Watts and speed so far out


(Mark Chambers) #1

Hi I’m new to Zwift and using as Phisio as recently had knee surgery and torn ligaments.
I’m using a kettler Racer S bike and it cannot connect directly to Zwift so I’m using a Wahoo Bluetooth speed and cadence sensor and have put the wheel size on the app to 20inch as that is the lowest setting. I am only riding flat at the moment and for around 10 minutes my problem is kettler bike watts is setting on 90 watts but Zwift is registering around 235 watts so first ride I was riding at apparently 30+ mph is there anyway to adjust this to be more accurate? As I can’t seem to change it

Thanks mark


(Paul Allen (Watopia Wayfinder)) #2

You need to enter the actual size of tire that you have on the bike that is mounted to the trainer. I highly doubt you are using a 20in tire (it’s a kids bike size tire), so that is the reason you are seeing the abnormally high speed and watts.


(Mark Chambers) #3

Thanks Paul
My problem is the sensor mounts to the hub and the trainer is like a spin bike it doesn’t actually have a proper wheel as such


(Paul Allen (Watopia Wayfinder)) #4

The only way you are going to get any accurate speed and power within Zwift for the is to put pedal base power meter on it (or crank arm if you can find one that will fit).

You could try different wheel sizes to see if you can get a more accurate reading withing Zwift.


(Kevin Ct) #5

Yes just mess with wheel size until it’s close. That will be the easiest and get you riding the quickest.


(Mark Chambers) #6

Ok thanks wheel size 20 inch gives the closest but is probably 8 mph faster and setting on 700c is about 17mph faster


(Gerrie Delport TeamZF) #7

Also the resistance setting on the spinning bike will make a difference.


(Danny Boyd) #8

so the question is; how many races have you done to destroy all the mere mortals?


(Mark Chambers) #9

No one as Like I said at the start I’m riding flat custom course for Phisio for no more than 10 minutes

Thanks for your input


(Mark Chambers) #10

Thanks I did think that but because of the recent surgery I need to keep the resistance lower.