Wahoo kickr18 Design flaws?

See the problem of shaft corrosion on the network,Kickr18 vibration and noise, is it just a matter of time?Look at the frequency you use, maybe 1-2 months, maybe half a year?

Article Source
https://www.cyclechat.net/threads/wahoo-silent-kickr-kickr-core-faults.241225/page-17

This is a picture I took the other week. I’ve had problems with vibration lately. The trainer is about 6 months old. I solved the vibration issue buy putting loctite on the axle, new SKF-bearings is in their way. Seems like a good idea to also put some grease on the shaft.
https://photos.google.com/photo/AF1QipMUCntSx8DVF1ZCkeN7emck2FqoxCvwx5adrSCV

As an engineer I’m surprised that Wahoo could screw-up such a simple construction.

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Thank you for your method

Glad if I could help!

I might as well expand on my thoughts regarding how I (temporarily?) solved my issues.

First a word on why it is made the way it is; Since the Poly-V pullies must line up with each other any axial play must be taken care of in the other end of the shaft, hence the wavy washer on the flyweel side. For that solution to work the left bearing must be able to float on the axle. With better manufacturing tolerances the axial play should be possible to be minimize so the washer could be omitted.
Over time this play seem to have increased with vibration resulting in vibrations. I guess the bearings also has loosened adding to the problem. My solution interfere with the original construction since the left bearing can no longer float. This is not a problem since the width of the base is fixed and is probably only a way to take care of variance in the manufacturing process.

The corrosion problem should be easy to solve putting some light oil or grease on the shaft. I’m surprised it has started so soon but if corrosion wasn’t one of the original construction parameters it could happen really fast in a sweaty “pain-cave”.

I just want to make sure anyone who tries this understands what they are doing since attempting what I’ve done potentially voids any warranty.

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Tomas,

Does the heavy flywheel create a combined load (radial + axial) on its supporting bearing? If so, does it make sense to replace the deep ball grove bearing with an angular contact bearing?

Thanks!

The shaft in my Core looked pretty much like that (photo in first post) when I pulled it all apart. It started to sound a lot like a didgeridoo a few days in to NZ lock down (a total lock down - no chance of getting it looked at or replaced for what turned out to be 7 weeks, by which time there would be no chance of a replacement for months so I just kept riding it). It was almost a year old, and probably just out of warranty by the time we came out of lock down.

For some reason I couldn’t get the bearings out at all, they seemed stuck fast. They were a bit grumbly to turn but really didn’t seem that bad. All I could do was spray them with CRC and put a bit of grease on the outer of the bearings. I greased the shaft as well and made sure the woodruff key was correctly in place just in case that was any part of the problem. And then for some reason the shaft would NOT go back in. I had to file it down. Probably part of the problem in the first place. It sounded exactly the same.

I’ve just replaced it with a gen 5 so I’m back to having a quiet trainer, and will pull the Core apart again at some stage and see if I can do any better without the fear of being without a trainer. Unfortunately I’ve already seen reports of issues with the gen 5.

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I’d say no, there are no significant axial forces to consider. The fact that the flywheel is positioned offset doesn’t impose any axial forces, if that was the hypothesis. I have replaced my bearing with high quality SKF bearings of the same type and put some Loctite where they are seated to keep them in place as the tolerance allowed the flywheel side bearing to fall out if the trainer where to be tilted sideways, which is to loose imo and could add to the radial play in the system increasing load on the bearing.

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Thanks for the input, Tomas!

Since I decided to fix my Kickr by myself here in Brazil, I spent some time learning about bearings, loads, shafts, fits etc. I’m not an engineer, but your thoughts about the causes of vibration are the most plausible from all the research I did.

I already bought SKF bearings to replace the original ones, but I’ll do something else in order to try to achieve a permanent fix: a new shaft made with high quality material and better tolerances.

I’m not sure if I’ll keep the original design (clearance/slip fit) with the flywheel side bearing, go to an interference fit like you did with loctite or, maybe, somewhere between the two (transition fit). The shaft is being fabricated by a shop specialized in precision motorsports parts, but any thoughts are very welcome!

As this project goes on, I’ll get back with my progress.

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