Guides: Bearing Basics: 608 vs. r188 Bearings
Which bearing is best for spinners? The most common bearings used in fidget spinners are the 608 bearing and the r188 bearing. We'll give a brief description of the 608 and r188 bearings, then we'll compare them in terms of the pros and cons of each bearing. We'll also give you some examples of which spinners user the 608 bearing and which spinners use the r188 bearing.
Which bearing is the best for fidget spinners?
Generally speaking, the r188 bearing is the best choice for fidget spinners if you are looking for the best spin time. A lot of this has to do with the actual dimensions of the bearings. A 608 bearing is 22mm in diameter, whereas the r188 bearing is just 12.7 mm. Most fidget spinners are small, under 2.5 inches in length. Larger bearings leave less room for the body of the spinner. The mass in that body is one of the major factors in helping it spin. So, less bearing, more mass equals more spin time. Of course, you could build up, rather that out, making a fatter bodied spinner like The Phat Boy, but this gives you less spin clearance. Of note is that there are two different thicknesses for the r188 bearings. 1/8" and 3/16". Most premium spinners are using the 3/16" r188 bearings.
Additionally, the center of mass is further from the central pivot point in the larger 608 bearing and the r188 balls are smaller and have less contact with the bearing races. This means they will have less rolling resistance/friction So all things being equal with a spinner's body, material etc. the r188 will spin longer than the 608 bearing.
So, what are the disadvantages of a r188 bearing? You'll have a harder time maintaining and cleaning your bearing because of the smaller form factor. Additionally, you're going to have more wobble or less stability in your spinner with the r188 bearing. The 608 bearing and other larger bearings run more stable than r188s creating a smoother more absolute spin. And lastly, you guessed it, they're generally more expensive.
Converting a 608 bearing spinner to an r188 spinner.
Since some fidget spinners are milled with a 22mm hole in the middle for 608 bearings, some ingenious makers are selling 608 to r188 adapters for the spinners. These are essentially housings or "cores" fitted for a 22mm diameter circle with an r188 bearing inside. This effectively adapts a fidget spinner built for a 608 bearing into a fidget spinner with an r188 bearing. A pretty neat trick if you ask me.
Besides being able to run a spinner designed for a 608 bearing with an r188 bearing there is another advantage to these 608 to r188 adapters. In most 608 adapters, not all, the r188 bearing is held in place by a twist off retainer making it easy to remove the bearing for cleaning or to replace the bearing with a new r188 bearing. This effectively turns the bearing into a modular design making it easy to swap out bearings at will.