Lots of wheels are light. Two wheels may weigh the same. But they won’t necessarily ride the same way or feel the same.
Some wheels just feel fast, and a portion of this is as a result of the wheel’s Moment of Inertia – how much energy is required to spin the wheel.
With the guidance of Ric@Wheelfanatyk, I have built a device he describes here to calculate a wheel’s moment of inertia, and from that, using an equation (again provided by Wheelfanatyk) figure out the amount of energy (in watts) required to spin a particular wheel from 0km/h to 30km/h (about 19mph).
I cannot specifically attest to the validity of either of the Wheelfanatyk formulas, but Ric truly is a giant in the world of wheels, and he certainly knows his stuff. I can state that I do multiple runs of each test to create an average, and generally try to be mindful of experimental procedures. However, I am not a scientist in a lab, so these numbers shouldn’t be taken as gospel, but are certainly interesting and worth considering.
Here is a spreadsheet with the information I have found so far. I believe it will continue to auto update as I add more to it. I have multiple columns: the weight of the front wheel, the watts of the front wheel, weight/watts for rear, and weight and watts for set. Each row is a specific wheel set. I have not tested front and rear of all the things I have here (some I only ever built a front or a rear). A lower watts number is “better” in a sense, meaning that that wheel requires less energy to get up to speed. I put better in quotes because it also requires less effort to lose speed, which means a wheel that makes a higher wattage number in this test will maintain speed better.
Again, I haven’t gotten very clever with formatting yet, so I am not sure what always shows up or how to force it to show a certain way. However, the columns are, from left to right, the wheelset, front wheel grams, front wheel watts, rear wheel grams, rear watts, set grams, set watts.
I WANT TO TEST YOUR WHEELS
If you have wheels you’d be willing to let me borrow for a brief moment to throw on the science machine, contact me and we’ll figure it out!