16 August 2010

Do The Laws Of Energy Apply To Cyclists?

Today, dear reader, I’m going to ask you to help me to solve one of the mysteries of the universe. 

All right, I was exaggerating just a bit.  But there is still something I haven’t figured out after more than three decades of cycling.

Here’s the dilemma:  Yesterday I rode for less than an hour, on flat roads.  Yet I felt more tired than I did after my ride to and from Connecticut last week.  In fact, I was so tired that I didn’t write last night. 

I don’t think I’ve lost any of my conditioning (such as it is) during the past week.  And, I don’t think the fact that I rode my fixed gear yesterday rather than my geared road bike (which I rode to Connecticut) should’ve made a difference.  If anything, my fixie is lighter, simply from having fewer components on it.  Otherwise, they are similarly built Mercians:  the geometry is slightly tighter on the fixie, but they are both built of Reynolds 631 tubing.

And I undertook both rides about an hour after eating breakfast/brunch.  Yesterday I ate a mushroom-and-onion omlette with corn tostadas and salsa.  If I recall correctly, I ate the same thing, or something very close to it, last week.

So why did I have enough energy after last week’s ride to make dinner but, after yesterday’s ride, I had some Chinese takeout and fell asleep shortly afterward?


  1. You've answered your own question haven't you? One of your bicycles is more efficient than the other. The weight is an insignificant factor on flat roads. Fixies are fun. They make you feel more connected. Alas, they don't coast. You can never rest. In spite of their current popularity, I do not think they are efficient machines for riding any distance.

  2. Some days are just better than others, or put another way, sometimes you just have an off day.

  3. I can't say about your situation. But after I rode my fixed gear roadbike for 26 miles for the second day in a row, I came home, changed, sat down for a moment, fell asleep and woke up 12 hours later. Normally I sleep less than 6 hours per night!

    In my (granted, very limited) experience, when I am on my fixed gear, it does not feel difficult while I am riding it. It is a comfortable bicycle, and pedaling it is fun. But later in the day and the next day, my body lets me know that I exerted it more than I normally do. So I no longer ride it for 2 days in a row or on the day after a strenuous geared ride. My working formula so far is that the energy spent on X miles on the fixed gear = energy spent on 2.5X miles on a geared roadbike.

  4. Gunnar, Prentiss and Velouria: What you all say makes sense. I guess I'm being impatient: I've done much longer rides on my fixie and have done much more riding than I'm doing now. I guess that in middle age it's harder to come back from surgery and other inactivity than it is when one is young.

  5. At mid life you are going to do cycling. Hence this may be going good thing for your health also.

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