Why do two identical bearings feel different?
Two bearings from two renowned manufacturers, same size, same specification. They should be interchangeable. They are not.
This one took two full days to diagnose.
How it showed up
I received new slats from the production run. They look great, but it turns out they are a bit shorter than before. Probably within expected tolerances. In itself that is not a big deal, the design compensates for it pretty well.
But then I tested them with the bearings I had bulk ordered. In theory those should be equivalent to the ones I used for the prototypes. The only difference is the brand, which everyone says should not make a difference.
It turns out the new brand has a bit more resistance. With the old slats that is not a big deal. But the combination of the new slats and the new bearings introduced a lot more resistance.
What resistance feels like on a manual pad
On a motorised walking pad, resistance in the mechanism is hidden. The motor absorbs it and you never notice until it fails.
On a manual one, you are the motor. Every bit of friction in those bearings is friction your legs have to overcome. Slightly stiffer bearings do not sound like much on paper. Underfoot it is the difference between a belt that rolls with you and a belt you have to push.
It is the single component that most decides how the machine feels, and it is the one nobody thinks about.
The diagnosis
I talked to the local bearings reseller and received some of the original brand I was testing. Those have a lot less resistance.
The seller was quite surprised. He only found out after talking to the manufacturer that there is a slight difference in how the bearings of the two brands are constructed, leading to a bit more resistance in the ones I have now.
It is not obvious knowledge. Even a supplier who specialises in bearings assumed they were essentially identical.
The catch
I had already ordered 120,000 of them.
We are now trying to adjust the order or cancel the deal and switch to the other brand. According to the supplier, neither will be easy. He has already met some resistance on their end, pun intended.
If anyone knows anyone who would be interested in 120,000 bearings, feel free to raise your hand.
Why I am not just shipping them anyway
Because this is the kind of thing that does not show up in a photo or a spec sheet. It shows up on the fourth day of owning the thing, when walking on it is slightly more effort than you expected and you cannot say why.
Nobody would return it. They would just use it less.
That is worse than a part that breaks, because a broken part gets fixed and this one just quietly makes the product worse forever.
Update, 21 August 2026: still unresolved
Unfortunately, there's no solution yet. We're still in talks with the manufacturer and the wholesaler sitting between us, and I hope we'll reach an agreement soon.
To make sure we're not blocked either way, I'll order bearings from the other manufacturer (the one I used for the prototypes) next week so they're here in time for when the slats arrive. Whatever happens with the disputed order, production won't have to wait on it.
Update, 4 September 2026: progress at last
Good news on the bearing front. The manufacturer sent us alternative bearings to test and they work very well. The catch: they're somewhat more expensive.
We'll try to negotiate the price down. The manufacturer has been resistant to taking the original bearings back and would likely charge a fee for it anyway, so the costs partially offset each other but we can't calculate it precisely yet. It's a bit annoying, and the higher price genuinely stings. But for now, accepting it and saving ourselves the hassle and endless back-and-forth is probably the best solution. I just hope we can still bring the price down a notch.
Update, 18 September 2026: a solution
We've found a solution with the manufacturer. They'll supply different bearings that run more smoothly and are therefore a good fit for us. They're unfortunately a bit more expensive, but that's better than a drawn-out dispute and potentially high restocking fees on top. The order isn't finalized yet, since we still need to sort out the return of the original batch but that should hopefully happen soon. In the meantime, we're bridging with smaller quantities from the alternative supplier so production keeps moving.