Thru axle-bang!

[tt601]

Strange one -to me at least.

Out for a ride in my gravel bike -puncture. Stop to change tube, can’t get wheel off.

Thru axle-6mm hex bolt -tried using Crank bros multi tool -no joy .its not shifting. Blast -4 mile walk home….

Got home ,used bike specific torque wrench to undo it and it comes loose with a mild ‘ crack’.

Pic below is what it looks like-is it common for them to break at the thread. ?

It’s a newish bike -2 years old low use. Thru axle was removed in jan for mudguard fitting so its not been in for years! And replaced/torqued using bike torque wrench. 15 NM as per specs.

I know nowt about thru axles-are there any good makes to go for/avoid? Any thoughts or pointers welcomed before I venture into google fu.

Thanks

As an aside I did get a Strava second place on a hill I walked up-inexplicable!

[Your Dad]

Looks very dry on the threads, was there any anti-seize applied?

[James_0541]

Your Dad said:

Looks very dry on the threads, was there any anti-seize applied?

Exactly this...

[pete]

Definitely use anti sieze or a small dab of good old fashioned grease on the threads. They're very exposed to spray and salt in the winter.

On a related note, does everyone really do them up 15nm as the max spec indicates? I suspect I do mine up to about 5nm if that, similar to the effort I'd put to close a traditional quick-release lever. I've *never* had a thu axle come loose on many miles of road, gravel and MTB with that approach; am I dicing with death?!

[tt601]

Fair points re greasing etc. having just checked the threads felt a ‘bit greasy ‘ so not completely dry but -hands up-I know I didn’t add any anti slip when I put them back in , in Jan. so likely contributory cause I guess. I usually would do but bike being newish I guess I just overlooked it.


Any ‘ go to’ or ‘ must avoid’ replacements makes?

[tt601]

pete said:

Definitely use anti sieze or a small dab of good old fashioned grease on the threads. They're very exposed to spray and salt in the winter.

On a related note, does everyone really do them up 15nm as the max spec indicates? I suspect I do mine up to about 5nm if that, similar to the effort I'd put to close a traditional quick-release lever. I've *never* had a thu axle come loose on many miles of road, gravel and MTB with that approach; am I dicing with death?!

A good point re torque. As I was walking home, to take my mind off the blisters I was reflecting on had I done it up too tight and did others use less NM to ensure a decent multi tool could undo when out and about. I also thought about death and dicing!

[WPA]

pete said:

Definitely use anti sieze or a small dab of good old fashioned grease on the threads. They're very exposed to spray and salt in the winter.

On a related note, does everyone really do them up 15nm as the max spec indicates? I suspect I do mine up to about 5nm if that, similar to the effort I'd put to close a traditional quick-release lever. I've *never* had a thu axle come loose on many miles of road, gravel and MTB with that approach; am I dicing with death?!

Nope, 5nm is fine as it is very easy to crush bearings etc if overtightened

tt601 said:

Fair points re greasing etc. having just checked the threads felt a bit greasy so not completely dry but -hands up-I know I didn t add any anti slip when I put them back in , in Jan. so likely contributory cause I guess. I usually would do but bike being newish I guess I just overlooked it.


Any go to or must avoid replacements makes?

Robert Axle are very good replacements: https://www.sjscycles.co.uk/the-robert-axle-projec...

And as others have said, grease or anti seize on the threads

[tt601]

WPA said:

Robert Axle are very good replacements: https://www.sjscycles.co.uk/the-robert-axle-projec...

And as others have said, grease or anti seize on the threads

Cheers, thats who id been starting to look at. Bemusingly the length I need is 161mm, they only do 159 or 163..... do I go longer, or shorter!

[Mr Pointy]

You need to know if the torque specs are dry or lubricated.

[WPA]

tt601 said:

WPA said:

Robert Axle are very good replacements: https://www.sjscycles.co.uk/the-robert-axle-projec...

And as others have said, grease or anti seize on the threads

Cheers, thats who id been starting to look at. Bemusingly the length I need is 161mm, they only do 159 or 163..... do I go longer, or shorter!

Go longer, it will be fine

[hidetheelephants]

The fracture looks almost like it's been overstressed; was it installed by you/LBS/other party? Where did the nut sit on the threaded section?

[tt601]

WPA said:

Go longer, it will be fine

That’s what I will probably do -I’ll pop down SJS Monday, having spoken to them this aft.

[tt601]

hidetheelephants said:

The fracture looks almost like it's been overstressed; was it installed by you/LBS/other party? Where did the nut sit on the threaded section?

There is no nut. The threaded end screws into the frame of the bike. As I didn’t quite make clear in my OP I removed and reinstalled in Jan this year. So any blame c est moi

[hidetheelephants]

Perhaps a manufacturing flaw in the bolt, something's gone quite wrong with it.

[gazza285]

WPA said:

Nope, 5nm is fine as it is very easy to crush bearings etc if overtightened

The through axle would break before you crushed any bearings.