Catastrophic breakdown of MPIII

[Lollandster]

I feel this picture is worth sharing.

This is the remains after a rather catastrophic breakdown of a magicpie3. The rim actually broke into 8 parts 
The bike was mainly built built by me, but is owned and driven by a mad friend of mine who doesn't know the word safety, only the word "more speed!!!". The mp3 was powered by a 72v Lifepo4 pack trough a 18 fet infineon controller at 60 amps. Its probably safe to say that those modifications will have reduced the lifetime of the rim significantly. On top of this the bike has been used extensively throughout the winter (meaning exposure to salt) and always driven very hard. The first few spokes broke before Christmas and by last month I think about 5 spokes where gone and probably more loose. of course with the high regard for safety this madman has he decided to ignore the spoke problem and continued driving the bike hard (although not as hard as before since by this time the brakes where long gone). Last week he was made aware that the rim had a huge crack right trough it and was very close to breaking. Still ignoring safety he continued to use the bike both on road and off road. The huge wobbling now experienced in the rim kept his speed down though. And today the rim more or less exploded 500 meters from his home. Lucky for him he slided to a halt without hitting any traffic (it was a remote road so very few cars) or tipping over. He says he slowed downed some before the breakdown as the bike started to shake violently, but with very little breaking power he didn't manage to stop before the rim exploded.

Some persons should not be allowed that much power, but with him paying I couldn't resist building the bike just to see what an e-bike can do.

[Lollandster]

Looking closer at the picture it actually looks like the torque arm has failed during the crash. I know it didn't fail before the crash, but I'm still a little curious to know why it failed. It looks like it was able to move the hose straps down towards the center allowing the axle to rotate about 45 degrees. I guess I have to find a better way to mount the torque arm in the future. The axle slot in the frame was already widen though as he insisted on riding without the torque arm wile on 45v/30A, and got it mounted only after he had a axle spinout.

[MAGICPIE3FOCUSPOWER]

hahaha sounds similar to me!
I had a wheel wobble after first ride (yes at high speed).
So I didn't trusted the rim and replaced it with a high quality rim (Mavic downhill rim).
Spokes are very short so more power stress for the rim....

He is carrying battery in backpack?

[Lollandster]

He is carrying battery in backpack?

Yes, one 24v pack plus one 48v pack serial connected, both 10Ah headway packs. That backpack ways a ton. If that weight was carried unsuspended on the rear rack I bet the rim would have failed sooner.

[MAGICPIE3FOCUSPOWER]

Also those spikes tires are okay at dry road?
I mean how about the spikes worn out resistance.

[Bikemad]

It looks like somebody was incredibly lucky, and it could also have been a whole lot worse if it had been a front wheel.

Think positive, a tyre, inner tube, rim and some spokes will soon have the wheel back in action again.

Alan
 

[Gurkelur]

Almost same thing happened to me. Four spokes had popped on my 250W motor the days before. In a steep down hill, going 50 km/h, my rear wheel collapsed over a speed bump and my bike slid to a stop. My rim didn't split in pieces, but half the spokes were ripped out of the alloy together with some minor fractures.

[Morgen 3Eman]

Hi Folks,

One of my jobs was in equipment maintenance.   I learned that if you take care of your (insert name here), it will take be safer, cheaper to use, more likely to be useable at any given moment, etc. 

So,

Please help me understand the logic that leads to the decision to ride a bike with 5 broken spokes at speeds of 50 kph.  Perhaps drugs or alcohol were involved? 

TTFN,
Dennis

[Lollandster]

Hi Folks,

One of my jobs was in equipment maintenance.   I learned that if you take care of your (insert name here), it will take be safer, cheaper to use, more likely to be useable at any given moment, etc. 

So,

Please help me understand the logic that leads to the decision to ride a bike with 5 broken spokes at speeds of 50 kph.  Perhaps drugs or alcohol were involved? 

TTFN,
Dennis

oh yes, lots of those. And did I mention the visible crack in the rim prior to crash?

[Morgen 3Eman]

Was the rider also 15-19 years old?  I can totally understand  (and remember) that situation!

TTFN,
Dennis

[GM Canada]

Lol, I remember. Those days as well. Unfortunately you have to add 30 years to those numbers   

Out of all the wheels I have sold I only ever had one rim crack. The rider hit a pothole hard and that did it. Personally I hit a pothole so hard I dented the rim, but did not crack it.

I have also had a few loose spokes over the years. Once it is more then two you can feel the wheel sag on the corners. But 5 missing?  It had to feel obvious that disaster was going to strike.

I have had people claim their wheel collapsed , others claim spokes pulled right through the rim. But when I ask for pictures they either say they don't have a camera, they don't know anyone that has a camera or I never her from them again. This picture certainly displays an issue though and it's obvious the wheel should have been attended to long before this.

 I'm certainly glad the rider was not hurt. I wonder if a lesson was learned though. Once a person is wreckless, it hard to become un-wreckless without experiencing pain. I have felt that pain.
 
Gary

[Marsbar]

I can see you are from Norway as I am. I thought it was a disaster when ONE spoke... I stopped to repair it immediately.

I hope wish you good luck in repairing it 

Unfortunately roads are bad, and I recommend to take it slow when you don't know the road or can see properly.

[Lollandster]

I can see you are from Norway as I am. I thought it was a disaster when ONE spoke... I stopped to repair it immediately.

I hope wish you good luck in repairing it 

Unfortunately roads are bad, and I recommend to take it slow when you don't know the road or can see properly.

Thanks, the repair job isn't my problem though since it's not my bike. My bike has a smartPie and I haven't had any big spoke problems with it (except that the wheel wasn't true when I got it so I had to true it). I'm Norwegian yes, did you guess it from my bad English or my profile information?

Was the rider also 15-19 years old?  I can totally understand  (and remember) that situation!

He might be 15 years old in his head, but he really isn't.

I have also had a few loose spokes over the years. Once it is more then two you can feel the wheel sag on the corners. But 5 missing?  It had to feel obvious that disaster was going to strike.

The crack in the rim plus the huge wheel wobble should have been good indicators that disaster was imminent. I am sure the wheel wouldn't have cracked and collapsed if the missing spokes were fixed and the wheel re-trued.

Also those spikes tires are okay at dry road?
I mean how about the spikes worn out resistance.

I'm not sure if I understand the question correctly, but as you can see on the picture the spikes are worned completely down so riding them on dry road probably isn't a good idea. On the other hand, my more expensive spiked tires with tungsten tips are still sharp as new even after several rides on dry asphalt. If you are asking about the traction on dry road I can't say I have noticed too much difference, but I don't ride hard.

[Gurkelur]

Please help me understand the logic that leads to the decision to ride a bike with 5 broken spokes at speeds of 50 kph.  Perhaps drugs or alcohol were involved? 

TTFN,
Dennis

In my defense, I was expecting a breakdown and deemed it safe if it was to happen. I never rode in traffic. The motor wasn't working anyways, and I had grown tired of trying to fix it.

OP's friend seems more like a proper madman

[MAGICPIE3FOCUSPOWER]

After reading this post I was just curious and did some inspection of my Mavic downhill rim.
Wooww I had some cracks around the valve, I think caused by salt (winter period).
And no spokes were broken....so...