There are lots of reasons you may want your wheels to line up with the edges of your deck. You don’t want to kick your wheels as you skate, you want to have full leverage over your trucks without it feeling too twitchy or unbalanced, or maybe you just want to be able to stand it up on its side. Totally valid, I’ve been annoyed by some of my setups that can’t stand up on their side! So, how can you ensure that your trucks line up with your deck?
For street setups, it’s easy. The width of the axle is the width of your deck. Street setups use narrow centerset wheels that generally don’t go past the axle. However, you likely noticed that longboard trucks are usually measured by their hangers. How do you know how wide your setup will be when the wheel goes past the axles?
Here’s how.
First: Some Terminology
Deck
Okay, you know what a deck is. It’s the thing you stand on. Usually wood. Sometimes plastic, aluminum, carbon fiber, or adamantium.
Rails
Rails are on the edges of the deck, where the concave ends. This is what you want to line your wheels up with.
Hanger
The hanger is the part of the trucks before the axles. It’s what presses up against your bushings. It’s the part that moves along the pivot axis. It holds your axles, wedges into the baseplate, and gives your trucks motion.
Okay, fine, it’s the part that looks like a ‘T’.
Axle
This is the part your wheels go on. They spin around these. You really should know this one already.
Mostly this section was just to make you know the difference between the hanger and the axle. So here’s a picture of that.
Good? Great.
The Formula
This isn’t very math-intense, fortunately. But you do need to know a few variables.
- Hanger Width
- Wheel Width
- Wheel Core Location (Centerset, Offset, or Sideset)
What you want to do is add up half of the width of your hanger to a few other constants (speed ring, bearing, and half the spacer width), and then the wheel. Now, if it’s a centerset wheel, it’s easy, you just use half the wheel width. If it’s a sideset, it might still be in a few millimeters, but it’s safe enough to just use the complete width of the wheel, unless you need it down to the millimeter, and then I suggest going to a shop and measuring the wheels. Finally, if it’s offset, and you don’t know the amount it’s offset, you can estimate by using 3/5ths the width of the wheel. That’s 0.6 * wheel width. Most offset wheels are between 1/3 or 3/5s of the way in.
Go with 2/3 (0.666) if you want to potentially underestimate the width of your setup, with the wheels sticking out a few more millimeters than you anticipated, or 3/5ths if you want to get very close, but potentially go under a small amount.
The number you’ll be matching this up with will be 1/2 the deck width.
Use millimeters for all measurements.
The 13mm will come from adding up a bearing width (7mm) plus half a spacer width (5mm), plus a speed ring (1mm), which I’ll assume you’re using at least one of, to prevent contact between the bearing and your truck or axle nut.
So:
One side of setup length = (Hanger Width / 2) + 13 + EITHER: (1/2 Wheel Width for centerset Wheels) OR (Wheel Width for sideset wheels) OR (0.6 * Wheel Width for offset wheels)
So, if I have a 160mm hanger, offset wheels that are 60mm wide, the math would look like this:
(160 / 2) + 13 + (60 * 0.6) = 80 + 13 + 36 = 129
Multiply that by two (258mm), and you should have something comparable to your deck width.
If my setup was around 10″ wide (254mm), this would be very close to the rails, sticking out only a little. This would be a good setup.
Many people guesstimate, and, honestly, that’s usually good enough. But if you want to be sure, you’ve got the formula now!
- H: Hanger Width
- C: 13: Constants of bearing + bearing spacer + spacer
- W: Wheel Width
- F: Fraction (1/2 for centerset, 3/5 for offset, 1 for sideset)
- D: Deck Width
- L: Length of one half of your setup
L = (H / 2) + C + (W * F)
For a perfect setup, L * 2 = D!
No go build out your perfect setup, you math wiz.
