for the KICKR as a workaround until Wahoo addressess the issue? Do you have any insight when/if Wahoo is going to fix this?

(Jürgen Waldick ZRG) #3


similar issues in other posts…all KICKR related it seems

(Jon Mayfield) #4

I believe this to be two issues:

  1. Zwift didn’t properly implement momentum. We always suspected this, but the new map made it very apparent.  This has now been fixed and will be sent out in an update very soon.  

  2.  Totally separately, the KICKR seems so responsive to grade changes that it reacts quickly - and it also doesn’t seem to take momentum into consideration.   This is a tougher one to solve, but I have a small workaround that I’ll try and get in before the next update.   In the meantime, the fix to #1 might actually fix this too as your avatar rider wont come to a stop in the dip anymore anyway.

(Ray Martin) #5

Great to see the Zwift team are on the ball! I have the same problem using the KICKR

(Rob Toeppner) #6

Geez, wish I had seen this first.   I posted something similar, noticed around the 8km mark.   It was a particularly aggressive increase in resistance for about 2 secs.

(Christian Wiedmann [X] 50) #7

Jon - I’m pretty sure it’s not just a Zwift issue. The divergence of Kickr and power meter power under acceleration and deceleration is very obvious using a crank-based power meter. I’m guessing that of the 700 watts my Kickr reports coming out of the dip, only 400-500 are real.

Having said that, if the momentum in Zwift is off too, I could see that amplifying the effect. 

(Rob Toeppner) #8

I’m getting a distinct whiplash, or “bungee” effect on the KICKR, which I believe it what the above is describing.   Entering into a downhill dip, I speed up drastically, then hit a resistance wall as I start up.   It only lasts a couple of seconds at most.

For whatever reason I noticed it quite a bit on the ride today.

I don’t have the latest KICKR firmware update, so I’ll definitely do that as well.