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Grunting / Whump Whump Sound

The grunting sound began appearing some time in mid-2018, and while not as common as some other reported issues, it is a well known problem.

Example of the grunting noise commonly reported
Video Credit: Justinas Striška

Root Cause

This noise is caused when the inner race of the inboard bearing of the Neo disc is dragged through the rotation by the disc. This is because the axle diameter is slightly too small for the bearing, and this allows the inner race to move.

By installing two o-rings on the axle, you add a friction element between the inner race of the inner bearing, and the axle attachment point inside the Neo. This additional friction prevents the inner race from moving, which then quiets the grunting sound. It is a very simple fix, and takes fewer than 5 minutes.

Steps To Resolve The Issue

  • Make a short video like the one shown above, and send it as an attachment to support@tacx.com
  • Tacx support will reply within two business days to let you know how they would like to proceed, and usually they will send you the o-ring repair kit shown later in this article.
  • While you’re awaiting the arrival of the o-ring kit, you can absolutely continue to use Neo without concern about damaging it. It is a minor friction sound that you’re hearing, and won’t harm the Neo.
  • Once your o-ring kit arrives, remove the disc with the extractor tool, and install the two included o-rings on the axle, one behind the next, in a stack.
  • Replace the disc, and enjoy your quiet Neo.

What’s Included In The O-Ring Kit?

  • 1pc of Din 933 M16x70 bolt
  • 3pc of Din 912 M6x25 bolts
  • 2pc of O-ring, thickness 2mm, ID 24mm, OD 28mm.
  • Disc extractor Tool outer diam. 97mm,height 66mm
    pitch circle diam. 84mm (to mount the tool with the 3 Din912 to the disc)
Photo Credit: András Beck
Updated on December 3, 2020

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    1. Thanks for the comment, Magnus. We want to make sure our content is absolutely perfectly accurate, so we’re waiting for additional information from Tacx before the video is published. Due to the holidays, it is taking longer than normal to get replies from Tacx, but we hope to have the video up in the next two weeks.

  1. Are there instructions where to o-rings go? My Neo2 started to make the noise and I have the tool and new o-rings from my original Neo.

    1. It’s very straight forward. Just slide the o-rings onto the axle as far back as they will go. When you replace the Neo disc, it will push the o-rings into position. There is nothing technical for you to measure or align.

  2. I have this exact issue on my Neo 2. Hoping to get it resolved soon with tech support. Its nice to see there is a solution.

  3. Still no video –
    Once your o-ring kit arrives, remove the disc with the extractor tool, and install the two included o-rings on the axle spindle (see video below)

    I do not see an instructional video on the YouTube page as best I can tell.

    1. Hi Paul,
      Yes, we had a video up but it was sort of nonsensical, as the o-rings simply slip onto the axle in a little stack, one behind the other. The video was superfluous, but thanks for letting us know. The article has been corrected.

  4. Hello,

    Thank you very much for the faq, I didn’t know it.
    I have encountered this problem since I bought the neo in June 2018, at the time I contacted Tacx and they never gave me a solution, and they sent me automatic responses unrelated to my problem, so I dropped it and I used little neo.
    Since the coronavirus, the neo has returned to service, now I know that this noise is not normal and that I can finally have a silent neo.
    So I contacted Tacx 2 days ago, and I had an automatic response again without any specific link to my problem.
    My neo is still under warranty but I find that Tacx makes no effort to give me a solution and send me the modification kit.
    I do not know what to do, for the moment I use it, but I would like it to be quieter.

    Thank you for your iade

    1. Hi Raphael. I’m glad you found our site!
      It may take some time for Garmin to reply right now since many places are on lockdown quarantine, and each region has its own support. Your response will vary depending on where you are located. It make take several weeks, so please be patient.
      Make sure you include a link to our article in your email to them, and as suggested, make a video of the sound that your unit is making.

  5. Hello, I think I have the same noise in my Tacx neo 2, where I have to send the video I made? I need the kit, to solve it.
    Thank you.

    1. You can send email directly to Garmin support. Their address is product.support@garmin.com
      It ordinarily takes upward of a week to get a reply, but with most places on lockdown, I am not sure how long a reply will take.
      Be patient.

  6. Hi

    My Neo 2T just started making the same noise, but I have only noticed it on free run. Do you think it is the same issue?


    1. Hi Mikkel. So many sounds are very similar, and there have been dozens of instances where folks went down the wrong path because they thought their sound was the same. Therefore, we don’t ever guess about what yours might be doing unless we have a video of your unit.

  7. Hi Drew,

    Great site thanks for your work. Long time Tacx user/Fan still got an i-Magic as backup unit.

    I think my Neo is 2017 or maybe older has now making occasionally making the Whump Whump Sound. Is the unit still in support?

    1. Hey Lee. Any chance you can post a video? So many of those noises are similar. It would be weird for the whump whump noise to develop over time. It usually happens straight out of the box, so it may be that something else is going on with yours.

      Your Neo won’t be supported, but we might be able to help get to the bottom of whatever is going on.

  8. Dear Tacx team,

    I have problem with my Tacx Neo trainer smart – Grunting / Whump Whump Sound.
    I tried to send video file with Grunting sound to product.support@garmin.com, but it is not working.
    I hope you will find solution for that problem.
    I hope listen soon from you.

  9. I’m getting the pig grunting noise now. Unit seems to have been fine or I have not noticed the noise too much before. Changed the cassette yesterday and now have the noise real bad; have taken the video and will send to Product support – I hope its an easy fix. I’m running a late 2017 Neo.

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