Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 42
  1. #1
    Theodore Roosevelt's idol TheKillerPenguin's Avatar
    Join Date
    Sep 2004
    Location
    Vagabond
    My Bikes
    Affirmative
    Posts
    9,006
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Aren't flat bladed spokes less aero than round spokes?

    Am I insane, or are bladed spokes more for show than anything? A round spoke directs air around it because of its shape. A bladed spoke, however, in addition to having flat sides also has a flat front end, which should cut through the air less efficiently, creating more drag and more air turbulence. Am I right, or does the bladed nature of the spoke counteract the turbulence created by the front end smashing through the wind? It seems to me that rather than aiding a rider, a bladed spoke does nothing more than create drag and catch crosswinds. If a wheel were to be really aero, one would want teardrop shaped spokes, followed by round spokes, and then finally the bladed spokes one finds on Ksyriums and Race Lites.

    Am I right, or am I just another carpet smoker?
    Masochism is a training adaptation.

  2. #2
    Senior Member
    Join Date
    Apr 2004
    Posts
    898
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Well from my experience I have ridden with a friend who have bladed spokes on a deep dish wheel (Mavic's). I on the other hand have a radial laced Velocity aerohead rim (32 spokes 14/17/14 DT Swiss). Both our bikes weigh the same and I am about 10 lbs. heavier than him. On a downhil ride, the Crest HWY we both take off rolling evenly and coast. As we both do the tuck thing we are rolling down the hill quite evenly at about 35 mph for quite a long while. So my feeling is that there is no difference between the two spoles set up.

  3. #3
    Senior Member shimanopower's Avatar
    Join Date
    Jul 2005
    Location
    chicago
    My Bikes
    lemond zurch, felt f55 '05
    Posts
    822
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Well according to God (sheldon brown)...

    "Æro (elliptical) spokes are a variety of double-butted spoke in which the thin part is swaged into an elliptical cross section, which makes them a bit more ærodynamic than round-section spokes. The most widely available spoke of this type is the Wheelsmith Æro. These are 1.8mm (15 gauge) at the ends, and the middles are equivalent to 16 gauge, but in the form of a 2.0 x 1.6mm ellipse. The Wheelsmith &Aelig;ro is my favorite spoke for high-performance applications, not just because of whatever ærodynamic advantage it may offer, but because the flat center section provides an excellent visual indicator to help the wheelbuilder eliminate any residual twist in the spoke. This helps build a wheel that will stay true.

    Æro (bladed) spokes have a more pronounced æro shape, flat, rather than elliptical. Although they are the most ærodynamic of spokes, they won't normally fit through the holes in a standard hub because they are too wide."

    http://sheldonbrown.com/wheelbuild.html

  4. #4
    Member
    Join Date
    May 2005
    Location
    Sacramento, CA
    Posts
    45
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by shimanopower
    Well according to God (sheldon brown)...

    "Æro (elliptical) spokes are a variety of double-butted spoke in which the thin part is swaged into an elliptical cross section, which makes them a bit more ærodynamic than round-section spokes. The most widely available spoke of this type is the Wheelsmith Æro. These are 1.8mm (15 gauge) at the ends, and the middles are equivalent to 16 gauge, but in the form of a 2.0 x 1.6mm ellipse. The Wheelsmith &Aelig;ro is my favorite spoke for high-performance applications, not just because of whatever ærodynamic advantage it may offer, but because the flat center section provides an excellent visual indicator to help the wheelbuilder eliminate any residual twist in the spoke. This helps build a wheel that will stay true.

    Æro (bladed) spokes have a more pronounced æro shape, flat, rather than elliptical. Although they are the most ærodynamic of spokes, they won't normally fit through the holes in a standard hub because they are too wide."

    http://sheldonbrown.com/wheelbuild.html
    And on the 7th day, he rested...

  5. #5
    You know you want to. Eatadonut's Avatar
    Join Date
    Jun 2005
    Location
    Norman, Oklahoma
    My Bikes
    Pinarello Prince, 1980's 531 steel fixie commuter, FrankenMTB
    Posts
    1,896
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I thought bladed spokes were for eliminating the threat of squirrels jumping into your front wheel and getting stuck.
    Weather today: Hot. Humid. Potholes.

  6. #6
    "Great One" 53-11_alltheway's Avatar
    Join Date
    Feb 2005
    Location
    Might as well be underwater because I make less drag than a torpedoE (no aero bars here though)
    Posts
    4,463
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by PenguinDeD
    Am I insane, or are bladed spokes more for show than anything? A round spoke directs air around it because of its shape. A bladed spoke, however, in addition to having flat sides also has a flat front end, which should cut through the air less efficiently, creating more drag and more air turbulence. Am I right, or does the bladed nature of the spoke counteract the turbulence created by the front end smashing through the wind? It seems to me that rather than aiding a rider, a bladed spoke does nothing more than create drag and catch crosswinds. If a wheel were to be really aero, one would want teardrop shaped spokes, followed by round spokes, and then finally the bladed spokes one finds on Ksyriums and Race Lites.

    Am I right, or am I just another carpet smoker?
    The most overall aerodynamic spokes are oval (like the sapim cx-ray, etc).

    The big flat blades are aero only in one direction (particullary the large aluminum Kysrium SSC SL blades), but at any angle greater than zero they can actually increase drag.
    "The Iron never lies to you. The Iron will always kick you the real deal. It never freaks out on me, never runs. Friends may come and go, but 200 pounds is always 200 pounds." -Henry Rollins

  7. #7
    MaNiC! NZLcyclist's Avatar
    Join Date
    Feb 2003
    Location
    Hamilton, New Zealand
    My Bikes
    2004 Cervelo Soloist 105, 2005 Apollo Apex, 2006 SCOTT Speedster S30
    Posts
    1,601
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    From www.velomax.com

    Q. Why doesn't Velomax use bladed spokes?

    We carefully considered using bladed spokes, but decided against it. In wind tunnel tests, bladed (and ovalized - hereafter "profiled") spokes have proven to be very effective. The caveat here is that they show their greatest advantages vis-a-vis round spokes when the airflow is from straight ahead. As soon as you introduce even a small component of side wind (yaw angle as low as 2 degrees), the larger surface area of profiled spokes acts either as a lifting surface, or develops airflow separation (with related generation of vortices), or both. The bottom line - creation of lift cannot be accomplished without corresponding increases in drag.

    Simply stated, a profiled spoke in a static or head-on air stream can be very effective. However, a profiled spoke in a side wind is a propeller.

    A round spoke always presents the same small profile to the air stream, whether the angle of attack is head on or from the side. When you consider the wind direction, speed of the bicycle, and rotational speed of the wheel, it becomes apparent that there is an alphabet soup of aerodynamic considerations happening throughout the course of the ride. For this reason, we believe that swaged (butted) spokes present the best real-world aerodynamic profile.
    Scott Speedster S30
    Shimano 105 Shifters and Derailleurs
    FSA Energy 50/34 Compact Cranks
    Spinergy Stealth PBO Race wheels
    Sram OG 1070 casette

  8. #8
    Senior Member
    Join Date
    Sep 2003
    Location
    fogtown...san francisco
    My Bikes
    Ron Cooper, Time VXSR, rock lobster, rock lobster, serotta, ritchey, kestrel, paramount
    Posts
    2,276
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I pretty much agree with what has been said here, oval is the most aero. I had a front wheel built with oval spokes and if you spin it and put your hand near it you can feel the air being displaced. I compared it with round spokes and oval is the way to go. I also have a front wheel with flat spokes...its still more aero than round spokes. you have to remember flat spokes are litterally created by taking a round spoke and flattenning it. This creates a narrower front and this wheel has 24 spokes. I have not noticed any control issues, but I don't use it in windy conditions.
    fogriderlooking for sun

  9. #9
    Senior Member roadwarrior's Avatar
    Join Date
    Oct 2002
    Location
    Galt Gulch
    My Bikes
    Cannondale Super Six High Mod, Evo, Sram Red, CAAD9 Rival
    Posts
    9,973
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    I guess if you are a really good rider, it does not truly matter...

    I ride SL's and have for over two years...stiff, bulletproof, and no problems in side winds.
    "Nothing is so typical of middling minds than to harp on the intellectual deficiencies of the slightly less smart, but considerably more successful."
    Bret Stephens, WSJ

  10. #10
    My toilet-Floyd's future
    Join Date
    Sep 2005
    Posts
    1,776
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    and no problems in side winds.
    That should be 'no perceivable problems in side winds'. For all you know, you could be loosing 2% of your power.

    I can’t perceive a 100g decrease in weight, but all other things being equal, I would take the lighter bike into a race.

    Pros and pros mechanics don't always know best. Many are still operating under cycling's 'old wives tails'.

  11. #11
    Know Your Onion! badkarma's Avatar
    Join Date
    Aug 2005
    Location
    Boston, MA
    My Bikes
    Kestrel Talon, Motobecane Le Champion SL
    Posts
    2,011
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Why do you think airfoils (i.e. airplane wings) have the shape they do? They create lift (irrelevelant in the case of bicycles), but they also have a low coefficient of drag due to their profile. Round spokes leave a large wake (i.e. more pressure drag) than bladed spokes. Let it be said though, the decrease in pressure drag due to bladed spokes is rather minimal, yet it is finite.
    We Are Penn State

    2006 Kestrel Talon

  12. #12
    "Great One" 53-11_alltheway's Avatar
    Join Date
    Feb 2005
    Location
    Might as well be underwater because I make less drag than a torpedoE (no aero bars here though)
    Posts
    4,463
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The sapim cx-rays don't have much side profile though and that is why you can use them with regular hubs and not elongate the spoke holes at the flange.
    "The Iron never lies to you. The Iron will always kick you the real deal. It never freaks out on me, never runs. Friends may come and go, but 200 pounds is always 200 pounds." -Henry Rollins

  13. #13
    Senior Member biker7's Avatar
    Join Date
    Feb 2005
    Posts
    2,850
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by NZLcyclist
    From www.velomax.com

    Q. Why doesn't Velomax use bladed spokes?

    We carefully considered using bladed spokes, but decided against it. In wind tunnel tests, bladed (and ovalized - hereafter "profiled") spokes have proven to be very effective. The caveat here is that they show their greatest advantages vis-a-vis round spokes when the airflow is from straight ahead. As soon as you introduce even a small component of side wind (yaw angle as low as 2 degrees), the larger surface area of profiled spokes acts either as a lifting surface, or develops airflow separation (with related generation of vortices), or both. The bottom line - creation of lift cannot be accomplished without corresponding increases in drag.

    Simply stated, a profiled spoke in a static or head-on air stream can be very effective. However, a profiled spoke in a side wind is a propeller.

    A round spoke always presents the same small profile to the air stream, whether the angle of attack is head on or from the side. When you consider the wind direction, speed of the bicycle, and rotational speed of the wheel, it becomes apparent that there is an alphabet soup of aerodynamic considerations happening throughout the course of the ride. For this reason, we believe that swaged (butted) spokes present the best real-world aerodynamic profile.
    Da real truth.
    George

  14. #14
    hill hater nova's Avatar
    Join Date
    Aug 2005
    Location
    norton ohio 5.5 miles from center road tow path trail head
    My Bikes
    cannondale t400 1987 model and a raleigh gran prix from 1973
    Posts
    2,127
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Eatadonut
    I thought bladed spokes were for eliminating the threat of squirrels jumping into your front wheel and getting stuck.
    Lol slice and dice

  15. #15
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The air drag of the spokes is proportional to its forward facing thickness. Wheelsmith/DT oval spokes are approx. 1.2/1.3mm thick which exposes less area to the wind. The advantage is far greater than the losses from side winds since the spoke velocity is greater as the wheel rotates at high speed around the hub.

    In practical terms, blade spokes do not fit though the holes in the hubs unless the hub is designed for the purpose. For that reason, oval spokes are used.

    For a real world comparison, I have several friends with Ksyriums and when coasting down hill these guys leave me with my round spoked Dura Ace/Open Pro wheels, alll other things equal. I'm convinced but not enough to get me to spend big $$ on wheels.

    My next purchase is going to be a conventional wheelset using oval spokes.

    Ed
    Last edited by Nessism; 09-27-05 at 10:37 AM.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  16. #16
    Theodore Roosevelt's idol TheKillerPenguin's Avatar
    Join Date
    Sep 2004
    Location
    Vagabond
    My Bikes
    Affirmative
    Posts
    9,006
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Maybe I'm being unfair to ksyriums.

    My old wheelset (Gipiemme Grecal Parades) had bladed spokes, but the front wasn't tapered at all; they were long rectangles, not oval, so the front of the spoke was flat and wouldn't really cut through the air. I assumed that they had the same spokes as my crap wheels, which is unfair.
    Masochism is a training adaptation.

  17. #17
    Hair Free bike756's Avatar
    Join Date
    May 2005
    Location
    Massillon, Ohio
    My Bikes
    specialized allez with misc. upgrades,commuter mtb
    Posts
    378
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    How do they get those things into the rim?

  18. #18
    Senior Member
    Join Date
    Jul 2004
    Location
    Cental New Jersey
    My Bikes
    Klein Quantum Pro
    Posts
    469
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    For the average rider, I doubt any of the choices makes a huge difference in performance. I'm sure riders at the pro level reap some benefit from the slight aero benefits of particular spokes, but they are also pushing 30 mph on a regular basis.
    My approach to building wheels has always been a practical one. Unless there is a compelling reason to do otherwise, I tend to pick spokes that could be replaced in the middle of nowhere if necessary (round).

  19. #19
    Senior Member formulaben's Avatar
    Join Date
    Sep 2004
    Location
    Les Bois
    My Bikes
    Felt F2C, Scott Spark 40, and Custom Fixie
    Posts
    1,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by 53-11_alltheway
    The most overall aerodynamic spokes are oval (like the sapim cx-ray, etc).

    The big flat blades are aero only in one direction (particullary the large aluminum Kysrium SSC SL blades), but at any angle greater than zero they can actually increase drag.
    Well, Velomax says the same thing, but Zipp disagrees (pdf file), and puts it in writing. Check out the first chart. If the wind angle is 0 degrees, it is riding behind the wheel and rim, so it is in turbulent air. It makes sense that as the angle is increased that drag goes down.
    "Strong, light, cheap. Pick any two." — Keith Bontrager

  20. #20
    Theodore Roosevelt's idol TheKillerPenguin's Avatar
    Join Date
    Sep 2004
    Location
    Vagabond
    My Bikes
    Affirmative
    Posts
    9,006
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    That's an awesome link ben. Thanks.
    Masochism is a training adaptation.

  21. #21
    Senior Member formulaben's Avatar
    Join Date
    Sep 2004
    Location
    Les Bois
    My Bikes
    Felt F2C, Scott Spark 40, and Custom Fixie
    Posts
    1,172
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    No problem. Zipp has some great info on the site. Here is a link to the Tech Articles index.
    "Strong, light, cheap. Pick any two." — Keith Bontrager

  22. #22
    DocRay
    Guest
    Quote Originally Posted by badkarma
    Why do you think airfoils (i.e. airplane wings) have the shape they do? They create lift (irrelevelant in the case of bicycles), but they also have a low coefficient of drag due to their profile. Round spokes leave a large wake (i.e. more pressure drag) than bladed spokes. Let it be said though, the decrease in pressure drag due to bladed spokes is rather minimal, yet it is finite.
    This is the theory used to sell bladed spokes. In practical application, it is total bull****. Bladed spokes would only make a significant difference if the wheel had no rims and tires, the air turbulence generated by the tire and rim causes eddys that mean that clean air is not being seen by the spokes. The air is coming from all angles, and with a wider spoke, will just give more drag. The larger surface area of the bladed spoke means more drag. Airplane wings are not designed to reduce drag, they are designed for lift. The airplane fuselage is designed to reduce drag. The best spoke shape is good old boring round. If there is any difference, I would put it as miniscule compared to riding with a stiffer, lighter round spoked rim.

    I would not quote Zipp sites for opinions on Zipp products. They try very hard to justify the most expensive wheels in the world.

  23. #23
    Dog is my co-pilot 2manybikes's Avatar
    Join Date
    Jun 2003
    My Bikes
    2 many
    Posts
    13,732
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Eatadonut
    I thought bladed spokes were for eliminating the threat of squirrels jumping into your front wheel and getting stuck.
    Flat bladed spokes are better for advertising stickers.

  24. #24
    Maglia Ciclamino gcasillo's Avatar
    Join Date
    Jul 2004
    Location
    Fairfield, OH
    My Bikes
    2011 Bianchi Infinito, 2010 Surly Long Haul Trucker
    Posts
    3,076
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Velomax dude in white lab coat
    a lifting surface, or develops airflow separation
    Lift and separate? How can that be a bad thing?

  25. #25
    Senior Member
    Join Date
    May 2005
    Posts
    137
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Aerodynamics is complicated. You have to take into account shape, radius, eddy currents, direction, surface effect, air pressure, ect. I have yet to see a decent bike-rider combo fluid flow model. Also a lot of the wheel models I have seen are just for the rims, ignoring the spokes. I was thinking of creating a model for my senior design project, If I do I will post it. Bike manufacturers are not infallable, a couple years ago some students at my university did a stress analysis of Trek's forks. They found stress concentrations so severe Trek ended up redesigning the fork.

    As to bladed spokes vs round. I am not sure on the aerodynamic properties. I figured that they were to help make the wheel stiffer. The flattened spokes are stiffer because they have a higher moment of inertia, Ix. This would help them to resist bending. So then you have to take into account power lost due to wheel flex vs. power lost due to drag. Sounds like a fun research project.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •