Power to Weight Ratio Errors


(Ryan Christianson) #1

My son weighs 33kg, but he was doing an FTP test and during the warmup at 70 watts, it shows his power to weight ratio at 1.5.  Why does it calculate like this.  This also happens at all other power levels too, we were just able to test it during the FTP workout test.  He struggles to keep his power over 3 watt/kg on rides, but I know his real ratio is actually much higher based on the power that it is reporting.  Seems like a simple calculation error.  Could it have to do with his lower weight?Thanks!


(Lindsay Ruppert) #2

Hey, Ryan -

Right now our minimum weight limit in the game is a bit higher than your son’s weight, and his w/kg ratio is based off that minimum. Rest assured, we are aware of the issues with our growing base of minor riders, and are working out how to better support them (and other petite riders) in the future.

Ride on!


(T acoma Cyclist (LVE)) #3

Glad to hear this.  My son is in the same boat.  He’s putting out tons of power and is demoralized to see that his w/kg is too low.  


(Maryka Sennema) #4

Hi, new to Zwift and joined (paid for subscription) in big part because my BMX-racer 6 year old loves the turbo trainer and was dying to give Zwift a go – and as there’s a free kids’ account for a paying adult’s, it as a no-brainer.  Great programme, wish I’d given it a go earlier mysefl!

However, her first ride with me sitting beside her watching the screen and I can see her w/kg are way too low for her weight.  She’s not on the game to compete, not going to fly past anyone with any serious intentions but it doesn’t seem fair that she’s penalised for being a lightweight kid!  What’s the minimum weight, as 20kg is obviously too low?  She’s barely crawling along, even with the wheel size set to 700x32 (her actual wheel is 20") and finds it frustrating seeing her avatar constantly stopping and climbing off the bike because the speed drops too low.  It took her 40 min to do a lap. 

Yes I know this is predominatly an adult’s cycling game/training system, but it seems silly to offer free kids’ accounts to under 13s then require their minimum weight to be 40kg?  Aren’t most u13s way under that weight?  If the problem is weight-cheating adults, then maybe a flagging system like Strava is a better way to solve that than to penalise small adults and kids?


(Karl Starling) #5

Hi, My son is in the same boat.  He has raced for 3 years, but only weighs 33kg.  His watts per Kg at the 45kg weight limit really affects him.  As far as cheating adults are concerned, who are they cheating.  I race in the real world and weigh 76kg, yes I could cheat and enter my weight at 70kg but what for.  I want to be pushed to my limits, not make it easier for myself.  I suggest anyone who uses Zwift for training for races would want their correct power to weight.

Anyway, if you could reduce the minimum weight to be lower than 45kg that would suite all the smaller riders you have out there.