Zipp's wheel claims: do you believe them?
08-29-07, 09:05 AM
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Zipp's wheel claims: do you believe them?
Zipp claims their new 2008 wheels, the "Sub 9," has a negative drag of 80 grams which should translate to about 11 watts of added power. Do you believe them? Is it even possible?
...they’ve also come out with a wheel (The Sub 9) that, at 15 degrees yaw, actually produces NEGATIVE DRAG… No worries, as the tunnel numbers are also exceptional at 5- 10 and 20, but the tunnel data I’ve seen for these at 15 degrees is way cool... Minus 80 grams drag, so roughly 11 watts forward power!
08-29-07, 09:10 AM
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No, not as worded. Wheels can't "add" power (can't add energy to the system), they can only require less power through increased efficiency.
08-29-07, 09:13 AM
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Right, you should be able to ride the same speed, but 11 watts less. That I might believe, but not that it adds watts.
08-29-07, 09:15 AM
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Sailboats.
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08-29-07, 09:22 AM
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Absolutely I believe them. At 15% yaw to the wind, a sailboat generates all kinds of power. Coming up with an airfoil that can spin and produce still off-axis lift is another thing, but it sounds reasonable to me.
08-29-07, 09:26 AM
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08-29-07, 09:31 AM
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08-29-07, 09:37 AM
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this coming from someone that prefers ISIS BB?
I guess we can just throw out all that "claimed" windtunnel testing that zipp did with the dimples.
I guess we can just throw out all that "claimed" windtunnel testing that zipp did with the dimples.
08-29-07, 09:38 AM
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Dimples are highly regulated in what is and isn't allowed by the USGA and The R&A in St. Andrews, Scotland because they can be changed to alter the flight path of a ball, same as how a wheel can move through the air.
08-29-07, 09:39 AM
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08-29-07, 09:43 AM
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Sailboats don't generate any power when pointed straight upwind, which is pretty much where a bike being pedaled at 20mph is pointed.
The only way these wheels are generating power is if you happen to be riding with a stiff cross-breeze, and even then...the shape is all wrong. (sails and wheels have opposite curves)
The only way these wheels are generating power is if you happen to be riding with a stiff cross-breeze, and even then...the shape is all wrong. (sails and wheels have opposite curves)
08-29-07, 09:43 AM
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Yes, but only with an angle of attack. A symmetric airfoil traveling straight into the relative wind (with zero angle of attack) will NOT produce lift (or asymmetric pressure) and that's what a Zipp wheel is - it does not have an angle of attack into the relative wind. The only forward "thrust" would have to come from some aerodynamic effect at the rear edge.
08-29-07, 09:46 AM
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Given that there seems to be a large component of BS in much of Zipp's promo literature over the years (re. ceramic bearings), so no I don't take their new claims seriously.
08-29-07, 09:53 AM
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08-29-07, 09:53 AM
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Every claim of Zipp's that has been tested independently in a wind tunnel or in the field has been borne out. That's a pretty good track record and proves their credibility to me.
08-29-07, 09:55 AM
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Studies have shown there is a very low probability of 0 yaw angle when riding. I don't have the data with me, but the statistics show most riding time is spent with a yaw angle somewhere between 5 and 15 degrees.
08-29-07, 09:55 AM
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Sailboats don't generate any power when pointed straight upwind, which is pretty much where a bike being pedaled at 20mph is pointed.
The only way these wheels are generating power is if you happen to be riding with a stiff cross-breeze, and even then...the shape is all wrong. (sails and wheels have opposite curves)
The only way these wheels are generating power is if you happen to be riding with a stiff cross-breeze, and even then...the shape is all wrong. (sails and wheels have opposite curves)
08-29-07, 10:01 AM
#21
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so I don't have 12,000 kms on my current BB?
1. None of the crap in Zipp's website has been independently proven. So it's just marketing.
2. Even if you believe in dimples, for some reason, after CAD design and windtunnel testing, it's just so happens that stamping "Zipp" into the wheel is the optimal design. How fortuitous for Zipp.
3. Dimples have been tried in other applications: they don't work, they never have.
If you believe in this sh+t, wear a crystal necklace and live in a cave. This is why Enzyte makes $50M a year.
While you're at it, buy the Q-ray bracelet:
https://www.qray.ca/InternetSpecial.aspx
It uses ionic energy and boosts power!
"Since wearing my Q-Ray I have won 2 international marathons in the span of just 35 days..."
Mbarek Hussein
Winner, Seoul International Marathon 2002, 3-time winner, Honolulu Marathon
...and my shampoo makes my hair 34% more radiant, while the other brand was only 32%. Lab data will verify all this.
But seriously, are you guys completely incapable of critical thinking and just believe whatever someone tries to sell you?
Last edited by DocRay; 08-29-07 at 10:09 AM.
08-29-07, 10:04 AM
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08-29-07, 10:08 AM
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It's interesting how this, https://forum.slowtwitch.com/gforum.c...engine#1460321
Gets translated to this
Originally Posted by Joshatzipp
it does in fact create -80 grams of drag at 15 degrees yaw using the 30-0 test protocole tom talked about. the negative drag window extends from 11-18 degrees and has 30-40 grams lower drag than any flat or lens disc between 0 and 20 degrees. using the 0-30 tunnel protocol it looks even better but experience tells us that protocol yields overly optimistc data.