# Bearing measurements

So when a C spec bearing is listed as having measurements of 0.250 x 0.500 x 0.187, what is each of those three numbers referring to?

I assume some combo of inner diameter, outer diameter, and width of the bearing (like how d-bearings coming in 4mm and 5(?)mm versions). In the size C specs you listed, Iâ€™m guessing it goes:

.250in Inner Diameter
.500in Outer Diameter
.187in Width

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Okay, so if the width of a C spec bearing is 4.75mm, how can a yoyo gap be wider than that?

Some sort of bearing seat shenanigans would be my guess.

The bearing seat is a recessed groove that the bearing sits in, right? Since that groove always has a depth > 0, that means the gap will always be less than the full width of any bearing.

The bearing seat/ post is making contact with the inner bearing race when the yoyo is assembled. You could then machine the inner walls of the yoyo out to a width greater than the bearing width. Idk why youâ€™d want to, but you could

If the inner walls are machined away from the bearing, wouldnâ€™t that leave a tiny space between them? Wouldnâ€™t you risk the string getting caught in that space during play?

That sounds kind of like the problem the Eetsit had:

The string gap on the yo-yo was just a little too wide, causing the string to occasionally slip in between the bearing and the side of the yo-yo. This design flaw could be remedied by replacing the stock Baz Pads with thick Dif Pads. Some players had instead opted to sand down the bearing seat of their Eetsit yo-yos in order to correct this problem. The Bapezilla was later released as a follow up to the Eetsit, fixing the problematic string gap.

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Yeah. I mean Iâ€™d imagine thereâ€™s some small amount wider that you can go that is still too small for a string to get lodged into but Iâ€™m sure there has to be a limit

I guess. I mean, there are quite a number of yoyos with gap widths > 4.75mm. The Replay Pro supposedly has a 4.80mm gap, and the Will has a 4.82mm gap. Hell, Iâ€™ve seen yoyos listed with a 5.00mm gap.

The recessed groove is actually an air pocket. The actual seat is the part that kinda moves out from the axle hole slightly.

Ah, okay, thank you for the clarification.

Iâ€™m asking about all this because Iâ€™m trying to understand the pros and cons of gap widths that are wider than the bearing.

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Iâ€™ll send a picture when I can to better explain it. Road tripping to PA atm.

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Many yoyo designs have a protruding ring at the inside of the response pad. This can be useful for:

1. Adding a tiny bit of centering for bearings that are flat
2. Expanding the gap (distance between the pads) beyond 3/16" without the string slipping past the bearing
3. Help keep the yoyo from snagging during wraps even when the gap is smaller

The bearing post is at the bottom, the two â€śmoatsâ€ť are the pad recess (top) and air gap (bottom)

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