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small gap in the left crankset

3882554
over 3 years ago

Hi everyone,

I received the tacx neo bike smart 2 weeks and been having the following issue. On every pedal stroke, there is a feeling on the left side as if there was a little gap coming from the crankarm and it was very slightly moving. It is happening on every rotation and that's the only thing I can think about (drives me crazy). It happens less if I am being really careful with my pedaling technique and making really nice circles...

I made a video that shows that the left crankarm is moving slightly from approx 135 to 235 degrees (check for the sound when moving the arm left/right)

https://1drv.ms/v/s!Ahs6UdVC8zZBn3fwG9qYm_yf5s4x

I did check the screw already and it is tight.

Anyone experienced this issue?

I bought the bike from Tredz, and waiting for TNT to pick up the parcel for warranty/exchange/refund but wanted to check in here in the meantime if there is an easy fix...

Thank you!

Benjamin

  • 0 over 2 years ago in reply to NeilJonesOnline

    I’ve managed to strip the plastic bolt and have already worked out to my expense the standard hollowtech II bolts are different. Be keen to know if you get a garmin part of if any posters can provide spec/dims/product ref for something that would do the job. 

  • 0 over 2 years ago in reply to SEANEDWARDS1

    Search for "M18 crank bolt".  I purchased one through Amazon.

  • 0 over 2 years ago

    Hi!

    The same happened to me. I had it still in warranty - i got the new unit immediately. So i would recomend that. I bought a new bolt - the problem renewed after 8h. They said that it is a known problem.

    Kind regards,

    Slovenian friend Sunglasses:D

  • 0 over 2 years ago in reply to 1601376

    Thanks. When you say "a new unit", do you mean they exchanged the bike, or do you just mean the cap? I really don't want another bike exchange; it's such a pain getting hold of a bike box and wrapping the old one for return, plus I'm running out of space for all the feet, saddles, handlebars and displays that I still have from my returned ones as Garmin only ever want the bike body back.

  • 0 over 2 years ago in reply to NeilJonesOnline

    Wow, they only take the bike body back. That's interesting because the other bits have value. We use two saddles and for convenience we ordered a spare saddle rail from Garmin at £138, including a new saddle that we didn't want. I guess there must be other users out there looking for spare parts.

  • 0 over 2 years ago in reply to 9077726

    Yeah, I guess it saves them a bit on return shipping and only having to manage the bike bodies when they get back to them. I had considered putting the spares on eBay, but stupidly and for no real reason I'd kind of feel guilty doing so. Plus, I guess it's always handy to have at least one of some of the spares lying around 'just in case', especially hearing how much they charge for a saddle rail!

  • 0 over 2 years ago

    Out of the box I had some slight movement of the left crank arm (in/out perpendicular to the frame) which would cause a slight knock around 12 unless pedaling really smoothly. If I lay my finger on the end of the crank across the crank arm and crank bolt then wiggle the crank arm in and out, I could feel a slight movement of the crank arm relative to the crank bolt. So the movement was there around the full rotation of the crank, but I would only get the knock around 12 just because of the change in force on the pedals.

    Firstly, the stock pinch bolt is not long enough imo and doesn't engage much of the thread. So I removed and replaced it. I used some Loctite blue on the replacement and tightened to 20nm. I didn't remove the crank arm or even touch the crank bolt. The movement is gone and hasn't come back yet, so fingers crossed.

    For the aussies, I replaced the pinch bolt with: Champion Socket Head Cap Screw - High Tensile - M6 x 30mm. Part No: SHM25
    https://www.championparts.com.au/product/shm25/
    They are high tensile, so there shouldn't be any worry about breaking it due to over tightening at these tensions. They are also pretty much the perfect length, engage more of thread but just short of poking through. They are about $6 for 5 pack from any of the usual automotive parts shops (Autobarn, Repco etc).

  • 0 over 2 years ago

    I have the exact same problem,... AGAIN.

    I got an exchange for my first bike and it was very laborious to exchange the body and send everything back to garmin, so that only after ~4 months i got the same problem again.

    Does anyone have a picture of the problematic bolt and or a little how to fix it? Even though i still got warranty, i dont want to exchange the whole bike again...

    Kind regards,
    nordx

  • 0 over 2 years ago in reply to nordx

    There is only two screws/bolt on the left side crank arm. 

    Loosen both the big plastic and the small pinching the arm to the axle.

    Take some electro cleaner or similar and remove excessive grease from axle and inside of the arm. 

    Buy some fast drying Loctite.

    Apply to the inside of the crank arm and the plastic screw/bolt thread. 

    Put back the crank arm, screw the plastic tight and then the smaller "pinching" tight. 

    And it is fixed.

  • 0 over 2 years ago in reply to nordx

    Also check the threads on the plastic bolt.  When my crank arm loosened up the threads stripped and the bolt fell off on it's own.  You can buy aluminum versions online that will replace the plastic one.  Search for "M18 crank bolt".

    The end bolt should be tightened first and it is only meant to hold the crank in place while tightening the pinch bolt on the crank arm.  The pinch bolt needs to be tight and should be tightened with a torque wrench to 20 N-m.  

    Since replacing the plastic bolt and torqueing the pinch bolt I have not had an issue with my cranks.