Another rear wheel collapse..

Oldrat said:
With reference to this closed thread..
https://www.ukgser.com/forums/showt...-Wheel-Collapse?highlight=Rear+brake+collapse

This morning a friend had a similar event on his LC.

It had been serviced by BMW 6 weeks previously, and luckily he was travelling relatively slowly.
He tells me it appears that the calliper mount on the hub casing has snapped, the calliper still has the bolts securely in place. It sounds like the mount has failed or the spokes have failed demolishing the mount?
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Get your friend to report it here , in fact all suspected defects should be reported , I’ve used this to record a fire with an Audi , they have far more clout to deal with manufacturers than us mere mortals.


https://www.gov.uk/vehicle-recalls-and-faults/report-a-serious-safety-defect


Sent from my iPad using Tapatalk
 
Warlord said:
I think they look great :thumb2
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So do I.

cohTVyi.jpg
 
peepingtom said:
my point is you shouldn't have to
Click to expand...

... and I agree 100% again.

So then it becomes a 'what are you prepared to put up with' type question

a) Battle it out under Warranty, if they accept it
b) Sell a perfectly good bike
c) Sort it out yourself for little cost with an alloy wheel replacement
d) Check the spokes every month or so of riding it.

Suppose it's down to the individual at that point.
 
e) buy a KTM .....?











:hide
 
Having built my own Mx wheels in the past which get hammered I know it takes many more than u might think, missing or loose spokes for a collapse. So is the trigger as simple as one spoke hitting the Caliper at speed and once the Caliper is into the wheel you get a collapse. A single spoke can become very loose quite quickly once it’s no longer stressed.
 
spoonz said:
Having built my own Mx wheels in the past which get hammered I know it takes many more than u might think, missing or loose spokes for a collapse. So is the trigger as simple as one spoke hitting the Caliper at speed and once the Caliper is into the wheel you get a collapse. A single spoke can become very loose quite quickly once it’s no longer stressed.
Click to expand...


The gap between the spokes and the calliper is only a few mm because they break with traditional and don't end in the well of the rim but instead the rim outer edges. When all this first started happening the talk was about home servicing and not doing calliper bolts up tightly enough. (There was a thread where this happened to some bloke who did his own servicing).
It's my opinion, and has been from the get go, that one or two lose spokes is all you need to get enough flex in the wheel (accelerating, braking, leaning) to just catch the calliper. From there its total disintegration.
 
Giles said:
The gap between the spokes and the calliper is only a few mm because they break with traditional and don't end in the well of the rim but instead the rim outer edges. When all this first started happening the talk was about home servicing and not doing calliper bolts up tightly enough. (There was a thread where this happened to some bloke who did his own servicing).
It's my opinion, and has been from the get go, that one or two lose spokes is all you need to get enough flex in the wheel (accelerating, braking, leaning) to just catch the calliper. From there its total disintegration.
Click to expand...

That’s a possibility but to get enough movement at the hub to hit the Caliper the movement at the rim would be considerably more. I think that would take more than an isolated loose spoke and possibly be felt by the rider. It would also be more likely to happen at lean when the wheel has side loads but I think both collapses happened whilst on straight roads.
 
There seems to be a chicken and egg situation developing here. Are the caliper mounting lugs breaking, leaving the caliper to destroy the spokes? Or are the spokes breaking and whipping the caliper so much it commits suicide by breaking its own lugs and jumping into the wheel? I know where I’m placing my bet.

Think about how broken spokes would behave under the influence of centrifugal force. They’d go outwards towards the rim not inwards towards the caliper.

Think about a wheel collapse, the swing arm goes down towards the road, the caliper is at the top. I can’t think of anything that could impact the caliper such that it breaks it clean away from the swingarm. Far more likely to be the mounting lugs suffering from inadequate design/poor materials/manufacture.

When it happens on a bike with spoked wheels the consequences are more destructive, alloy wheels would be more likely to just batter the caliper out of the way.
 
The damage on the pics looks very similar to that which one of my 1100GSs suffered.

On that occasion I was off road and a small rock got kicked up and struck the caliper. This broke the mount, and the caliper went into the spokes, trashing 6 or 7 of them and writing off the wheel.

So... as has been speculated above, the issue could just as easily be the caliper or its mounting, rather than anything to do with the wheels.

Whatever - it's certainly not something you want to experience at speed.
 
But there have been no reports of this happening with cast wheels! Its only happening with spoked wheels. So .. I don't agree :D

It aint the mount, its the spokes.

Blimey ..... look at all the dozens and dozens of people that have been affected by loose spokes in their wheel. Twizz on here had about 6 spokes that went thud when you twanged them.

It aint the calliper mounting bolts!! Its the wheel. :thumb2
 
It’s all possible but the failures seem to be spoked wheel related. Granted a cast wheel might not collapse but the Caliper mount failure would still be reported on forums. If it’s simply a lug failure the wheel type should be irrelevant.
Also I can see the Caliper easily falling into the spokes at off road speeds. At motorways speeds I think the Caliper would bounce off and away from the wheel initially, at least giving some pre collapse warning.

Try spinning a wheel at speed and poking something into the spokes. It’s not easy.
 
Tarka said:
And I'm asking why you keep saying this.

Road-only orientated bikes had wire spoked wheels for years without problems, even after cast wheels appeared.
It's still so now, only Bee Emm Troubleyou wheels are falling apart like this.
Click to expand...
This is very true - but those older style spoked wheels were designed to run with tubes and didn't feature the extreme spoke angles that the tubeless orientated wheels have to have in order for the spokes to engage with the outside of the wheel rim.

Maybe it really is all about the design then, per Giles' point.
 
[QUOTE=Tarka;

One thing though.....has anyone looked at all of these BMW wire spoke wheel collapses and checked on the bike's loaded weight?
Just think of your typical fat cnut in all the "adventure gear" with a similar heifer on pillion, along with all the metal boxes loaded to capacity and a gazillion "farkles" and other shite bolted on wherever possible.

Thanks for that comment. It brightened up my day. I laughed out loud at that one.
 
max7 said:
This is very true - but those older style spoked wheels were designed to run with tubes and didn't feature the extreme spoke angles that the tubeless orientated wheels have to have in order for the spokes to engage with the outside of the wheel rim.

Maybe it really is all about the design then, per Giles' point.
Click to expand...

Or the weight..... or the tyre grip advances..... or the speed involved.....
 
The fact the spokes are now locked by a grub screw tells you that the angle of the spoke is an issue maintaining tension wise. Spoked wheels of yesteryear had no such issue and had no need for nipple locking.
It’s possible the spokes are snapping in the collapses rather than coming loose. That would account for the lack of warning or noticeable loss in tension pre incident.
 
I think for once Warlord has posted a valid comment ... :D

You are now able to buy a spoked bike, that can do 140mph, with the latest in modern tyre technology. What do we all regularly do on our bikes, daily? Drop it a gear and gun it! Oooooo its fun! The torque that you are putting through that rear wheel, with sticky rubber, in those 50 to 90 mph throttle stop squirts on the motorway is in a different league to what you could do on an R80 in the seventies!

Its a bit like the old argument about mapping your ford Fiesta and gaining 100bhp but not touching the transmission and then wondering why you've just shreaded your gearbox!

Modern spoked bikes are delivering modern sports bike performance. Just maybe those wheels aren't up to it.
 
* to add ....

We gun it hard dozens of times a day, but we don't all go out and practise emergency stops dozens of times a day. The front probably gets a fairly easy time by comparison ..... (evidenced by a sort of two rears to one front tyre purchase unless your stick !)
 
Warlord said:
I keep saying it because BMW spoked wheels over the past 3 years have had catastrophic failures and BMW won't accept liability.

So.... if you like your bike and do a lot of road miles, switch wheel types.

It only cost me £450 to do it. The alloy wheel-sets come up on ebay often. It's not a huge expense, especially for extra piece of mind.

I think they look great :thumb2
Click to expand...

Spoke wheels look better.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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