Why aren't road bike wheels tiny?












1















My understanding is that air resistance is where most of the pedal power goes to at high speeds, and that this is a concern not least for the wheels: What you pay for in a road bike wheel is aerodynamic and/or light wheels, not so much to other losses like rolling resistance and bearings.



So if air resistance is the thing to optimize a wheel for, the wheel should be tiny. Obviously in width, but also in radius, because even shortening the length of a surface reduces boundary layer drag. Has anybody thought of this?





Postulate: The faster angular speed of a small wheel is irrelevant to air resistance: If the forward speed is given, every point on the wheel at a given fractional wheel radius has a speed compared to the ground that is independent of the wheel radius. In other words, shrinking the wheel does not speed up any point on its surface; you just get less surface. Which should be good!










share|improve this question







New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





















  • 552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

    – gschenk
    5 hours ago






  • 1





    Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

    – Daniel R Hicks
    4 hours ago











  • And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

    – Daniel R Hicks
    2 hours ago
















1















My understanding is that air resistance is where most of the pedal power goes to at high speeds, and that this is a concern not least for the wheels: What you pay for in a road bike wheel is aerodynamic and/or light wheels, not so much to other losses like rolling resistance and bearings.



So if air resistance is the thing to optimize a wheel for, the wheel should be tiny. Obviously in width, but also in radius, because even shortening the length of a surface reduces boundary layer drag. Has anybody thought of this?





Postulate: The faster angular speed of a small wheel is irrelevant to air resistance: If the forward speed is given, every point on the wheel at a given fractional wheel radius has a speed compared to the ground that is independent of the wheel radius. In other words, shrinking the wheel does not speed up any point on its surface; you just get less surface. Which should be good!










share|improve this question







New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





















  • 552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

    – gschenk
    5 hours ago






  • 1





    Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

    – Daniel R Hicks
    4 hours ago











  • And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

    – Daniel R Hicks
    2 hours ago














1












1








1


1






My understanding is that air resistance is where most of the pedal power goes to at high speeds, and that this is a concern not least for the wheels: What you pay for in a road bike wheel is aerodynamic and/or light wheels, not so much to other losses like rolling resistance and bearings.



So if air resistance is the thing to optimize a wheel for, the wheel should be tiny. Obviously in width, but also in radius, because even shortening the length of a surface reduces boundary layer drag. Has anybody thought of this?





Postulate: The faster angular speed of a small wheel is irrelevant to air resistance: If the forward speed is given, every point on the wheel at a given fractional wheel radius has a speed compared to the ground that is independent of the wheel radius. In other words, shrinking the wheel does not speed up any point on its surface; you just get less surface. Which should be good!










share|improve this question







New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












My understanding is that air resistance is where most of the pedal power goes to at high speeds, and that this is a concern not least for the wheels: What you pay for in a road bike wheel is aerodynamic and/or light wheels, not so much to other losses like rolling resistance and bearings.



So if air resistance is the thing to optimize a wheel for, the wheel should be tiny. Obviously in width, but also in radius, because even shortening the length of a surface reduces boundary layer drag. Has anybody thought of this?





Postulate: The faster angular speed of a small wheel is irrelevant to air resistance: If the forward speed is given, every point on the wheel at a given fractional wheel radius has a speed compared to the ground that is independent of the wheel radius. In other words, shrinking the wheel does not speed up any point on its surface; you just get less surface. Which should be good!







wheels aerodynamics






share|improve this question







New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 5 hours ago









user2394284user2394284

1091




1091




New contributor




user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






user2394284 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.













  • 552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

    – gschenk
    5 hours ago






  • 1





    Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

    – Daniel R Hicks
    4 hours ago











  • And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

    – Daniel R Hicks
    2 hours ago



















  • 552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

    – gschenk
    5 hours ago






  • 1





    Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

    – Daniel R Hicks
    4 hours ago











  • And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

    – Daniel R Hicks
    2 hours ago

















552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

– gschenk
5 hours ago





552 mm wheels are probably UCI legal in road races. Fore and aft same wheels of same diametre are required though

– gschenk
5 hours ago




1




1





Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

– Daniel R Hicks
4 hours ago





Uh, what is the single largest (by far) source of both weight and wind resistance for a bicycle (that's being ridden by a human)?

– Daniel R Hicks
4 hours ago













And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

– Daniel R Hicks
2 hours ago





And concoct an adult-sized bike with 16-inch wheels. Take it out on a highway and ride it 50 miles. Then come back and explain why wheels should be small.

– Daniel R Hicks
2 hours ago










2 Answers
2






active

oldest

votes


















2














Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else.



Smaller wheels have higher rolling resistance, at some point that become significant compared to aero drag.



There are a host of other practical reasons, for instance:



As the driving wheel decreases in size the gear ratios have to increase to maintain the same distance travelled for a turn of the cranks. This is why folding bikes have huge chainrings.



Small wheels are less stable, as anyone who has ridden a Razor scooter knows.






share|improve this answer































    1














    You also have to count for stuff you can get over - that's why 29-inch wheels are so popular with the mountain bike crowd these days. They suck at cornering, and that's why they came up with 27.5's. Smaller wheel diameters are great for accelerating quicker, hence the popularity of 650C wheel sets for triathlons. Scooters have tiny wheels because they ideally are ridden on paved roads or sidewalks, and can therefore get by without hitting any major potholes or bumps. At some point, people got together and determined an ideal threshold for wheel size that would prevent accidents by their sole ability to get over stuff. That's the best explanation I've got!






    share|improve this answer
























      Your Answer








      StackExchange.ready(function() {
      var channelOptions = {
      tags: "".split(" "),
      id: "126"
      };
      initTagRenderer("".split(" "), "".split(" "), channelOptions);

      StackExchange.using("externalEditor", function() {
      // Have to fire editor after snippets, if snippets enabled
      if (StackExchange.settings.snippets.snippetsEnabled) {
      StackExchange.using("snippets", function() {
      createEditor();
      });
      }
      else {
      createEditor();
      }
      });

      function createEditor() {
      StackExchange.prepareEditor({
      heartbeatType: 'answer',
      autoActivateHeartbeat: false,
      convertImagesToLinks: false,
      noModals: true,
      showLowRepImageUploadWarning: true,
      reputationToPostImages: null,
      bindNavPrevention: true,
      postfix: "",
      imageUploader: {
      brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
      contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
      allowUrls: true
      },
      noCode: true, onDemand: true,
      discardSelector: ".discard-answer"
      ,immediatelyShowMarkdownHelp:true
      });


      }
      });






      user2394284 is a new contributor. Be nice, and check out our Code of Conduct.










      draft saved

      draft discarded


















      StackExchange.ready(
      function () {
      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fbicycles.stackexchange.com%2fquestions%2f60483%2fwhy-arent-road-bike-wheels-tiny%23new-answer', 'question_page');
      }
      );

      Post as a guest















      Required, but never shown

























      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      2














      Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else.



      Smaller wheels have higher rolling resistance, at some point that become significant compared to aero drag.



      There are a host of other practical reasons, for instance:



      As the driving wheel decreases in size the gear ratios have to increase to maintain the same distance travelled for a turn of the cranks. This is why folding bikes have huge chainrings.



      Small wheels are less stable, as anyone who has ridden a Razor scooter knows.






      share|improve this answer




























        2














        Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else.



        Smaller wheels have higher rolling resistance, at some point that become significant compared to aero drag.



        There are a host of other practical reasons, for instance:



        As the driving wheel decreases in size the gear ratios have to increase to maintain the same distance travelled for a turn of the cranks. This is why folding bikes have huge chainrings.



        Small wheels are less stable, as anyone who has ridden a Razor scooter knows.






        share|improve this answer


























          2












          2








          2







          Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else.



          Smaller wheels have higher rolling resistance, at some point that become significant compared to aero drag.



          There are a host of other practical reasons, for instance:



          As the driving wheel decreases in size the gear ratios have to increase to maintain the same distance travelled for a turn of the cranks. This is why folding bikes have huge chainrings.



          Small wheels are less stable, as anyone who has ridden a Razor scooter knows.






          share|improve this answer













          Assuming a bicycle with a conventional rider position, the rider cannot be positioned any lower because there has to be a certain amount of clearance between the cranks and the road. As wheels shrink, the frame has to extend downwards to reach the axles, so you are not really removing structure that causes drag, you are replacing it with something else.



          Smaller wheels have higher rolling resistance, at some point that become significant compared to aero drag.



          There are a host of other practical reasons, for instance:



          As the driving wheel decreases in size the gear ratios have to increase to maintain the same distance travelled for a turn of the cranks. This is why folding bikes have huge chainrings.



          Small wheels are less stable, as anyone who has ridden a Razor scooter knows.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 1 hour ago









          Argenti ApparatusArgenti Apparatus

          38.2k23995




          38.2k23995























              1














              You also have to count for stuff you can get over - that's why 29-inch wheels are so popular with the mountain bike crowd these days. They suck at cornering, and that's why they came up with 27.5's. Smaller wheel diameters are great for accelerating quicker, hence the popularity of 650C wheel sets for triathlons. Scooters have tiny wheels because they ideally are ridden on paved roads or sidewalks, and can therefore get by without hitting any major potholes or bumps. At some point, people got together and determined an ideal threshold for wheel size that would prevent accidents by their sole ability to get over stuff. That's the best explanation I've got!






              share|improve this answer




























                1














                You also have to count for stuff you can get over - that's why 29-inch wheels are so popular with the mountain bike crowd these days. They suck at cornering, and that's why they came up with 27.5's. Smaller wheel diameters are great for accelerating quicker, hence the popularity of 650C wheel sets for triathlons. Scooters have tiny wheels because they ideally are ridden on paved roads or sidewalks, and can therefore get by without hitting any major potholes or bumps. At some point, people got together and determined an ideal threshold for wheel size that would prevent accidents by their sole ability to get over stuff. That's the best explanation I've got!






                share|improve this answer


























                  1












                  1








                  1







                  You also have to count for stuff you can get over - that's why 29-inch wheels are so popular with the mountain bike crowd these days. They suck at cornering, and that's why they came up with 27.5's. Smaller wheel diameters are great for accelerating quicker, hence the popularity of 650C wheel sets for triathlons. Scooters have tiny wheels because they ideally are ridden on paved roads or sidewalks, and can therefore get by without hitting any major potholes or bumps. At some point, people got together and determined an ideal threshold for wheel size that would prevent accidents by their sole ability to get over stuff. That's the best explanation I've got!






                  share|improve this answer













                  You also have to count for stuff you can get over - that's why 29-inch wheels are so popular with the mountain bike crowd these days. They suck at cornering, and that's why they came up with 27.5's. Smaller wheel diameters are great for accelerating quicker, hence the popularity of 650C wheel sets for triathlons. Scooters have tiny wheels because they ideally are ridden on paved roads or sidewalks, and can therefore get by without hitting any major potholes or bumps. At some point, people got together and determined an ideal threshold for wheel size that would prevent accidents by their sole ability to get over stuff. That's the best explanation I've got!







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 1 hour ago









                  M. HernandezM. Hernandez

                  464




                  464






















                      user2394284 is a new contributor. Be nice, and check out our Code of Conduct.










                      draft saved

                      draft discarded


















                      user2394284 is a new contributor. Be nice, and check out our Code of Conduct.













                      user2394284 is a new contributor. Be nice, and check out our Code of Conduct.












                      user2394284 is a new contributor. Be nice, and check out our Code of Conduct.
















                      Thanks for contributing an answer to Bicycles Stack Exchange!


                      • Please be sure to answer the question. Provide details and share your research!

                      But avoid



                      • Asking for help, clarification, or responding to other answers.

                      • Making statements based on opinion; back them up with references or personal experience.


                      To learn more, see our tips on writing great answers.




                      draft saved


                      draft discarded














                      StackExchange.ready(
                      function () {
                      StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fbicycles.stackexchange.com%2fquestions%2f60483%2fwhy-arent-road-bike-wheels-tiny%23new-answer', 'question_page');
                      }
                      );

                      Post as a guest















                      Required, but never shown





















































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown

































                      Required, but never shown














                      Required, but never shown












                      Required, but never shown







                      Required, but never shown







                      Popular posts from this blog

                      How to label and detect the document text images

                      Vallis Paradisi

                      Tabula Rosettana