# Let's talk about bearing and axle weight **URL:** \ **Category:** Yo-Yo Mods and Maintenance\ **Created:** [December 5, 2019, 4:10pm UTC](https://forums.yoyoexpert.com/t/lets-talk-about-bearing-and-axle-weight/311661 "2019-12-05T16:10:07Z")\ **Posts on this page:** 1\ **Showing post:** 1
**Author:** ![beezy](https://sea1.discourse-cdn.com/flex015/user_avatar/forums.yoyoexpert.com/beezy/32/161690_2.png) [@beezy](https://forums.yoyoexpert.com/u/beezy)\ **Post date:** [December 5, 2019, 4:10pm UTC](https://forums.yoyoexpert.com/t/lets-talk-about-bearing-and-axle-weight/311661/1 "2019-12-05T16:10:07Z")
Even though a typical monometal is made of aluminum alloy that is 2.8 g/cm^3, in the center is an axle and bearing of steel that is 7.8 g/cm^3. Since the axle and bearing are easy to swap out, changing to a different axle and bearing has the potential to change how a yoyo plays by altering weight at a sensitive location, the yoyo’s center – this is of course a feature that OD side effects offers, for example. Specifically, I’m interesting in reducing the center weight, if possible, so I weighed some axles and bearings on the scale at work (accurate to 0.01mg) and tried swapping some stuff out in a couple yoyos that I’m very familiar with to see what kind of difference is possible. Here are the results 🤓 … **Axles** 5mm: 0.28g 10mm: 0.61g 16mm: 1.13g **Bearings** YYR DS (10-ball), deshielded: 1.90g Dif-e-yo KK (8-ball), deshielded: 1.81g BB concave ceramic (8-ball), deshielded: 1.83g YYF center trac (8-ball), shielded: 1.93g OD flat (10-ball), deshielded: 2.08g YYJ flat (8-ball), deshielded: 1.85g **Notes on weights** There were rumors YYR used titanium axles. At least for their early stuff, it can be seen that maybe they were stainless steel, as the 5mm axle here came from an OG 44re:creation Stargazer. I was curious if ceramic ball bearings made much of a difference in weight but it seems like here they don’t. Perhaps a full ceramic bearing makes more of a difference but so far I’m not feeling the loud ceramic sound. All said, it seems like it’s hard to improve the bearing situation too much, as they are generally ~2g and there aren’t nicely performing materials available other than steel. However, swapping out long heavy steel axles for something shorter or a different material (titanium is half the weight of steel, for example) could be good. **Tweaking a Sparrow** I’ve been almost exclusively throwing an A-RT Sparrow for some weeks now and I’ve really been enjoying the small size and light weight. Sometimes I want a bit more stability so this yoyo is a perfect candidate to try and tweak by swapping out axle and bearing for an effective higher rim:center weight ratio. Sparrow specs from A-RT: diameter: 50.3mm width: 41.3mm weight: 60.5g I measured the Sparrow’s axle (in the list above) and it is 10mm long and 0.61g. It’s equipped with a YYR DS bearing that weighs 1.90g deshielded. I swapped out the axle for the tiny YYR 5mm 0.28g one (using electrical tape to keep the little axle centered), and changed to a KK that is 1.81g. Center weight decreased by 0.42g. In play, the small decrease in center weight was most noticed in a more nimble feel and lighter presence on the string. No, it’s not a big dramatic difference but the yoyo certainly felt lighter and more floaty without sacrificing stability. In fact, it feels more confident in play. After playing this yoyo for weeks, it felt fresh again. I’m keeping this change but will probably eventually get a titanium axle that is a bit longer but a similar weight as the tiny steel YYR axle that’s now in it. **Tweaking a CLYW Peak (3rd run)** So it’s crazy how big the Peak axle is, 16mm and 1.13g. We can easily swap it out for something shorter and save some substantial center weight. With a 10mm 0.61g axle in place, we save 0.52g. Peak specs from HSYY Diameter: 54.5mm Width: 42.15mm Weight: 67g In play, there is less thunk on a throw by changing to a bit less weight in the Peak and it has a hair more speed. Here, the difference is not as dramatic as in the Sparrow, as you might expect given their respective sizes and starting weights, but it is appreciated. I don’t notice any change in its stability. **Final thoughts** I estimate that a typical yoyo has between 3% to 4% of its total weight concentrated in the center, in the bearing + axle. While there is not much of an option to change bearing weights, there is improvement to be had (maybe 0.5 to 1% weight loss) by changing out axles for something shorter and/or of a lighter material. This is especially appreciated for undersized yoyos that tend to have relatively more weight concentrated in their center versus larger yoyos. Since the center vs. rim weight is an important aspect for how a yoyo plays, lowering center weight can lower the overall weight, while effectively increasing the rim vs. center weighting at the same time. What else?.. I’m thinking an undersize with short titanium axle and D bearing could be nice. Anyone tried the Something magnesium axles? What do D bearings weigh? --- _[View the full topic](https://forums.yoyoexpert.com/t/lets-talk-about-bearing-and-axle-weight/311661)._