Bora WTO

Everything about building wheels, glueing tubs, etc.
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kgt
Posts: 6964
Joined: Sun Jun 18, 2006 10:29 am
Location: Athens, Greece

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.

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kgt
Posts: 6964
Joined: Sun Jun 18, 2006 10:29 am
Location: Athens, Greece

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...

by Weenie


TobinHatesYou
Posts: 1758
Joined: Mon Jul 24, 2017 12:02 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.

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Beaver
Posts: 501
Joined: Wed Aug 18, 2004 6:06 pm
Location: Lower Saxony - Germany

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...

ImageImage

TobinHatesYou
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Joined: Mon Jul 24, 2017 12:02 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.

syplam
Posts: 84
Joined: Thu Feb 02, 2017 7:30 am

by syplam

Does anyone know if the WTOs are available on any online bike stores yet??

zappafile123
Posts: 348
Joined: Sun Jun 01, 2014 8:24 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.
De Rosa Protos | Bianchi Oltre XR4 |BMC SLR01 16 |Cannondale SS Evo HM 12| Focus Izalco Max | Ridley Helium SL 15 | Basso Diamante 15 | Bianchi Oltre XR2 | Scapin Dyseys S8 | Time ZXRS | Giant TCR SL 12 | Ridley Noah 08 | Look 585 | Cervelo Soloist SLC

WorkonSunday
Posts: 33
Joined: Tue Jan 16, 2018 4:39 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

Noctiluxx
Posts: 396
Joined: Tue Feb 07, 2017 7:17 pm
Location: Southern California

by Noctiluxx

WorkonSunday wrote:
Sat Sep 15, 2018 8:40 pm
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
There is NO WAY those wheels are 2K a pair, NO WAY!
2018 Bianchi Oltre XR4, (Celeste Matt)
2018 De Rosa SK Pininfarina (Blu)
2017 Giant TCR Advanced SL (Red)
2016 Specialized Allez DSW Sprint (Gold)
2016 Giant Anthem Advanced SX (FS)
2018 Trek Farley EX 9.8 Fatty (FS)

zappafile123
Posts: 348
Joined: Sun Jun 01, 2014 8:24 am

by zappafile123

Noctiluxx wrote:
Sat Sep 15, 2018 11:20 pm
WorkonSunday wrote:
Sat Sep 15, 2018 8:40 pm
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
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
De Rosa Protos | Bianchi Oltre XR4 |BMC SLR01 16 |Cannondale SS Evo HM 12| Focus Izalco Max | Ridley Helium SL 15 | Basso Diamante 15 | Bianchi Oltre XR2 | Scapin Dyseys S8 | Time ZXRS | Giant TCR SL 12 | Ridley Noah 08 | Look 585 | Cervelo Soloist SLC

Noctiluxx
Posts: 396
Joined: Tue Feb 07, 2017 7:17 pm
Location: Southern California

by Noctiluxx

zappafile123 wrote:
Sun Sep 16, 2018 12:53 am
Noctiluxx wrote:
Sat Sep 15, 2018 11:20 pm
WorkonSunday wrote:
Sat Sep 15, 2018 8:40 pm
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
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?"
2018 Bianchi Oltre XR4, (Celeste Matt)
2018 De Rosa SK Pininfarina (Blu)
2017 Giant TCR Advanced SL (Red)
2016 Specialized Allez DSW Sprint (Gold)
2016 Giant Anthem Advanced SX (FS)
2018 Trek Farley EX 9.8 Fatty (FS)

zappafile123
Posts: 348
Joined: Sun Jun 01, 2014 8:24 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
WorkonSunday wrote:
Sat Sep 15, 2018 8:40 pm


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
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
De Rosa Protos | Bianchi Oltre XR4 |BMC SLR01 16 |Cannondale SS Evo HM 12| Focus Izalco Max | Ridley Helium SL 15 | Basso Diamante 15 | Bianchi Oltre XR2 | Scapin Dyseys S8 | Time ZXRS | Giant TCR SL 12 | Ridley Noah 08 | Look 585 | Cervelo Soloist SLC

maxice
Posts: 19
Joined: Wed Aug 15, 2018 11:05 pm

by maxice

WorkonSunday wrote:
Sat Sep 15, 2018 8:40 pm
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
The literature suggests they're only available as a pair so £2k for a pair

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