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rear wheel failure

Calvin Cran

Tuned and Synch'ed
Joined
Feb 11, 2021
Messages
42
Location
Calgary, Alberta Canada
On July 15th I was riding my 2021 V85TT on a smooth well maintained gravel highway in NWT Canada 30km from Fort Liard I felt my rear end start to wobble and then woke up standing beside the bike saying holy Sh** I was doing the speed limit which was 80km/hr. I told the RCMP that I thought I had a flat rear tire but when they towed the bike the tire was still 42 psi but a whole lot of spokes were pulled out of the hub and some were broken. It was an ordeal getting to a hospital a little more than 2 days. I have a lot of injuries but am getting better, the 4 neck and back injuries are healing on their own. My chest and arms are the worst but should be OK
I attach some photos of the rear wheel, please check your spokes! The entire front dash was taken off the bike by my chest I asume.
Cal
SAM 3325 SAM 3326 SAM 3322 SAM 3298
 
On July 15th I was riding my 2021 V85TT on a smooth well maintained gravel highway in NWT Canada 30km from Fort Liard I felt my rear end start to wobble and then woke up standing beside the bike saying holy Sh** I was doing the speed limit which was 80km/hr. I told the RCMP that I thought I had a flat rear tire but when they towed the bike the tire was still 42 psi but a whole lot of spokes were pulled out of the hub and some were broken. It was an ordeal getting to a hospital a little more than 2 days. I have a lot of injuries but am getting better, the 4 neck and back injuries are healing on their own. My chest and arms are the worst but should be OK
I attach some photos of the rear wheel, please check your spokes! The entire front dash was taken off the bike by my chest I asume.
Cal
Cal, man! So sorry to see and hear this! Hope you heal well and fast.
One more thing to keep an eye on for those here and bikes in my shop.
 
Wow. That is absolutely wild. Sorry to hear that you sustained so many injuries. Hope that you’re able to recover fully, and quickly! It seems to me that Guzzi/Piaggio may be liable for such a catastrophic failure -especially given yet the injuries you sustained.

Did the bike give any prior warning other than wobbling right before failure? How many Km/miles on the bike?
 
Good grief Calvin! But thankfully it sounds like you're on the road to recovery.

That's a strange rear wheel failure. For some forty years I've laced and ridden spoked wheels on: Kawasakis; Triumphs; Nortons, Aermacchi; Harley; Jaguar and many bicycles and have never experienced a failure where the spoke pulled through the hub.

This is a very strange failure and hope to learn more about it.

Wishing you all the best during your recovery.

Jason
 
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Wow. That is absolutely wild. Sorry to hear that you sustained so many injuries. Hope that you’re able to recover fully, and quickly! It seems to me that Guzzi/Piaggio may be liable for such a catastrophic failure -especially given yet the injuries you sustained.

Did the bike give any prior warning other than wobbling right before failure? How many Km/miles on the bike?
No prior warning, I had just changed the oil and filter 200km before this in Fort Simpson and did not notice anything out of place but then again I was not looking at the wheel specifically. I think the insurance company wants to talk with Moto Guzzi, Ill let it play out with them. My expenses to get home were high due to the location. New tires were put on the rims at a shop in Calgary 1800km prior, you would think the tech would have seen a spoke out of position or broken when he did the tire change. I was loving the new Mitas E07/s Bike had 9800km at the time all gentle 68 year old rider km/s
 
No prior warning, I had just changed the oil and filter 200km before this in Fort Simpson and did not notice anything out of place but then again I was not looking at the wheel specifically. I think the insurance company wants to talk with Moto Guzzi, Ill let it play out with them. My expenses to get home were high due to the location. New tires were put on the rims at a shop in Calgary 1800km prior, you would think the tech would have seen a spoke out of position or broken when he did the tire change. I was loving the new Mitas E07/s Bike had 9800km at the time all gentle 68 year old rider km/s
Thanks for the info. Good to know about the tires! I hadn’t heard of them. As the owner of a 21 V85tt, I take your cautionary tale to heart: will definitely ensure that my spokes are double checked at tire change time. I hope that your insurance company is able to work out an acceptable settlement with Piaggio/Moto Guzzi. Best wishes for a speedy recovery!
 
I’m grateful that you are alive.

I’m saddened that the overwhelming response seems to be one of immediately putting blame upon Moto Guzzi / Piaggio, even though we truly know nothing.

The photos are not the highest quality or angle but from what I could see, I saw a lot of rust on the wheel and the spokes.

Is it possible that maintenance or lack thereof might have some part of this? I don’t know.

It is difficult to ascertain with so little to go on.
Still, I’m glad you are alive and I wish you a speedy recovery.
 
I think you are seeing road grime. Dirt in construction zones in Alaska and NWT sticks to everything when mixed with rain. My nephew and I rode BMW GS 1250 rentals from Anchorage to Portland, OR in 2019 and they were both covered with that gray residue after riding through construction zones in rain. A 2021 has not had enough time to develop significant rust. I am concerned that the angles of the spokes on the tubeless wheels may put different stresses on the hub compared to the tube type wheels on the 2019 and 2020. I will be visually inspecting my rear wheel frequently since I have the same model as the OP. I would really like to see pictures that show more of the hub where the spokes attach.
 
Perhaps.

My point was that it was disconcerting that the first impulse was to immediately assume Piaggio / Moto Guzzi, had done something wrong or made an engineering mistake. Some even encouraged litigation and lawsuit against them.

Am I the only one here who thinks there is insufficient information available to jump to conclusions like that? I hope not.
 
But was it the same owner? If there are now two broken wheels we need to know. I know I saw this same issue posted several weeks back on one of the forums but don't remember which one.
Cal, are you that same guy?

He said July 15.

That would be 26 days before his post here.
 
My mistake, it wasn't on Facebook that I saw a similar failure. Its on ADV, go to Beast then Moto Bellisima then go to page 866 MitchG posted it .

Whoops davethewelder:

You forgot sub-forum details and got the post incorrect.

Beast - Moto Bellisima - MotoGuzzi V85 TT - Page # 876


"Any experience with failed rear spokes on the new tubeless wheels on the V85TT?
10,000km of non aggressive riding and catastrophic rear spoke failure at highway speed on a straight hardpacked gravel road.
Needless to say, with the spokes broken, instant massive speed wobble and down it went.
Looks like tension failure of spokes.
Just wondering if anyone has experienced rear spoke failure on the new tubeless wheels?"


V85TT Rear Spoke Failure





OH SHIT! NOT GOOD!!!
 
As the rider of this bike, I can say there is absolutely no rust or corrosion on these wheels. Bike is stored in dry climate garage and had only 9800km. Mitch posted this photo on Advrider, he is the person who drove 280km 1 way over night to pick me up and get me to an airport to go to a hospital. Nearest ambulance was 600km away. Bike is still at his house waiting for the Insurance company to make up their mind what to do. It is 1700km north of my city. Insurance wants to preserve the wheel for inspection.

Scott, question? if you were riding along at 80km/hr and your rear wheel started to wobble and then threw you to the ground would you not think something was amiss with the wheel? My RCMP report stated that I thought just before the accident that I had a rear flat. Upon picking up the bike they noted the rear still had 42PSI and was not flat. I just want to heal and be treated fairly with a pay out or new bike. I have not spoken to MG and realize that shit happens, I am happy to be alive as the pressure from the chest against my heart caused me to flat line for 3 to 5 seconds at a time literally a few dozen times. I was asked if I wanted to be resuscitated and they also put the pads on me ready to paddle me and jump start the heart.
Why was the spokes like this? We may never know.
 
It appears that the shear stress in the hub where the spoke adjusters react was too high.

Having said that, I'm merely looking photos, which are not great. But I think a simple shear stress analysis would help answer some questions. But in order to do the calculation you need to know the yield strength of the hub material and the thickness of and diameter of the hole in the shear location, coupled with the dimensions and material of the spoke adjuster. Lastly you would need to know the force acting on the spoke.

This should be basic analysis that any reputable engineering firm could perform.

Jason
 
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