Aerodynamic Drag of Wide Tire on Box Section
Moderator: robbosmans
Has anyone seen wind tunnel data that they can post here of what a worst case wheel looks like? Thinking 32 spoke Nemesis with a 27mm tire. It seems that a Hed Belgium with 23mm Conti tire is only a few watts slower than a Zipp 303:
Sheesh, I don’t think I’d ever run a 27mm tire on a Nemesis rim. 25mm is pushing the limit. I find the best size is 24mm on that rim, so you can still get the wheel out easily when you release the brakes. Aerodynamically it certainly won’t be the fastest but I’ll tell ya... I doubt there’s anything that’s going to be more stable coming down that windy mountainside.
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https://novemberbicycles.com/blogs/blog ... lculations This baselines a Velocity A23 versus some other older shapes.
The width of the rim has an effect and the spoke count has an effect, as does the gauge of the spoke. We measured a 1w difference of 1.5mm mid section Lasers vs CX Rays (same # of spokes), and Flo measured a bigger difference comparing straight gauge 2.0mm spokes vs CX Rays.
There’s a lot of info out there, you just have to take all of what’s credible to you and distill that into your best answer.
The width of the rim has an effect and the spoke count has an effect, as does the gauge of the spoke. We measured a 1w difference of 1.5mm mid section Lasers vs CX Rays (same # of spokes), and Flo measured a bigger difference comparing straight gauge 2.0mm spokes vs CX Rays.
There’s a lot of info out there, you just have to take all of what’s credible to you and distill that into your best answer.
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27mm paves on nemesis are possibly the plushest, most special feeling sunday getting lost type ride thing going...
I have never really understood why bike manufacturers neglect to tell the customer that when they test, their increasing yaw angle is effectively reducing the forward speed.
ie 50km/h at 15 degrees is actually 48km/h
You'll also get a different line if you are coming from attached to detached (0 yaw to 15+) vs detached to attached (15+ towards 0yaw).
ie 50km/h at 15 degrees is actually 48km/h
You'll also get a different line if you are coming from attached to detached (0 yaw to 15+) vs detached to attached (15+ towards 0yaw).
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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