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Is a more aero bike more efficient than less aero bike at 10mph? At what speed does Aerodynamics affect your speed significantly.

update: "The question is dealing with the minimum speed that a cyclist will notice the effects of a modern aero frame vs a non-aero frame. via @user"

nolawi
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3 Answers3

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As long as you are moving through the air, aerodynamic drag will account for some portion of total drag. Here is a plot that shows the relative contribution of aerodynamic drag vs. rolling drag on total drag for a rider at constant speed on a flat surface with the given CdA (drag area) and Crr (coefficient of rolling resistance). There is no magic threshold speed at which aerodynamic drag suddenly appears. Whether the amount of drag is important or significant to you will depend on your power and riding goal, but for this example roughly 25% of total power will be consumed by aerodynamic drag at about 10 km/h (or about 6 mph).

enter image description here

R. Chung
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    Of course it should be noted that there is probably a 4x difference in rolling resistance between narrow high pressure racing tires and knobby low-pressure mountain biking tires. – Daniel R Hicks Jul 12 '16 at 23:07
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    Though the chart is good, but the relative graph pct of power quite misleading. i.e., where the rolling drag and aero drag meet, are not equivalent of power output. E.g. you just need ~30w 99% to push the bikes to rolls. When speed reach 35mph, 95% air actually produce 600w of resistances. – mootmoot Jul 13 '16 at 09:16
  • the first curve is what i wanted to know 'aero drag vs speed' – nolawi Jul 13 '16 at 15:10
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Schwalbe has a great chart from their rolling resistance page on major resistance force for bicycling. Noticeable air drag started from 15km/h and increase exponential after 20km/h. At 10Mph(16Kmh), good aero bikes doesn't show significant advantages. Even above 30km/h, typical aero bike cannot do much to reduce the air resistant : human are not aerodynamic in the first place.

True aerodynamic-cycle look something like velomobile . No professional cyclist with their expensive bicycle can beat any amateur that is riding a fast velomobile, unless it is a hill climbing competition.

andy256
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mootmoot
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    I think I must have missed why the velomobile reference is relevant. – Ealhmund Jul 12 '16 at 17:48
  • true. question is not hon rolling resistance – nolawi Jul 12 '16 at 18:49
  • Rolling resistance could conceivably come into play in the context of your question; in the context of "noticeable", as one could argue that air resistance that is less than rolling resistance may not be significant enough to be noticeable. – Ealhmund Jul 12 '16 at 19:34
  • @nolawipetros : major resistance force for bicycling – mootmoot Jul 13 '16 at 07:27
  • Also, note that there are velomobiles that are not designed to be fast, just comfortable. "velomobile" really just means "enclosed" or "has a fairing" plus more than two wheels. – Nuі Jul 13 '16 at 07:51
  • @altomnr : Though every bit play its part. If you read the chart, at 25kmh, rolling resistant(RR) ~60watts(w), but air resistant(AR) ~180w At 30km/h, RR~80w, AR~ 280w . – mootmoot Jul 13 '16 at 08:03
  • @mootmoot: Agreed, it all plays a part in terms of overall resistance, however, at the speeds where rolling is greater than air, it might be difficult to notice the effect of a decrease in air resistance, since the wattage costs are low at (and below) that point. In the context of this question, presumably, both the aero and non-aero bikes have the same wheels, tires, components, etc; so the difference would strictly come down to the aerodynamic benefits of the two frames (rolling resistance would be a constant between the two and could be effectively ignored). – Ealhmund Jul 13 '16 at 13:39
  • @altomnr : Let's check out the good old sheldon brown site :
    http://www.sheldonbrown.com/rinard/aero/aerodynamics.htm     – mootmoot Jul 13 '16 at 14:13
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    @mootmoot : The question is dealing with the minimum speed that a cyclist will notice the effects of a modern aero frame vs a non-aero frame. So I agree that a velomobile is very aero, the question is not "what is the most aero setup", so not only do I fail to see the point in mentioning them, I also don't see the point in referencing a 26 year old article. – Ealhmund Jul 13 '16 at 14:25
  • Folks, read through the content given by the link. It is unethical for me to copy and paste other people chart here. – mootmoot Jul 15 '16 at 07:25
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In my experience it is begin at about 30 kmh and at like 50 kmh you really feel how the wind is hitting you in the face I guess faster you goes stronger the effect is. But it is important at any speed really, if its windy and you have loose clothes they act like a sail.

aero bike for like 10mph ? you can walk faster I guess it will have less air resistance that regular bike but just in theory maybe you couldn`t even measure it.

kifli
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