"legal" wheel for Mid America open Scout race

[JSG]

Looking at these rules, what aftermarket wheels would be considered legal for the open Scout race?

Thanks

Rules:

IV – Wheels
Only Official BSA Wheels are allowed (either new style & old style) all markings must be intact on inside and outside of wheel. You may use the Official BSA Colored wheels
Outer wheel surface may be sanded, shaved, lathed or polished to remove any imperfections, true roundness, remove mold castings and burrs, but must not be reshaped in any way to minimize tread contact or alter aerodynamics.
The fluting (small decorative dots on the edge) must remain visible around the entire circumference.
The tread / contact surface must remain flat and parallel to the bore.
The width of the tread must not be less than 7.5mm
No removing or reducing the letters or spokes or drilling additional holes.
The following wheel modifications are NOT Allowed
No Rounding of the wheel treads – they must remain flat.
No Grooving, H-cutting, V-cutting, Crowing, Tapering or Dishing
No Altering the wheel profile
No Drilling sidewalls
No Filling of any wheel surface with any type of material
Coning the hubs, truing the inside edge of the wheel, and removing the outer hub step down is allowed.
Wheel Bore treatment is allowed including polishing, sanding and / or tapping.
Wheel bores may not be filled and re-drilled

[Speedster]

I'm going to say 1.4 gram wheels are allowed. Some vendors allow you to name the mold number you want. Be careful with the wheels. You can't be tugging on them or you'll ruin them and they are expensive. They were available through Maximum Velocity (Derby Worx) last year but are a special order. Other vendors advertise them on their sites.

Off Topic - Lots of choices for axles. Stainless steel, grooved, .091, .093, cut groove in axle head by vendor if desired.

[ODDRacing]

you can actually get wheels that are 1g that are still legal. The wheels must contain the decorative bumps, lettering on the inside and outside. Just watch, because they lighter the wheel, the more flimbsy the edge becomes if you're RRing.

[JSG]

Now I'm debating if we should just go with the 2.5 gram wheels. Do the top scout cars have the 1.5 gram wheels? Really don't want to spend $40 or $50 to get the parts to build a competitive car.

[Speedster]

Axles, wheels, tungsten, bodies from Derby Evolution with Steve drilling the holes cost me $93.80 for each car. Shipping charges from the various Vendors and then to and from Nebraska is about another $40.00. Other supplies I already had. It was a lot of Fun for my wife and me but it wasn't cheap because we entered 2 cars. I tried to buy the best of everything because no matter where we finished I would know it was me and not the fault of wheels and axles out of the box. I knew it would be a one time experience and I'm happy we did it. My main interest is in scouting and building cars that are legal under our District rules.
It is a great experience no matter how your Team decides to build the car. From what I've seen there is going to be some great video. Your son will surely enjoy seeing his car racing on T.V.
Best of Luck.

[Noskills]

Would be tough to place with 2.5 gm wheels but not impossible. I toyed with buying a laser cut body and fancy plastic fenders but it the end I wanted the car to be made by me; I enjoy the making more than racing. (The kids all made there cars too by the way). Just posted pics of my mid American build on the photo section. St. Patty Day theme!
Noskills

[ODDRacing]

To answer your question. The gentleman and son that won last year were using the lighter wheels. Fortuneatly for you, he's not going to be entering this year as he does not have a scout. BUT that being said lets put this into perspective. I will be using the 1g wheels on my sons cars. He worked to hard on these cars for me to not get him the best. I however have a friend with a lathe so I dont have to spend $40-$50. We'll show this in weight. If you use the 2.5g wheels that's 10g or 0.35oz. Us using the 1g wheels is only 4g or 0.14oz. So having a 0.21oz advantage allows us to add more weight to the rear where you would not be able to. Now 0.21oz may only be 3-4 more tungsten cubes, but that equals more potential energy. And we all know the more PE = more speed.

[FatSebastian]

So having a 0.21oz advantage allows us to add more weight to the rear where you would not be able to. Now 0.21oz may only be 3-4 more tungsten cubes, but that equals more potential energy. And we all know the more PE = more speed.

The ability to add more ballast to the body is not the primary advantage of having lighter wheels. Rather, energy is needed to spin up each wheel. The more massive the wheel, the more the car resists acceleration and thus more energy is required to accelerate. This is energy that could be used to accelerate the car. This is why raising one of the front wheel results in an increased speed.

Mass moment of inertia is not just a function of mass, but of mass distribution; mass away from the center of rotation (such as the tread) increases the moment of inertia more than mass near the center of rotation (such as near the hub or sidewall). Thus the biggest performance boost one can give a wheel is to remove the tread mass (hence razor wheels).

If you care about math, you can find some here.



For a raised wheel, the rotation rate (omega) is zero, so there is no energy lost at all. For the other three wheels, if the mass moment of inertia (I) is reduced, it results in a smaller energy loss (Er).

So here's an experiment. Consider a 5.0 ounce car with conventional wheels and replace them with razor wheels without adding the extra 0.21 ounces (or whatever the wheel weight difference is) to the body. Which car is faster?

[Speedster]

I knew that was true but I'm surely glad I didn't try to explain it. Anyhow, on my scale 3 - 3/16" cubes weigh 0.210 oz. just in case anyone was wondering.

[TXDerbyDad]

Would be tough to place with 2.5 gm wheels but not impossible. I toyed with buying a laser cut body and fancy plastic fenders but it the end I wanted the car to be made by me; I enjoy the making more than racing. (The kids all made there cars too by the way). Just posted pics of my mid American build on the photo section. St. Patty Day theme!
Noskills

Your car is looking good. I feel the same way. I'd love a pure stock adult division, because while I realize that it takes skill to build a winning car even if you buy the best off-the-shelf components when you race at the Mid-America level, it still bugs me to have anything on my car I didn't work myself. So, I'm having a hard time wrestling with that. Do I buy components and build a car in the hopes of even placing, or do I "do my best" and get trounced?

I am still on the fence, but will probably register anyway.

[LightninBoy]

You guys have touched on the reason I'm hesitating to send cars into Mid America: to be competitive you must have lightened wheels. Looking around, these wheels are $40 - $50!!

For the adult cars I guess that's ok, but its silly for scout cars IMO.

[JSG]

I didn't realize there were 1 gram wheels available with the inside lettering on the wheel still in tact. We'll spring for some 1.5 gram wheels and see how it goes.

[birddog]

We all used 1.8 gram wheels on our cars in last years mid-america race and we were very competitive. 2 of my 3 kids won trophies.

birddog

[ODDRacing]

You guys have touched on the reason I'm hesitating to send cars into Mid America: to be competitive you must have lightened wheels. Looking around, these wheels are $40 - $50!!

For the adult cars I guess that's ok, but its silly for scout cars IMO.

Not sure I understand why they're ok for an adult car but silly for a scout car...

[Speedster]

Adult cars are special built cars for the Mid America because of their very generous rules. When you think about a "scout" car folks normally think about stock wheelbase, slots, stock wheels, axles that come out of the box. A $5.00 car, more or less. I suppose a scout thinks, "I wonder how my car would do against others in the Mid America race"? He could send it in and it would probably be interesting to see what a "basic" stock scout car would do against the "rockets" but I think everyone already knows. It's a "Scout" class but the cars are far from being "Scout" cars and they are very expensive.
The Mid America is lots of fun. Go ahead and send in your car and enjoy the race.