Lightweight Obermayer aerodynamics

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petromyzon
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Joined: Mon Apr 05, 2010 4:14 pm

by petromyzon

What do the Fernweg and Autobahn have to do with the Obermayer?
Aerodynamics does not suddenly kick in at 25mph.

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mendiz
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by mendiz

Ineos has not used Obermayer never.Always they are used Meilenstein 24 E tubular with the front wheel with 20 spokes.
You don´t stop riding when you get old, you get old when you stop riding.

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spdntrxi
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by spdntrxi

I've seen Obers with front 20..
2019 BMC TM01 Road UCI config 7.36kg

eurostar
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by eurostar

.
Last edited by eurostar on Fri Nov 19, 2021 5:57 am, edited 1 time in total.

eurostar
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by eurostar

.

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mendiz
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by mendiz

Show a pic, I asked LW and they confirm that os Meilenstein 24 E
spdntrxi wrote:
Tue Nov 16, 2021 10:23 pm
I've seen Obers with front 20..
You don´t stop riding when you get old, you get old when you stop riding.

spdntrxi
Posts: 4593
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

Image

not mine... I have 16 spoke genIV
I guess the center sticker could be faked?
2019 BMC TM01 Road UCI config 7.36kg

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mendiz
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by mendiz

Ah, ok, I wanted to say that Ineos always used only Meilenstein. About your pic, I saw in Instagram "lightwheelsrepair" ( a spanish man that repair LW) a pic where he shows a fake sticker Obermayer in hub of Meilenstein, the owner of that wheel did know it.
You don´t stop riding when you get old, you get old when you stop riding.

handler
Posts: 59
Joined: Mon Aug 18, 2008 9:28 pm

by handler

So after plenty of thinking and some internet digging I’ve come a bit further on the topic. We’ve have some interesting insights on the topic. This analysis is only applicable to those who ride at 35 km/h and above (which could be during races) as it’s then the yaw angle drops toward +-5 degrees.

If we look at the analysis made by Jürgen Knupe and David Farmer at wing-light, both former F1 mechanical engineers, the result is unconventional to by todays standard, but still a result worth mentioning. They did conduct an analysis on six different wheelsets, Zipp 303, Campagnolo Bora, Lightweight, Zipp 808, Zipp 1080 and Zipp 900. The analysis is where done in ca 2010 (a bit unsure about the exact year, but the site give some hints it’s done during that period).
Without copy-pasting the whole analysis which can be found here http://www.wing-light.de/CFD/wheels.htm, let’s look at the chart below.
cwa.JPG
The chart shows the power which is needed to move the wheel through the air, also called the translational drag coefficient (cw) and the frontal area (A) of the wheel. Translational drag is just drag what we visualize it to be, the force acting on the wheel trying to slow it down and accounts for 75 % of the total drag, which the rest is due to rotational drag of the wheel. Rotational drag is the drag caused by the wheel rotating in another medium, highly affected by the viscosity of the medium and speed of rotation. Think about it as running a propeller in air or water. Rotational drag is why spoke nipples become interesting to hide, it’s like adding a piece of welded metal to a propeller in water, the rotational drag would jump.

Image

Back to the chart! As we can see the drag is very similar to each wheel to yaw angles at 0-5 degrees at 40 km/h. Only at increased yaw angles we can notice a diverge in the lines. Both the Zipp 303 and the Campagnolo Bora wheel have decreasing efficiency in all yaw angles with a almost linear pattern. As expected, the Zipp 900 shows negative propulsion at extreme yaw angles, while the Zipp 808, Zipp 1080 and the Lightweight wheels does have increasing and then stabilizing drag in the more extreme yaw angles (which only accounts for a couple of percent of the total ride time, note from earlier posts in this topic). This part of the analysis does not account for the rotational drag, so what could have an impact is e.g. the spoke area and width or nipples. Please read further!
They provide us with an analysis accounting for the rotational drag which can be seen below and shows similar results, hence hinting about that the rotational drag is relatively less important, just what SwissSide reports. https://www.swissside.com/blogs/news/ro ... g-insights
drag.JPG
The analysis completes the CFD analysis done by Knupe & Farmer with a wind tunnel test by German journal Velomotion. They are noting that their (Knupe & Farmer) analysis is resulting in lower drag numbers compared to the analysis made by Velomotion, although they criticize the use of forks used upside down for holding the wheel. Velomotion shows similar results as above, wheels are quite similar at lower yaw angles and only difference by a single digits watts. Hence, for any fast race with no strong crosswinds, most profiles above ca 40mm will be comparable good.
veomotion.JPG


TL;DR

My conclusion is that cross wind speeds and expected race speed is more important when picking the right wheel for the race, as it’s when we have the unusual wind patterns as we see difference in wheel performance, otherwise almost all high profiles (>40 mm) as similar good. Including the old “V-shaped” Lightweight design. Tyre resistance and fit is not part of the analysis, which could affect the end results, just as the frame, the rider, and the surrounding riders (lots of dirty air in the peloton/group).
And as a final note, did you know that Swiss Side is (or was?) actually the aero consultants to Ineos? https://www.swissside.com/blogs/news/sw ... h-team-sky

petromyzon
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Joined: Mon Apr 05, 2010 4:14 pm

by petromyzon

So they weren't too bad aerodynamically, if you ride fast, a decade ago. You still might find it hard to take advantage of the vast improvements in tyres over the past decade. And they cost 3-4x more than competing wheels, without being much lighter.

Is it just me or are they a product you buy just to show how much money you have?

handler
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Joined: Mon Aug 18, 2008 9:28 pm

by handler

petromyzon wrote:
Mon Nov 29, 2021 12:42 pm
So they weren't too bad aerodynamically, if you ride fast, a decade ago. You still might find it hard to take advantage of the vast improvements in tyres over the past decade. And they cost 3-4x more than competing wheels, without being much lighter.

Is it just me or are they a product you buy just to show how much money you have?
That's certainaly a point, but as for now, the fastest tested rubber is recently available for tubular.
https://r2-bike.com/VITTORIA-Tubular-Co ... full-black
däck.JPG
https://www.bicyclerollingresistance.co ... 6&minpr=21
Although, we don't have the great allround tyre GP5000 available for consumers.

Trying not to make this a tubular vs other tyres topic.

The data shows that the passé is not blasé, we just need more objective wheel testing.
Last edited by handler on Mon Nov 29, 2021 1:41 pm, edited 3 times in total.

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