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I have purchased a Coho XC trailer to use with my 2021 Orbea Avant H-60 (disc brake) bike.

I ordered a Burley Thru-Axle after following the Burley axle guide, but on attempting to install it (without applying excessive force) stripped the threads of the axle (luckily no damage to the rear derailleur hanger).

Left is the Burley Thru-Axle, right is the stock Orbea axle.

enter image description here

It was at this point I realised the issue: the Orbea axle is double-lead (Mavic Speed Release?) but the Burley axle is single-lead.

It does not appear that anyone manufactures a Mavic Speed Release compatible Burley Coho axle. I am not able to return either the Coho XC nor the Burley Thru-Axle. I see the following options and would love advice with respect to them as well as any additional options.

  1. Sand/drill the derailleur hanger thread smooth, meaning the only thing keeping the axle on the bike would be drive-side bolt (would thread lock help here?).

  2. Use a helicoil thread repair kit (like this?) on the rear derailleur to drill out and insert a new thread. So far this seems like my best option.

  3. Find/manufacture a rear derailleur hanger with a M12x1.0 thread. Nothing seems available so far.

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The Helicoil option is a good one and should work fine. For that application you should use high strength threadlocker on the outside of the insert. That means getting the new master threads fully degreased, applying the threadlocker and the insert, letting it cure 24 hours, then cleaning the inside of the insert thoroughly and using a pick to remove any threadlocker that seeped through into that area. Then grease the axle threads. Retraction of Helicoil inserts is never hugely probable, but it would be such a disaster in this case that you want to minimize the risk.

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  • Amazing, thank you so much. Just to be clear, is acetone sufficient to prepare the surfaces? And red thread locker appears to be the permanent stuff, would you recommend that? Thanks again
    – Ferdia McKeogh
    Commented Mar 6, 2023 at 15:04
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    @FerdiaMcKeogh Acetone would probably be fine, anything that degreases and doesn't leave a residue. The red "high strength" type threadlockers are ideal for something like this. In practice medium would probably be fine too - helicoils have spring tension and don't "want" to come out, but getting a little bit of extra security against it coming out randomly when you get a flat in the middle of nowhere would be good. Grease or anti-seize on the axle is important too.
    – Nathan Knutson
    Commented Mar 6, 2023 at 18:25
  • Perfect, really appreciate the help!
    – Ferdia McKeogh
    Commented Mar 6, 2023 at 19:47
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Helicoil solution works!

First drilled out the rear derailleur hanger:

enter image description here

Then tapped:

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Then re-assembled with helicoil and lithium grease, with appropriate number of washers to correctly centre the ball mounts:

enter image description here

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