Fat Tire Roundness and Flex at PSI

If you fat bike, you talk about tire pressure. The goal for many is to run as low a pressure as possible. I was curious just how much it differed at various pressures.

So with that, an Intel Edison and Flex sensor were used to look at PSI.

The flex sensor was stuck to the inside of a Maxxis Minion FBF 4.8″ tire on an 82mm DT Swiss rim.

The amount of flex of the tire was measured using Python on the Intel Edison and attached poorly to the wheel.

The test rig is my Moots Frosthammer and the test route was simple loops around my driveway.

Four tests were performed at 10,8,6 & 4 PSI.  The result below is an amount of flex relative to being totally flat.

Raw data graphed, the lower the number the more flexed the tire.

Since the Edison has Wifi I just SSH’d in and ran my test.

So what is the most interesting here too me, the tire gets the most flex at 6 PSI! Not 4 like I would have assumed, and is the most round at 10 PSI.

I would have assumed 4 was the most flat, but interestingly while 4 PSI does not provide the widest footprint it does react the most. By that I mean the profile of the tire changes the most at 4 PSI.

Just some Friday nerdery.

-Joe

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