When choosing hubs, a beginner will think about whether to take bearings or cones? We tried to figure out whether one or another design has an advantage in terms of rolling. Will a hub on cones or bearings roll better, with less friction, and which one? What we came to may surprise many. This is the first part of the video about bearings in hubs. Link to the graph of theoretical power losses that I compiled based on a variety of data. Unfortunately, the data on the CdA of the cyclist and the bicycle are approximately averaged. https://docs.google.com/spreadsheets/... As we can see, the friction losses of the bearings are the lowest of the given values. Even less than the losses due to the aerodynamic drag of leg hair. The data used were https://www.facebook.com/photo?fbid=3... Useful links that I used: Testing wheels with different bearings. Power loss table: https://www.hambini.com/testing-to-fi... https://betterbicycles.org/science/sp... Article on how bearing grease and dust seals affect power loss: https://cyclingtips.com/2016/05/frict... Friction loss calculator from SKF (You must select the desired section). https://www.skfbearingselect.com/#/si... Tests directly from CeramicSpeed ​​- manufacturers of ceramic bearings: https://www.ceramicspeed.com/en/cycli... Article in English from SKF about what energy is spent on when a bearing rotates: https://evolution.skf.com/us/using-a-... Table with test results for determining power losses in hub dynamos: https://www.cyclingabout.com/dynamo-h... General article about bearings, types of friction and resistance: https://betterbicycles.org/science/sp... Thanks to you, the content can become even better: / vasile Theoretical calculations of power losses. Let's imagine that the wheel rotates on 1 bearing. There will be no fundamental difference, but it is easier to calculate. To find out the rolling friction force of a bearing, we need to multiply the rolling friction coefficient by our mass and by the acceleration of gravity (This is the normal reaction force of the support). For simplicity, let's take the mass of 70 kg. This means that for wheel A the force will be equal to 0.002*70*9.8 = 1.372 N. Wheel B rotated 1.5 times longer. We can safely assume that the coefficient of rolling friction is 1.5 times lower. And it is equal to 2/1.5=1.(3) The force is equal to: Fb= 0.1333*70*9.8 = 0.915 N. Now, to find out what power we need for the wheel to rotate at a certain speed, we need to multiply the force by the speed. Let's write down the formula. P=F*V Wait, what is the speed? We spun the wheel at a rotation speed of 300 rpm. For a regular road wheel, this is approximately 38 km/h, or 10.8 m/s. However, although the number of revolutions per minute of the wheel and bearing is the same, it is clear that the edge of the tire manages to travel much more in one revolution than a small bearing. In other words, although our angular velocity is the same, the linear velocity is different. So we need to calculate the linear velocity of the balls rolling along the bearing. Let's take a standard bearing 61902. The outer diameter of such a bearing is 28 mm. We will assume that the balls roll only along the outer race along a circle with a diameter of 25 mm. In this case, in 1 revolution they travel 25 * 3.14 = 78.5 mm or 0.0785 m. We know that the bearing rotates at a frequency of 300 rpm, but we need to know the speed in m / s, since the SI system uses m / s. In a minute, the bearing travels 0.0785 * 300, which means in 1 second - 0.0785 * 300/60. It turns out 0.0785 * 5 = 0.3925 m / s. So, we know the force in wheel A, and the rotation speed. Now we can calculate the power. This means that for bearing A it will be equal to 1.372 * 0.3925 = 0.54 watts. And for bearing B = 0.915 * 0.392 = 0.36 watts. We got very small numbers. Just some half a watt. We can imagine that ½ of the power is spent on rolling friction and ½ on lubrication resistance. This means that approximately 1.08 watts will be spent on one wheel in one case, and 0.72 watts in the other case. And the difference will be only 0.36 watts. The calculator showed that a hub with 2 SKF 61902-2RS bearings loaded in the center with a mass of 70 kg will consume 1.5 watts of power at 300 rpm. And 2 wheels with 6 bearings about 3-4 watts. Timing: 00:00 - Hello everyone! 00:45 - Terms 02:24 - Radial bearing 03:34 - Cup & Cone 04:37 - Friction 05:59 - The coasting paradox 07:07 - Calculation results 08:46 - Gypsy trick 09:09 - Preliminary conclusions 10:25 - Ceramic bearings 11:40 - Other factors 12:57 - The ending #Bearings #cones #bike #coasting