Second snapped 142 Thru Axle in 6 months

[JXV]

No "rests". If the TA snaps the wheel is just hanging by the other side of the TA and completely loose on the broken side. Hence, quite a dangerous design.

 

Frame design: i am really skrikkerig for the technical stuff. i don't hit jumps intentionally or go through anything gnarly unless it was a poor choice of line. i am at best probably an average weekend rider on chilled singletracks or jeep tracks. Not sure if this is beyond what the frame was for. Unless i'm too heavy.

 

i don't mind getting a solid TA if that will help. i checked out Myles' link but not sure exactly what i should be getting.

142 x 12mm TA standard has normal 135mm QR axle geometry as far as the spacing of spoke flanges, disc flange and cassette are concerned but the ends of the axle/end caps are larger diameter than a normal QR axle and 3.5mm longer each side and designed to fit into specially shaped 3.5mm deep recesses in the dropouts.

 

Some 142TA hubs come with aluminum axles that flex more than steel and some designs have the bearings more inboard than others which can increase the bending moment on the axle. Certain Easton hubs are notorious for this.

 

The 142 TA system is designed to be preloaded reasonably tight in order that the clamping force and the axle fit in those recessed dropouts work together to stiffen the rear triangle and reduce frame flex. However the length of the lever on that axle is chosen so that the average person will not overtighten it by hand. You should not be using full strength or tools to tighten it.

 

At 105kg you might be above the average cyclist's weight but by no means unusual. Lots of heavier guys around and we are not seeing loads of axle failures. So I do not think the root cause for these failures is your weight.

 

My TBLT has 142mm TA rear hub using the exact same DT Swiss 142x12 axle to secure it. I weigh about 90kg with cycling kit and am running a DT Swiss 350 hub. 2,5 years and 1000's of km of technical trail riding on this bike, including mild jumps with no failures so I think there is something amiss with your setup. Either frame flex, axle flex or poor hub design.

 

A solid aluminum axle is not necessarily more resistant to bending, only shear, so if necessary, try a high tensile or stainless steel M12x150mm Allen-head bolt in there. Just check the threads are compatible first and get one with as much unthreaded shaft as possible.

 

Sent from my SM-G935F using Tapatalk

[Ferro]

Thanks JXV. Appreciate the input.

[Ferro]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

[Headshot]

DT QRs and axles as well no doubt are pricey. I was looking at a DT screw up 135 QR and its over R400!

 

One trick i saw mentioned on another website forum - I forget which, was to buy the correct diameter bolt and cut it to the required length and then use a tool to cut the correct thread at the screw in end.

[BaGearA]

DT QRs and axles as well no doubt are pricey. I was looking at a DT screw up 135 QR and its over R400!

 

One trick i saw mentioned on another website forum - I forget which, was to buy the correct diameter bolt and cut it to the required length and then use a tool to cut the correct thread at the screw in end.

you will need a tap and die kit , or at least the die part and these start at R1k 

[BaGearA]

DT QRs and axles as well no doubt are pricey. I was looking at a DT screw up 135 QR and its over R400!

 

One trick i saw mentioned on another website forum - I forget which, was to buy the correct diameter bolt and cut it to the required length and then use a tool to cut the correct thread at the screw in end.

Are the rear axles usualy cheaper? Cause I ve seen fox 15mm fronts axles going for R1299.

[JXV]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

Yes 1.75 is the thread pitch....corresponding to standard Metric (Coarse) thread for M12 diameter. This is the normal M12 bolt thread.

 

You could buy any M12 x 200 smooth shaft allen-head bolt and get an engineering works to cut it to length and re-thread it for you. A well equipped workshop is likely to have a die set of the correct size or a programmable lathe that can do it .

 

Sent from my SM-G935F using Tapatalk

[Pulse]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

A lot of the stuff on KTMs are non-standard, or rather not the most commonly used standard

[JXV]

A lot of the stuff on KTMs are non-standard, or rather not the most commonly used standard

Metric coarse is the standard for 12x142 TA. A sensible choice for this robust application where the bolt threads into alloy dropouts and could easily be cross threaded or damaged if they were finer. It needs to be able to engage easily. Downside of coarse threads is that they are deeper than fine threads and therefore reduce the shaft diameter under the threaded part.

 

Sent from my SM-G935F using Tapatalk

[Headshot]

you will need a tap and die kit , or at least the die part and these start at R1k 

Ouch! Only good value if you plan on breaking a few more...

[droo]

So, i need a new TA either way and want a spare too. Will use a loan one for now.

 

According to the KTM spec sheet the TA is: DT Swiss IRWS Standard 142-M12x1.75

 

I'm assuming the 1.75 means the thread pitch. Problem is not all the sites state the thread pitch and most that do are the 1.0 ones...

 

I'm pretty pure that's the problem right there... that's the same pitch as the Giant one, which Mayhem said also has a problem with coming undone.

 

My guess is that the axle came loose, which then caused shear on the shaft where the hub meets the frame. Snap.

 

The standard one has a finer thread, which means more clamping force per unit torque, so it won't come undone as easily. You'll have to wind that axle up pretty tight for it to survive.

[Ferro]

i wonder if it is also not an inherent weak point right where the thread starts. Maybe the inner core should be slightly thickened around this point.

 

Thanks for the insight so far. Enjoying it very much.

 

Will definitely routinely check that the axle is still tightly engaged.

[Captain Fastbastard Mayhem]

i wonder if it is also not an inherent weak point right where the thread starts. Maybe the inner core should be slightly thickened around this point.

 

Thanks for the insight so far. Enjoying it very much.

 

Will definitely routinely check that the axle is still tightly engaged.

FWIW mine is now MOER tight. And I can put a fair bit of force on it...

 

But then it's also the Giant one, so same TP as yours. .

[BDF]

Just a thought but could the chainstay or triangle be slightly bent. This would mean that there is always pressure on the TA to bend where the thread ends. 

 

If you look at the bike from behind, I suspect that the chain side wheel insert lug will be at an ever so slight angle. i.e. the bottom of the lug will be bent toward the non-drive side just a tiny bit.

 

Just check it out.

[Ferro]

Just a thought but could the chainstay or triangle be slightly bent. This would mean that there is always pressure on the TA to bend where the thread ends. 

 

The first TA (DT Swiss) broke on my first frame. The second one (KCNC) broke on the second but identical frame. So maybe the first frame also damaged the second TA which was built over onto new frame or the KCNC was not a lekker replacement.

 

It does not seem to be a recurring issue with the frame itself as far as google shows.

 

Edit: ...unless both frames were bent.

[BDF]

The first TA (DT Swiss) broke on my first frame. The second one (KCNC) broke on the second but identical frame. So maybe the first frame also damaged the second TA which was built over onto new frame or the KCNC was not a lekker replacement.

 

It does not seem to be a recurring issue with the frame itself as far as google shows.

 

Edit: ...unless both frames were bent.

Cool. Do you fall to the right a lot? (ha ha)