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Broken Wahoo Kickr – How Bad?

What happens if your Wahoo Kickr breaks and you keep riding it?

Kevin Biggs managed to get a cheap Wahoo Kickr that the original owner had listed as damaged and needing repair.

This Kickr had suffered the classic loose woodruff key which led to lots of banging and clunking when the trainer was used. The loose key means that the bearings can move in a way they aren’t meant to, which means they eventually fail.

The following images and words are from Kevin.

The guy ran the trainer for me and it had the usual clonking noise. When I got it home and the cover off it wasn’t obvious what the problem was. I had to hammer the fly-wheel shaft through using a sacrificial bolt screwed in to hit.

Broken Wahoo Kickr - How Bad?
Broken Wahoo Kickr – How Bad?

Once the pulley and bearings were out it was fairly obvious; the drive side bearing had seized and the v-belt pulley had worn into the bearing.

Broken Wahoo Kickr – How Bad?

You can see how the pulley has profiled to the bearing and worn the bearing seal and race, and how the two fit together perfectly!

As the fly-wheel shaft had been spinning on a seized bearing, it had also worn a groove in the steel of the shaft the width of the bearing.

Broken Wahoo Kickr – How Bad?

To complete a ‘temporary’ repair, I shimmed the inside of a new bearing with a thin sheet of copper and put a crush washer on the pulley side of the bearing. I filed the back of the aluminium pulley to remove the burrs and get it flat, also needed to file the key a little shorter so it didn’t protrude beyond the locking surface of the pulley.

Broken Wahoo Kickr – How Bad?
Broken Wahoo Kickr – How Bad?

Reassembled, it runs great, although the crush washer is a little too wide and the pulley just rubs against the cover; so I’m running it with it off at the moment. So I’ve done a few miles on Zwift and it running smooth and quiet, long term repair will be to rebuild the diameter of the shaft with JB Weld and remachine, then install with a shim washer to centre the pulley on the belt line.


  1. Fernando

    Hey!! I has the dame problem Authy the será out of the axis. I refilled with Stainless steel welding and bored down to design measure. Installed new bearings and voila!
    I am looking to build the pulley on steel to avoid future worn out.
    Anyone know how to take the axle out of the weight wheel ?

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      It’s a press fit.

  2. Louis


    Having the exact same problem with my Kickr – How long lasting would you say the crush washer and shim setup has been? I could realistically do this myself, but unlikely be able to do any axle remachining.


  3. Stu

    I’d recommend to anyone who has the above problem to get a new shaft machined put of EN8 steel. There’s nothing technical about it, it’s a stepped shaft with a keyway and tapped hole in one end. It won’t cost the earth.

    It’s such a shame that the pulley on the flywheel shaft is so small otherwise I’d have modified mine to a Tollock locking bush and omitted the key and bolt / washer completely.

    PS mild steel / stainless steel is not a suitable material for a Wahoo Kickr flywheel shaft.

    If you do go down this route, re-tension the belt fairly loosely and have the bike set up on it. With the pedals at 3 and 9 o’clock positions, crank down as hard as possible. Be prepared for the pedal arms to slip.

    Keep tensioning and repeating until the slipping stops. In my opinion a lot of Kickrs come tensioned WAY too tight from the factory, don’t underestimate the damage an over-tensioned serpentine belt can cause.

    Perform the full factory calibration upon completion.


    There’s company from Taiwan advertising shaft replacement with a new aluminium pully wheel, bearings and fittings. You’ll need facility to press out old shaft and new one in. Search for “Custom shaft/axle replacement kits with NSK 6003 bearing for Wahoo Kickr 4 2018+”

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      It is $180 though. If you catch the bearings starting to fail early then a new shaft and pulley shouldn’t be needed. I’ve done around 10 or so now and as long as you stop riding it once it starts making a noise then all is good.


        Totally agree, but if it’s gone too far and warranty claim not an option it could be useful. Unfortunately they don’t supply the aluminium pulley as a standalone item. I’d already carried out the repair as noted in your post. It worked great for a good while and whilst it wasn’t making any noises, it started to slip under load. I’d bought the old unit as a repair project but the previous owner had chewed a couple of the grooves on the bely pully. Although I cleaned it up, it started to chaff the new belt. This “might” have been the cause of slippage, but it may also have been an “electronics” issue. I decided to cut my losses and took the wahoo discounted replacement option at £250 (GBP) with 3 months warranty. If the aluminium pully had of been available separately I might have tried it out. Phew, that took a lot of telling lol.

  5. Garry Foster

    Custom shaft/axle replacement kits with NSK 6003 bearing for Wahoo Kickr 4 2018+ search ebay for this, will require press out and in for new

  6. Gosy

    hi is there a chance to buy the steel pulley (left near the bearings ?

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      Wahoo don’t seem to sell spare parts. Which is a real shame given the price of each unit.

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