Mtn bike spin out

I’m looking for help. I have a 1x12 gearing on a trek mountain bike. I have on my wahoo kikr that seems to spin out when I’m racing my top gear is 36 x 11. is there a way to adjust the kicker so that I’m not spinning out during races?

Unfortunately, in the drive for realism, Wahoo and Zwift are accurately recreating the fact that even in real life, 36x11 is a low gear if you’re racing against others who will be using more traditional 52x11 road bike gearing.

Its great gearing for rough terrain and climbing but not for flat tarmac. So until Zwift add a bunch of off-road races, if you really want to race you might be better of getting some second hand road bike for you indoor machine and save the nice Trek for outdoors when allowed.

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Mark. Thanks for your reply. So nice to hear an honest answer.


People just change the wheel circumference in the Wahoo app. Not sure what they use but a few posts here might mention specifics.

Also make sure you are 100% Trainer Difficulty in your settings.

I looked there but the range in the Wahoo app on Android appeared to be limited to real sizes. Going for 29ers will only compensate a little (and it would undo the fact that the Trek at least has stonking gears for going up Alpe du Zwift).

If that can be done in another interface then worth a try.

Tks. I’ll look for a road bike.

Nuh you just manually type in 3 in wheel diameter (custom setting) and its all good as normal. Some people say that 2.75 also works fine too but I never tried that.

Having said that, what a faff having to put the bike on/off trainer! I lasted about a week before I popped a dedicated bike on so I didnt have the hassle of my mtb’s not being ready for a quick spin - best bang for buck if OP finds a bargain.

Duh! So busy scrolling the list of different wheel sizes, I didn’t spot the custom option at the top. Yes, that’s worth a fiddle to see the effect. Nice one.

Thanks for your response. Lastly, how do you change your wheel circumference?

I can’t find anything that has you change it.


I’ve got an old MTB permanently mounted on my trainer and was having the same problem, so I changed the crank for a road one with a 50T ring, it all works perfectly with the rest of the MTB drivetrain. Another option for you if you don’t plan to ride the bike outdoors again.

Thanks Mark. unfortunately I’ve got one of those one bys cranks where a 50 tooth would not work with the chain stay.

I’ll look to change wheel size…you say it’s on the wahoo app?

Tks again

Open up the Wahoo app, and once the Kickr is highlighted (sensors found), tap “Kickr”. On the following screen you will have Kickr name, current power etc. Scroll down until you get to “Wheel circumference”. You will get a lot of standard wheel sizes to select from or you can enter a “Custom Size”.

In the Wahoo app on Android, click Settings / Sensors. Click > next to Kickr and click Wheel circumference.

You’ll see a scrollable list of common wheel sizes, but right at the top you can enter a size of your own.

Thank you.