Tokyowheel Engineering

This post will be a general place to discuss topics relating to Tokyowheel’s engineering process.

Our goal as a company is to provide the worlds fastest bicycle wheels, and we also want to engage and support the Tokyowheel community as much as possible.

I’d like to introduce one of our newest team members Cy Scott (@cy_scott)! Cy is very bright engineer and as part of his role in the company, he is going to do his best to engage the Tokyowheel community through engineering. This means fostering discussions, sharing information, showing our engineering process, explaining our engineering hypothesis, and explaining our experiments and solutions.

What types of engineering discussions or explanations would you like to see?

1 Like

Hey guys! I am super excited and honored to be apart of Tokyowheel! Like James said, I am a mechanical engineer, from a small town in Alabama, USA, and I love all things related to science and technology. Currently, I am involved in many areas of ever-growing Tokyowheel company. I’ll say it again, I am pumped to be apart of Tokyowheel’s bright future.

Anyways, please feel free to ask me anything! What do you guys want to talk about? We can make different threads, and what not, to talk about these things. So what engineering topics are you guys interested in right now?

2 Likes

Hi Cy,
I’ve been a Tokyowheel customer for a few years and bought 3 sets and about to purchase a 4th set for my wife. It’s a surprise gift for her triathlon bike but she’ll never see this post so I’m good there.
My question is about the shape of the rims. To me it seems there is a reason that so many manufacturer’s rims are very near the same shape as long as there isn’t patent infringement or intellectual property issues. Given the data that can be collected in silico how much more can be learned from fluid dynamics modeling? You may not be able to discuss yet but in your opinion what is next for wheels?
As I stated you may not be able to discuss yet so no worries; oh, and welcome.
Jeffrey

Hey Jeffrey,

That’s awesome that you will have 4 sets of our wheels; I hope they are serving you well. Well, you have a great question, and it pertains to almost the core principles behind manufacturing carbon wheels. So, firstly, the reason why we see so much homogenization between rim shapes (and by that I am talking about the rim cross-section, or the profile, if you will) is simply due to the fact that air flows well over tear-drop shaped profiles. This tear-drop profile is know as an airfoil.

Now, fluid dynamics modelling, using a computer (CFD) is a tool that helps us figure out exactly how well that air is actually interacting with our rims and wheels. Most notably, CFD shows us the pressure gradients caused by the air on the wheel, which can basically tell us how much force is being exerted against the wheel while you are riding. You may know this pressure as drag (or pressure drag if we are being exact :smile: ) In most cases, the lower the pressure, the better. And this is very important; for instance, we can test a rim profile and see if that shape is going to perform well in a cross-wind or not, or if the shape is simply creating a ton of drag in any condition. CFD can also show us how fast and what direction the air is moving over the rim while it is being ridden, which can us help determine the amount of turbulence that is being created, or how much friction drag is being created.

So, as you can see, a lot of data can be collected from CFD (and there is more where that came from haha). The manifestations of this data can be seen in many areas of the rim. For instance, when aero wheels first came out for purchase, the designers were only really concerned with the outside of the rim (the leading edge that the tire rests on), but with the advent of CFD, people began to notice that the inside of the rim (so the side that is pointing towards the hub) also interacts with the air and creates drag. And more so when you are turning! As such, engineers are coming up with designs that compromise both edges of the rim for an all-around faster, better handling, and more stable wheel. And this is just one example. CFD allows us to test not only many different shapes, but also different spokes, different surface finishes, etc., without ever making a prototype or spending thousands on a wind tunnel test. And it gives us numbers!

As far as what it will bring in the future, that remains to be seen. Beyond a shadow of a doubt though, wheels will get faster and handle better in wind gusts. Using CFD, we can continually optimize the product. You know, even it is a small advance with each new model, eventually we will have a super duper wheel that performs way better than anything that is out now. In the future, I see wheels with crazy surface finishes to reduce drag, and specialized rim profiles that are intended for different conditions, like rain or strong cross-winds. WHO KNOWS!!

What do you see becoming popular in the future? Do you see any improvements that could made to Tokyowheels right now for better aerodynamics? Or have you noticed any interesting effects from cross-winds while on our wheels?

Thanks for the reply. Well, seems to me that for those who are at the front of the pack or individual TT specialists (or competing in the triathlons that don’t allow drafting) that the next big thing would be to take the entire package into consideration in the modeling. I guess what I’m saying is that the wheel are only part of the equation. The drag created by the bike, bars, helmet, rider, skinsuit material, etc all play into the overall drag. So while a wheel may demonstrate certain drag coefficients are those really considered real world numbers since fork, frame, water bottles, water bottle cages, etc. really contribute to the air flow across the entire bike. The most un-aerodynamic variable is the engine powering the bike but to your knowledge do most engineers consider the entire package in their modeling or is it only the leading and trailing edge of the wheel?
Popular in the future? Well, I feel that a wheel that can perform in multiple conditions that are experienced in a 1 day race is the key. I think Tokyowheel already offers this though in the combinations that can be purchased. the 38/50 50/88, etc. is what I’m talking about. I’ll give your question some thought, shake the trees around my area a little and let you know what drops out and what I hear from others.

Our goal is to prove scientifically the superiority of our wheels. To do that we need to establish our Key Performance Indicators. These are the numbers that matter, making these numbers better is our goal.

KPI’s

  • Aerodynamic Drag
  • Rolling Resistance & Internal Mechanical Friction
  • Crosswind Stability
  • Rotational Inertia
  • Mass
  • Stiffness
  • Ride Analytics Sensing and Data Driven Ride Optimization
  • Price & Cost of Goods & Value
  • Durability
  • Emotional Desirability

Should we add any others? Do some of these not really translate into real world success?

But more importantly, what are the Units of each KPI? Mass is easy (g). but what about durability? What about crosswind stability??Grams of drag at 90 degree yaw angle?

Emotional Desirability could be a statistically significant A/B test between two images of products.

I don’t want to hi-jack Cy leadership of this discussion, but we have a lot of info internally that only I should decide when and How to make public, so I’m doing that via these posts.

We have also decided a few hypothesis to test and base our new product line on.

  • 4 specific wheel options are preferable to 14. Lightest, all-around,
    most aero, race-day-only-lightest

  • Independently engineered front and rear rim shapes will outperform symmetrical.

  • Real world performance can be modeled better with a combination of aero, stiffness, rolling resistance, moment of inertia and braking performance , than weight and aero alone

  • Radically different rim shapes (T, foil sections, skeletonize ) will decrease forward drag and reduce perpendicular drag, more than conventional shapes.

  • Results from rim only CFD will be drastically different than in frame with rider models.

  • A distribute worldwide company structure will outperform one that is centralized.

  • Reducing crosswind instability (stability ratio = perpendicular drag/parallel drag) will allow a more aerodynamic wheel to be used in more situations, therefore increasing aerodynamic advantage.

Can you think of any other fundamental hypothesis that could potentially provide an order of magnitude improvement in a Key Area of Performance?

Hey Jeffrey,

So yeah, your points are valid. The first thing that comes to my mind is project scope. You are right that the wheels are only part of the equation when considering overall efficiency when riding. But yes, a model that excludes these other aspects of the package like the fork, frame, water bottle, and handlebars would still generate real numbers; the numbers are still valid for the control volume around the wheel. Now, a model that does include the other features would generate simply generate numbers for that larger, much more complex control volume. I think that modelling these parts could be beneficial though. For instance, we could look at how our wheel is “shedding” the air, after it has passed along the wheel. We might be able to condition this air (make it more laminar and slow it down), which would subsequently create less drag on the rest of the bike and rider.

But, I believe it depends on the scope of the project. We are currently focused on making FAST wheels. Shedding may help the air detach from our wheels more smoothly, and in turn decrease drag, but I think the condition of the air leaving the wheels is almost void when considering the rest of the bike once you consider the magnitude of new air (control air or flow) that is entering the large control volume that encompasses the rider. Does that make sense? I think that engineers are considering the whole enchilada when they are designing frames. Or if they are in fact designing an entire cycling system. Fluid dynamics is very computationally demanding, so these studies would have to be piece-meal and most likely are being conducted in a wind tunnel.

I agree. It is important to have that variety that we offer in the wheels. The front steering wheel will always feel the cross winds most, so keeping its profile slim is important to the handling of the entire bike.Yeah man! Let me know what you come up with. Actually riding a bike and getting real results and findings is the best sort of data.

I was reading about turbulence created at the tire / rim junction and wondered if there’s a better way than what Mavic tried to do with their CX01 technology? I haven’t looked into all of the patents likely surrounding their intellectual property but was wondering if there’s an easy way to fuse a silicone or some other highly flexible (and light weight) material to the rim that would serve the same purpose as Mavic’s aero-blades. The key would be that it’d have to be flexible enough to allow mounting of the tire without significant damage to this aero blade is the part I’m struggling with. How to have something that is almost a permanent part of the rim that’d allow removal of tire? Wouldn’t necessarily have to be easy to remove and remount tire but still allow that without damaging this aero surface.

1 Like

This is a very interesting idea! Let me do some thinking and get back to you!

What about carbon/Kevlar spokes? Would building a wheel with a spoke like the Topolino carbon/Kevlar spoke provide significant benefits in a wheel? Are carbon spokes really that much lighter than say the Sapim CX-Ray spokes? Does anyone know about durability of carbon spokes? Just curious.

Hey man, sorry I haven’t been around!
So, with regards to the CX01 technology: it is a very promising idea, if, like you say, the technology can be absorbed into the wheel itself. Apparently, the UCI aren’t too found of them, because they are designed solely to reduce aerodynamic drag. This is really a bummer to me. But I’ve read that these sorts of regulations are kind apprehensions. My friend told me that most of the time, once a product becomes popular enough, the UCI will eventually okay it.

http://cycletechreview.com/2012/news/mavics-wheels-disallowed/

Back to Tokyowheel, what would you think about a simple carbon projection that serves the same purpose? It wouldn’t be as effective and would create a small gap that would still produce turbulence, but it would definitely address the same issue. What do you think? I imagine that the carbon lip may be damaged easily, though, if the tire went flat…

mmm I know that carbon fiber does not handle compressive forces well at all. But they may very well be lighter than an alloy spoke, especially if less spokes need to be used. But not by much. I don’t have numbers but I will try to find some. They are also expensive, in form and in application on a wheel (like all new cycling gear :smile: ). For instance, an LBS probably couldn’t true them or otherwise tweak them… I imagine that the carbon spokes would have to be somewhat thicker too, or those Topolino spokes are, which also increases the drag force.

The durability cannot be great though, for sure. Not unless there is some other material interstitial with the carbon fibers and resin that allows some flex. Then there’s this video: https://www.youtube.com/watch?v=L3q05uTa8fc

What do you think of the large carbon “spokes”? Like the tri and penta - shaped wheels? These are interesting too: https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.bloggen.be%2Famiciditilrodabici%2Farchief.php%3Fstartdatum%3D1346623200%26stopdatum%3D1347228000&ei=d9RtVYXsFczzsAXL6oLQBg&bvm=bv.94455598,d.b2w&psig=AFQjCNEFlayb8rpBNxBFqAF64oKYFtaWuA&ust=1433347515921809

Wow, he took a hammer to the spokes in that youtube link you provided… That’s is impressive durability but I bet it’s tough to find any details concerning the exact composition of the spoke material. You bring up some good points about # of spokes, cost, thickness affecting drag. I’m just thinking out loud and like to throw everything at the wall an see what sticks or just get others thinking as well.
Concerning the large carbon spokes; I need to find some specifications concerning weight, aero performance, etc but one has to believe that is Team SKY is using the large carbon spoke front wheels then they have some data they feel is compelling. Seems like a good set of data to generate by CFD.

So I’ll just leave this here.


We’ve been working pretty hard lately and I like to show off haha. Pictured is a 3D rendering of the EPIC 50 with a DT Swiss 240 front hub and standard spokes. We are currently full-steam ahead on the next generation wheels, so keep your ears to the streets!

1 Like

So, how soon until I can buy a set? Thinking I need to pass my wheels along to a younger rider who might not have the money for carbon wheels and get me a new set.

Yo! We are actually working on a release date now, so I will let you know as soon as that is concrete. We were originally looking at a Fall release.

1 Like

Thanks for the update. Looking forward to it.

1 Like

Hmm. I understand the benefits of a toroidal shaped rim and the disadvantage/advantages of a v-rim. Now I am wondering if the toroidal in the back is over-rated. Rather, you should have a toroidal in the front but stick with v-rim on the back? Has anyone ever tested this combination?

Many of us could test what you’ve asked but everything would be subjective and not measured data. I doubt wheel manufacturers has looked at too many variables because so many bikes will have such different affects that even using _in silico_CFD would be very time consuming.