Crash Bars On Your F650 / F800

[johngil]

Originally Posted by Bayner

Is there anything you can't break?!

4 minute mile?

[F800 Rob]

Originally Posted by johngil

Pictures to follow.

I will be ordering a replacement set, because I do like them, but I think I have found a bit of a weakness.

If there had to be a first, I'm glad it's you. Can't wait to see what they look like and hear the story behind it.

[johngil]

Originally Posted by F800 Rob

If there had to be a first, I'm glad it's you. Can't wait to see what they look like and hear the story behind it.

No real story. I've never really even crashed the bike. Unless a tipover going a couple of MPH counts.

Rob will be getting a credit card # soon enough.

[johngil]

Here you go. I'm tempted to make a sleeve for the front tube and through bolt it. I don't know.

[Bayner]

4 minute mile! Nice!


Strange it sheared right there, and not at the bolt hole...

[johngil]

Holans are listed as a special order now. May look in to the Altrider bars.
Please tell me they aren't made in China.

Found my own answer

Made in America

From the earliest stages of design to packing up the finished piece for shipping, AltRider products are made entirely in the United States. We are proud to stay local with our manufacturing. We believe a high level of quality is possible thanks to strong relationships with all our suppliers.

[Numb]

i have the altrider crashbars on my 658gs - just put them on a couple weeks ago, look great and more importantly are very solidly mounted

install was a snap, and their service is good to (revzilla left a part out, but AR shipped it immediately upon contacting them)

[EnderTheX]

Originally Posted by Bayner

Strange it sheared right there, and not at the bolt hole...

Not strange at all... The sharp corner on the bar is a giant stress concentration and a great place for a fatigue crack to start. While holes also exhibit these qualities they do much better than sharp corners. (Trust me, I studied fracture mechanics, the most common methods of introducing a crack into a sample coupon is to machine a 90 deg sharp corner into it)

Like John suggested a sleeve with new holes and removing that whole mid section crap should be strong enough to keep going.

[Motorfiets]

Originally Posted by johngil

4 minute mile?

+1

[Bayner]

Originally Posted by EnderTheX

Not strange at all... The sharp corner on the bar is a giant stress concentration and a great place for a fatigue crack to start. While holes also exhibit these qualities they do much better than sharp corners.

Thanks Ender, that's good info.

[EnderTheX]

Originally Posted by Bayner

Thanks Ender, that's good info.

Anytime

A quick comment on the theory behind corner design in mechanical systems...

Outward pointy corners (example: the corners of a cube) are no problem for stress.

Inward pointy corners (like on that bar) are problems for fatigue, anything that experiences cyclic loading may eventually fail due to a crack originated at the point.

How do we avoid this?... simple add a radius to the corner.

While parts with a radius or a sharp corner have minimal overall strength differences the resistance to fatigue stress is significant for a smooth corner with a generous radius.






On a complete side note and mainly for my own amusement, I have to say none of this holds true for composites and parts made of carbon fiber or kevlar layers may exhibit the exact opposite characteristics. One of my favorite stories is about some engineers at Bell laboratories working on a composite helicopter rotor assembly part originally made of aluminum. When they mimicked the shape of the aluminum part (radii in the corners) it would tear itself to pieces. No one knew what to do until one engineer had a revelation and eliminated the radii from the composite part. The forces experienced by the part were exactly 90 deg apart and isolated from each other. This means the radii in the composite part were transmitting forces from one direction to the other... the composite was designed for strength only in the required direction and the fibers pulled themselves apart because they did not have any support in the opposite direction. Once the radii were eliminated the part functioned perfectly. (It's been a while since I've told this so I could be missing one part of the story but you should get the point )

[dirt-n-tar]

It loooks like some crashbars will work with the BMW aluminum bash plate (Hepco Becker) and others will not (Wunderlich). Any other observations as to which will work and which won't?

[johngil]

Altrider crashbars ordered.

[markymcd]

Looking forward to some good photos and feedback on the AltRider Bars...

Saw them at the Seattle Moto Show and thought they stuck out a bit too far... but that might not be a bad thing. My Touratech upper bars are getting far too close to the fairing from drops.

Maybe you can do us a favour and drop your bike a few times

cheers,
Mark

[johngil]

AltRider bars installed.

I will miss the looks of the Holan bars, but after more than 15,000 miles I can see some of the undesirable characteristics they possess.
I will say that initially I would like to see the AltRider bars hug the bike a little tighter.
Fit was perfect, as compared to the Holan bars. Funny, but after they (Holans) snapped, the right side seemed to fit better. I think the jig used was a little off.