The Velocite RT50 Aero Wheels May Be The Most Extraordinary Use Of Computer Design In Cycling

So… another company managed to use another new method to come up with what HED did 7 years ago. Sweet.

Yeah, was just going to say that. Despite the fancy computer modeling, still came out pretty similar to every other wheel out there. Not to be a hater, just don’t see what’s so extraordinary about the end product.

CFD software is used by most of the top end aero companies on the market. Not sure why these guys think they’re special in that regard.

That’s what everybody has been doing for at least 5 years on wheels, frames, helmets, etc. And many did that at least for some projects since the 90s.

But whatever… for the vast majority of us most of these gains are more than cancelled by what we ate 2 days or 2 hours ago.

@AlanM, pro teams have gone to 25mm, especially on the rear wheel, because it reduces rolling resistance and improves grip and comfort. Thin=fast is an oldskool road cycling myth. That’s only true on the smoothest of roads, which barely exist in the real world.

@JeroenK, I’m very aware of the switch to 25mm from my work with some teams. It would be interesting to see data that is more relevant, not just from a wind tunnel, which only takes into account one of the factors a rider faces. A 23mm tire might be more aero in this setup, but is a 25mm tire still faster overall? Just the things I think about.

@Dude, aero improvements might beat rolling resistance improvements, but there is always so much more at play than static data from a computer. How much of an aero gain are we talking between 23 and 25mm? What about rider fatigue from a harsher ride? Again, I know there isn’t going to be one answer, but food for thought when companies use computer data that only focusses on a single element.

It often times is not easy enough to say a 23mm or 25mm tire is faster. In the little data that’s out there, width seems to mostly affect stall. Also, rolling resistance increases in proportion to speed, whereas aero drag increases moreso. So whether a lower RR, or more aero tire is faster often depends on rider speed and the wind conditions.

All that said, the Conti gp4000s has proven again and again to roll fast, and be very aero in the 23mm version soon. And really it runs close to 24mm, particularly on wide rims.

A set of road wheels for Johny Storm?…well the brake track will have to take more than 377 F.

Flame on!

Horses for courses. Even if 23 might be more aero, it’s going to work differently under a 170lb rider vs a 140lb rider and even if it’s more aero, that’s not necessarily faster overall if you’re less confident in fast corners or on rough or loose stuff and lose the wheel in front of you. Even so, it’s not like it’s *not* going to be aero with a 25mm tire, and it’s not like 23mm is “un-raceable”under most circumstances.

Either way 25mm+ works really nicely for me personally and it would be cool to see more stuff optimized for that size. Wondering if that would make for a tight fit in the chainstay/bb area on a lot of current frames though.

Haha there is a 25 and also 23 mm wide tubeless carbon farsports rim now. Not saying I think they’d do that.

Tubeless carbon is interesting I agree with Tyler on that point. More players in the game is fine with me I never understand why people get all hyped up saying who’s idea it was first, waste of time.

Regarding aero vs crr, this is the hot debate in tires – wider versions of same tires (new zipp, spec tires) have better crr, while narrower (24 vs 27mm) are slightly more aero. You’d have to measure both sizes for aero and crr, and then convert that to time over a distance to find the ideal. I would say that the 24-25mm width of the fast crr tires are the fastest. Currently my favorite combo is the new zipp slspeed tubulars 24mm – that’s what I have on my 404 tubs, and on clinchers I have 23mm Conti 4000s II in front and Zipp Speed Clincher 25mm in back.

Look at this guy’s data for some interesting data – https://docs.google.com/spreadsheets/d/1f398PSxFhSj6Zdsjllo14l5XyhOhcmlkzjvHwfKjNOs/edit#gid=361584932

It’s just roller crr testing, but it’s fun to look at.

Bang on, @scotty. The software is only as good as the guys interpreting the data. I do get a heck of a kick out of this article, though. To the earlier points, who ISN’T using CFD these days? Maybe next we’ll hear about a breakthrough company making bikes from (gasp!) CARBON FIBER!

23c tires are Over!

I am starting to think I am an idiot for not going tubeless. I have had 3 flats in the last month. Can someone please tell me why I should not go tubeless?

@AlanM you might find this analysis interesting http://speedtheory.co.nz/marginal-gains-tyre-selection-part-two/ – combining aero and CRR for a total cost on tyres.

Folks, I wonder how many of you own a math or science degree. It doesn’t take much IQ to ride a bike, but it does take some above average knowledge to build them and to explore the possibilities in the technologies. The fact that Victor takes the time to create and verify everything with the latest, and some “before their time”, measurements and tests, before he offers them to the public is rare. There is no hype, no marketing. No almighty bottom line, either. Just science and improved products through diligent use of available technologies and real life testing. Sure other companies test and use CFD, wind tunnels, etc. to what end? For many it’s a marketing tool to the ignorant. Don’t be ignorant. Take the time to do some homework and maybe add some useful knowledge so you can debunk the BS coming from your coffee house riding group. Don’t just be mediocre and regurgitate loads of crap you’ve heard, or read. You’re only as fast as your body and fitness level allows. The improvements in bicycle technology allows you to go a bit faster with the same wattage output. I rather see real science applied to real world situations and then simulated to produce the best parts available at any price. Wouldn’t you?

@DB, thanks for the link.

If only I could edit my post, I could delete the duplicate link 🙂

@Jason

tl/dr version:

Sorry for the lack of technical information in my reply, and on our blog post. You and anyone else familiar with or interested in CFD, FEM/FEA and computer aided engineering and research in general are welcome to get in touch with us directly and I’ll be happy to discuss everything in as much detail as you would like.

We are hardly unfamiliar with the “state of CFD simulation in general”. We have used various solutions all the way from custom DNS (direct numerical simulation), “standard” Navier-Stokes (Fluent, Comsol, OpenFoam and derivatives), had and have lengthy discussions with CD-Adapco, trialed XFlow, worked with Janusz and Sailfish, and many others including more custom GPU based solvers thanks to our relationship with the NCHC (national supercomputing center) and The NCKU (very good university in Taiwan).

Palabos is a library, not really a ready to use application. What we have is a custom made low speed virtual wind tunnel application built using the Palabos library in an arrangement more aptly described as commercial open source. In my mind this is the best of both worlds – we get commercial grade software and support, but the solver code and the mathematical models are open to all researchers in the field to see and contribute to. Lattice-Boltzmann field is very active and new research is continually refining and adding to the body of knowledge. Both Palabos and Sailfish incorporate new breakthroughs as they become available. Legacy, closed source code by default does not benefit from this scientific (or crowd-sourced) process.

Regarding the use of constant resolution domain, yes it is both a limitation, but also a benefit as for wake resolution the only mathematically consistent way to do it is to resolve the entire domain to the same resolution. Modified LBM solvers like XFlow and a few others have models for adaptive domain resolution, and one of the custom codes that we used on a GPU did that as well, but it is not optimal and in my mind does not capture the full benefit of LBM when it comes to its ability to accurately resolve wake. A simpler and better way is to increase computational resources and grow the cluster or buy some supercomputing or compute cloud time.

Regarding the boundary layer, completely true, but the boundary layer thickness depends on the Reynolds number so we make sure that we stay within the range where we can resolve it. We are not simulating fast moving vehicles or aircraft. Bicycles are perfectly fine.

Regarding the work that Fairwheelbikes did, we are actually using it as one of the very few reference points for our work. There really isn’t much research in this field. The difference with what we are doing is that we are simulating a bike, not just a crankset so we will hopefully be able to contribute towards answering the question “does frame/wheel stiffness matter, if it does, how much?” We are using Comsol for this.

Victor, CEO (and R&D Director) Velocite Tech.

Hi Victor,

I was perhaps too blunt when I wrote that. Also, I left out an important part. What I meant to write was that the article made you sound like you were “unaware of the state of CFD and simulation in general *in the bike industry.*”

The headline of the BikeRumor article was pretty breathless, and I still maintain that using different (but very interesting) tools does not by itself imply an extraordinary use of computer design. So my point was simply that anyone who would think that the application of CFD to bicycle aerodynamics was extraordinary simply hasn’t followed the industry. But again, this was probably too blunt; I apologize.

Furthermore, I imagine that you would agree that the application of CFD to bicycle wheels is not in itself extraordinary. That was the point I meant to make, and I could have done it better.

I have to say that your use of LES made for some nifty looking plots. My previous wheel simulations (in CFX) have all used K-Epsilon turbulence models because LES was too computationally expensive for the hardware I was running on. I’d be interested to see whether LES models give more realistic results when there’s interaction between the leading-edge rim wake and the trailing edge of the rim.

I would be glad to discuss your FEA work on strain energy whenever you’re ready. I’d be interested to see how you guys handled certain problematic aspects of this sort of modeling…I’d love to know if you guys figured out a better way to handle them.

I’m not inclined to post my contact info here, but if you get in touch with Fairwheel, they should be able to put us in touch with one another. Or you could just get an account at the Fairwheel forums and PM me there.

@ everyone

after researching the CFD servicing industry in particular with Ansys it was very clear to us that inexperienced one dimensional non-specific computer aided programmers were simply supplying hyped-marketing via a white elephant generic data interpretation smoke screen !

hence we were ready to begin working with the highly accredited Ansys & the experienced skilled team that implements their software until we contacted Victor Major the real deal in house bike detective whom we have been effectively collaborating with for the last month !

their is absolutely no question about his authenticity, nor his honestly & pure passion for transparent scientific methodology while being based in Taiwan the heart land of the bicycle industry, where his integrity, wealth of knowledge & demand increase on a daily basis !!!