Null Winds AeroTaper aero bicycle spoke

Earlier this year, Null Winds introduced their upper wheel fairing concept to block wind from the top section of spokes that typically push into the wind, creating multiples of drag compared to other parts of the bike. Aesthetically that device left quite a bit to be desired, but it looks like their new AeroTaper spoke could be just the solution.

The design works like this: A round spoke profile is used closer to the hub where the spoke is moving slower in relation to the wind. Because they’re round, they don’t impose as much penalty in a cross wind and have minimal aerodynamic penalty for the headwind. Closer to the rim, where the spokes are moving relatively faster, it flattens out to create an aero shape where they need to slice through a head wind better. Thus, an optimized cross sectional profile.

It’s not dissimilar to the idea of deep section aero rims, and you’ve got plenty of choices in rim depths to suit conditions. Likewise, Null Winds founder Garth Magee says they’ll have different taper depths to suit varying degrees of cross winds. No, you won’t rebuild your wheel every time. Rather, you’ll have a rim that you really like and have several different wheels built with different AeroTaper spokes and choose according to the day’s conditions.

Null Winds AeroTaper aero bicycle spoke

Some interesting snap-on spoke fairings at their booth caught our eye…

Null Winds AeroTaper aero bicycle spoke

…but the real deal is far more practical. The underlying concept is simple, really. As speed increases, drag increases at a much higher rate. The faster you go, the higher percentage of your energy is spent overcoming drag. Since the top of your wheel is moving at least twice as fast as the rest of your bike, reducing drag there makes a more significant impact on overall speed per watt than other parts of the bike. But, there’s always a balance between straight line aerodynamics and drag (and stability) created by crosswinds. The AeroTaper spokes look like simple, cost effective solution. Check their technical breakdown of drag mechanics here.

Null Winds AeroTaper aero bicycle spoke

These are plastic proofs of concept, actual spokes will be made of steel and likely be thinner in the round section. At the moment, there are no specific production plans, but he is looking for partners and/or licensees for the patent pending design.

NullWinds.com

28 COMMENTS

  1. The fact that they haven’t made a real prototype tells me they don’t have any production methods lined up. I doubt this will hit the market any time soon, at any sort of reasonable price unless they are prepared to invest in building their own production machine for these.

  2. I wonder how much improvement these would yield over a Sapim CXray that is already available, proven to be bomb-proof tough, have a very slender front profile and are very very light.
    Also, the idea of having several wheel sets with varying degrees of formed spokes to suit the anticipated conditions seems a bit much.

  3. a. What purported aero/weight advantage does this have over a current SAPIM, DT Swiss, or Alpina bladed spoke? (that are easily accessible and available to shops today)

    b. “Null Winds founder Garth Magee says they’ll have different taper depths to suit varying degrees of cross winds.” Snake oil at its finest. Only because there is no such thing as a isolated yaw vector range in regards to what the wheel encounters.

    b. Way to much previous art for this to be patented.

  4. Here’s hoping they have better luck with these than the original project which only raised $1,362 of their $120,000 Kickstarter goal.

  5. Spoke sections near the hub also have the least leverage over the steering axis in a crosswind. There’s no aero or steering advantage to having round cross sections there. So basically, use the thinnest bladed spokes that build a strong & stiff enough wheel for you.

    What we have here is a typical case of an engineer coming up with his best solution to no-body’s problem and failing to understand consumer needs before pushing into development. Snap on spoke fairings? He might want to go pitch that over at bentrideronline.com.

  6. @ Dude,
    Agree, except that in regards to the spokes, at least, “consumer need” can be displaced by marketing, translating to “consumer want”. Consumer need is all a consumer needs, consumer wants is all a business needs.

  7. @Dude
    “bentirderonline”

    Funny, because bents solve a lot of problems people have with normal bikes, like butt comfort, and speed.

    Pretty sure the bent was a solution to a lot of people’s problems and would have dominated competition if not banned.

  8. So much negative feedback! It’s almost as if these spokes were a terrible idea looking for an uneducated consumer.

    Oh wait, they are…

  9. Flip has you ever ridden a recumbent? I have ridden a handful of them while working as a bike mechanic and I can assure you that they are stupid fast on flat ground, in the hills that is another thing.

    As for this spoke design CX-ray spokes I think would achive a better result. They are quite “aero” and have a minimal side profile. This guy would probably have better luck working with one on the major spoke manufactures and not trying to get public funding.

  10. seems like in these days of straight pull, no drama builds of fully bladed spokes, or fairly good(like the aforementioned CX Ray) aero spokes that don’t require slotting your hub, a j-bend spoke that requires hub cutting is a fairly hard sell.

  11. “Since the top of your wheel is moving at least twice as fast as the rest of your bike…”

    Actually, it is moving at MOST twice as fast. Don’t know who is more stupid, the people who write this stuff or those who call themselves editors yet let this junk pass.

    Of course, the spokes on the bottom are moving much less fast than the bike. Flattening them offers no benefit but still comes at a penalty in crosswinds. Classic masturbatory engineering…

  12. Well, spokes do have such an small aerodynamik profile*, that even at low speeds you have an 100% turbulent flow around the spokes. With such turbulences the shape of the spokes is not of any concern at all. Spokes which can make a differnce would be much thicker, like the “spokes” in trispoke wheels.

    *ok the “characteristic linear dimension” is so small, that the Reynolds number is extremly low. Wikipedia can help you:
    http://en.wikipedia.org/wiki/Reynolds_number

  13. @Dan: With the right breathing technique, bents are fast in the hills too.

    Anyways, I’m inclined to believe that in the total surface of a bike which is affected by cross wind, the spokes might not play a major role.

  14. CX-Ray will destroy this thing all day and for years to come. There’s no benefit to the round profile at the hub no matter what BS they are trying to sell you. If you think that varying lengths of taper for different conditions is going to help you, I think you need to get off the Internet and go ride your bike,

  15. He reinventt aero spokes?? Please see first generation of Fulcrum Racing zero w red spokes .he had exacly same spokes schape and probably patent too

  16. @ Bikerumor…
    Please explain, because I just don’t get it, how can the top of my wheel move twice faster than my bike?
    Thanks, a bit confused.

  17. Frippolini, do the wheel of your bike spin so part of your wheel passes between the top of the fork and really is going faster? And the bottom part of the wheel stops to touch the ground? Or are the wheel fixed solid and the whole thing just slides ahead?

  18. @Frippolini

    Just in case you are not being sarcastic, think about it a little with reference to the ground. Unless you are skidding the bottom of your wheel is stationary with reference to the ground, the hub is moving at the same velocity as the rest of your bike (and you). The angular velocity developed to enable this to occur means that the top of your wheel has the same differential in speed to the hub as the bottom, but in the opposite direction. So the top of your wheel is going EXACTLY twice as fast as the bike. Never a little less, never a little more.

  19. Sorry @somone, you got a couple of facts backwards:

    1) smaller size = lower Reynolds number = more likely to have laminar flow.
    2) you are mixing up ‘turbulent boundary layer flow” and “separated turbulent flow”. They are entirely different things. Shape does not matter much after flow separation (e.g. in the wake of a bluff body), but shape matters very much in turbulent boundary layers.

    Many years of testing have shown that round spokes should be avoided with medium/deep section wheels. A modest amount of streamlining is enough though: a 2:1 ovalized spoke section provides most of the benefit and probably nothing is gained beyond 3:1 for conventional metal spokes (while crosswind performance starts to degrade). We are talking more or less 10% of the total wheel drag for round spokes and just a couple percent for oval spokes such as cx-rays.

  20. @ Villem
    … what? Sorry, I just don’t understand what you are saying. Yes, usually my wheels spin when I cycle, and they move forward and thus I move forward sitting on my bike. My frame moves forward at the same speed as my body, hence I also believe my wheels move forward at the same exact speed.

    @ Chris
    … thanks, I’m absolutely not sarcastic in any way, I’m really trying to understand this.
    The speed that I move forward is the same speed as my frame; and the wheels are part of my frame; as such the three of us (myself, the frame, and the wheels) should have the same forward going speed (velocity). If not, then I guess something has fallen off or coming apart or has left behind???

    Thanks for taking the time to explain, but I need some more input. 🙁

  21. @ Psi squared: THANK YOU! 🙂
    Now I got it.
    “The point at the bottom of a rolling wheel is instantaneously stationary. The axle is moving forward at speed v so, from the geometry shown, the top of the wheel is moving forwards at 2v. We can also understand this in terms of relative velocities.
    To an observer standing on the road, the axle of the bicycle is travelling at v. The cyclist sees the bottom of the wheel travelling at -v (speed v backwards, see diagram above), so the observer sees this point as having velocity v-v = 0. The cyclist sees the top of the wheel ‘overtaking’ him at speed v, so the observer sees it moving at 2v.”
    Thanks again for finding and posting the link to me, really great, I appreciate it. 🙂
    Wish you a good day!

    @ Villem + Chris: Thanks. Now I understand what you were writing about, now it makes sense to me. 🙂

What do you think?