BST Carbon Wheels - MVAgusta.net
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post #1 of 113 (permalink) Old 02-27-2006, 01:38 PM Thread Starter
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Unless the bike is on display in your living room, stay away from CF sturctural components. Especially wheels, handlebars and brake levers.
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post #2 of 113 (permalink) Old 02-27-2006, 01:55 PM
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Quote:
Originally Posted by luvtolean
Unless the bike is on display in your living room, stay away from CF sturctural components. Especially wheels, handlebars and brake levers.
That's a bold statement. Care to elaborate?

Jack
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post #3 of 113 (permalink) Old 02-27-2006, 02:02 PM
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I'd like the hear the issue w/ CF wheels also. Is there any history of them failing? I just bought some for my Ducati 749R. From everything I've read they are an excellent way to eliminate some unsprung weight.

Steve


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post #4 of 113 (permalink) Old 02-27-2006, 02:07 PM Thread Starter
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Not really as bold as you might imagine.

CF wheels are banned by every racing organization you can think of. F1, MotoGP, the pinnacle of their respective sports, have outlawed them.

Both of these sports used forged magnesium, which outside of possibly beryllium of which the dust is deadly to humans and the material immensely costly, is the best material for a racing wheel.

CF when developing stress cracks are practically undetectable. There is no means of non-destructively testing a CF component. (This is why only MotoGP, where the teams all have big bucks and will scrupulously throw away rotors at their recommended service interval, or after a crash despite no signs of damage), allows carbon rotors. Magnesium/aluminum can be x-rayed, and especially in the case of alumiunum, have significantly more ductility in the material, meaning you have more time to catch cracks.

CF also has to be very well designed to be strong on all load axis. The BST wheel, which I've gone over in detail, has a serious design flaw in how they connect the inner rim spokes to the rim outer. Basically, in their design, all load that is being transferred between the inner and outer goes through resin only where the two are bonded.

If you surf the internet boards, there are several instances of catastrophic failure of these wheels.

Last week, a member of another board I frequent, fireblades.org, had a CF clip on fail catastrophically on the race track. This is not to say metals don't fail, but they're typically a much more forgiving material.

Last edited by luvtolean; 02-27-2006 at 02:17 PM.
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post #5 of 113 (permalink) Old 02-27-2006, 02:11 PM
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I don't know much about the structure but I have seen (i believe maybe those very same cf wheels) photos of the cf inner rim completely torn away from the outer.

Trying to find the pictures but don't remember where...

http://www.amaproracing.com/rulebook/05rrrules.pdf

Chapter 1 paragraph A.i.3. Wheels may be replaced with aftermarket parts provided
they are not constructed of carbon fiber or carbon composites.
Maximum rear wheel rim width is 6.25".

Although many don't have problems w/their CF

Last edited by alvin; 02-27-2006 at 02:16 PM.
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post #6 of 113 (permalink) Old 02-27-2006, 02:13 PM Thread Starter
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I also forgot to mention, CF has a limited fatigue life (both the resin and the fibers). So it will eventually crack. BST does not give a service interval for their product.

Here is some reading for you.

A failure on WERA. (cause unknown)

http://forums.13x.com/showthread.php...t&pagenumber=1

A beautiful 998 destroyed, blamed on BST failure. (probably the one you're thinking of admin)

http://www.southbayriders.com/forums...ht=bst+failure

And CF clip on failure.

http://www.fireblades.org/forums/gen...hlight=clip+on

I would say the evidence is not ironclad. But I will NEVER use a CF wheel on anything.
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post #7 of 113 (permalink) Old 02-27-2006, 02:18 PM
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Those would probably be the pics i've seen
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post #8 of 113 (permalink) Old 02-27-2006, 02:31 PM
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I was at ThunderHill that day. I rode in with the corner workers for lunch and they said the bike cartwheeled. So, who knows? I was also at Pahrump a few years ago when an instructor from Keigwin crashed his RC and we picked up pieces of the magnesium front wheel that shattered. Magnesium is porous and there have been reported problems of wheels losing air. So I stay away from Mg too.

It's interesting that the e-bay auction says the BST wheel is unique in that it is formed as one piece.

I stick to forged aluminum because I think it's safer and it fits my budget.

Like you said, the evidence isn't iron clad, but it's enough for me too that I wouldn't go out and spend the extra money on wheels, clip-ons, or levers.

My mountain bike has a carbon frame, carbon seat post, carbon riser, and a carbon bar. I'm not too worried.


PS: Sorry for bastardizing this For Sale thread. Step Toe are you selling these wheels? Are you Martin from MotoWheels?

Jack

Last edited by Gladio; 02-27-2006 at 02:36 PM.
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post #9 of 113 (permalink) Old 02-27-2006, 02:39 PM Thread Starter
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Yeah, for me it's simple.

On the road, forged aluminum is where it's at. Far more ductile than Mg, lower notch sensitivity (for chunks taken out by potholes and errant tire changers) and just all in all cheaper/more forgiving. 10 Spoke forged Al 'sinis will be on the SPR sooner rather than later. (I also wonder if this why the Tambo came with Al over Mg?)

On the race track, I think Mg is worth the cost/risk for classes that allow aftermarket wheels. I ran them, but kept a real careful eye on them. If I do it again, it will be Marchesini only, they seem to be the best current maker of them.

Proper Mg wheel usage includes blasting off the paint and carefully inspecting them every year according to Carrol Smith. But most people, myself included, don't really do that. I do have a friend who does...incidentally he's had two different Mg wheel failures over a long racing career...

Last edited by luvtolean; 02-27-2006 at 02:42 PM.
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post #10 of 113 (permalink) Old 02-27-2006, 02:46 PM Thread Starter
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Quote:
Originally Posted by Gladio
PS: Sorry for bastardizing this For Sale thread. Step Toe are you selling these wheels? Are you Martin from MotoWheels?
Oh man, I hope not! I read that e-bay ad and thought StepToe was just showing them.

Heh, I'd planned to order my wheels from MotoWheels when the time came too. I wonder if it's going to take a few extra weeks?
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