Shock springs instead of spokes?

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Permalink Reply by Thunder Snow on April 17, 2013 at 3:33pm

Great idea!  And if you could use airless-never-fix-a-flat-again tires with these rims and dial in the suspension to compensate for the lack of air-filled tubes...I'd buy these in a heartbeat.

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Permalink Reply by Far'arned Retrogrumpalunkus #63 on April 17, 2013 at 3:42pm

Looks like there would be a bit of a wind-up issue.   

Powering uphill and especially hard braking would be...interesting. 

Rim brakes are out of the question as rim/caliper alignment would be impossible.   Then there would be clearance issues at the stay bridges and the fork crown.   Effective fenders would be impossible as well. 

Hitting a large enough bump to cause the front tire to contact the fork crown would cause an instant endo as the front wheel would come to an instant stop. 

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Permalink Reply by WillG on April 17, 2013 at 3:45pm

Do you think that off the shelf rims are able to span 1/3 of the 20" wheel's circumference and still stay radially and laterally true?

It's my understanding that a lot of the inherent strength (laterally and otherwise) of a rim is due to the enormous amount of compression it is under from the traditional tension spokes. Since this wheel doesn't have tension spokes (nor compression spokes) since the "spokes" are springs, how does the wheel work?

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Permalink Reply by millenial removing Bernie tattoo on April 17, 2013 at 4:11pm

Strength of the rim is determined by the number of supports (i.e spokes) and the beefyness of the rim itself.  The compressive force from tensioned spokes doesn't do anything for the strength of the rim , in and of itself, other than that a untensioned spoke is no longer effective as a support.

 

I'm assuming this wheel works in reverse, and the springs are pre-loaded in compression, putting the rim under tension.  Since there are only three spokes, you'll need a hefty rim.  These are obviously heavy wheels.

 

This is pointless, you are trying to make the spokes do the job of the tire.

Will G - 10mi said:

Do you think that off the shelf rims are able to span 1/3 of the 20" wheel's circumference and still stay radially and laterally true?

It's my understanding that a lot of the inherent strength (laterally and otherwise) of a rim is due to the enormous amount of compression it is under from the traditional tension spokes. Since this wheel doesn't have tension spokes (nor compression spokes) since the "spokes" are springs, how does the wheel work?

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Permalink Reply by Far'arned Retrogrumpalunkus #63 on April 17, 2013 at 4:18pm

Agreed.  The military tried various approaches to this with "honeycomb" structures instead of these three springs.  They did work but the performance of these wheels were abysmal.  For a Hummer it's not a big deal, for a performance vehicle it is.   Weight is an issue, and so is undampened rebound of the spring.

Ideally a tire needs to keep in contact with the ground or there is no traction when it is bouncing.   Putting an undampened spring for suspension inside the tire is not an improvement, even if the wheel isn't any heavier than a typical bicycle wheel.  Anyone who has ever run a suspension fork where the dampening oil is no longer functioning knows how much this sucks.  At least with a suspension fork there is always SOME stiction acting to dampen the suspension even when the oil has leaked out.   This bouncy-ball wouldn't even have that. 

Sheldon, on airless tires.

envane (69 furlongs) said:

These are obviously heavy wheels.

 

This is pointless, you are trying to make the spokes do the job of the tire.

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Permalink Reply by Gort 12-mile Pinklegneep on April 17, 2013 at 6:41pm

It's cool how the wheel in their showcase demo video is massively out of true. That bodes well. 

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