We have a new derby web site!     Note the spelling:   gravityGRANprix.com

NEXT DERBY:   Saturday, August 30, 2025   3:00 pm

Races are held on the Peteeneet Hill 100 S 500 E in Payson, the hill just south of Peteetneet School. Many thanks to Payson City for sponsoring this race! Racers, please show up at 2:00 to register and get ready. Please let me know if you have any questions. You can e-mail me at fleany 'at' gmail.com I have a couple of cars available to use. Contact me to make arrangements. Jump to results of the last race The rules are here. You can also find them by clicking "Rules" in the menu at the top of this page. This excerpt from the rules gives a quick overview of the car specs. Ages are at the discretion of the parents. What is listed are only rough guidelines. The difference is how much the car, with driver, is allowed to weigh. Also, the Colts start from in front of the ramp so they don't build up as much speed. We can use different divisions to shift people to balance numbers, for example if we have more trophies for a division than we have racers. (click on thumbnail for larger image): This is the spec wheel we use from Harbor Freight

Seated dimensions--I need data 11.06.23 What derby car dimensions are comfortable for your kids? I'd really like to know so I can design cars to fit.

My daughter had one of the fastest cars in the race, but it was too small to fit anyone older than about 10 or 11. At any given time I have between two and four cars that I can loan out for the race, and I'd like to build cars that could be used by people of any age. I’ve designed a pretty slick mechanism that will make the brakes adjustable on a derby car. I think I can get away with just three positions on them, but . . . Read more . . .

Timing advantage from car length 11.02.23 Since the starting bar indexes off the nose of the car and the finish line stops the timer when the front wheels hit, there's always some discussion about how much advantage a shorter nose might give you. This same effect comes into play with the Colt class, who are started from their back wheels and are also timed by when the front wheels cross the tube. Well, here's your answer.     (Click on the thumbnail to see table.) Not much. Read article on derby geek page

Bearing Lubricant Test 11.02.23 I conducted a set of tests to determine what lubricant is most effective at reducing friction on a derby car wheel. This is the 13” Harbor Freight internal bearing wheel specified in the rules. I tested five lubricants —Cooking oil, UltraTech spray lubricant, WD40, motor oil, and graphite—against a baseline of a dry bearing... Read more . . .

	Weighing a Derby Car on the Ramp   11.01.23 For some time I've been messing with how to weigh the cars. Back in the Salem Days days I used a giant ramp that I built. It worked pretty well, but it was heavy and hard to move around. So for the last few years we've just been blowing off weighing the cars. For 2024 I am building a svelte scale that can be easily used and moved around.
But quite awhile ago I came up with the idea of just weighing the car on the ramp. My original idea was to use the starting posts themselves as the scale, but every car touches the post at a different height, so... Read more . . .

Scaling a Derby Car   10.10.23 If you're building a car based on a full-sized vehicle you can use the tires for a scale factor. Just divide the 13" diameter of the derby tire by the diameter of the full-sized tire. Use this factor to scale things like the wheelbase, length, and width. This table shows the derby car wheelbase based on the full-scale tire size and wheelbase. The outlined cells correspond to the cars in the list below this table....

Read more . . .

2023 Payson Derby   9.05.23 Another great race this year. Thank you to everyone who participated and helped and all of those who showed up to watch and support. If you have pictures of the race (this year or any of years past) you'd be willing to share we'd love to see them. Please e-mail them to me or post them on the Facebook page. Four cars ran this year with eight drivers. Sawyer Page turned out in the brand new Full Metal Jacket car. Eli Nielsen and Camdan Bytheway ran in the newly refurbished GT Mach 2 (the car formerly known as Mach 5). Ron Norviel brought out his revamped Blue Streak, raced by Darrell Adams, Finn Clark, and Maizey Clark. Sklyer Montgomery and Lilly Black ran in Orlon Black’s Ideal Machine #32.     Sklyer ran into a bit of trouble on his last race and the car ended up damaged, so Lilly did her second run in the Full Metal Jacket. Race Results: Colt Division 1st Darrell Adams, Blue Streak 2nd Finn Clark, Blue Streak 3rd Sawyer Page, Full Metal Jacket Mustang Division 1st Skyler Montgomery, Ideal Machine #32 2nd Maizey Clark, Blue Streak Stallion Division 1st Eli Nielsen, GT Mach 2 2nd Camdan Bytheway, GT Mach 2 3rd Lilly Black, Ideal Machine #32 People's Choice car: Ideal Machine black racer Special thanks to Shaun Black for coordinating the tow vehicles, and his helpers William, Lane, Shane, and others. Thanks to Shaun, Jordan Leany and Trina Leany for running the ramp and timing. We hope to see you back next year—the Saturday of Onion Days. Encourage your family and friends to come out and watch and to consider building—nay, to actually build-- a car and race with us next year.

Results of all past races can be found in this document.

I am working on plans for a derby car chassis that people can use. I had this grand idea to build rolling chasses people could buy so they didn't have to struggle with brakes and steering. But when I totaled everything up the cost is pretty high. I am working on steering and brake sub-assemblies that might be a better option. In any case I will post the plans and bill of material when I get them done. You can use those plans or a variation of them, or, if there's any interest I could come up with a quote for me to build it. I also want to work with local manufacturing business to supply materials for the cars or even chasses. They could build one from my plans, or your plans, or a proprietary plan they make (Like a special Barber Steel or Ideal Machine chassis). Racers would work with the companies to get discounts in exchange for sponsorship. I'd like to see racers go around to local businesses and ask for sponsorship. This gives them real-world experience in funding as well as designing, building, and racing. My plan is to write a rough script that racers can use to approach businesses about sponsorship. It would include data about expected costs. I'm wide open to any ideas you have about this. We are on Facebook. Click here or on the Facebook icon at the top of the page to visit us there.

Race format: Here is the .pdf file of the rules for the race. Clicking on "Racer's Packet" above gets you the same thing. Meet on the north side of 100 S on 500 E by 2:00 if you plan to race. That's the street just west of Peteetneet at the bottom of the hill. There is NO FEE to race. We are trying to keep it simple, so in addition to having no registration fee, you show up by 2:00 pm on Saturday to register. Even though there is not a pre-registration it would be very helpful if you contact me if you are planning to race. Also, please ask about any questions or concerns you have about the rules. Above all we want this to be a safe event. The new electronic scoring system makes everything go much smoother and faster. There are no brackets. You get back up the hill and get right back in line. There are no limitations on who you race against or the order you race in. Please tell everyone you know about this event. If they can't build a car they should at least come watch. Please contact me at fleany "at" gmail.com if you are interested in building or racing a car. There are enough cars out there we could find you one to drive if you aren't able to build one. But building a car is a lot of fun. If you intend to race in someone else's car you need to make arrangements for that before the day of the race. That will go a lot smoother than trying to fit people into cars when we're trying to get the race started.

Yeah, when I say "we" I mean "I." It's just me running this show, but I figured the "Lindberghian We" might give us (see what I did there?) some credibility.

Check out this story Fox 13 Utah did on the race.
Last revised:   3.07.25	Return to top	Click here for earlier posts
This Gravity Gran Prix has no affiliation with The All-American Soap Box Derby