Warning: boring thread (Inspired Fourplay Team 2020 weak point?)

[javimic]

Hello everyone, this is another boring post unless you have a Fourplay Team 2020 edition and you broke its rear through-axle.

Two months after I bought the bike as a total beginner with minimal stress to the bike, I broke the first rear axle on its thread. Last night I broke another one (the revised version by Inspired) in the same place with a "pedal hop to the front wheel" not with a big drop or something! So this time I checked the bike and noticed at first glance that the respective dropout has a bigger hole than the opposite side and the strong section of the axle is in the air with all the load on the thread. I am not Euan Beaten (engineer) to say this with authority, but the frame or the axle is not doing its job! If you take a look at the media I uploaded, you can see what I mean (SOUND ON IS CRUCIAL). When I analyze the axle I see that this doesn't occur on the opposite side. The axle has a wider section there (minimal but enough to fit perfectly in the disc side dropout).

The question is Where is the problem (recurrent!)? 

 

Edited August 4, 2022 by javimic

[LEON]

Euan Beaten! Ha, I'm gonna use that. 

I can't help with your axle, but that's bad, sorry. 

[javimic]

3 hours ago, LEON said:

Euan Beaten! Ha, I'm gonna use that. 

I can't help with your axle, but that's bad, sorry. 

Bummer, bro. It's the thought that counts. 

[Chakers1998]

This happened to my dads Skye. The thickness of the material at the threads isn't the best and Inspired could do with having the Allen key fitting having less depth just to give the threads at the weak point some much needed material.  

[javimic]

3 hours ago, Chakers1998 said:

This happened to my dads Skye. The thickness of the material at the threads isn't the best and Inspired could do with having the Allen key fitting having less depth just to give the threads at the weak point some much needed material.  

Thanks for your comment mate. I think the problem is in the dropout of the frame, the Fourplay's first rear through-axle version. The 12mm through-axle doesn't work with the drive-side dropout, it's in the air and all the load is on the thread. It is clearly not designed to work like this. The thread should only fix the axle for the axle to do its job. I love this bike, maybe Inspired can provide a solution. Tartybikes, my right hand always, is asking for advice.

[craigjames]

Not much of a solution as there is an obvious design fault, but you could get a custom axle machined up in in steel (hollow to save a bit of weight) or Ti?

[SergeL]

I'd try to wrap a beer can stripe around it for a tighter fit.

[AdamR28]

Have you tried the Pro axle?

[javimic]

19 hours ago, craigjames said:

Not much of a solution as there is an obvious design fault, but you could get a custom axle machined up in in steel (hollow to save a bit of weight) or Ti?

Inspired has spoken. According to them the play it would be normal. But they recommend to install the pro version of the through-axle on my Team whip. This will be the third. I said yes but I honestly don't think it's a definitive solution. A new fear is unlocked... So I will take in account your advise!

[javimic]

14 hours ago, AdamR28 said:

Have you tried the Pro axle?

I sent an email to Charlie today and said what would Adam do to fix it!? That seems to be the next step to try, because the threaded section is solid. thanks man.

[javimic]

18 hours ago, SergeL said:

I'd try to wrap a beer can stripe around it for a tighter fit.

If I tell you that I thought it... I'll make a note for the next one. Today Inspired has said that an alternative is to try a pro axle. I hope the third time's a charm because it kills me to be out of the game. I had a few problems with this bike but to be honest the warranty on some components like Hope or Inspired was very good. For sure thanks to the support of Tartybikes.

[Mark W]

The frame is designed like that intentionally, it's not a 'design fault' or by accident. If the axle made contact with the bore of the dropout on the drive side, you wouldn't be able to tighten the axle up correctly. It's not unique to Inspired - on both my mountain bikes with through axles there's a similar setup, albeit with a different way of getting to it as they each have bespoke dropout and threaded insert designs. The clearance and securing principle is the same though.

The contact between the end of the hub and the insides of the dropout due to axle tension will be enough to keep things in place, so you don't need to have the axle fully in contact with the inside of the frame as it passes through it. That is why it's really important to make sure they're tight though as if the axle isn't tensioned correctly it will be taking more of the load than it should be. 

On that note, in the photo of the frame it looks like it may have been ridden with it a little loose as there are witness marks from the hub that are elliptical rather than circular:

The red circle is about Hope end cap size, and it looks like to the bottom left there's been movement from the way the frame has been marked. It's almost impossible that's just from when the axle broke, it looks like its from repetitive movements over time going by that image.

In any case, the Pro axle has more material there, so hopefully that should resolve things. Just make sure you use plenty of grease under the axle head and on the threads, and check it regularly (especially from new).

[javimic]

17 hours ago, Mark W said:

The frame is designed like that intentionally, it's not a 'design fault' or by accident. If the axle made contact with the bore of the dropout on the drive side, you wouldn't be able to tighten the axle up correctly. It's not unique to Inspired - on both my mountain bikes with through axles there's a similar setup, albeit with a different way of getting to it as they each have bespoke dropout and threaded insert designs. The clearance and securing principle is the same though.

The contact between the end of the hub and the insides of the dropout due to axle tension will be enough to keep things in place, so you don't need to have the axle fully in contact with the inside of the frame as it passes through it. That is why it's really important to make sure they're tight though as if the axle isn't tensioned correctly it will be taking more of the load than it should be. 

On that note, in the photo of the frame it looks like it may have been ridden with it a little loose as there are witness marks from the hub that are elliptical rather than circular:

The red circle is about Hope end cap size, and it looks like to the bottom left there's been movement from the way the frame has been marked. It's almost impossible that's just from when the axle broke, it looks like its from repetitive movements over time going by that image.

In any case, the Pro axle has more material there, so hopefully that should resolve things. Just make sure you use plenty of grease under the axle head and on the threads, and check it regularly (especially from new).

Thank you very much for your detailed comment!

What I see is that the shear force is in the same place, so I'm wondering why it can happen. Clearly something is. Inspired already revised the axle, so something was wrong (or not perfect). It can happen, no problem. Inspired's solution at this point is "to try" the pro axle in my team fourplay like a next "logical step" (in their words). They're not saying put another brand new revised axle  which tells us something too... Anyway, I appreciate what the manufacturer is doing. Inspired is not just denying the issue or blaming the user. Try to provide me with a solution.

Going back to your comment, to instal a team axle is very easy if we follow the owner's manual. Also it is a system that does not loosen, at least according to my experience of 2 years riding this whip. I never had to re tighten those bolts when I checked the bike out with the torque wrench.

However, if despite following the instructions, the axle is not fully tightened and the end of the hub generate those elliptical marks, I would not be able to tell where the cause is. What happens to the torque when the axle bends a little before the final break? 

I have finally bought the pro axle and one more as a back up (mental insurance). 
Thanks again mate

[Mark W]

6 hours ago, javimic said:

Inspired already revised the axle, so something was wrong (or not perfect). It can happen, no problem. Inspired's solution at this point is "to try" the pro axle in my team fourplay like a next "logical step" (in their words). They're not saying put another brand new revised axle  which tells us something too...

I was working at TartyBikes when they brought in the revised axle design. From memory, it was due to a production issue with the axles, more specifically with the tooling used for the broaching. There was a conflict between the design of the axle and the tooling used, so the axle design needed to be tweaked. This is why Inspired were replacing any of those original 2020 axles free of charge with the updated designs. It's worth noting that not all of the axles broke though, there are still some going strong out there now.

It's weird that you've had one of the new axles break as in my experience at TB once riders had the new ones installed they didn't have any further issues. I expect that that might be why they're suggesting the Pro axle as it's effectively a fail-safe solution, even if the simpler design is slightly less 'refined'.

Just going back to what I said in my last post about my mountain bikes, this is my Radon's dropout setup:

It effectively works the same way that the Inspired system does in that there's no contact with the frame save for the end cap of the hub and the axle in the threaded insert. My Commencal is the same. 

To put it another way, it's best to think of the axle as a bolt and the threaded insert as a nut. If you have a bolt passing through an object before going into a nut, you have to drill the hole out to be larger than the bolt. For an M12 bolt (like an axle), that would 13mm at least for a 'close fit'. It looks like the hole for the axle on your frame is larger than that, but essentially if it was 13mm or 130mm it wouldn't make any difference functionally. If the axle's not contacting it, the axle doesn't 'know' it's any different.

[javimic]

First hand information, Mark W! I really love this bike (one of five I have). In this topic I feel that we delve into the subject. Grateful because I learned a lot. I'll update this story when I have the replacement. Thank you all, especially Mark W.