Open mold wide profile carbon wheels

[alcatraz]

Interesting. Thank you for replying. (I like that we can write about the different schools of thought without being arrogant about it. )

I'm curious about the higher yaw angle turbulence heat graphs that pop up occasionally. (I don't have one here right now.) If my memory serves me when the air path around the front and the back has similar travel distance and thus pressure you get less turbulence and a centralized pressure point away from the ends which would help stability in different angles. The wheel could be more predictable sort to speak.

Fishtail being more naca-profile than toroidal should be less turbulent at 0 degree yaw, no?

I'm confused at the moment. Trying to get my head around it... obviously I'm not an aerospace engineer haha.

Are reynold wheels V-shaped?

By the way Beaver, I saw on youtube that you've been talking with Hambini about rim profiles. Respect! Do you think there is something unexplainable about what makes wheels fast? Why isn't there a clear winner by now? Hmm...

/a

[Beaver]

That's how it should look like. Everything else it low manufacturing quality. ACE Bike/Yishun and especially Light Bicycle are a better choice.

I have now contacted Farsports regarding the issue. Hopefully a new rim will be provided under warranty.

In 99% of the cases it will be only cosmetic, but you never know how it looks on the inside unless you cut it open.

[Beaver]

Interesting. Thank you for replying. (I like that we can write about the different schools of thought without being arrogant about it. )

I am no "professional" either, but after the years and having a look at several tests from Zipp, Bontrager, SwissSide, November, Tour Mag. and so on, one can see certain tendencies.

I'm curious about the higher yaw angle turbulence heat graphs that pop up occasionally. (I don't have one here right now.) If my memory serves me when the air path around the front and the back has similar travel distance and thus pressure you get less turbulence and a centralized pressure point away from the ends which would help stability in different angles. The wheel could be more predictable sort to speak.

Like this?

Fishtail being more naca-profile than toroidal should be less turbulent at 0 degree yaw, no?

Yes, but even a very low rim is great at 0° yaw (which rarely occurs in real life) and the frontal area is the most important factor. Here the Oval 724 was best in test (they tested on a track, so no crosswinds at all) as its hub flanges are very close together: http://procycling.de/assets/magazine/67 ... ketest.pdf (again only German, sorry)

I'm confused at the moment. Trying to get my head around it... obviously I'm not an aerospace engineer haha.

Maybe @hambini can help?

https://www.youtube.com/watch?v=BUih_emc54M

Are reynold wheels V-shaped?

I think a torodial shape just offers more "flat" space to the wind. With this "slope" there will be less turbulences directly at the rim (but more after it). And again, the differences are tiny, an overlapping tire will be worse.

[alcatraz]

Yes yes that graph. Isn't it in favor of toroidal being less affected by crosswinds?

I've never ridden a V-shaped rim. I've mostly read about people on this forum warning against going deep rims because it's life or death if you do. I ordered 58mm toroidal rims thinking I'm going to have sore arm muscles correcting the crosswinds. Now I'm riding an 88mm deep toroidal front completely relaxed (plenty of warning when a gust comes as it hits = predictable) and I'm wondering what the fuss is about. I guess I'm trying to make sense of it. Why is it like that? The city where I live is coastal on three sides (!) and can be very windy. Sincerely my scariest crosswind moments have been with narrow alloy 20mm rims and balloon tires going over hillcrests. I just don't get it.

Ps. I wrote something at the end of the previous post you might want to see. Small edit. Cheers!

[Marin]

with narrow alloy 20mm rims and balloon tires going over hillcrests.

Funny, I'm riding 25mm rims with 42mm tires on the road a lot currently (650b, on an allroad bike) - and I'm really feeling crosswinds. My setup is basically the opposite of the usual aero wheels

[Beaver]

By the way Beaver, I saw on youtube that you've been talking with Hambini about rim profiles. Respect! Do you think there is something unexplainable about what makes wheels fast? Why isn't there a clear winner by now? Hmm...

Torodial is the aero winner and Reynolds the less affected by crosswinds - you can't have everything, these are just two contrary interests.

That's why Bontrager now ended up with a round V-shape as a compromise and Campagnolo WTO now has a more torodial shape (they wanted better aerodynamics).

BUT overlapping tires or not has a much bigger influence. I started 21C rims with Zipp 30 Course (26x25mm) and 25mm Conti 4000 S II. Those were less stable in crosswinds than the 21C Light Bicycle (36x28mm) now - 3.5mm tire overlap vs. 0.5mm overlap... It's no gigantic difference but noticable.

So, overlapping tires are a true wind catcher.

Yes yes that graph. Isn't it in favor of toroidal being less affected by crosswinds?

Actually it shows (with the arrows) where the windstream looses contact to the wheel. As the Bontrager is the only one wider than the tire, it can hold it longer than the others and the drag area is much smaller. Crosswind stability will also be better. But if the rims had the same width, the V-shape would be better in crosswinds.

And this car is also more aerodynamic than without the air curtain, but more affected by crosswinds:

I've never ridden a V-shaped rim. I've mostly read about people on this forum warning against going deep rims because it's life or death if you do. I ordered 58mm toroidal rims thinking I'm going to have sore arm muscles correcting the crosswinds. Now I'm riding an 88mm deep toroidal front completely relaxed (plenty of warning when a gust comes as it hits = predictable) and I'm wondering what the fuss is about. I guess I'm trying to make sense of it. Why is it like that? The city where I live is coastal on three sides (!) and can be very windy. Sincerely my scariest crosswind moments have been with narrow alloy 20mm rims and balloon tires going over hillcrests. I just don't get it.

Put 28mm tires on your 58mm torodial rims on a windy day, then you will know what they mean.

But this is a very subjective matter. What for some is unridable is a no brainer for others.

[NovemberDave]

Thre's some oversimplification happening in this thread, but generally the wider the tire relative to the rim, the less stable. This is well established across a bunch of tests - ones we've done and published, ones that others have done and published, and ones which I've seen but which haven't been published.

It's no surprise that a 20mm deep and narrow rim with a large tire on it proves unstable - that's basically a relatively large surface area tire with no facility to shape the wind flow around it.

[Beaver]

Thre's some oversimplification happening in this thread, but generally the wider the tire relative to the rim, the less stable. This is well established across a bunch of tests - ones we've done and published, ones that others have done and published, and ones which I've seen but which haven't been published.

It's no surprise that a 20mm deep and narrow rim with a large tire on it proves unstable - that's basically a relatively large surface area tire with no facility to shape the wind flow around it.

Sorry, but I am no professional engineer. But as long as we come to the same conclusions, I guess everything is fine.

[NovemberDave]

Well, we don't always come to the same conclusions (I don't agree with the blanket sentiment that "toroidal is fastest and v is most stable," as I don't agree with it in the absolute, and there are way too many variables that get thrown in there), and I'm not a professional engineer either (my father, who was, taught me my healthy skepticism of "I'm an engineer" as the be-all end-all authoritative credential). But as long as statements are based on credible and defensible evidence, then it's worth having the conversations.

[Beaver]

Zipp wheels always had (with matching tires) the best aero drag performance in most tests (although those differences were always tiny and low on digit watts when 450 watts are needed overall at 45 km/h) and real world (surely subjective) comments of the users agreed. And the latter is my favourite source of information as sometimes only on the road things are noticed.

Because e.g. the 454 NSW are proclaimed as very stable in crosswinds, where as people I know and reviews on the internet stated otherwise. And later on also Tour Mag. tested it to be the same.

Also SwissSide wheels (and now DT Swiss with the same rims) with a quite similar shape performed very well, so this seems to be the best choice regarding aerodynamics at the moment. It may not be the absolute, but the differences are so low anyway, that this whole topic is more theoretical than really being experienced on the road.

One should avoid overlapping tires, pure rim height will help more than shape (at the same width) and slim hubs, few bladed spokes and internal nipples will be the final touch.

But you always should feel fine with your wheels as you will reduce power when the bike feels instable in crosswinds or the rear wheel rubs on the brakes when climbing. That way one will loose a lot more watts than ever possible with a wheelset alone.

[Hexsense]

Lets get to developing history and generalization of rim shapes. All these info, ofcourse are not represent every wheels, just general recap of what industry and marketing told us.

I recalled that NACA shape were most aero efficient head on. But got critisize that it's only best at 0 yaw angle but performance sharply drop off as the Yaw angle increase.

Toroidal U shape come into the picture. It must be a fair bit wider than the tire , it has lower drag at higher yaw angle hence they said it is more aero in the real world. Some case it even sail in cross wind, having a negative drag number. With careful shape, they also said to not having too much "turning force" on your front wheel (but still some "pushing force" though). Best choice at a time.
Main resistance that still likes NACA shape more are Campagnolo and Reynold which can get away with narrower rim that weight less while supporting the same tire width.

Then the wide tire train comes, 27mm wide rim for 21c tubular tire is no longer sufficient. Rims can't simply exploded to 33mm+ wide for your 25c clincher because it won't fit between frame and brake calipers (and of course, heavy). There are also some researches that high yaw angle are not as important as previously thought in real world cycling. Most of the time people are riding in <10degree yaw. So some brands go back to V-like shape, to reduce weight and making rim support wide tire without being super wide. All at the expense of more drag at higher yaw angle (and hard to market because it's not U shape). Venn, Light-bicycle (at the time, promote the wheel as CX or Gravel as it is so wide and being non U) and recently Bontrager see this and adopt the shape. Recent Enve is also kinda looks like a V.
For the stability side, Venn also state that their V-shape rim have both low turning force and low pushing force by design carefully.
I believe the 105% rule are established on Toroidal U-shape rim (Zipp 303?). With V-shape rim we may get away with wider tire than that.

[NovemberDave]

Again, some to agree with, some to disagree with. Raw height is not that important, at least not when a 32mm high AForce Al33 (toroid shape) and a 31mm high Kinlin XR31T perform as well as a 45mm high 303 in the conditions that are established to occur most frequently (<8* yaw angle). We tested that, fully expecting that 303 would be substantially better. These are all farily similar width rims. I know Hambini did a video showing "it's all rim height" based on his CFD, but the wind tunnel disagreed. https://novemberbicycles.com/blogs/blog ... her-alloys

People love to cite that Laser spokes cost 1w from CX Rays, and the knowedge of that also comes from a test we did. https://novemberbicycles.com/blogs/blog ... rodynamics But Flo did a test that shows a straight gauge spoke giving up substantially more to a CX Ray, so bladed spokes all day, right? Where's the test with a broad array of "bladed spokes"? If round spokes can perform differently from one another, bladed spokes can as well. So the problem I have is with saying "bladed spokes are best." This may sound pedantic, but parsing out half watt differences in wind tunnels at speeds most people never ride at is, to me, at least as pedantic.

Internal nipples - where's that info coming from? Is it reliable? We did a run with the cap from a ball point pen crudely taped to the valve stem of a wheel that had just run. The difference was outside of the margin of error, but barely. I simply can't see internal nipples being a repeatable savings.

I've never seen a test that isolated hubs, if there is one I'd love to see it.

We broadly agree on tire width's effect, with my knowledge of it coming primarily from a test we did a few years ago. https://novemberbicycles.com/blogs/blog ... der-faster

I'm really not trying to be a jerk (in fact really trying not to be a jerk), but I can't acquiesce to "no problems as long as we come to the same conclusions." I can only come to the conclusions that data gives me. People telling me one wheel or another spins up faster or holds speed better just, I can't. No. And having ridden a bike in a wind tunnel, I can tell you that small little movements that you have NO IDEA you're making bounce the data around like crazy, beyond the difference between one wheel/tire and another.

So after all this, I don't believe in hard and fast easy rules. I think there's a lot that people can do to avoid horrible aerodynamic speed and behavior from their bikes, but to have people believe they can resolve their on bike experiences to within a watt or three goes against all of the considerable first hand research I've done as well as what I've seen from reliable places. The true and honest end of this long loop for me is that you need to either go in to a tunnel or velodrome or do Chung method (ie do a very reliable "you and your equipment" specific test) to get to what works best for you as an entire system, or just avoid the known terrible stuff and leave it there.

[Beaver]

For the start of the cooperation with DT Swiss, SwissSide did a lot of marketing, that's where these came from:



Reynolds has higher drag at high angles but less side forces...





And I tend to believe this, as the competitor is better in one regard.

Slim hub and internal nipples, bladed spokes:







Even the missing skewer lever is supposed to save one watt, but maybe one shouldn't point in downwards:



Higher inner width reduces rolling resistance:



SwissSide really did a lot of testing, like HED and Zipp, and I think there should be a bit of truth in it.

[Beaver]

This is indeed interesting and would raise a few questions.

Is the higher inner width (19C vs. 17.25C) with straighter tire flanges that effective (Al33 vs. 303) / does the transition between rim and tire have such a high effect (Mavic supplied its older aero wheels with a rubber band to be placed between tire and rim)?

But a "lower rim is worse" seems to be right for higher yaw angles in general?

And Kinlin is best in low angles as the frontal area is the lowest (17C so the tire will be the slimmest here)?

In contrast Flo 30 and HED Belgium the worst with 19.4/20.3mm inner width and therefore widest tires?

And what yaw angles matter most is also a point of view: https://www.slowtwitch.com/Tech/Real_Wo ... _5844.html

My personal experience is, that with straight headwind (which hardly ever appears) I feel hardly any difference between wheels, with wind from "front-left" or "front-right" aero wheels are a tad better. How often a certain angle appears, depends on where I ride. But maybe I am too slow after all.

And again, we are talking about one digit watt differences of 450 watt.

[NovemberDave]

Thanks, had never seen a hub comparison before and I'll take that one at its word. Their comparison of round versus bladed (which is actually specifically straight gauge 2.0 vs DT Aerolite) is more in line with what we found with Laser vs CX Ray and understated compared to Flo's straight gauge vs CX Ray test. The test we ran with the pen cap, and what Zipp has said with respect to hidden nipples (they say no effect at all), disagrees with the magnitude of impact they show with hidden nipples, but their info agrees with what Enve has said. No consensus on that one.

Overwhelmingly, wow those wheels are not very low drag! But that comes back to what I've come to believe in - when a HED Belgium+ is within speaking distance of a 303 after the wind tunnel 40k, the whole "aero wheels can turn you into a new rider!!!" hyperbole seems, well, weak.

On next post and our graph - Kinlin is 19mm inside width so it inflates tires wider than Zipp, as does Al33. 303 overall width is wider than either, so given that it inflates tires smaller against a wider overall width, that contradicts blanket statements about tire width versus rim width.

There are differences beyond depth that occur with the 303/Kinlin/Al33/others so you sure couldn't isolate the 303's better high yaw performance to depth. Flo30 has the most toroidal shape of all these rims, was relatively bad head on and relatively better at wide yaw.

For yaw angle distribution, the Flo and Trek analyses that we refer to in that series of posts are "case closed" for me. Also bear in mind that effective yaw angle closes down A TON when you draft because the actual wind's speed is slowed so much that its contribution to your apparent wind vector is much diminished.