Downhill Time Trials

So last week I went to InterBike with Boyd Cycling. It was a pretty cool experience, really a thing I always see on all the bike tech sites out there but finally going there is a totally different experience. First of all, the coverage that all the online venues covering the event combined don’t even begin to scratch the surface of the number of exhibits there. It’s pretty overwhelming. For instance there are foreign sections, China, Japan, Italian “villages” that essentially get no media coverage. There was a HUGE e-bike section of the show as well (which also seemed to be the best funded). However the best section, in my opinion, was the “Urban” village. This encapsulated everything from custom cruisers, fixies, to folding bikes. By far these were the most creative and off the wall exhibits and products.

Our booth was tucked into the “Triathlon” section…..yeah yeah. I spent most of my time hand modeling for BikeRadar in the booth:Boyd Eternity Hub
Tubeless Nut

Hand ModelAnd also showing off our one gimmick:

Boyd Cycling Wheelset

Climber’s Wheelset

Yes the most entertaining part of the show for me was to tell people to go pick up our “Climbing Wheelset”. Weighing in at 15 lbs, this thing could serve as a flywheel for an old school steam tractor. There’s a lot of hype around 3D printing right now and a lot of questions were fielded at the show about why we didn’t go that route. The reason is two fold: 3D printing is finite and not continuous. This means that the finish for a curved surface would be stepped surface which would require further finishing (another possibility for imperfections). Additionally 3D printing is typically done with plastics which do not carry high loads well (think spoke tensions and tire pressure).

Why does all that matter? The Aerodynamics of bicycle wheels is converging onto a single (correct, sorry reynolds) design. This means that the variation between the best aerodynamic wheel-sets are getting smaller and smaller. Aerodynamics is VERY sensitive to small variations. Something like 20 psi vs 100 psi in a road tire or low tension (bent) spokes could also greatly alter aerodynamic drag results. So by doing a solid Aluminum wheelset in the wind tunnel we could model a REAL wheel.

Why go through all this trouble anyway? If you see a wheel company showing their slick carbon wheel in the wind tunnel, it means they’re testing a finished product (cough #AeroIsEverything cough). It’s well known carbon molds are very expensive, and if you’ve made the mold, you’re pretty much married to the shape you created, so you’re either wasting money and translating that stupidity to high costs to your customer, or you’re just going with a bad design. This prototyping allows us to make small design changes or evaluate several design at a relatively low cost before making the costly investment in a mold.

Mistakes are how you learn, so it’s better to make i

Bike Wheel Wind Tunnel Testing

Aluminum Prototype in A2 Wind Tunnel

nexpensive small ones than expensive big ones.

Also see my other post (excessive rant) on why Wind Tunnels are absolutely necessary.

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