Measuring rear track width - Ideas for a non PITA method?

I always find measuring rear track width to be a chore when I’m by myself at the track. In the past I’ve made scribe marks on axle or key…

Wondering what others do, or if such a “one person” tool exists to measure it.

I use different color, thin vinyl tape with a legend on my toolbox lid.

I use KartMaster axle spacers. I just know my base track width with hubs buried and I know what the spacers measure.


I push a tape measure through the axle then use a metal ruler to hold the tab of the tape.
A little bit of tension holds the ruler, then when done let it off ruler falls down and tape rolls up


Yes. A trammel bar. Bend, or cut and weld, a steel tube into a “U” such that the two legs of the U are 1400mm apart. Hold one leg of the U against the far wheel, measure between the near wheel and the other end of the U. Subtract. If it doesn’t fit at all you’re not legal.

Bruce Woodrow would probably use a clothespin and a fluorescent light tube (highest bending stiffness to weight of anything you can readily obtain) and eyeball against Sharpie marks, but I don’t have a good way to transport anything that big and fragile.

One of these.

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El-cheapo way is:
-Get 2 wooden paint stirring sticks from Home Depot (free)
-Attach one flat to the rim so it stays in place, using a rubber band or piece of tape
-Move to the other side and insert a measuring tape. It will bump into the stick on the other side
-Use the second stick as a guide by laying it flat across the rim so you can take a precise measurement


i have heard that those spacers stiffen the axle… never tried it… I dont have much to worry bc my mechanic does it for me but, is this true

Not true.

I use the same method as Burpo. I know my width and know my spacer sizes and adjust from there.

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I know the width but dont really care about the measurement. Does it need to be wider or narrow? Doesnt really matter to me what it measures as long as its in the window for handling.


Where does this thing come from? Is it narrow enough to use w/ a 30mm axle?

Axle spacers have saved my butt a couple times. Didn’t get that pinch bolt completely tight. No worries the axle spacers will keep it from sliding inward during the race.

I slide the hub on until it touches the spacer then slide it out a millimeter or so. I know it probably shouldn’t effect axle stiffness but my brain won’t let me just slide them on without some air gap.

It looks like a massive T-Square from architecture/technical graphics.

My main method relies on starting with an accurate reading, usually done with a tape measure through the axle, using straight edges on each side, and a buddy to hold one of them. From there I always just measure from the inside of the rear wheel to the axle bearing cassette. For instance, with 212mm wheels installed on my current chassis, 17.2mm on each side will yield a 55” total width.

I then use the metal axle spacers to adjust in known increments. If I’m running single-bolt hubs, I ALWAYS use the axle spacers (KZ application), and they do not stiffen the axle.

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Similar to TJ and Burpo, i know what my width is at a certain distance between the hub and bearing. I then only have to measure that distance on each side to adjust. I have a cheat sheet on toolbox lid of what that measuement corresponds to for track width.

Seems like people are measuring the distance between the hub faces.

Is that the right measurement or is the contact patch more relevant? Or?

99% of people I know measure outside edge of the wheel to outside edge of the wheel, because that’s the measurement that matters when it comes to legality. 1400mm or 55 1/8” is legal max width.

But for measuring width adjustments many people just measure from the bearing face to the hub instead of taking a full width measurement every time.


A local place in New Zealand makes them. Don’t think it would fit through a 30mm axle

The spacer-based methods are good if you never change axles. Murphy’s law says that you’ll put the kart on pole using a 1000mm axle, get slammed into the wall on your cooldown lap by some plonker, then thrash to put in the spare axle only to find in tech after the race that your new axle is 1060mm and you can’t even get through the gate into tech let alone pass it.

x2 for the kartmaster axle spacers. Those things are a god send