Setting the correct tire size

(TJ Ooms) #1

I got bored of my numerous indoor training sessions (recovering from an accident) with just music to listen to, so when I found Zwift a whole world opened up, thanks!

As it states a simple speed sensor and ANT+ dongle is sufficient to ride. My problem is is that I have a spinningbike set up at home and since Swift assumes my wheelsize is 700C, which it isn’t cause I got a small flywheel, the speed is messed up big time (like 210%).  Somehow that also seems to mess up my cadence which I don’t understand.

Is there anyway to let me change the wheelsize (or any other setting to get the speed in order)?

(Matt Canna) #2

Is it the magnet based?


Or garmins hub style.


If magnet based then you will need to borrow a garmin head unit or similar, to calibrate and flash the firmware in the unit.


What you should do is just this pack.

(TJ Ooms) #3

I got a GSC-10 installed on the spinningbike connecting to a Suunto Movestick. Your saying I can tweek the internal firmware of the sensor?

My regular bike is rigged with Polar sensors and headunit. Basicly I only got the GSC-10 to connect to Zwift :slight_smile:

(Matt Canna) #4

Yeah.  just see if you can borrow a garmin

(TJ Ooms) #5

No luck so far. Haven’t been able to get my hands on a headunit.


Nobody knows of a simple software program I can run to get the correct settings going?

(TJ Ooms) #6

I got my hands on a head unit, calibrated, but it didn’t solve my issue. Seems like Zwift uses a default tire size which doesn’t come close to my trainingbike.

Free Trial is ending, so won’t really be an issue after that, I will be looking into different software until this gets fixed. 

(B V) #7

+1 on this. Training on an old mountainbike (650B), quite disheartening