<For Road Cyclists> How much does the wind effect your average MPH?

There is a 7 mile flat route in my town. I usually complete one lap around 20 minutes. Last time I did the loop and finished almost under 18 minutes. I thought I gained some fitness in just two weeks. Today I was literally flying down the road and if I had my bike computer I swear it would read that I was going about 30mph. But then I turned around and found out that there was a tailwind coming over. So now I was facing the wind and it felt like I was going 17mph at best.

I also remember this time when I was going in one direction facing the wind and it took me an hour and 15 minutes to get to my destination. I turned around with the wind on my back and I came back home in less than one hour!!! So I just want to know if this is normal? Or am I really getting beat up by the wind more than most people?

Two major things that effect speed are:
1. Rolling resistance of tires
2. Wind.

Wind plays a huge role in all forms of transport. It can be strong enough to move ships. Car manufacturers make great effort to reduce drag to get better fuel efficiency. And with bikes, people try to minimize it with slippery covers. You can see it in action with the velomobile. Just check out the site below.

That's perfectly normal. At normal cruising speeds, most of your effort is cutting through the wind. A couple years ago, I was on a long weekend ride and I knew there was a strong west wind, so I intentionally headed west so I would have a tail wind coming back. The ride took me 2 hours and 45 minutes going out and coming back took 2 hours and 10 minutes.

Wind can play a part in how fast you go on a ride, and it's a great way to push yourself to grow stronger. I know I find myself going out on windy rides, just watch yourself more, because the wind can really push you around.

I noticed the same effect too. Make big difference. Against the wind averages 11.5 mpg. With the wind 15 mpg,

mostly about 5mph but it depends on how powerful the wind is

Wind affects all cyclists, not just people on road bikes.

That sounds about right.

As you get a good feel for your normal speed (respective of effort), you'll be able to tell when you're being helped by a tailwind. Don't count on swaying tree limbs to indicate the presence and direction of wind; "ground" winds are deceiving.

When you do detect the presence of a tailwind, be prepared to get hit with a headwind somewhere on your loop. If you've already worn out your legs at that point, expect your speed to drop noticeably.

Also, you'll have good days when otherwise annoying headwinds don't affect you much...as well as bad days when they do.

In regards to possibly hitting 30mph on the flat; that's a considerable increase (nearly 50%) over your average lap speed. You should be able to detect such a wind immediately.