How to Build a Rail Rider Pinewood Derby Car | Pinewood Pro

Discover expert tips to build a fast, stylish rail rider Pinewood Derby car for your next race.

Joe Gargiulo

November 09, 2017

Rail Rider Pinewood Derby Car

How to Make a Rail Riding Pinewood Derby Car

Why would you want to make a rail rider (also known as rail runner) car?

The assumption is, when a car races down a track that has a center guide rail (some don't!), the car's wheels will inevitably hit the center guide rail. When it hits the rail, the car loses speed due to friction against the rail and drag on the wheel's rotation.

This is not good.

Even cars that "steer straight" could hit the rail once or twice as it speeds down the track. Rail riding, if done correctly, addresses this "rail banging" by guiding the car gently into the rail, making it ride the rail all the way down the track. It sounds counter intuitive, but the idea is that you are trading off constant friction on the one wheel that is riding the rail for potentially multiple speed losing bangs on all four wheels.

But be careful! Rail riding is not the be all, end all for creating the fastest car. There are dangers! I don't recommend it for everyone. See important reasons to NOT make a rail rider at the end of this section.

How Do You Build a Rail Riding Pinewood Derby Car?

What Do You Need?

Assume the right front wheel is your dominant wheel (the one that will ride against the rail).
One 1.5 Degree Bent Steering Axle for the right front dominant wheel.
Two 2.5 Degree Bent Axles to cant the rear wheels.

Prepare the Block

Cut the right front of the car body back 1/16". This moves the right front wheel, your rail riding dominant wheel, closer to the center guide rail. This ensures the right front wheel hits the rail first, keeping the rear wheels away from the rail because you don't want more than one wheel riding the rail.

Steer the Car

Insert one of our 1.5 Degree Steering Axles into the right front wheel and into the block. Align the screwdriver slot in the axle head vertically, so the steering slot is straight up and down.
Next, you need to measure the car's drift to steer it for rail riding. You will need a long table or wide board to roll the car on.
Put something under the table legs or the board to lift it about 3" to make an incline for rolling your car.
Create a "lane" for your car by putting two pieces of masking tape about 6" apart. You will use this lane to see how far your car steers to the left.
Now, place the car on your incline in the center of the two pieces of tape and release it so it rolls. Observe the car's drift.
Adjust the steering axle left or right so the car drifts gently to the left no more than 1" over 4' (or about 2" over 8' if you have a longer "track"). Your car is now configured to drift into the rail.

….but you are not done!

Cant the Rear Axles

Insert 2.5 Degree Bent Axles into the rear wheels. Again, start with the axle slot in the axle head vertical. Turn the bent axles until the rear wheels migrate toward the axle head when you roll the car down your simulated track.
- This canting reduces friction of the wheel against the car body and moves the rear wheels away from the center rail so only the front wheel is riding the rail.
When your car is adjusted properly, glue the axles in place with a good epoxy so they don't get knocked out of alignment during the race.

Added Advantage of Rail Riding

Riding the rail stabilizes the car as it runs down the rail, which allows you to bias the center of gravity further back. So instead of COG being 1.25" in front of the rear axle, you can get away with 1" or even a little less. Moving COG further back converts more potential energy to kinetic energy. Basically, your car goes faster, longer.

IMPORTANT! DON'T Make a Rail Riding Car…

If your track sections do not mate perfectly! If a lower track section sticks out, even slightly, your rail-riding dominant front wheel will slam into the lower section, potentially damaging the wheel or knocking the wheel out of alignment. In the worst case, the car could hit the bump and jump off the track. If your track sections don't have clean transitions where the sections meet, don't make a rail rider car!
If you don't make all the modification above! You must make ALL of the modifications above for your car to ride the rail properly. For example, if you ONLY steer your front wheel into the rail, your car will actually be slower than if you just adjusted your car to steer straight! The reason is that the other wheels will hit the rail and cause more drag than if you made the car run perfectly straight.
If your track does not have a center guide rail! This may go without saying, but it doesn't hurt to double-check that your track has a center rail. Some plastic tracks, homemade tracks, and even professionally-made tracks just have left and right lane guides so the car rides freely down the middle of the lane. It would be too late to change your car on race day if you made a rail rider and there is no center rail to ride!

Bottom line: Rail riding works if the car is adjusted properly and your track sections match perfectly when it is assembled. If you don't have a test track, I suggest running the car dead-on straight. If you have a test track, or access to one, run your car as a rail rider several times, then run it straight several times. Use whichever is fastest.

Do you need to raise a front wheel to make a rail rider?
No. Raising a front wheel is another proven speed advantage (see Triple Threat in my Winning Pinewood Derby Secrets book) but is not required for rail riding.

Rail Rider is a registered trademark of Warp Speed Derby, Inc.

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Winning Tips and Hints

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Tips & Hints

Before cutting your car, use a straight edge to draw lines down the center lengthwise and widthwise across your car. Then draw your car design template over these straight lines. The template and straight lines help guide your cutting on both sides of the car so everything is square.

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Wheels Tip

If you have a bad wheel and you don't have time to replace it, raise that wheel so it doesn't touch the track. Since it doesn't touch the track, it won't have any negative effect on your car's speed.

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Winning Hint

Winning Pinewood Derby Secrets contains all the tips you need to win your race. Updated annually with the latest tips and speed products, our book has proven results with 1000s of winners... but don't take our word for it! Read over 100 customer reviews and check out our Winners Gallery!