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Re: Bora WTO
Posted: Mon Jul 23, 2018 12:36 pm
by kgt
TobinHatesYou wrote: ↑Sun Jul 22, 2018 6:44 pm
You’re basically asking for proof that the sun is hot, so just load up your favorite web search and punch in “toroidal vs v-shaped rims crosswind stability”
Obviously it is not as simple as you think it is. I have seen the claims but these are just claims, usually from a marketing point of view. I asked for a comparative test since the only data I know is the numbers from TOUR which do not confirm your opinion.
BTW thanks for the info Beaver and RyanH.
Re: Bora WTO
Posted: Mon Jul 23, 2018 12:57 pm
by kgt
A (real) scientific paper confirming that "The CsA [coefficient of side force area] of wheels is primarily controlled by the rim depth (D) and only weakly correlated with tire width (T)."
http://fluidsengineering.asmedigitalcol ... id=2674736
Interesting that Bontrager's white paper also disproves TobinHatesYou's 'certainties'. That does not mean I believe Bontrager either...
Re: Bora WTO
Posted: Mon Jul 23, 2018 12:57 pm
by Weenie
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Re: Bora WTO
Posted: Mon Jul 23, 2018 8:11 pm
by TobinHatesYou
Total side force isn’t really what matters here. It’s the difference in side force on the leading edge and trailing edge of the wheel which causes your wheel to steer. This absolutely has to do with the shape of the rim. Of course rim depth is the primary factor, but when you compare two rims of equal depth and max width, the toroid should be slightly more aero and have less differential between side force at the front of the wheel vs back of the wheel.
Let's think about what causes you to be blown sideways on your bike. Is your tire slipping laterally? No. It’s because the crosswinds made your wheel steer suddenly. Think about why the wind makes this happen...because the wind was effectively pushing one end of the front wheel with more force than the other. Now how do you combat this? You increase the symmetry of the tire/rim combo so that the forces on the front and rear of the front wheel are close to equal. This is also why companies like ENVE use more U shaped rims in front and slightly more V shaped rims in the rear of some wheelsets...because the rear can’t steer and side force imbalance is not as important. If you are having trouble visualizing what's happening to the front wheel...think of it as a balance scale and the wind as gram weights. If you put more weights on one side of the scale, it tips (steers.) If you put an equal amount of weight on both ends, everything stays nice and level/straight.
All those times people anecdotally say a deeper wheel was more stable in crosswinds than a shallower wheel? It’s because of the side force differential.
Now do I think blunted toroid rims are the be all? Not sure. The best rim shape for pure speed and stability is probably a narrow toroid (put two Vs together) with narrow tires. This would be more reminiscent of older Zipp designs, but have been phased out with the rise in prevalence of wider tires.
Re: Bora WTO
Posted: Mon Jul 23, 2018 10:36 pm
by Beaver
TobinHatesYou wrote: ↑Mon Jul 23, 2018 8:11 pm
Total side force isn’t really what matters here. It’s the difference in side force on the leading edge and trailing edge of the wheel which causes your wheel to steer. This absolutely has to do with the shape of the rim. Of course rim depth is the primary factor, but when you compare two rims of equal depth and max width, the toroid should be slightly more aero and have less differential between side force at the front of the wheel vs back of the wheel.
Let's think about what causes you to be blown sideways on your bike. Is your tire slipping laterally? No. It’s because the crosswinds made your wheel steer suddenly. Think about why the wind makes this happen...because the wind was effectively pushing one end of the front wheel with more force than the other. Now how do you combat this? You increase the symmetry of the tire/rim combo so that the forces on the front and rear of the front wheel are close to equal. This is also why companies like ENVE use more U shaped rims in front and slightly more V shaped rims in the rear of some wheelsets...because the rear can’t steer and side force imbalance is not as important. If you are having trouble visualizing what's happening to the front wheel...think of it as a balance scale and the wind as gram weights. If you put more weights on one side of the scale, it tips (steers.) If you put an equal amount of weight on both ends, everything stays nice and level/straight.
All those times people anecdotally say a deeper wheel was more stable in crosswinds than a shallower wheel? It’s because of the side force differential.
Now do I think blunted toroid rims are the be all? Not sure. The best rim shape for pure speed and stability is probably a narrow toroid (put two Vs together) with narrow tires. This would be more reminiscent of older Zipp designs, but have been phased out with the rise in prevalence of wider tires.
I own NOX S36R (torodial) and LightBicycle RR36C02 (round V) and swapped the front wheels several times on a windy day. The round rim was noticable less stable and had the wobble in certain wind angles Ryan mentioned. A Reynolds Aero 46 was far less affected than those 10mm lower rims. I can't explain it, but that's how it is.
And I would guess Enve uses round profiles in front for the last few watts in windtunnel tests...
The difference between Zipp 303 Disc and Reynolds 46 Aero Disc was 1,3 watts (of 450 watts needed at 45km/h in the drops) btw.
I would always opt for the teardrop shape - if only it was lighter.
And Mavic also used that shape and those were regarded as quite stable in cross winds - until round Zipps were a few watts faster in wind tunnel tests...
Re: Bora WTO
Posted: Mon Jul 23, 2018 11:00 pm
by TobinHatesYou
That Mavic teardrop isn’t a V though, as it clearly bulges with rounded edges. It’s certainly different enough from the Reynold’s AERO profile with the sharp inside edge. It’s close to the symmetrical rounded diamond or narrow ellipse I surmised would be the best compromise in crosswind stability. The trade-off is that it requires narrow tires for optimal performance. Of course this is moot since the latest UST aero wheels are more U-shaped than before.
Also WRT what you guys are feeling with crosswind “flutter,” could it be that with the V-shaped wheels, you guys are focusing more on front wheel alignment all the time vs with the blunted wheels where you are riding a bit more loosely at a subconscious level? I ask because my own experiences have been the opposite going from older Ritcheys (old Reynolds V-shaped rim molds) to various blunt rims. The Ritcheys would basically force me to ride at a constant lean on Skyline, Crestview, etc.
Re: Bora WTO
Posted: Thu Jul 26, 2018 5:33 pm
by syplam
Does anyone know if the WTOs are available on any online bike stores yet??
Re: Bora WTO
Posted: Fri Aug 24, 2018 11:12 am
by zappafile123
syplam wrote: ↑Thu Jul 26, 2018 5:33 pm
Does anyone know if the WTOs are available on any online bike stores yet??
Distribution in Australia is supposed to start at the end of this year so presumably they should be available online a little earler. Pricing is supposed to be in between the One's and the Ultra's.
Re: Bora WTO
Posted: Sat Sep 15, 2018 8:40 pm
by WorkonSunday
syplam wrote: ↑Thu Jul 26, 2018 5:33 pm
Does anyone know if the WTOs are available on any online bike stores yet??
UK price is out. Although not immediately clear to me that is 2k for the set of 2k each wheels
http://www.chickencyclekit.co.uk/show_p ... =0&p=11844
Re: Bora WTO
Posted: Sat Sep 15, 2018 11:20 pm
by Noctiluxx
There is NO WAY those wheels are 2K a pair, NO WAY!
Re: Bora WTO
Posted: Sun Sep 16, 2018 12:53 am
by zappafile123
Noctiluxx wrote: ↑Sat Sep 15, 2018 11:20 pm
There is NO WAY those wheels are 2K a pair, NO WAY!
$3500 sounds about right for the pair - remember, more expensive than the Ones, cheaper than Ultras
Re: Bora WTO
Posted: Sun Sep 16, 2018 2:15 am
by Noctiluxx
zappafile123 wrote: ↑Sun Sep 16, 2018 12:53 am
Noctiluxx wrote: ↑Sat Sep 15, 2018 11:20 pm
There is NO WAY those wheels are 2K a pair, NO WAY!
$3500 sounds about right for the pair - remember, more expensive than the Ones, cheaper than Ultras
Where did you see that they are "More expensive than the Ones, but cheaper than Ultras?"
Re: Bora WTO
Posted: Sun Sep 16, 2018 2:23 am
by zappafile123
Noctiluxx wrote: ↑Sun Sep 16, 2018 2:15 am
zappafile123 wrote: ↑Sun Sep 16, 2018 12:53 am
Noctiluxx wrote: ↑Sat Sep 15, 2018 11:20 pm
There is NO WAY those wheels are 2K a pair, NO WAY!
$3500 sounds about right for the pair - remember, more expensive than the Ones, cheaper than Ultras
Where did you see that they are "More expensive than the Ones, but cheaper than Ultras?"
One of the Australian distributors told me
Re: Bora WTO
Posted: Tue Sep 18, 2018 12:52 pm
by maxice
The literature suggests they're only available as a pair so £2k for a pair
Re: Bora WTO
Posted: Fri Nov 02, 2018 7:20 pm
by wintershade
Retail price for the WTOs will be $2600. Through an industry connection, I have access to a set prior to general public availablity, and that was the MSRP I was quoted. Not yet sure if I'll take them since I already have a set of 404 NSWs which are a damn fine wheelset (and I don't really want to sell the 404s because I've been pairing the 404 front with an 808 rear on windy days).
Re: Bora WTO
Posted: Fri Nov 02, 2018 7:20 pm
by Weenie
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Re: Bora WTO
Posted: Fri Nov 09, 2018 5:19 pm
by Noctiluxx
Just got off the phone with Campy USA. Wheels start rolling in next month at a price of $2580.