Rims - Flo vs. Gigantex

[steelbikerider]

I'm planning to build up a set of carbon wheels for next season - 20/24, CX-Rays, White and/or Shimano DA hubs with 50 - 60 mm deep rims. Any preference between the 2 rims? Weight is not an issue since any ride/race around here has at most a few hundred feet elevation change for a 50 -60 miler.

[gtinut]

I use wh133 from BHS in 24/28.
Great and strong rim. Gigantex makes quality product that other big brands use them.
Thomson carbon bars are make by them - road and CX bars are one piece construction.

[Multebear]

Sounds like a very good and well thought over idea. As long as the rims are U shaped, I'm pretty sure, you'll be happy with both.

[vmajor]

Sorry for the mild necromancy and jumping into your thread, but the forum listed it as a related topic in "my" thread.

So, my question is why is this "U shape" in deep section rims seen as a good thing?

In our research the U shape is not actually that good as it presents itself as a thick flat plate in cross winds and stalls badly with a lot of high energy turbulence. The rims that are assumed to be "U-shaped" for example new Zipp rims are not actually the generic "U" shape, but carefully designed extended laminar flow airfoils. They are not flat plates.

Second even the most modern properly implemented (not generic) "U shaped" rims do not work that well with wide tires, ie. they are not entirely effective with 25mm wide tires. This is why Enve for example uses a more traditional looking airfoil shape for their latest rims.

Anyone else please jump in and let me know what seems to be the attraction towards the generic "U shape" rims as we can make it too, ie. I may be missing something and I am happy to learn.

V.

[Multebear]

This is Enve's 3.4 rims. Are you saying, they are not U shaped? Not sure I understand, what you mean by "more traditional looking airfoil shape":

[vmajor]

No, I mean this: http://www.bikeradar.com/road/news/arti ... ecs-46419/

[vmajor]

...and just to clarify we do also make a "U" shaped rim, the Venn Alter 44 http://www.venn-cycling.com/index.php/rims/ctl-rims which indeed works well at low yaw angles with 23mm tires, but its main benefit is in a very good strength to weight ratio given its more or less "I" beam shape so we place it mainly as a rim for very wide tires - CX or Gravel bike.

[Multebear]

So now they're moving back towards the V shape Again! How will we ever be able to trust what they try to tell us? It's all marketing BS anyway...

[vmajor]

...well in the defense of the move to "V" shape it is actually not a "V" shape, just like the "U" shape is not a "U" shape. Using letters to approximate the shapes was just a way to explain the new rim shape to customers.

Both the new "V" shape and the real not generic "U" shapes are in fact airfoils designed to work with the tire and deliver low drag and good handling in cross winds. The problem with the "U" shape is that to make it work well with the currently popular 25mm tires the widest section would need to be something ridiculous like 30-32mm wide which besides looking strange would also result in higher rim weight. The profile would also need to go well beyond 50mm in depth.

[Multebear]

True. But first they made V shapes. Then they made U shapes. And now they make something in between. Why not just make the airfoil right away?

[mattr]

Cos it's not really an aerofoil. It's spinning and moving. So you've got all sorts of things going on.

Just look what they've done to the fans on a gas turbine engine over the years to try and account for the spinning and forward motion.....

[kgt]

V is the new U.

[F45]

Specialized claims their CLX32 is just as efficient as their previous deeper section rims. It's like 28mm wide, designed for a 25mm actual tire. But I agree, we need 32mm wide rims to go with our 28mm tires. It will happen.

The Chinese U shape rim did pretty good in the Tour test, Issue 8.

[junchen]

V is the new U.

I don't often agree with kgt, but... +1!

Sent from my SM-G920I using Tapatalk

[Hexsense]

...and just to clarify we do also make a "U" shaped which indeed works well at low yaw angles with 23mm tires

Isn't that the most important criteria to consider when designing a rim?
According to Flo, their real world test shows that cyclist are facing Yaw less than 10 degree for 70% of the time (i think their test subject ride pretty fast so that explain it).
http://www.slowtwitch.com/Tech/Real_Wor ... _5844.html

I mean, for now when i look at aerodynamic test, i focus on the 0-10 yaw angle the most and don't care anything after 15 degree at all. So i would take a wheel that perform better at 0-15 degree but not so good at 15 degree+ than a wheel that compromise 0-10 to have good performance at high yaw angle. So generic U-shape are shape already work well then?
PS. or your definition of low Yaw are different than mine and 10 is already not low?