Inmotion V13 Speculation

[Bizra6ot]

This Inmotion V13 is no longer "in motion"  broke while riding by a speed bump
https://www.facebook.com/groups/ElectricUnicycle/posts/5819135288184386/

Edited January 21, 2023 by Bizra6ot

[Paul g]

12 hours ago, conecones said:

I don't mean to repeat myself, but this is exactly the kind of distracting, baseless comments that should be ignored and why I brought up Kuji's review being superior to these other "reviews" from people describing a feeling. Torque is torque, there is no special "climbing torque". In Kuji's video, he showed that he was able to accelerate on par with Master. The Master Pro and V13 also made it up this hill(can't find the video right now but its the same hill Jack's EX30 review): https://youtu.be/AQqzukZx3WU&t=1m35s

There is already enough useful evidence from capable testers to prove this wheel's capabilities. I like Dawn's content overall but that video of her head-scratching initial impression of the V13 due to settings mix-up was straight up disappointing. Like c'mon now, how about you figure out how to use the wheel before making a "review" video and confusing people. Anyone who has used InMotion's app from any of their other wheels (V8F and up) will know about this feature (used to be called "Sensitivity", which made more sense actually).

Here's some videos of V13 abuse just for fun:
https://t.me/mono_man/12627
https://t.me/mono_man/12628
https://t.me/mono_man/12629

 

Again, this comment is just another reason to not take these baseless opinions seriously. I've not seen video evidence of anyone being able to overpower the V13.
BTW, MTen4 has nothing torque. I can cut it out on flat ground with no pads. It easily runs out of torque on even  small inclines.

   Roger had previously rode the V13 at high speed and on steep hills a lot more then Marty did with the CPro, so is it possible that for the battery(a lot less then CPro) it had the V13 was limiting the torque output?

   And then is the fact that V13 is a bigger diameter wheel than CPro and also was purposefully built for speed not torque, so why going so hard on it any way? I am surprised they test a wheel that is obviously made for speed on those gnarly steep climbs as if it was built for that. And I am also impressed by what the V13 is able to accomplish at the big diameter wheel it has.

 

[UPONIT]

2 hours ago, Paul A said:

Damaging a wheel does not seem to be a major concern to influencers.

The interesting thing to me about that giant drop was that the wheel was so UNdamaged at the end of it. Don't know what the small panel was that flew off, but that looked to be about it. Conclusion: Durable. I wonder how an exposed-battery-style EUC would have done?

58 minutes ago, Bizra6ot said:

This Inmotion V13 is no longer "in motion"  broke while riding by a speed bump
https://www.facebook.com/groups/ElectricUnicycle/posts/5819135288184386/

Ludicrous (is not just a rapper turned actor).*

Read the commentary under the picture. The OP calls the speed bump "the last straw." There are a lot of nutty assertions and guesses and musings. The OP is asked several relevant questions and doesn't answer. Etc.

Also: The simple act of going over a speed bump, all by itself, with no contributing factors, caused motor attachment bolts to shear off?  That's like a Black Barbie doll in Arizona. **

________________________________________________
*     I know he spells it Ludacris. Denial/Da Nile. Nevermind.

**   Nobody's buying it. (Credit: Tracy Jordan, 30Rock)

[Punxatawneyjoe]

3 hours ago, Bizra6ot said:

This Inmotion V13 is no longer "in motion"  broke while riding by a speed bump

Sure thing, we believe you.

[Paul A]

If suspension was locked, could that cause the shearing?

[Punxatawneyjoe]

19 minutes ago, Paul A said:

If suspension was locked, could that cause the shearing?

Sure, if the rider was 350lbs and rode it off a 3 meter drop.

1-m6 bolt can hold the weight of an elephant.

[rebeuc]

3 hours ago, Bizra6ot said:

This Inmotion V13 is no longer "in motion"  broke while riding by a speed bump
https://www.facebook.com/groups/ElectricUnicycle/posts/5819135288184386/

The user that posted that photo to facebook states that they heard back from inmotion in the comment thread there:

Quote

inmotion said that we didn't torque them to spec. If we over torque or under torque it could put a lot of strain.
My response: I can't torque it to spec, if you don't release any specs

That implies to me that this user had dissassembled and reassembled this wheel, so unless we start hearing from other v13 owners that this is an issue I am not too worried.

[SquallLHeart]

1 hour ago, rebeuc said:

The user that posted that photo to facebook states that they heard back from inmotion in the comment thread there:

That implies to me that this user had disassembled and reassembled this wheel, so unless we start hearing from other v13 owners that this is an issue I am not too worried.

this is exactly what I got from that comment as well.

I've disassembled my wheel, done all the other crazy riding and drops.. have had heavier friends ride my wheel and abuse it.. and those bolts are fine.. there is something else that's going on and the only conclusion I can get to is exactly what you got as well..

those guys messed up.. and yes, they admitted that the wheel was taken apart.. so there's your answer.

Edited January 21, 2023 by SquallLHeart

[rebeuc]

3 hours ago, SquallLHeart said:

those guys messed up.. and yes, they admitted that the wheel was taken apart.. so there's your answer.

Yep, just found the comment:

Quote

yes, this was taken apart before. Yes those bolts are the factory bolts

 

[rebeuc]

More comments by the original poster of that image on facebook hidden in the thread:

Quote

inmotion said cause was under torque btw.

Quote

But for sure it was tight and not overtorqued.

Quote

Our goal was to teardown the v13 into it's small pieces for exploratory reasons.
We do this with all wheels, and publish a first impressions. The filming happens on the first time I see and disassemble a wheel. (Usually less than 1-2 hours of filming) Once the camera is off, then we slowly do some investigative work and try to see if there are weak points, and or efficient methods of fixing / accessing certain parts of the wheel

Quote

the goal is to give the community and unbiased true first impressions as quickly as possible.
We don't script, or curate, or pre-disassemble anything.

Quote

It is definitely something weird. I told inmotion that they need to release torque specs if it is required. Otherwise need to design with better safety margins if this is that sensitive and if they can't rely on all users torquing it exactly to a spec. I share this pic not to bash a manufacturer but for full transparency and for possible improvement in communication, repair manuals, etc.
That's why I'm very open to the fact that it could be failure induced by reassembly of the wheel. (But if this happened to me, it can very easily happen to anyone who does a tire change)

Quote

yeah we are going to use screw extractors in the next couple days.
I wasn't the rider fortunately, but it didn't cut out. Just started jack hammering mid ride after the speed bump. I was the support vehicle.
As of this moment, inmotion says it is caused by under torquing the motor bolts. I told them I can't torque it to spec, if they don't release a spec. For sure it was tightened similar to any other screw or bolt that I normally do.
There wasn't any real symptoms prior to. No rubbing or weird sounds.

 

[HEC]

12 minutes ago, rebeuc said:

That's why I'm very open to the fact that it could be failure induced by reassembly of the wheel. (But if this happened to me, it can very easily happen to anyone who does a tire change)

(I know you've quoted that, this is a general question) Do you actually need to take those 4 bolts on each side off while changing the tire? I might be wrong but it should be possible without removing them ...

[rebeuc]

2 minutes ago, HEC said:

(I know you've quoted that, this is a general question) Do you actually need to take those 4 bolts on each side off while changing the tire? I might be wrong but it should be possible without removing them ...

I haven't formally reviewed this photo in comparison to one of the teardowns, but I had the impression these bolts were only needed if you wanted to break the seal to get into the motor, and not for any sort of 'normal' maintenance. I could be mistaken about this, though.

[rebeuc]

8 minutes ago, rebeuc said:

I had the impression these bolts were only needed if you wanted to break the seal to get into the motor, and not for any sort of 'normal' maintenance. I could be mistaken about this, though.

I think I was mistaken.

Looking at the ecodrift teardown, I think these are the bolts that hold the suspension sliders in place:

[Punxatawneyjoe]

7 minutes ago, rebeuc said:

More comments by the original poster of that image on facebook hidden in the thread:

I'd blame my over torquing of the bolts on lack of torque specs also if they sheared while riding it also. Rule of thumb Always blame the guy who isn't there.

Size (mm)	Typical Maximum Tightening Torque (Nm)

Property Class
Grade 8.8	Grade 9.8	Grade 10.9	Grade 12.9
M5	7.0 5.17	7.8 5.76	10.0 7.38	11.7 8.63
M6	11.8 8.71	13.3 9.82	17.0 12.5	19.9 14.7
M8	28.8 21.3	32.3 23.8	41.3 30.5	48.3 35.6
M10	57.3 42.3	64.1 47.3	81.8 60.4	95.7 70.6
M12	99.8 73.7	112 82.7	143 106	167 123
M16	248 183	277 204	354 261	413 305
M20	500 369		690 509	809 597
M24	865 638		1195 882	1395 1030
M30	1719 1269		2377 1754	2774 2047

[HEC]

1 hour ago, rebeuc said:

I think I was mistaken.

Looking at the ecodrift teardown, I think these are the bolts that hold the suspension sliders in place:

While it would most certainly make the tire changing more comfortable, it's not strictly necessary to remove the suspension sliders to do so. I personally would leave them on if I need to swap tires. 

[novazeus]

haha, ur the one i was thinking of, who i trust!

i can tell u are honest!

and i am subscribed to u!

17 hours ago, SquallLHeart said:

you can trust me. I'm not making money.. I am so far from having enough subscribers to be monetized. 🤣

I'm not tooting off affiliate links or anything either. 🤪

you guys can always ask me any questions. I've had this wheel for awhile now.

 

Edited January 21, 2023 by novazeus

[techyiam]

Notice that the sliders have a formed recess that the axle fits in.

That means the vertical and torsional loads on the sliders are supported directly by the axle as well as the bolts.

If there was a big enough impact to shear the steel bolts, there should be telltale signs of damage on the sliders as well. Yet there was no mention of that.

 

If you look at the fractured surfaces of the four bolts, 3 of the bolts have brittle fractured surfaces, while the top right bolt have a ductile fractured surface. 

Also, the ductile fractured looks to have been twisted, suggesting it failed while being twisted. Not under a shear load.

Could it be that the technician did not bother to extract the broken bolt and only use only three bolts upon reassembly?

Moreover, brittle fracturing is more susceptible under a strong tensile stress field orthogonal to the fractured surfaces. This implies over tightening can worsen the situation.  Over tightening the 3 remaining bolts cannot compensate for a missing bolt.

Time will tell. If the fault lies with Inmotion, many unworked on V13 will have broken axle bolts across the global, since bolts are certainly mass produced. 

Edited January 22, 2023 by techyiam

[Mango]

Is this wheel the one they used in their disassembly video?

The technician was using an impact driver to remove these screws. The force of the impact driver could be enough to weaken the structural integrity of these screws.

[fbhb]

17 minutes ago, Mango said:

Is this wheel the one they used in their disassembly video?

I believe it is the very same V13 example they tore down in the eevee's video!

Edited January 22, 2023 by fbhb

[Josiah]

12 hours ago, Mango said:

Is this wheel the one they used in their disassembly video?

The technician was using an impact driver to remove these screws. The force of the impact driver could be enough to weaken the structural integrity of these screws.

If you going to use a screw gun, set speed to #1 (slow), the torque setting to a lower setting, and go easy on the trigger.  Stay away from impact drills.  Most Impacts don’t have adjustable torque. 

Edited January 22, 2023 by Josiah

[novazeus]

i bought nice bondhus t-handle metric allen wrench set just for wrenching on wheels. 

i had one difficult bolt changing the pedals on the s22 to a lowered forward position and i used a lighter to heat a standard allen wrench and it was enough heat to break it loose. 

china is not known for having the best quality bolts and nuts. drills are faster but much better to do by hand. 

and always clean ur bolts and nuts with 99% isopropyl alcohol or acetone before applying blue loctite, and i bet they don't when they assemble these wheels. 

[novazeus]

i think the mechanic used a hammer to loosen those bolts.

[UPONIT]

22 hours ago, Punxatawneyjoe said:

Sure, if the rider was 350lbs and rode it off a 3 meter drop.

1-m6 bolt can hold the weight of an elephant.

Even more. Aren't bolts stronger in shear than in tension? I'm too lazy to look it up so I'll just assert it and take my chances...

17 hours ago, rebeuc said:

More comments by the original poster of that image on facebook hidden in the thread:

 

Another small point that bugged me. I'm not sure if it was the OP, but someone said proudly that they were going to replace those stock bolts with "stainless steel" ones. Most types of stainless bolt will be weaker  than alloy steel counterparts. I refer you to  the McMaster-Carr Catalog the Bible for reference.

We armchair engineers aren't always smarter than the people who design these things...

16 hours ago, HEC said:

(I know you've quoted that, this is a general question) Do you actually need to take those 4 bolts on each side off while changing the tire? I might be wrong but it should be possible without removing them ...

Yup.

Edited January 22, 2023 by UPONIT
whim

[Punxatawneyjoe]

7 hours ago, Mango said:

The technician was using an impact driver to remove these screws.

^ this. As a long time mechanic in my youth, you learn to never use an impact gun on small bolts and screws and definitely not on re-assembly when it's as important as an axle bolt. i was also noticing after you mentioned it that the axle housing fits into the slide and as you said and there is paint worn off the bottom edge like it wasn't seated down into the chamber when the bolts were tightened down. That would defiantly not be good, the recessed area on the slide takes up most of the downward force i would imagine so its not all on the bolts.

[techyiam]

Below is Bob Yan's reply to the thread in question on Facebook.  Noticed it's anecdotal with a lot of assumptions. Too bad he did not include details, and clear pictures of the fractured surfaces of the bolts, the recessed area in the slider, and the axle end.

 

Quote

Bob Yan

The self balancing wheel is rotating back and forth all the time, so once the bolts has any loose, they’re facing a severe shaking condition, plus V13 motor has huge torque, so the bolts are easy to be cut out at this condition. We’ve one failure case just like this one during our testing phase, and the root cause is like above. Since your wheel has teared down before, we suspect the bolts were not tightened properly again. The Loctite is medium level as we don’t want to make it too hard to take out for tire change, to improve this one, we’ll test stronger materials for bolt and also stronger level sticky Loctite

Those axle bolts have countersunk heads. Therefore, if the bolts are not sufficiently tight (allowing relative motion between the slider and the axle), the back and forth torqueing would at the same time cause the bolt head to pull on the bolt shrank, due to the taper shape of the head. But telltale signs should also be evident on the slider recessed area.

If this is indeed the case, or something equivalent, then I think it is onerous upon Inmotion to provide the required tightening torque, or simply use stronger bolts.

Isn't the sliders made of aluminum. It is hard to believe the bolts would under normal loading. If the installation needs to be this sensitive, stronger bolts should be used.