Wheels

Discussions related to building cubmobiles.
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sporty
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Wheels

Post by sporty » Mon Apr 10, 2006 1:03 pm

Okay,

Here is it, a topic for wheels.

So, I am going to yack about and talk about what I have learned or not learned.

Since I have only tested a few different type of wheels. I will talk about them.


Commtech wheels 10 inch-

Intial testing showed these wheels slow.

But due to two reasons, the bearings and it being a light wheel.

How did I come to this conclusion-

In a event that you are not allowed to add weight. a 10 inch steel wheel is heaver, and adds over all weight for the vehicle.

Meaning two equal Cubmobiles set up the same, the 10 inch steel wheels would have the advantage (in regards to weight)

Now- Bearings-

The Commtech wheels have sealed bearings, they are good quality, precion, no wobble. However, lacks in free spin time.

What does this mean -

If both Cubmobiles are equal, The cubmobile car that has more free spin, Less bearing drag. will be the faster Cubmobile.

Why, less drag, means the Cubmobile will slow down less.

Remember, its not the car going the fastest that wins, its the car that slows down the least.

Other factor -

The other factor is distance and track-

If the track gives enough energy to the cubmobile and the track is short. The other factor, will not come into play.

Free spin is a factor, when most of the energy from the ramp or hill has been used mostly up.

But also, the easier something spins, that faster or longer it is likely to spin.

Now

Width - This is one of the commtech wheels true advantages.

The narrower the wheel, the less energy is used up, when transfering to the ground.

Whats this mean, A narrower wheel under low speed conditions will have a advantage.

More energy concentrated to a smaller area. versus a wider wheel.


Now, if you remove / modify or tinker with the bearings, you will be able to get a faster spining wheel. However, you will still have to over come the weight factor, if both cubmobiles are equal except for the wheel weight.

The commtech wheel is a smooth, accurate wheel.


Now -

Blains farm in fleet 12 inch or 10 inch wheel. Also from Shepard hardware.

This is not a precision wheel.

As I have have picked through them to find better ones.

They wobble, have mold impefection in wheel mold, but they are heavy.

It's a Wider wheel also compared to the commtech.


Non precision bearing.

The good news, you can get over 3 minutes of free spin on them with a little bit of work. They free spin easy. The fast free spin, does not seem to drop off as quickly as it begins to slow down, while free spinning.

The weight, well, more weight give advatange to a Cubmobile that has less weight, when it comes to ramp racing. Provided once again the track is long enough, where that factor starts to take affect.


1960's Soap box Derby Wheel.

Wow

What Can i say, they are heavy, narrow, precision and fast.

Free spin of over 6 minutes,

Bad news, they dont make them anymore, hello e-bay.

Now they make the new style which is fiberglass. I have not seen them yet, But I will have a set before to long.

I can mention many more things and details. Ill start with this for now.

Sporty

P.S. If the two cars are equal, but the rider weighs 20 pounds more that the other driver ? buy what distance will the heavier driver when buy ?

ramp 3.5 feet tall, 16 foot slope, 150 foot long.

I know the answer, do you ? a puzzler



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Re: Wheels

Post by Stephen's Dad » Mon Apr 10, 2006 9:10 pm

Sporty,

As a boy I had a killer set of wheels that we used on our Cubmobiles every year. I got them off an old Radio Flyer wagon. We alwasy won with these old wheels. They were heavy hard rubber with open ball bearings. No grease. As you have noted with sealed bearings, grease makes it harder to get & keep the wheel moving. We used sowing machine oil (very light) that someone had recommended to us.

One year we were defeated soundly by a kid running on some scooter wheels that I had given him :shock: He had a pair of baby carriage wheels on the front & my old scooter wheels on the back. These scooter wheels were solid plastic of lighter weight & smaller diameter. They were also wider so I had never expected them to be fast. But they were fast as all heck. I don't remember what kind of bearings they had.

I think the best wheels would be hard, light & skinny with an open race loose ball bearing. The Com-Tech wheels seem too soft & the bearings are too tight for speed. These are built for comfort for their primary wheel chair market.

We know we need a hardy, skinny wheel with cheap open bearings if such a beast is made today. The ideal weight of such a wheel eludes me after my bad experience of 30+ years ago.
.


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Re: Wheels

Post by sporty » Mon Apr 10, 2006 10:26 pm

Thanks for sharing, thats some good info and a nice story along with it.

Now I wont reveal a secret I have, but I will lead towards it.

I contacted a few bearing MFG's. I was able to get one that would work with me.

I sent him in a set of wheels and were able to hook me up with a set of bearings that are fast and pretty good free spin. Not race tested yet though. Soon to be.

I was hoping to have a bigger variety and testing done, However, alot of MFG's just seem not that interested in working with small buyers these days.

I even talked to a few mfg's of wheels trying to special order a set of wheels and I had not luck. And some of them were not willing to even give me the name and info of the Actual MFG, So I could contact them.

So I hit some dead ends, on my path for more testing and better options.

And having a low budget, its hard to come up with funds to just buy and try and go buy alot of guess work.

I have also just started testing a new light oil and need to find some more to test with.

Really for the cubmobile, a bad bearing is what makes a good bearing for a cubmobile. you want enough play and tolerance that the wheell will spin fast and long and very easily for a low speed aplication.

Most makers of bearings are into sealed bearings or high speed bearings or just a standard industry grade bearing or long term reliable bearing.

It's getting a maker of a wheel that is close to what would be best suited, along with a bearing that is also suited to our needs to work with us.

But right now there is many different types of cubmobile races, and so many other factors in a non standardized racing event.

Sporty



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Re: Wheels

Post by Stephen's Dad » Tue Apr 11, 2006 5:57 am

Sporty,

Last night I was searching around for an "off the shelf" wheel & ran into some semi-pneumatic 10" hand truck wheels but I'm not sure they had open bearings. More research tonight since I'm on the road today.

I think if it came down to installing a new bearing in an existing wheel, i would opt into cutting an entirely new wheel from a Delrin cutting board. Or maybe Starboard.

Are there any size restrictions on Cub Mobiles?

Steve
Last edited by Stephen's Dad on Tue Apr 11, 2006 2:02 pm, edited 1 time in total.


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Re: Wheels

Post by sporty » Tue Apr 11, 2006 6:11 am

our rules allow for 10 inch and 12 inch, but most of the kids run 12 inch. very few ever win with the 10 inch on our track/ramp.

SInce our track is 150 feet long, a good portion of the cars are fairly even at 50 and even 75 feet, but around 120 / 130 feet. The 12 inch wheels seem to come into play.

I think again, it's almost finding a MFG that is willing to work with some of us to come up with a wheel specifically for a Cubmobile.

If More local CUb scouts put on the race, or the ones that did posted or came to the forum, we might just have a idea as to what the potential for the MFG was to sell more than just a dozen or so wheels.

As for bearings, perhaps you will have some luck that I did not.

It is sometimes not so easy to take out and remove bearings and install different ones, on the thin walled stamped metal rims, there is a chance to bend the steal in the process.

Sporty



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Re: Wheels

Post by Teeeman » Tue Apr 11, 2006 7:52 am

The same basic principles that work in PWD should apply to CMB, that is one approach we have used in our designs.

I thought it was an agreed upon point with PWD that a lighter wheel robs less energy from the car and the only time a heavy wheel would have advantage is on a track with a very long flat where the stored energy in heavier wheels can keep your car from slowing down (and you have time to recover the ground you give up in the early part of the race).


That said, the Commtech 10" wheel is light and has a medium-hard rubber tread, as hard or harder (I thought) than any other wheel I've seen.
They have sealed bearings, but for all-out performance one could remove the seals, degrease (flush) and re-lube with light lubricant.
For that matter, if you want to "break in" a wheel, it would be a simple matter to create a rig with a vice and a clamp to spin the bearings with a drill (or drill press)... a fancier rig could even apply load and spin them at the same time.

I'm sold on Commtech... thus far.

We have not had a close enough competitor to drive us to flushing and re-lubing either, but I think our CMB racers (locally) aren't all that serious compared to you guys.
Since we use the car as a play toy all summer long, we have not modified the bearings (we leave them sealed and greased for long service life, low maintenance).

Either that, or the PWD tricks applied to the CMB have put us in a new class... and I have no way to know...

I dunno how close any of you are to Huntsville... and I have no idea how to get a true apples/apples comparison of CMBs "virtually"...

PWD is different, folks have beaten that topic for 50 years and it has boiled down to almost a proven science... guys like Warp and other WIRL racers...

but CMB, the topic seems much more wide-open to explore new ideas.


Uh, sorry... this thread is on wheels, I have really strayed.


-Terry


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Re: Wheels

Post by sporty » Tue Apr 11, 2006 8:32 am

Terry,

I don't think you got to far off the point. You make good points on your view and information.

I do feel that some of the same principles with PWD, do co inside with CMB.

Then in other ways, it does not.

The one that stands out, that I have mentioned on alot. Is weight.

In PWD, the weight is all pretty much the same and very close, Except placement, types of weight.

Just on weight, not the 50 other things with PWD.

If all cubmobile's were made equally, you still would run into the problem of the differance of driver weight.


I also agree with how you described how the heavier wheel would come into play over the lighter wheel.

You said it much better than I can and that is correct for how it happens on our track.

The same factors of control with the PWD, dont really come totally into play with the Cubmobile. Do to so many factors, that end up affecting how you would choose a wheel.

Thats why for many months, I have been hoping and trying to get a lot of info from other Cubmobile events. To give suggestions on wheels that would work for those other events.

But some of the info that has been posted, has been limited, with not including enough info and data to support it.

Meaning, I will hear about a winner, and a picture, sometimes get the distance of the track, once in a while the track time and ramp demensions.

Since I have gotten all that data for my testing, I am able to compare and go buy something to give atleast some sound data on wheels.

Sporty



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Re: Wheels

Post by Teeeman » Tue Apr 11, 2006 8:56 am

I didn't get any firm "data" on our track for CMB this year.

The event is run so poorly (manual start, stopwatch timed, even "make something up" when the timer missed a car!... I heard them say that!!!!)...

it didn't seem valid to bother correlating firm data to the "times"...


... just sent e-mail a few minutes ago to our Pack leader about our pending (in a week and a half) Pack CMB event.

At the very least, I would like to run a 2X4 in front of the cars and have 2 volunteers snatch it forward and away... or better, build just enough of a ramp to serve as a proper starter...

still not sure what to do for timing the runs save stopwatch volunteers cued from a bullhorn...

we'll probably end up doing an elimination tree type event and just visually assess the winners at the finish line.


-Terry


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Re: Wheels

Post by sporty » Tue Apr 11, 2006 9:07 am

Off topic


In the software section of this forum is a link to a nice cheap and easy software program to check out for double elim race.

Now we just have a light tree for the end, who ever crosses first, is the winner.

However, last year, I spent a portion of the day timing many races, myself.

Our ramp has a lever release system that works well.

Sporty



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Re: Wheels

Post by Stephen's Dad » Tue Apr 11, 2006 2:01 pm

Wheel weight is an intriguing subject. I assume that (as in PWD) a light wheel favors a fast start & heavy wheel favors longer runs. Is that the experience of those who have compared?


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Re: Wheels

Post by sporty » Tue Apr 11, 2006 2:16 pm

So far om my comparison's, that is what I have came up with with.


I have a local hill spot, that lead to a flat level road, and test there every year.

Comparion, cubmobiles. I had 2 previously to compare, this year I will have 3, all different in some way shape or form.

I have made them weight all equal for some of my testing.


I have found, the commtech wheels, fast off line and down the hill, but about 10 to 15 feet after that, the comtech wheels slow down.

The shepard wheels, are slow off the line and are back about 1/2 the length of the cubmobile with the commtech wheels on it.

However, around 50/80 feet, the shepard wheels just pull away from the commtech wheels. And mantain that lead.

Now I will note the commtech at 10 inches and the shepard at 12 inches.

I did not have a 10 inch to 10 inch comparison.

The cubmobile's were also equal in height and length and width.

Sporty



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Re: Wheels

Post by Stephen's Dad » Tue Apr 11, 2006 5:17 pm

Hey Sporty,

I just checked out your cool website. Are the Shepard wheels the blue ones on the 2004 car? Where did you get them?

Steve


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Re: Wheels

Post by sporty » Tue Apr 11, 2006 5:55 pm

ahh, you are to modest. But thank you.

The blue ones and the red ones, our the shepard wheels.

We painted them.

Blains farm n fleet. E-mail me and ill give the the part # from shepards web site also. Though the store part number and shepards part number are different.

Sporty



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Re: Wheels

Post by Stephen's Dad » Wed Apr 12, 2006 6:02 pm

Sporty,

Is it the Shepherd #9584? If it is, I found it.


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Re: Wheels

Post by Smell of pine » Wed Apr 12, 2006 7:53 pm

I will be able to add some more data after our June race. As for now, I'm testing theory.

Sporty, or anyone else for that matter, do you have any pictures of your starting mechanism and the "lever". I have a few ideas, but I'd like to see more. I've seen some of the SBD ramp pictures but not very good pictures of the mechanicals of the ramps.

I have the vintage SBD wheels, and I was getting a spin time of 12 mins. I noticed that they are not well balanced though. I would like to see if I can get them balanced. The rubber on these wheels is in great shape and still have the mold marks on them.

I have a few other possible tricks that we will test.
Last edited by Smell of pine on Wed Apr 12, 2006 10:36 pm, edited 1 time in total.



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