$1,013
pledged of $30,450pledged of $30,450 goal
33
backers
Funding Unsuccessful
The project's funding goal was not reached on Mon, June 22 2015 1:10 PM UTC +00:00

Spoke Fins Reduce Bicycle Wheel Drag, Even in Crosswinds

Spoke Fins cut spoke drag more than 50% in both headwinds and crosswinds.

Spoke Fins Reduce Bicycle Wheel Drag, Even in Crosswinds

Spoke Fins cut spoke drag more than 50% in both headwinds and crosswinds.

$1,013
pledged of $30,450pledged of $30,450 goal
33
backers
Funding Unsuccessful
The project's funding goal was not reached on Mon, June 22 2015 1:10 PM UTC +00:00

About

Spoke Fins Reduce Bicycle Wheel Drag, Even in Crosswinds

Spoke Fins cut bicycle spoke drag by more than 50%, even in crosswinds.  Streamlined Spoke Fins swivel like a wind vane in response to variable crosswinds, which constantly change orientation as the wheel rotates.  Your help is needed to purchase a 12-cavity injection mold required to economically produce our innovative bicycle Spoke Fins.

Spoke Fins: Convert round spokes into bladed spokes

  • Cut Spoke Drag more than 50%
  • Effective in both Headwinds and Crosswinds
  • Reduce Pedaling Effort in All Winds
  • Enhance Stability in Crosswinds
  • Colorful Fashion Accessory for the Kids' Bicycle

Optimally streamlined Spoke Fins reduce the spoke drag coefficient by more than 50% in the critical, faster-moving, drag-inducing region located nearest the wheel rim.  Since round spokes have relatively high drag coefficients — thereby becoming the major contributor to overall wheel drag — reducing critical spoke drag also reduces total wheel drag. Spoke Fins are also tapered lengthwise to reduce drag principally on the critical uppermost spokes, where wheel drag most retards vehicle propulsion.

3D-printed Spoke Fins: Road tests confirm substantial drag reduction
3D-printed Spoke Fins: Road tests confirm substantial drag reduction

As the wheel rotates, Spoke Fins automatically adjust their streamlined alignment for the changing orientation of the effective wind vector impinging on the spoke. Spoke Fins swivel to reduce pedaling effort under any wind condition, becoming especially effective on typical recreational bicycles with higher spoke-counts.

One can readily feel the difference. Test our Spoke Fins for yourself, or give them to a friend or family member. Help us produce this new invention by contributing to our campaign and becoming one of the first to enjoy our new Spoke Fins on your bicycle.

About the Product

Bicycle racers know that bladed aero-spokes quickly become ineffective in crosswinds. Spoke drag quickly increases when impinging winds are directed crosswise across the flat blades. In a direct headwind, the common round spoke develops more wind drag than does a bladed spoke. However, against a crosswind the bladed spoke can actually produce much more drag than a round spoke.

Spoke Fins are narrowly tapered, limited to about the width of standard 14 gauge spokes.
Spoke Fins are narrowly tapered, limited to about the width of standard 14 gauge spokes.

When competing outdoors, bicycle racers often choose round spokes over bladed aero-spokes, since a cyclist on average typically faces a significant crosswind during as much as 85% of the ride, especially when cycling in windy conditions. Thus, a cyclist normally faces a direct headwind relatively infrequently. Instead, there often exists some crosswind component of the wind vector impinging on the wheel, often negating the low drag benefit of bladed spoke.

Spoke Fins increase aerodynamic transparency, reducing drag and increasing stability.
Spoke Fins increase aerodynamic transparency, reducing drag and increasing stability.

Attaching a streamlined tailfin to a round spoke reduces the spoke drag coefficient from a relatively high 0.4 to a comparatively much lower 0.13 (from Fluid Dynamic Drag, Hoerner, 1965, page 13-19, figure 50), a three-fold reduction in drag. Since the fin is attached in the critical drag-inducing region near the wheel rim, Spoke Fins can easily decrease overall spoke drag by more than 50%.

And since Spoke Fins swivel about the spoke in response to crosswinds, they are effective in all wind conditions — rather than when only facing a direct headwind.

Tailfin drag coefficients compared to that of a Round Spoke (= 0.4)
Tailfin drag coefficients compared to that of a Round Spoke (= 0.4)
Clipping this simple device onto each spoke provides a surprising reduction in upper wheel drag. And upper wheel drag is the most critical drag retarding vehicle propulsion, especially in headwinds.
3D-printed Spoke Fin
3D-printed Spoke Fin

As demonstrated by of our upper wheel fairings, reducing spoke drag in the critical upper wheel region can dramatically reduce overall vehicle drag, especially at faster speeds and when facing headwinds. Our fairings have been extensively road tested and shown to produce typical speed gains from 10 to 20% when facing moderate to strong headwinds.

Upper Wheel Fairings: Road testing demonstrates dramatic speed gains achieved facing headwinds through reducing critical upper wheel spoke drag.
Upper Wheel Fairings: Road testing demonstrates dramatic speed gains achieved facing headwinds through reducing critical upper wheel spoke drag.

Spoke Fins prototypes were recently first tested in late March, by Manuel Quiros — a veteran racer who has set several UCI velodrome records, as well as a three-time participant of the prestigious RUSA-Paris Brest Paris endurance cycling event. Quiros has confirmed substantial drag reduction at speeds above 15 mph, where speed gains quickly increase as drag becomes the dominate force opposing vehicle propulsion. Quiros reports that the gains also become readily apparent whenever facing an external headwind.  He also reports remarkable stability in crosswinds. 

After his first 100 miles of testing while commuting around Los Angeles, Quiros states that this bike is both faster and simply feels different. And Quiros also reports that with Spoke Fins installed on his own bike, his bike has become not only faster, but is actually more enjoyable to ride .

Optimized for injection molding with detachable retaining clamp, which keeps fin from sliding down the spoke.
Optimized for injection molding with detachable retaining clamp, which keeps fin from sliding down the spoke.

Recall just how quickly a moderate headwind slows a bicycle? The exposed upper wheel surfaces cause much of this slowing, since drag on these fast-moving surfaces is also magnified by leveraging (by nearly a factor of two) against propulsive counter-forces applied at the axle. Leveraging greatly magnifies the propulsive power simply needed to overcome upper wheel drag.

And as the headwind increases, overall vehicle drag shifts from being mostly on the rider, to becoming more and more concentrated on the exposed upper wheel. This effect is largely responsible for the dramatic slowing caused by a headwind. Consequently, the critical upper wheel surfaces should be the first to be optimized for minimizing drag.

Each fin also includes an optional 14 gauge retaining clamp, which snaps onto the spoke, preventing the fin from sliding down out of position from near the upper wheel rim.

Our Campaign Need

Spoke Fins reduce drag on bicycles in both headwinds and crosswinds without the need for costly investment in expensive carbon wheel sets. Since Spoke Fins are made of tough nylon plastic, they can be simply produced using injection molding. However, in order to reduce the retail cost of the final product, a large multi-cavity steel mold must first be purchased.

Since a typical bicycle often requires as many as 64 spoke fins, it becomes essential to reduce the unit cost in order to keep the retail cost of an entire set reasonable. Utilizing a 12-cavity mold should enable us to keep the retail price low once in mass production. And exceeding our goal substantially could fund an even larger 24-cavity mold, further reducing the final retail price.

Our campaign goal has been set to the minimum amount needed to purchase the 12-cavity polished steel injection mold. Our goal is simply the cost of the mold, plus Kickstarter fees (and including the high proportion of shipping expenses, to account for the large number of rewards needed to reach goal). If our goal is reached in this campaign, we will purchase the mold, spend an additional $10,000 to fund the first injection run, and ship the rewards.

Spoke Fins reduce critical drag on uppermost wheel surfaces.
Spoke Fins reduce critical drag on uppermost wheel surfaces.

Since the high cost of international shipping compared to the low cost of our rewards would greatly raise the amount needed for our campaign goal, we have limited our initial campaign-goal rewards for delivery to the U.S. only. Once our goal is reached, we can then offer stretch goals to include international shipping.

Your help is needed to fund the expensive, but cost-effective, injection mold for future production. Later, if Spoke Fins become popular, we hope to eventually turn profitable and recover our own investment in funding the rewards of this campaign.

About the Technology

As demonstrated by our upper wheel fairings — another recent invention of a pending patent application — reducing drag on a bicycles’ faster-moving upper wheel surfaces yields dramatic increases in speed when penetrating headwinds. The most critical vehicle-drag-inducing wheel surfaces are always located above the axle near the top of the wheel, where wind speeds far exceed the vehicle speed. Below the axle, wind speeds are greatly reduced and impart little drag on the vehicle. The swiveling tailfin streamlines the round spoke — to both headwinds and crosswinds — while positioned in this critical upper wheel region.

Since headwinds exacerbate drag on these upper wheel surfaces — which move forwardly against the oncoming headwind much faster than the actual vehicle speed — reducing drag on these critical surfaces is essential to reducing drag on the bicycle. Spoke fins reduce drag on these critical upper wheel surfaces, even when facing significant crosswinds.

Consider the wind profile across a moving wheel: under null headwind conditions, the wind is null at the bottom where the wheel is in firm contact with the stationary ground; and near the top the wind rises to twice the vehicle speed. By reducing drag on the upper surfaces, the effective drag on the wheel is greatly reduced.

The wind profile diagram also demonstrates that while the headwind component varies in elevation on the wheel — from null speed at the stationary ground to twice the vehicle speed at the top —the crosswind component of the wind must be constant with elevation across the wheel.

Minimizing Drag on Upper Wheel (where Fins are most effective) Reduces Overall Vehicle Drag
Minimizing Drag on Upper Wheel (where Fins are most effective) Reduces Overall Vehicle Drag

Spoke Fins swivel on the spoke in response to crosswinds. As the fin rotates through the critical drag-inducing upper wheel region, the effective headwind component dominates over the crosswind component. The tail fin responds by becoming more aligned with the headwind near the top of the wheel.

As the fin rotates into lower positions, the crosswind component eventually dominates over the headwind component, and the fin swivels to be more aligned with the crosswind. In this way, the fin reduces drag on the spoke throughout the rotation of the wheel.

Spoke Fins swivel, responding to the changing wind vector at various locations around the wheel.
Spoke Fins swivel, responding to the changing wind vector at various locations around the wheel.

While expensive bladed spokes are often used to reduce wheel drag, they are most effective only under null wind conditions. Crosswinds impinging across the bladed portion cause flow separation turbulence, dramatically increasing drag and negating any benefit of the bladed design.  In a severe crosswind, the drag coefficient of a flat bladed spoke can quickly increase to much more than that of a round spoke.

Spoke Fins increase the aerodynamic transparency of the wheel. As an example, consider a cyclist traveling forward at 15 mph in a 10 mph crosswind, where the effective wind vector impinging the topmost spoke is off-axis from the bicycle center-line by at least 20 degrees.  This angle only increases as the spoke rotates to a lower position, and the dominance of the crosswind component increases still further.

A crosswind angle of more than 20 degrees will certainly increase drag on a bladed spoke, quickly becoming even more drag than that on a round spoke.   Spoke Fins swivel to adjust automatically for the sidewise wind, reducing drag on the round spoke even when facing stronger crosswinds. In a crosswind, the bike becomes not only faster but also more stable.

More information regarding the drag mechanics of a wheel is summarized in our Drag Reduction Flyer, which recently has been well-received both by the professional auto racing community in Indianapolis (Dec., 2014 - PRI Trade show) and by the industrial trucking community in Louisville (March, 2015 - Mid-West Truck show).

About the Invention

Spoke Fins are but one embodiment of a comprehensive pending patent application (now with allowable claims). Other embodiments of this invention include upper wheel fairings, an aerodynamic bladed spoke which is also effective in crosswinds, an aerodynamic automotive wheel with oval spokes, and an off-road tire having aerodynamic tire tread pattern.

As described in patent application US2013/070498, upper wheel drag is a far greater source of vehicle drag induced by the wheel than has been previously recognized. Lower wheel surfaces induce very little vehicle drag and can be largely ignored. In fact, the net wheel drag is actually centered very near the top of the wheel. And upper wheel drag is actually magnified through leveraging (pivoting about the point of ground contact) against propulsive counter-forces applied at the axle. Thus, it becomes essential to reduce upper wheel drag in order to minimize propulsive counter-forces.

About the Campaign

In order to expedite reward shipment to our contributors, once our goal is reached during the active campaign we will proceed to borrow funds for the deposit and place the order for the polished steel mold. Promised delivery of the mold is only about six weeks, being fabricated locally in Southern California.

Upon delivery of the mold together with approved sample parts, we will order the production run and begin shipping rewards. We should be able deliver most of our initial campaign goal rewards within two months thereafter. Our aim is to deliver all campaign goal rewards by end of summer, if not earlier. Please help accelerate reward delivery by contributing early in the campaign.

Rewards to be injection molded from strong, red or black nylon plastic.
Rewards to be injection molded from strong, red or black nylon plastic.

Our production prototype has been fabricated in strong nylon plastic and road tested on bicycles in strong crosswinds. The fin design has already been optimized for production molding. Our final step is ordering the mold and producing the parts in quantity.  We are now ready to go. We just need your support.

We still need to design the packaging and product label. However, we will complete this effort during the campaign cycle, and before delivery of the mold.

No doubt there remains considerable work ahead. Still, the innate simplicity of producing a single plastic part minimizes the complexity of our reward delivery process. We simply need to count parts, place them in a bag with a label, and ship the rewards to our contributors.

Bike Requirements

Spoke Fins are less than six and one-half inches long and weigh about 1.5 grams each. A typical full set of 64 fins weighs about 3.5 ounces.  The fins are optimized to fit most bicycle wheels employing standard 14 gauge round spokes (2.0 mm or 0.079 inches in diameter) with standard diameter spoke nipples. (A few rims with very short spokes having acute angles at the nipple connection may inhibit free rotation of the fin at the nipple.) 

Spoke Fins are very light and less than 6-1/2 inches long.
Spoke Fins are very light and less than 6-1/2 inches long.

The fins may also attach securely to thinner 15 gauge round spokes (1.8 mm or 0.071 inches in diameter), although the larger 14 gauge retaining clamp cannot then be used.

Small diameter wheels on bicycles for younger kids may not have sufficient spoke length to permit installation. Please measure the free length of the spoke on your bicycle to ensure proper fit.

Spoke Fins are very lightweight and easily swiveled by the wind when installed on clean steel spokes. Painted spokes may induce a bit more friction against the fin than does a clean steel spoke. We recommend using unpainted stainless steel spokes for best performance.

Final Thoughts:

We are especially grateful for the congratulations received from many cyclists who viewed Spoke Fins on display for the first time recently at the San Diego Gran Fondo. Many triathletes were especially interested in this advance.

One triathlete called Spoke Fins 'a disk wheel without the disk', which is only partially true. While the smooth surface of the disk has a low drag coefficient, drag is also a function of total exposed surface area. Since a deeper rims have greatly expanded surface areas located at the top in the critical drag-inducing region of the wheel, disk wheels can actually produce more vehicle drag while also being more susceptible to crosswinds.

As a result, Spoke Fins can obviate the need for the use of heavier, deeper rims to minimize wheel drag. And at least one pro triathlete intends to use Spoke Fins unseen in an upcoming Ironman race in Colorado later this season.

Our rewards have been priced low with the hope that many will understand the pending invention and want to contribute to launching this product. The reward delivery schedule assumes that our goal is reached within the first 30 days of the campaign. In order to deliver the rewards as soon as possible, we are committed to ordering the mold as soon as our goal is reached. Please contribute early to the campaign in order to help us reach our goal quickly, which will expedite an early reward delivery. Thank you for your support.

Spoke Fins are also tapered to include streamlining of standard spoke nipples, which are significant drag-inducers.
Spoke Fins are also tapered to include streamlining of standard spoke nipples, which are significant drag-inducers.

 Mentioned on:

Risks and challenges

With any endeavor there will exist some level of risk. We see the major risk in the production mold design. Should early sample parts not fit properly in the clips surrounding the 14 gauge spokes, the mold may require some rework to fix the problem. This will result in additional expense. However, we expect that the additional expense to be substantially less than the cost of an entire mold.

To minimize this risk, we have optimized the design and road tested 3D prints of the final model. Even with this, we have included a margin of safety in the design specifications to account for varying spoke diameters and slight nylon swelling. Thus, we remain confident that the mold will be correct on the first effort.

Still, it is possible that some unforeseen problems will occur. We will inform contributors of any delays or unexpected issues that might affect delivery schedules. Our contributors are our friends. They will be the first to experience our product, and will help us spread the word about this exciting innovation. Until every reward is delivered to our friends, this will always be our focus. Thank you for your support

Learn about accountability on Kickstarter
Questions about this project? Check out the FAQ

Support

  1. Select this reward

    Pledge $5 or more About $5

    For those few simply wishing to support this product concept without the need for a reward. Thank you.

    Less
    Estimated delivery
    0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  2. Select this reward

    Pledge $20 or more About $20

    Nearly Freebies: One standard-count bike set of 64 Spoke Fins in RED.
    (Early-Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 18 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  3. Select this reward

    Pledge $25 or more About $25

    Earliest Adopters: One standard-count bike set of 64 Spoke Fins in RED.
    (Early-Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  4. Select this reward

    Pledge $25 or more About $25

    Early Adopters: One standard-count bike set of 64 Spoke Fins in RED.
    (Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  5. Select this reward

    Pledge $30 or more About $30

    Early Adopters: One standard-count bike set of 64 Spoke Fins in BLACK.
    (Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 10 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  6. Select this reward

    Pledge $30 or more About $30

    Still Early Adopters: One standard-count bike set of 64 Spoke Fins in RED.
    (Late Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  7. Select this reward

    Pledge $30 or more About $30

    Still Early Adopters: One standard-count bike set of 64 Spoke Fins in BLACK.
    (Late Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  8. Select this reward

    Pledge $35 or more About $35

    Still Early Adopters: One standard-count bike set of 64 Spoke Fins in RED.
    (Late Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  9. Select this reward

    Pledge $35 or more About $35

    Still Early Adopters: One standard-count bike set of 64 Spoke Fins in BLACK.
    (Late Summer delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  10. Select this reward

    Pledge $35 or more About $35

    One standard-count bike set of 64 Spoke Fins in RED.
    (Fall delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  11. Select this reward

    Pledge $35 or more About $35

    One standard-count bike set of 64 Spoke Fins in BLACK.
    (Fall delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  12. Select this reward

    Pledge $40 or more About $40

    One standard-count bike set of 64 Spoke Fins in RED.
    (Fall delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 0 backers
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  13. Select this reward

    Pledge $40 or more About $40

    One standard-count bike set of 64 Spoke Fins in BLACK.
    (Fall delivery)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 1 backer
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  14. Select this reward

    Pledge $45 or more About $45

    One higher-count bike set of 72 Spoke Fins in RED. (For wheels having an even greater number of spokes – such as often found on many tandem and electric bikes.
    (Fall delivery.)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 1 backer
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.
  15. Select this reward

    Pledge $45 or more About $45

    One higher-count bike set of 72 Spoke Fins in BLACK. (For wheels having an even greater number of spokes – such as often found on many tandem and electric bikes.
    (Fall delivery.)

    Less
    Estimated delivery
    Ships to Only United States
    Limited 1 backer
    $

    By pledging you agree to Kickstarter's Terms of Use, Privacy Policy, and Cookie Policy.

    Kickstarter is not a store.

    It's a way to bring creative projects to life.

    Learn more about accountability.

Funding period

- (60 days)