After another 100 mile ride some oddities I've observed


(Jeff Hirsch) #1

The biggest issue I noticed is that it seems to miscalculate speed in some instances. For example, I’'ll be climbing the hill with a few folks all together. Then after we crest the hill, one or 2 people at say 2.5 w/kg move ahead by 1m - 2m even though I’m at 3.2 w/kg. I keep my pace going but can’t seem to catch back up unless I kick it up to 4+ w/kg.

I’m on a computrainer, and I’ve observed this even with one of my buddies who is also on a computrainer. I’ve also done 10 laps with someone (not sure what trainer they were on) where this NEVER happened even once.

My only guess is that it’s somehow overstating the impact of weight when going downhill. I’m pretty light (138 lbs), so I’m thinking maybe it makes me put out a ton more wattage to stay with heavier folks going down hill. Still 3.5 w/kg and still get dropped by folks doing 2.5? That seems way off.


(Eric Min) #2

This is something we’ve noticed as well. We’ll be tweaking this in the coming weeks!


(Ron Sines [odz] B) #3

I rode a couple laps with my wife’s profile last week, and could really go up the hills without much effort, easily keeping up with other people on the road, but when it came to the descents I really had to get on it to catch up, She weighs 125lbs, I haven’t noticed this with my normal 178lbs avitar.


(Eric Min) #4

I weigh 160 and I notice it so it needs some tweaking. Thanks for the feedback.


(Craig Pate) #5

Plus CTs always have load on even on downhills…same issue in RacerMate1. Other smart trainers seem to have addressed the downhills more accurately.


(Brian Cheung) #6

@Ron: That isn’t surprising. A lightweight rider will require fewer watts to ascend a given slope than a heavier one. Similarly, a heavier rider will descend a given slope at a greater speed than a lighter one (all other variables controlled, e.g. CdA, rolling resistance, etc.)


(J Schaeffer (AMOROSO)) #7

As a heavier rider (82 kilos for me and the bike) I would expect that some time lost on the way up should be made up on the way down (hey, we need the help!). But my experience is that I get a bit too much help on the way down. Great for the current downhill sprint though…


(Michael Henasey) #8

I’m 5’7" (~143lbs) and “fearless” on downhills according to people I often ride with. I’m the first down, often way ahead of the “heavier” riders. With my size, I can get low, small and more aero and make up for the gravity advantage heavier riders have. So in other words, I don’t think weight should give such general, across the board, advantage to “heavier” riders.


(Stewart G teamWBR) #9

It doesn’t really give that much of an advantage to be honest. The downhill parts are so short (CCW) and you only gain a few seconds but will have lost a lot more on the way up the hills. Give the fat boys(I’m one) a chance.lol


(Brian Cheung) #10

I’m 5’7" (~143lbs) and “fearless” on downhills according to people I often ride with. I’m the first down, often way ahead of the “heavier” riders. With my size, I can get low, small and more aero and make up for the gravity advantage heavier riders have. So in other words, I don’t think weight should give such general, across the board, advantage to “heavier” riders.

That’s great! Unfortunately there’s no way for Zwift to know how aero you are. With the data measured, Zwift has to make certain assumptions (your overall CdA being one of them) and aerodynamic resistance will not be as responsive or representative as in real life.


(Michael Henasey) #11

@Brian, yea I realize there’s no way to accurately calc. CdA for everyone and that’s why I said that maybe the game shouldn’t just give heavier/larger riders such a noticeable advantage simply based on their weight. The difference should be more subtle.

I feel the same way about drafting, specifically when someone passes you and there’s the very significant and noticeable “pull” that “sucks” you towards their wheel. Again, I feel this should be more subtle and not so instantaneous. At least that’s my perception of it.


(Duane Gran [Vision]) #12

I also ride a CT and weigh around 143lbs/64kg and I’ve found that I need to really punch it over the crest of hills in order to keep pace with others even if they are going steady. It is good practice though! Craig is right about the resistance factor. Sometimes I end up working harder on the downhill sections, which is quite unlike the outdoors.


(Jonathan Pait (X)) #13

Amen! Stewart Gemmell.


(Timothy Salkauskis (QCW)) #14

I agree with Jeff. CT paired with zwift definitely have some ‘kinks’.

  • overestimation of resistance on transition to downhills and flats. Everyone else seems to rocket off while I’m laying down 4+ watts/kg and then coming off the downhill I grind to a halt. In real life while sitting upright coming off a 6% gradient hill I don’t go from 40mph to 24mph in a few hundred feet.

Hoping this gets solved soon!