Durometer Theory

Ok so I’d like to open a discussion about bushing hardness scales.

What I’ve gathered:

  • Bushings are measured in Shore Hardness A (HA or A) [Shore Hardness]

  • cheap-ish Durometers exist Link

  • Diy tester should be easily buildable but likely not much cheaper or better

  • bushings can be close to the 100A mark and therefore may exceed the irl tolerances of the device linked.

I have roughly 15 bushings lying around that I don’t have a good way of comparing.
Unless I squeeze them. But what works with avocados shouldn’t work with high-speed death machines with which fine tuning can mean life or death.

Questions I have:

  • how do you guys measure the hardness of unknown bushings?
  • anybody here already measure them using a scientific tool?
  • Ill very likely be ordering one once my build is done, so if you want your bushings tested lemme know. [Ventura County, CA]
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durometer may not be the best test for skateboard bushings.

I would recommend something like a handheld fish scale. mount the bushing, brace the board in something, hook the scale and pull a set amount – say 50#. measure how far the hanger deflects.


sounds like a much more elaborate test setup. would take a whole afternoon rather than 15min
And it also includes more variables. width of truck/board as well as bushing shape

But I do like that its more akin to the use case of the skateboard. telling someone their board will deflect 25 deg is easier to comprehend intuitively than telling them the bushing is a 85a.
Then again. if you measure durometer for all bushings, and keep the shapes the same, then you only need to do the deflection measurement twice and you could work out a correlation easily

@RipTideSports any input?

Do you guys measure at all or do you trust what comes from the manufacturer?

WoW, this could become an elaborate answer so I will try to keep it simple. Since we manufacture virtually everything we make, we test with a PTC device found here: https://www.ebay.com/sch/i.html?_sop=10&_nkw=ptc+durometer&ul_noapp=true

Durometer is a poor measure of what a bushing does so we do torque / deflection tests to understand the effect of compound and shape but we never talk about it because of the blank stares we get.


Those cheap durometers can be a piece of shit that break as soon as you open the box, be very careful.

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So you use both the PTC measurement as well as the torque/deflection technique?

Care to explain your measurement setup?
do you have torque/deflection curves?
Any data you are allowed to release on the topic would be great. Does not need to be up to date but I would love to get an insight on how you characterize each bushing

Blank stares of lust for measurement theory?

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Ill bid on one of those ptc devices. Old school tech like that is what I live for. No batteries mmmmmmhmmm


Sorry but our test fixture is proprietary and we do not want our competition to know what we do. I may have already said too much…


ahh yes I assumed I’d hit a wall in that regard. no worries! I hope I didn’t get you into any trouble!

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All good so no worries, we use the setup mainly for developing new compounds, where the PTC unit is used daily.

In a pinch, the bite test is also accurate to determine is one bushing is harder than another in the field.

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I feel like this becomes greatly subjective. and quite ineffective if I’m trying to sort out my bushing pile.
I think Ill develope a rig and method, after I do some other testing.

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In that case, get a PTC

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Hadn’t heard of ya’ll before, but with you doing that sort of testing, I’ll be looking at your parts.

My thought on mounting the bushing for a deflection per x force test is that it would get a value based on actual usage independent of shape, and could easily show the tester the effect of tightening and loosening the kingpin.

As long as the point where one was applying the deflection force was a consistent distance from kingpin, it would normalize results for different widths of hangers…

One could go so far as using several force settings to get a judge of effort for light turns versus hard turns – although I would expect it to be close to a linear relationship for most bushings.

Now if wheels had a wear rating based on something like .1mm of erosion per 100km of continuous rolling 1 degree offset from straight on 60 grit sandpaper with 100kg of weight… could be done with a belt sander, a stop watch and some weights.

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You got me interested in buying a durometer. After 5mins of testing, I have come to a conclusion that duro testing is useless. I’m returning this piece of junk.


Oh boy that’s unfortunate. Which durometer did you order?

The $28 one. The main take away is. Duro is not a good metric of wheel quality. All my wheels reads 75-78A. I know which ones are good. IMHO, wheel quality should be measured on compression, impact dampening, wheel profile, core set location and color :stuck_out_tongue:


Hmmm agreed. That said I was talking about. Bushings?

I feel like there’s too little benefit of going harm on material analysis on bushings. Just throw them on and try them. Eventually you will find the right ones. My personal favorite bushings are seismic bushings because of the different profile and the acting forces is distributed nicely and we’ll balanced.

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Should there be another rating for wheels? The duro rating seems to be outdated, or does anyone know if the duro ratings on most wheels are falsified?

I have 78A (China) which feel less squishier than 82A (Slayer USA) - are the ratings even correct?

Looking mainly for comfort.