- Aug 2, 2000
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- #51
'Splain this to me . . .:think I don't get how that would work.
Crazy, oddball, whacked out, dirt bike ideas . . .
- Thread starter XRpredator
- Start date
KawieKX125
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- Oct 9, 2000
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Rich, the way it was explained to me by a Ducati mecahnic was that there is a "push-rod" of sorts the opens the valve and another that closes the valve.
Can you elaborate on exactly how this works?
Also, would this be a good thing for a dirt bike motor? It seems to me that this style of valve train could allow very high revs without ill effects on valve timing. :think
Can you elaborate on exactly how this works?
Also, would this be a good thing for a dirt bike motor? It seems to me that this style of valve train could allow very high revs without ill effects on valve timing. :think
Ben is right. One cam opens the valve and a second cam closes the valve.
The quality of springs these days makes desmo valve gear really unnecessary, but it's a Ducati signature technology so it thankfully lives on.
Too expensive, too complicated, and unneeded in the dirtbike world.
The quality of springs these days makes desmo valve gear really unnecessary, but it's a Ducati signature technology so it thankfully lives on.
Too expensive, too complicated, and unneeded in the dirtbike world.
- Aug 2, 2000
- 13,504
- 19
- Thread starter
- #55
How about the little electronic solenoids I saw a while back in <gasp!> Dirt Bike or MXA? (I can't remember which)
Seem like a good idea--less reciprocating mass, etc.:think
Seem like a good idea--less reciprocating mass, etc.:think
Pnuematics have proven themselves in F1 racing, but electronic systems up till this point have been seriously RPM limited. BMW and a number of other companies have electronic solenoid cam-less engines running in test, but the last news I saw they were still running under 9000 rpm. For the size and weight of the valves we are talking about and the quality of the spring material available we should be good till close to 17,000 rpm with springs. In relative terms they are cheaper, lighter, and less complex then any of the gee-whiz technologies . The Japanese are nothing if not practical . The Euro companies are smart enough to see this as well. Desmo valve gear has been trick since Mercedes ran it in GP cars 50+ years ago, but it's just a cool technical oddity these days.
pyromaniac
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- Jun 25, 2000
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I think rubber is a interesting material. Soft but yet very durable. Cant you use rubber instead of plastic. Fenders, etc, thats made stiff enought to hold the dirtflow away and not bend on crashes! I mean plastic isnt cheap and do break/bend or "misscoloring" easy!
Pyromaniac
Rubber indeed has some interesting properties. It has very high elongation.
Low stiffness elastomers ( 'rubber' is generally considered natural rubber, elastomers can be synthetic or natural) can have elongations well over 1000%.
Rubber has a very low bending modulous so it's not usually used for fenders and things that have to hold their shape. If the elastomer is reinforced with textile to make it hold a shape it gets stiff enough but the process is costly. Conveyor belting for example is really tough and flexible stuff but expensive ot make.
Rubber really excels when used as a spring. More energy per CM3 can be stored in rubber than any other material. There is an excellent opportunity for somebody to make a torsional spring bushing that would take the place of the rear spring/damper of a dirt bike. There are even mechanical methods to add damping that could be end-user tunable covered in patents. Michelin is planning to make torsional bushings for auto suspensions using this technique.
Jim
Rubber indeed has some interesting properties. It has very high elongation.
Low stiffness elastomers ( 'rubber' is generally considered natural rubber, elastomers can be synthetic or natural) can have elongations well over 1000%.
Rubber has a very low bending modulous so it's not usually used for fenders and things that have to hold their shape. If the elastomer is reinforced with textile to make it hold a shape it gets stiff enough but the process is costly. Conveyor belting for example is really tough and flexible stuff but expensive ot make.
Rubber really excels when used as a spring. More energy per CM3 can be stored in rubber than any other material. There is an excellent opportunity for somebody to make a torsional spring bushing that would take the place of the rear spring/damper of a dirt bike. There are even mechanical methods to add damping that could be end-user tunable covered in patents. Michelin is planning to make torsional bushings for auto suspensions using this technique.
Jim
Scott in KC
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- Aug 28, 2000
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Didn't the Corvette experiment with fiberglass suspension springs (or maybe they still are?)
NorCal_Red
Member
- Jun 29, 2001
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carbon ideas
i say look into bmx and mountain bikes.. some of this ideas are already tried and true.
i say look into bmx and mountain bikes.. some of this ideas are already tried and true.
What I'd really like to see is a good quality neoprene/plastic toolcase with CFRP or aluminum mounts that bolt on to the upper forks and replace the number plate and also mounts the license plate. Strap on bags bounce around way too much and a sturdy, waterproof case would be fantastic.
There is my $100,000 idea (not quite a million).
There is my $100,000 idea (not quite a million).
David Trustrum
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- Jan 25, 2001
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How about riding gear that doesn’t smell like a rancid goat when you forget to take it out of the bag & wash it after the last time?
David Trustrum
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- Jan 25, 2001
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Not if she reads this!
OK, here's my $.02
Mountain bikes do need to be looked at suspension wise. The weight lost by going to an air shock should be worth the time to look at upscaling some of the Fox air shocks for mountain bikes. Technology has advanced in the last two decades. Why not elastimers instead of springs? How about molding the upper fork tubs and triple clamps into one piece? Machine it or injection mold it.
Why not use the twin spar aluminum frame rails as a gas tank on a Honda?
Why not cast the engine as the frame? How about making the swingarm extra long and mounting the engine to the swingarm?
Why have the heads and cylinders been on backwards for so long? Why isn't the intake on the front of the engine and the exhaust on the rear? Why is it only now Cannondale is answering this question?
Why inflateable tires at all? Why not just replaceable bands of rubber? Why rubber at all? Why not plastic tires for dirt or sand use?
Why not design a rim that acts as the disc brake? The fork tubes have a brace connecting them above the tire. There is a little half caliper on each fork tube that pushes in toward the center.
Why not upscale Cannondale's "leftie" fork? Single sided front fork anyone?
Why not use the exhaust as the rear subframe?
Mountain bikes do need to be looked at suspension wise. The weight lost by going to an air shock should be worth the time to look at upscaling some of the Fox air shocks for mountain bikes. Technology has advanced in the last two decades. Why not elastimers instead of springs? How about molding the upper fork tubs and triple clamps into one piece? Machine it or injection mold it.
Why not use the twin spar aluminum frame rails as a gas tank on a Honda?
Why not cast the engine as the frame? How about making the swingarm extra long and mounting the engine to the swingarm?
Why have the heads and cylinders been on backwards for so long? Why isn't the intake on the front of the engine and the exhaust on the rear? Why is it only now Cannondale is answering this question?
Why inflateable tires at all? Why not just replaceable bands of rubber? Why rubber at all? Why not plastic tires for dirt or sand use?
Why not design a rim that acts as the disc brake? The fork tubes have a brace connecting them above the tire. There is a little half caliper on each fork tube that pushes in toward the center.
Why not upscale Cannondale's "leftie" fork? Single sided front fork anyone?
Why not use the exhaust as the rear subframe?
David Trustrum
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- Jan 25, 2001
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Not trying to be negative but here are possible answers;
Mountain bikes value lack of weight over all else, as you have to pick them up & run with them when you get to anything hard. This compromise would plunge us back to an era where suspension was garbage. Air has been tried before but was bleerk.
Swingarms on engines has been done on ducati’s as a compromise because their engine was too long being a 90 deg V twin. The racetracks were littered with broken crankcases.
Engine as a frame? Britten did this on his V-twin but the penalty was the engine was VERY heavy.
Tires have to be light so aren’t solid. Plastic? They wouldn’t grip.
Disc brake rim like a bicycle, problem is the energy you have to put into stopping a bike is much higher so the rim would need to be heavier at the rim just where you don’t want it to be.
And some more but I’ve got sick of my own rambling.
Mountain bikes value lack of weight over all else, as you have to pick them up & run with them when you get to anything hard. This compromise would plunge us back to an era where suspension was garbage. Air has been tried before but was bleerk.
Swingarms on engines has been done on ducati’s as a compromise because their engine was too long being a 90 deg V twin. The racetracks were littered with broken crankcases.
Engine as a frame? Britten did this on his V-twin but the penalty was the engine was VERY heavy.
Tires have to be light so aren’t solid. Plastic? They wouldn’t grip.
Disc brake rim like a bicycle, problem is the energy you have to put into stopping a bike is much higher so the rim would need to be heavier at the rim just where you don’t want it to be.
And some more but I’ve got sick of my own rambling.
KXaggerator
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- Feb 4, 2001
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Let's see, my Santa Cruz Superlight MTB has air sprung forks and shocks, Ti axles and seat rails, and carbon fiber handle bar. I have ridden a carbon fiber framed Kestrel with carbon fiber wheels. I have also had wheels with Ti spokes. I have seen Ti aftermarket springs for MTB forks.
Will, I am confused with the whole modulus of elasticity thing. Why is my aluminum framed Klein MTB sooo much stiffer the a steel or carbon fiber frame if the other two have a higher modulus of elasticity. I guess you could put the '97 CR250 in the same example.
I would like to see a light weight hydraulic drive instead of a chain. This way you could have a 2 wheel drive bike and maybe the breaking system could be incorporated in the same system. It would also cut down on the shock to the transmission's gears. Maybe the clutch could also be hydraulic.
Will, I am confused with the whole modulus of elasticity thing. Why is my aluminum framed Klein MTB sooo much stiffer the a steel or carbon fiber frame if the other two have a higher modulus of elasticity. I guess you could put the '97 CR250 in the same example.
I would like to see a light weight hydraulic drive instead of a chain. This way you could have a 2 wheel drive bike and maybe the breaking system could be incorporated in the same system. It would also cut down on the shock to the transmission's gears. Maybe the clutch could also be hydraulic.
Aust 520exc
Member
- Jun 19, 2001
- 37
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What about teflon coated engine parts - if it works in the pan why not in an engine??:think :think
How about electromagnetic suspension?
How about electromagnetic suspension?
