Tuesday, December 6, 2016

Wheels Part 3: The 5-lb Proposal

So if you read the early posts about the design I built in CAD it shows an unusual wheel called a 'Marathon Flat Free Cart Tire' which includes the wheel.

Marathon Flat Free Cart Tire
Now looking at this one might as "that doesn't look strong enough" but believe me it is. This sucker is made from long strand glass fibers and composite resins and one wheel can handle about 100 lbs weight before starting to show signs of fatigue. Also the hub is reinforced inside and outside to help avoid shear when cornering. This thing is BOMBER and it only weighs 5 lbs. The foam alloy used for the tire is very tough, and unless you decide to go faster than 35mph this will be just fine.

So lets recap.

  1. Total weight penalty for 4 wheels is only 20-lbs
  2. Outside diameter is the same as the 17" CT90 wheel and tire
  3. The bearing sizes it comes standard with are 5/8" ID so no need to modify
  4. This tire is tubeless and even though it's stiff will provide quite alot of jounce
  5. it's possible to order on Amazon and its only $29.00

You may ask "Wait did you just say 'top speed' of 35mph? Isnt that too slow?" the answer is no. The point is that you can use this tire with a stock engine setup and get incredible performance. After testing these they tend to 'roll' a bit when doing insane cornering, but as long as you remember it's a foam wheel and tire, and you aren't driving like Markku Alén it should be fine.


Ok fine. here's the answer: There is another type of cart wheel used for towing deer parts and usually saved for donkey carts called a 'Tire on Spoke' wheel made by Northern Industrial.

This wheel is also very tough and comes standard with 5/8" ID bearings. If you want it even can be ordered with 3/4" bearings, which gives you slightly more hub diameter in case you find your 'keyway hub' adapter plate is on the larger side (more to come on that later). This setup costs about $32 a wheel and also weighs about 5 lbs (slightly more because of the rubber). Also available on Amazon, or direct from Northern Industrial. Easy to find, order, and count on for the future, and not from a scrap yard.

This is a standard bike construction wheel and is rated also for 100lbs each. But because the spokes and hub are steel, it will tend to flex alot more. Plus the tubed tire combo is alot more robust at speed. I have not been able to test this design at any speed higher than 40mph but it was plenty stable when I did. I estimate that top speed with this guy is around 50mph - but to verify I will do a high-speed-test run in the spring next year. -CW

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