# At what speed does Aerodynamics of a bike come into play?

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"

• How do you define "significant"? Noticeable? "X watts saved"? Jul 12, 2016 at 15:05
• significant = apparently noticeable Jul 12, 2016 at 18:01
• @nolawipetros - what is "apparently noticeable" depends on the person. Jul 12, 2016 at 21:08
• My gut feel is about 12 mph. Jul 12, 2016 at 23:05
• @nolawipetros - Just a note, a "@user" in the comments is who that comment is in reply to, rather than the source of the comment. Jul 13, 2016 at 17:35

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).

• 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. Jul 12, 2016 at 23:07
• 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. Jul 13, 2016 at 9:16
• the first curve is what i wanted to know 'aero drag vs speed' Jul 13, 2016 at 15:10

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.

• I think I must have missed why the velomobile reference is relevant. Jul 12, 2016 at 17:48
• true. question is not hon rolling resistance Jul 12, 2016 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. Jul 12, 2016 at 19:34
• @nolawipetros : `major resistance force for bicycling` Jul 13, 2016 at 7:27
• @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. Jul 13, 2016 at 14:25

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.

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Jul 13, 2016 at 20:16