The Science Machine

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.


The Data:

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!