Crazy, oddball, whacked out, dirt bike ideas . . .

will pattison · Jul 20, 2001

yup.

wp.

MikeT · Jul 20, 2001

LB400 · Jul 20, 2001

I drool when I think of how cool looking, and how light a carbon bike would be (fenders, numberplates, guards, etc) , and I work with the stuff everyday making sailboards.

BUT.....as has been stated, when it fails, it is NOT a pretty sight -- hugely dangerous, with very jagged splinters.

When all is said and done, you really can't beat good-old polyethelyne for parts that are going to be abused severly.

Still -- carbon handlebars could be made strong enough that they would NEVER break, but there would only be a very slight weight advantage, if any.

Carbon rims -- lighter, but EXPENSIVE. Dymag makes some streetbike rims that are WAY cool, and really strong, but are $7000 CAD a pair.

Carbon gas tank? Why not -- they don't get quite the abuse that other parts of the bike do.

In the future, I can see titanium getting more affordable, and it would be excellent for rims, bars, engine cases, springs, frames, swingarms, you name it -- now that's something to get excited about!

MACE · Jul 20, 2001

Recycled Post From April... Sorry...

I posted this in April. http://dirtrider.net/forums3/showthread.php&threadid=5318&highlight=20xx

I see MXA has caught up to me in a few areas...
:confused:
==============================================================
New for 2002

Handlebar clamps come standard setup for Protaper bars but big three use filler sleeves for standard 7/8 inch bars.
Low prices on Russian titanium sees increased use. Pegs, pipes and other high visibility parts are spec'd in Ti.
BNG includes reflectorized materials because they look cool on TV and in magazines.

New for 2003

Embracing MTB technology, lightweight tubeless tires are introduced.
Thumb operated shifters appear. Incorporating ignition interupters, they are particularly handy when wearing the new age CFRP hybrid boots.
Fulfilling their part of the USFS trail building program, riders demand and recieve lightweight, extrememly quiet, high performance exhaust systems.
The new KX shocks the offroad scene with full downdraft carburetor, tank and airbox positions swapped - with a board flat seat from rear fender to the steering stem.

New for 2004

Keronite is applied to pistons and sprockets. Durability improves five-fold. Radiator capacities reduced due to less heat loss to coolant system.
All carb circuits are externally adjustable.
Improved fatigue properties due to counterbalanced engines allow reduction in frame mass.
Factory SX/MX teams experimant with expansion chamber water injection.

New for 2005

Yamaha releases hydrostatic/chain two wheel drive off road bike.
Honda cancels ill-concieved four stroke off road bikes. Licenses the Gorr valve for new two stroke line.
Using thermoplastic technology from Airbus leading edge surfaces, KTM introduces monocoque airbox/fuel tank "subframe" with it's own "downdraft" engine.
Vane type steering dampers built into top triple clamp become oem standard.

New for 2006

Patents on PDS suspension expire. MX bikes abandon linkage.
KTM releases air sprung suspension.
Yamaha/Ohlins releases "adaptive" suspension.

It gets a bit fuzzy out this far....

New for 2007

REV! factory rider Travis Pastrana surpasses JMGs record for SX wins.
Secretary of Interior, Don Amadour dedicates Big Sur ORV park.
Dirt Rider magazine presents Rich Rohrich with Product of the Year for his "Tighties". "Tighties" remain in R&D for thirty more months.
KDX 200 remains unchanged.

MACE · Jul 20, 2001

Originally posted by will pattison
....you are right about concrete, but with the pre-stressed variety, the rebar is stretched while the concrete is wet. after it's dry and the tension is release, the bar attempts to return to it's original length. as the concrete wants to go along, tremendous compressive forces are built up, and that's when concrete is strongest. it sucks in tension.

Carbon fiber reinforced plastic (CFRP) is fantastic in tension but in compression it is limited by the integrity of the matrix (epoxy).

Maybe we can build XRPreditor some Carbon Fiber / Concrete sandwich handlebars.;)

Seriously, in commercial aerospace structures, we have to knock down the properties of CFRP tremendously on compression structure because it is so intolerant to damage. If the "glue" isn't holding the fibers together there is virtually no compressive strength - like pushing a string. In commercial aerospace we realize much less weight advantage (compared to aluminum) than the basic material properties would lead you to expect due to the requirement that imperfect parts must not fail.

CFRP production is EXTREMELY labor intensive as well. Small complex curved parts are laid up by hand by highly skilled workers (some of the best are from the garment industry.:)). Very large parts can be made with tape laying machines - but each ply is still inspected by hand. This labor makes the parts very expensive even if the material cost were ignored.

Finally, we haven't been able to apply CFRP to only the tension structure very well because of the difference in thermal expansion of aluminum and CFRP. If you built the top surface of a wing (compression side) out of aluminum and the bottom surface (tension) with CFRP, the difference in temperature from the ground in Saudi Arabia and the temp eight miles high would cause the wing to vary in shape tremendously - with an attendent huge shear load in the vertical webs attaching upr and lwr panels together.

Anyone still reading this?????

Re: Nitrogen. Air is (uh like) 97% Nitrogen. NASCAR tires and shocks use nitrogen not because it is closer to a noble gas but rather because it is free of moisture, safe around open flame, cheap and readily available. Moisture is the biggy because a little atmospheric humidity heated up becomes steam which will spike the pressure noticably. If you had CLEAN air in your tires it would behave the same as N2

MACE · Jul 20, 2001

Superplastic Forming

http://www.uscar.org/techno/superplas.htm

This is a quickie search hit on Superplastic forming (SPF). This is a process where titanium or aluminum sheets are attached together with laser welding, the sheets are heated and put inside a die cavity. The area between sheets is pressureized (with nitrogen;) ) and the sheets expand within the die. You can weld the sheets together such that when expanded there are internal webs for stiffness. Think about a square parachute, the parachute cells are analogous to a simple application of SPF.

I've been wondering if Yamaha is using SPF to make their 2002 swingarms...

biglou · Jul 20, 2001

The bottles used for inflating the tires for Naval/Marine Corps fighter aircraft are labeled "Oil-Free Nitrogen". This is one area where temperature extremes are reached in a hurry and where proper inflation is crucial. The tires on the A-4 "Skyhawk" were inflated to some insane pressures, like 185 PSI shore-based and 360 PSI carrier-based. If I remember correctly, it was a purity issue with the nitrogen. (I was on the Avionics side of the house)

Question for the big brains: Would the purity (or lack thereof) of the nitrogen have any appreciable effect on the rotational inertia of a wheel? Meaning, if there are a lot of impurities spinning around inside the tire/tube, would there be a measurable difference in the amount of force to slow/stop the rotation compared to a "purer" source?

01HondaCR · Jul 20, 2001

This is the company that makes the ATV Carbon Fiber rims http://www.hiper-technology.com/index.htm

MACE · Jul 20, 2001

Marketing Hype

If you go to:
http://www.hiper-technology.com/FAQ.htm
And go to the item that addresses the rims looking like plastic...

Sounds like this product is injection molded graphite reinforced nylon. This material will be only a fraction of the strength and stiffness of a true CFRP. Basically the fibers are oriented randomly. The fibers that are not oriented with the load do nothing but take up space. To get real strength they would need filiment winding.

I expect that the injection molded rims are sufficiently strong for their job, but they would probably be just fine with glass fibers as well. Carbon Fiber is so much sexier than glass.....

This is a fun thread - hope I'm not peeing in the pool.:(

woody51 · Jul 20, 2001

Not to get technical or anything but Air is not 97% N :). Here is the breakdown of air if anyone cares
Nitrogen N2 78.084%
Oxygen O2 20.946%
Argon Ar 0.934%
Neon Ne 0.0018%
Helium He 0.000524%
Methane CH4 0.0002%
Krypton Kr 0.000114%
Hydrogen H2 0.00005%
Nitrous oxide N2O 0.00005%
Xenon Xe 0.0000087%
:)

MACE · Jul 20, 2001

That explains why I'm so dizzy....

Lack of O2 in my world - maybe an excess of methane as well :eek:

Woody 51, what is the chemical differences in oils of different viscosity. I bet I got that wrong over on the suspension forum too.

I feel like a real da/dt:D

will pattison · Jul 20, 2001

ok, now i KNOW i am a geek, because i got mace's last joke. i suspected it before, when i got "a=dv/dt" embroidered on the back of a pair of fox pants, but now i'm certain. thanks, mace, for helping me out of the closet!

and no, impurites in the air would not cause a noticible difference in the inertia of a spinning wheel.

wp.

XRpredator · Jul 20, 2001

I thought one of the reasons for the Nitrogen used by the NASCAR/CART teams was they could run the air through the impact wrenches quicker . . .

Yes this is a fun thread, and you're not peeing in the pool!;)

Jon K. · Jul 20, 2001

So Woody; where is all that carbon dioxide that the greens keep going on about?

marcusgunby · Jul 20, 2001

I once did my own scientific test on Carbon fibres ductility at a bike show a few years ago.The part in question was a frame guard.I held it and bent it to say 5 degress from normal and i heard a load crack followed by alot of dust.Luckily for me the show was really loud and the guy running the stall didnt notice-i looked at him sheepish,placed the guard down, smiled than left as fast as my 28" legs would carry me.Those guards were expensive in 94 and the pair i was looking at wouldnt fit my bike so i wasnt about to pay for them.:scream:

Kramer · Jul 21, 2001

MACE, it's great to have someone with practical experience. If that's peeing in the pool, I just won't swim anymore:)

Big Lou, I would think that if the impurities were heavy enough to have a significant effect on rotational inertia, they would fall out of the nitrogen. I say this with absolutely no knowledge of the compression/storage/delivery of the gas, so take it with a grain of salt.

Hey Will, what's the sq root of -69? only a real da/dt can appreciate that one!!

Keltracer · Jul 21, 2001

Originally posted by yzeater
[*]Carbon fiber plastics (you know what I mean)

Reminds me of an idea I had awhile back. Why not make plastics out of "Rubbermaid" type of a material? I think this would be a great seller for people who replace plastics frequently, such as myself.

spanky250 · Jul 21, 2001

Originally posted by Keltracer

Reminds me of an idea I had awhile back. Why not make plastics out of "Rubbermaid" type of a material? I think this would be a great seller for people who replace plastics frequently, such as myself.

It would also be good for some laughs, watching all those fenders flopping around like a hound dog's ears on the track.:p

Jaybird · Jul 22, 2001

Mace,
I'm with you on the clean air thing.
My tires only see CLEAN, DRY air. Matter of fact, the air that hits my tires is dry as a bone and clean to .001 microns. Try getting THAT out of your local gas stations air compressor! :D (a common filter cleans to 40.0 microns)
When air shocks DO become popular again, I suspect I can gain a huge market for my clean air system. :)

David Trustrum · Jul 22, 2001

Well one of the items in the crystal ball -tubeless dirt tires I can gaze into my garage at my 12yr old Beta trials bike.

Mountain bike technology my arse! But lets not start that again.

MACE · Jul 23, 2001

David, please elaborate on the execution of the Beta tubeless.

Do the spokes penetrate the rim?
Is there anything to serve as a rim lock?
What kind of pressures can be run (problems with low pressure).
Any peculiarities in mounting tires?

Generally, any comments on the merits of the system.

David Trustrum · Jul 23, 2001

Std practice on trials bikes, my one has non penetrating type spokes on a centre ring which doesn’t sound ideal but remember people (not me) jump these things off huge heights at 0mph. There are penetrating ones with seals on other models/makes.

Was pretty trick in 1989. Everyone does it now.

Low pressures how does 4-5 PSI strike you? Rim lock? You know I can’t remember!, I have so many damn bikes in my head but I don’t think so. Then again there isn’t a whole lot of power going thru there. We Dyno’d a late model Beta 250 & got like about 11 or 12 hp.

Buzz Bomb · Jul 23, 2001

I was browsing through an old issue of Dirt Bike, and I just saw a picture of a bike with carbon fiber plastics...I never knew they were made? Maybe these were just custom ones for the ad??:think

KawieKX125 · Jul 27, 2001

posted by Kramer,
Ever see CF ski poles? They can nearly bend end to end without breaking, .25" or so in dia., and are a good bit lighter than their Al counterparts. Cost an arm & a leg, and who wants to land on a splintered CF stick if it gets broken.

I believe those poles are graphite. I have a pair, and although they are light and flexible, they break and splinter.
I have seen the CF plastics. They are brittle and EXPENSIVE!

I had an interesting and practical idea;
Why not use a Ducati style valve train for a MX bike? I does not float and is very accurate. No springs, just 2 pushrods per valve to open and close it.

Rich Rohrich · Jul 27, 2001

Originally posted by KawieKX125
No springs, just 2 pushrods per valve to open and close it.

There are NO PUSHRODS in a Ducati.

Crazy, oddball, whacked out, dirt bike ideas . . .

will pattison

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MikeT

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