Thru Axle Annoyance: Orbea/Tailfin/Ortlieb

[Boopop]

Riddle me this. Why would the top two thru axles thread in (front, rear Tailfin) to my 2021 Orbea Orca, yet the bottom one won't? It's an Ortlieb thru axle for their quick rack. They're all M12x1.0, supposedly. It just doesn't bite in to the thread, wheel in or out.

On the bright side, in the face of minor adversity and frustration, I haven't damaged my frame trying to jam in the Ortlieb axle (as in, I didn't try to jam it in).

 

[bikingdad90]

Have you cleaned out the threads in the bike frames? Maybe there is dirt in the other two which allows it to bite?

 

[wafter]

The thread on the end of the Ortlieb item looks a little shiny, suggesting something's not happy.

Have you inspected it to ensure that the leading thread isn't damaged, and tried a vernier over the OD to check it's not oversize?

 

[Boopop]

Thanks for the replies, someone on Reddit explained it to me. My Orbea uses double start threads, as are the original Orbea and Tailfin thru axle. The Ortlieb axle is single start. I'm going to return all the Ortlieb stuff and get a different Tailfin rack instead.

Really quite irritating, Ortlieb licence the axle tech from Tailfin yet they don't make a double start thru axle, nor is the actual Tailfin axle compatible. The Ortlieb axle seems harder to remove to fix a flat tyre too as you have to remove all the mounting hardware for the rack...crazy.

 

[bikingdad90]

A single start, just has one start point so requires more turns where as a double has two points so each turn goes twice as far to make it faster to screw in/out the axle. Frame dropouts are specific to a particular type I believe.

Looking at the picture the top axle is a double and the middle Tailfin one is a single. You haven’t accidentally damaged the dropout threads by using the tailfin one?

 

[Sea of vapours]

Looking at the picture the top axle is a double and the middle Tailfin one is a single. You haven’t accidentally damaged the dropout threads by using the tailfin one?

The box with the letters 'SR' on the Tailfin universal axle indicates that that section is for speed release threaded frames. i.e. twin start threads.

 

[bikingdad90]

@Sea of vapours, that makes sense. I can’t quite zoom in enough so assumed the second letter was an L not and R.

 

[wafter]

After an adult lifetime begun with and education in engineering and subsequently spent with engineering-adjacent interests today is the first day I've heard the term "double start" thread.

I think my brain is melting..

EDIT - so it seems this is two threads of effective pitch twice that of, and thread depth the same as what's stated, presumably starting equispaced / 180 degrees apart about the circumference.

So, for example an M12x1.0 double-start thread would be two M12x2.0 threads 180 degrees out of phase, but with the same effective thread depth (0.5mm) as a standard 1.0mm pitch thread.

Presumably this retains similar mechanical properties to the single-start 1.0mm pitch thread, but takes half the amount of revolutions to screw into a given depth.

Every day's a school day!

 

[Vapin' Joe]

After an adult lifetime begun with and education in engineering and subsequently spent with engineering-adjacent interests today is the first day I've heard the term "double start" thread.

My working life began as an apprentice engineer and "Two start" was the term we used.

 

[Boopop]

Looking at the picture the top axle is a double and the middle Tailfin one is a single. You haven’t accidentally damaged the dropout threads by using the tailfin one?

No damage that I'm aware of fortunately. If I had I'd be in a much worse mood about this than I am!

 

[wafter]

My working life began as an apprentice engineer and "Two start" was the term we used.

What context / applications were such threads being used in?

 

[Vapin' Joe]

What context / applications were such threads being used in?

Long time ago now and I left engineering almost as soon as my apprenticeship finished so I can't remember. I do recall drawing one when I worked in the drawing office.

 

[Webbo2]

What context / applications were such threads being used in?

I would hazard a guess screwing things in to things.🫣

 

[JonBuoy]

What context / applications were such threads being used in?

The cap on my bottle of orange juice has a two start thread.