Back by popular demand, the general all-things Road forum!
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alcatraz
- Posts: 4064
- Joined: Mon Aug 29, 2016 11:19 am
by alcatraz on Tue Oct 02, 2018 7:43 am
Assymetric rims are only used in the rear (or possibly some odd disc brake front wheels). In the rear the aero benefit is really small, so I wouldn't worry too much about that.
The difference between an 808 and a 404 in the rear accoding to zipp is 1w.
Last time I raced on an undulating course with many windy flats I had an 88mm front and a 58mm rear. Must have looked hilarious but it worked well.
As a separate topic I'd like to add that I don't understand enve wheelsets with deeper rear than front. I understand crosswinds are an issue but why add more rear wheel weight when it does close to nothing.
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mattr
- Posts: 4671
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- Location: The Grim North.
by mattr on Tue Oct 02, 2018 8:11 am
alcatraz wrote: ↑Tue Oct 02, 2018 7:43 am
As a separate topic I'd like to add that I don't understand enve wheelsets with deeper rear than front. I understand crosswinds are an issue but why add more rear wheel weight when it does close to nothing.
It looks cool.
There might have been (historically) a small benefit in stiffness.
FWIW a mate i used to TT with was using an 80 or 90 mm deep front and a 50mm rear for maximum aero on gusty days. He found that the lack of sail effect on the back meant he could keep control of the front without worrying about the rear. (Still used a disc on still/calmer days.)
Never changed the front.
(Sub 20 minute 10 man, so not a slow rider!)
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TobinHatesYou
- Posts: 12549
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by TobinHatesYou on Tue Oct 02, 2018 9:40 am
alcatraz wrote: ↑Tue Oct 02, 2018 7:43 am
As a separate topic I'd like to add that I don't understand enve wheelsets with deeper rear than front. I understand crosswinds are an issue but why add more rear wheel weight when it does close to nothing.
The added weight is also close to nothing. I don't see anything wrong with the strategy. The cross-sections on the rear rims are different too...typically not as blunt.
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CrankAddictsRich
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by CrankAddictsRich on Wed Oct 03, 2018 5:11 pm
alcatraz wrote: ↑Tue Oct 02, 2018 7:43 am
The difference between an 808 and a 404 in the rear accoding to zipp is 1w.
Last time I raced on an undulating course with many windy flats I had an 88mm front and a 58mm rear. Must have looked hilarious but it worked well.
As a separate topic I'd like to add that I don't understand enve wheelsets with deeper rear than front. I understand crosswinds are an issue but why add more rear wheel weight when it does close to nothing.
I don't agree with this...
For sure, the advantage of going deeper and more aero is more dramatic on the front wheel, but I don't agree with the fact that the rear wheel has little effect. I think it does, and with little penalty for going deep, I see no reason not to go deeper in the rear, if you can. If you're trying to maxmize aero for the amount of money you have and can on;y buy one wheel, I'd say go deep on the front for sure, but if you can buy two, might as well go equally deep ore more on the rear.
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hambini
- Posts: 580
- Joined: Tue Nov 15, 2016 8:13 am
- Location: Cologne, Germany
by hambini on Wed Oct 03, 2018 8:09 pm
The disc wheel is faster but the magnitude is dependent on how fast you are going.
The faster you go, the more the advantage becomes because the turbulence caused by the spokes and uncontrolled flow is eliminated.
This one is at 50km/h
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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RyanH
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by RyanH on Wed Oct 03, 2018 8:25 pm
I always thought that deeper in the rear helps settle the front. So a rear disc/808 combo handles better in the wind than an 808/808. I can't remember where I read that though.
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ericoschmitt
- Posts: 186
- Joined: Fri Apr 21, 2017 7:47 pm
by ericoschmitt on Thu Oct 04, 2018 1:25 am
Have you tested some of the other wheels adding the same rear disc? Or maybe Planet X on both, but 80mm rear? This way we can know what is making all that difference, front rear or a bit of both. Maybe Yoeleo with the same rear disc could still beat at 30, and possibly Reynolds is still the fastest if it has a rear disc.
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ericoschmitt
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by ericoschmitt on Thu Oct 04, 2018 1:40 am
RyanH wrote: ↑Wed Oct 03, 2018 8:25 pm
I always thought that deeper in the rear helps settle the front. So a rear disc/808 combo handles better in the wind than an 808/808. I can't remember where I read that though.
I've also read many people say that deeper rear feels more stable, even rear disc is better than deep/deep. I've tried 58f/24r on my fixie (beacuse I obviously wont spend on a fixie rear wheel) and had no problems to control it. In 2008 a man did Kona IM on a fixie with Zipp 1080f and shallow rear, said no problems with it. But according to FLO, their 60/90 mix always beats 60/60 or 90/90.
So having a rear disc probably wont hurt, and can make you faster when it's allowed.
And it's quite cheap to make one with expansive foam and an old wheel!
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spdntrxi
- Posts: 5832
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by spdntrxi on Thu Oct 04, 2018 3:35 am
Full Disc > Deep >Swallow Trust me... it's 99.99% true.
2024 BMC TeamMachine R
2018 BMC TImeMachine Road
2002 Moots Compact-SL
2019 Parlee Z0XD - "classified"
2023 Pivot E-Vault
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hambini
- Posts: 580
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- Location: Cologne, Germany
by hambini on Thu Oct 04, 2018 2:13 pm
CrankAddictsRich wrote: ↑Thu Oct 04, 2018 11:48 am
ericoschmitt wrote: ↑Thu Oct 04, 2018 1:40 am
But according to FLO, their 60/90 mix always beats 60/60 or 90/90.
I find that highly suspect... and it goes against all of my experience in TT's.
I'd agree.
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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WorkonSunday
- Posts: 540
- Joined: Tue Jan 16, 2018 4:39 pm
by WorkonSunday on Thu Oct 04, 2018 2:43 pm
disc at the back is that much better? wow.
as mentioned by others, would like to see planet X 80/80 and see how much if it comes from the disc!
Some say pour 10ml water out of your bottle to save that last bit of the weight. Sorry, i go one step further, i tend to the rider off my bikes.
n+1...14 last time i checked, but i lost count