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Old 09-24-2012, 04:57 PM   #746
Studly Adventurer
Joined: Nov 2008
Oddometer: 800
Originally Posted by reenmachine View Post
It looks to me like the rider hit something and the fork broke at the weakest spot, which we all know and love. As others have said numerous times, it's unfortunate that the fork fails here when forced instead of degrading more gracefully, but I still think that's the nature of the old design vs. a manufacturing defect. I'm not calling it a design "flaw" either -- everything will fail somewhere when prompted to, and these forks seem to do it at the RH axle boss instead of somewhere else. BMW realized this was not optimal and reinforced the area on later forks.

That still doesn't explain the OP's failure, but neither does anything else. I doubt we'll ever know. My problem is that I enjoy my G so much I apparently don't care. I did tell my wife that if I mysteriously stack it to make sure the front fork is scrutinized, and she's got the bookmark to this thread.

I really don't have a dog in this fight, I just find it interesting to think about.

I do have trouble applying "logic" to the theory of forced failure, over the theory of a degrading failure over a period of time. That period of time could be 30,000 miles or 95 miles. The 95 miles might come after 29,905 miles of trouble free service and an improperly installed front wheel.

The failures that offer the most information have happened on improved roads with no mention of striking anything significant. If these were forced failures as claimed by BMW and others, logic would suggest the fork would need to be bottomed out in order to apply enough force to break an otherwise OK fork. They are considered "shock absorbers" right?

On the other hand a fork tube put in stress by a bent axle or a missing spacer, or possible other improper installed front end component, could fail over time. That time could be influenced by the amount of stress, an out of alignment wheel, loose spokes, unbalanced tire, etc.

I think most of us have held a spinning wheel by the ends of the axle and have some idea of the gyroscopic effect of the spinnng wheel. If an axle is bent or a spacer is missing the forks can be pulled / twisted in such a way as to not be aligned, as designed. When the bike is not moving it's just a slight twist or bend against the stability of the fork brace. When the wheel is rolling against the ground the gyroscopic effect wants the wheel to run straight and upright. The rider wants to run down the road on his chosen line. The fork is absorbing a lateral stress that it may not be designed to withstand. The stress could be compounded by any number of factors as mentioned above or possibly unnamed

I wouldn't wait for a failure to scrutinize my forks.

Some would suggest their fate is in the hands of the unknown. If it fails, it fails. That's fine with me.

If I'm wrong, I'm just wrong, if I'm right, a little bit of preventive maintenence might save somebody..

Center-stand screwed with this post 09-24-2012 at 05:19 PM
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