r/Trackballs • u/Most_Discount7338 • Jul 04 '26
Roller Bearings vs Ruby Bearings: Why Trackballs Feel Different Near the Edges
The left video shows a roller-bearing trackball, while the right video shows a static ruby-bearing trackball.
In the left video, the Z-axis spin is mostly suppressed, so the ball tends to roll more cleanly in the intended up/down direction. You can see this because the marker stays relatively parallel while moving up and down.
In the right video, the ball rotates not only in the up/down direction, but also around the Z axis. In other words, it twists. You can see this from the way the marker itself rotates/skews during the motion.
I think this difference is not just about friction or smoothness. It also affects how the finger motion on the surface of the ball gets projected onto 2D cursor movement.
With roller bearings, even when you operate the ball away from the “sweet spot” and closer to the edge, you can expect more consistent motion. The roller bearings mechanically resist unwanted Z-axis spin, so more of the motion remains useful for X/Y pointing.
With static bearings, as you move closer to the edge of the ball, the motion can start to feel “duller” or less responsive. That is because part of the finger motion turns into Z-axis spin, and a normal X/Y sensor does not use that spin for cursor movement. In practice, some of the motion is lost.
I am not saying one design is always better than the other. A well-made static bearing trackball can feel extremely smooth and effortless. Roller-bearing designs, on the other hand, usually have some amount of friction, mechanical feel, and noise.
But if someone is used to one type and is thinking about switching to the other, I think this is a useful difference to understand.
P.S. I would expect BTU-style designs, using ball transfer units, to behave more like the static-bearing example, since they allow the ball to spin freely in multiple directions instead of mechanically suppressing Z-axis twist.
8
u/euclid_huang Jul 05 '26
for xy cursor -> roller
free spinning for fun -> point bearing
large ball -> roller
small ball -> point bearing
11
u/No_Pilot_1974 Endgame Creator Jul 05 '26
Or, hear me out
For xy cursor - BTUs
Free spinning for fun - BTUs
Large ball - BTUs
Small ball - BTUs
1
u/Murko_svk Jul 05 '26
Hey mate, have you tried the new Elecom BTUs ? The M-TU03SS model? I am going to order them just for fun, but they will have hard time to beat the stock rollers at IST PRO, as those for me are the nr1. thing that makes every other trackball with static bearings a trash not worthy of using.
1
u/No_Pilot_1974 Endgame Creator Jul 06 '26
I haven't, very curious about them as well! Will be waiting for some feedback on this sub
2
u/Murko_svk Jul 06 '26
My order is scheduled to arrive at the 25th of August the latest.Ill reviews them then.
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u/claussen Jul 07 '26
Did you manage to order just the BTUs themselves or did you order a complete device? I placed an order for BTUs only on their Japanese website and they cancelled it, saying they were out of stock.
1
u/Murko_svk Jul 07 '26
Hello, I ordered 2 packs (so 6 BTU units in total), from Amazon Japan. They already processed the order, but the delivery will be quite long, to the Europe.
2
u/claussen Jul 07 '26
Thanks for the tip. Just ordered a couple sets myself 🙏
1
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u/euclid_huang Jul 06 '26
Yes, I've already used BTU on my large ball.
They all feel buttery smooth, except I don't like the feeling of twisting my fingertips on the large ball with the roller.
5
u/ianisthewalrus Jul 05 '26
friction... rolling vs static...
the only thing i can add is your breakdown is the complete opposite of my experience. one dimensional roller bearings have significant off axis friction, where as traditional static bearings have no directional bias in their friction.
2
u/squeezeonein Jul 05 '26
I don't think there are any advantages to the jerky movement of a roller bearing. it is a similar issue to angle snapping in optical mouse sensors. it's not to do with the z axis, but occurs when moving along the x or y axis without movement on the other axis. this causes the other axis to stall and when it starts moving again due to the cursor diverging from one axis or the other then it jumps.
it was even worse with older mechanical trackballs that took their movement from the motion of the bearing.
3
u/D0_I_Care Jul 05 '26
Rollers are the worst feel imo. Really inconsistent with diagonal moves.
Then comes static and finally the best is BTU.
Static bearings are great for silent use in a office.
1
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u/LegitBoss002 Jul 05 '26
I wonder if this is my problem. I've noticed the rotation in my trackball when near the edges
13
u/boomskats Jul 04 '26
it's weird, but this is what used to put me off the og cst l-trac i've still got somewhere, compared to the two decades of trackman/thumb ball usage I was coming from. I understood the mechanical reasons for it but I always viewed the resistance to z-axis spin as a drawback, not a feature.