Hairiest Chinese Guy Alive Shaves His Legs

It’s been a long time coming, but it finally happened over the weekend.  Yes, the fur is gone!  With my daughter going back to college next week I had only this Saturday to solicit her assistance.  So I finally pulled the trigger despite my wife’s objections.  How did my daughter get involved?  Let me explain before you call child protective services.  I’ve been wanting to perform a wind drag experiment for some time now.  I’ve been thinking about which hill I’d need to coast down that didn’t have much wind, that I didn’t need to brake on, that was relatively straight and smooth, that had just the right grade so I wasn’t going too fast, that didn’t have too much traffic, and that was long enough for the drag of my hairy legs to be measurable.  Ideally such a road would be 3-4% grade so I could coast at ~40 km/h, and at least 3 km long or roughly 270s at 40 km/h.  Unfortunately I couldn’t find anything long enough at that grade.  Instead, my choice was a middle section of Big Basin Way(Congress Springs Rd), from the Savannah-Chanelle fork at the base to just above the “R-clip retaining pin” section two miles (3.2 km) up.  The average grade on this section is 6.25% (200 m elevation/3.2 km).  I probably would have chosen the bridge at Sanborn Rd for my base, but there’s construction just below the Savannah-Chanelle fork which has two opposing lanes of traffic forced into a single alternating direction lane.  So Savannah-Channelle fork it was.

The tests were performed on my new 2014 Cervelo S5 VWD.  The equipment was only important so long as everything stayed the same between tests.  Tire pressure was 110 psi rear/100 front on Schwalbe One Clinchers if you’re curious.  Thankfully I didn’t get a flat between test runs so tire pressure was essentially a constant.  A test run consisted of coasting down the section of road from a dead stop.  Left and right feet were kept level (left foot forward/right foot back).  Chain was kept in the same gearing, 34/15, although I didn’t pedal at all, just coasting.  I kept my hands in the drops and my arms as straight as possible with just a slight bend when going into the turns to maintain control.  I tried to keep the same line while descending, keeping 2-3 ft from the white line marking the road shoulder.  Basically I kept everything that I could control as constant as possible.

It’s extremely important to maintain a consistent weight when doing a test like this.  At the start my total weight including the bike was 79.3 kgf.  I brought my bathroom scale in case I needed to pee and had to replenish my weight.  As it turned out I had to pee at the top of the road section, but there wasn’t a level area for the scale to work.  So I “sacrificed” one of my water bottles to know how much water to drink.  I emptied my other “clean” bottle  to the same level as the “sacrificial” bottle, and then drank all the water in it.  After topping off my “clean” bottle with more water I was ready for more descending. My weight after testing was 79.2 kgf.  I lost 100 g perspiring over three hours. I’m not gonna sweat it, pun intended.

There were several aborted runs where traffic got too close and I had to brake slightly or I felt I got a draft.  Here are the results of what I considered clean runs:

Unshaven:

#1  216.68 s

#2  218.56 s

#3  218.37 s

#4  222.61 s

#5  219.18 s

Ave: 219.08 +/- 2.18 s

Shaven:

#6  212.40 s

#7  210.25 s

#8  211.89 s

#9  212.31 s

#10 215.33 s

Ave: 212.44 +/-1.84 s

Most of the 6.64 s time difference is a result of the drag difference at the terminal velocities, ~55 km/h. Whether shaved or unshaved it took almost the same time, 36 s , and distance, 160 m, to reach 50 km/h.  Therefore for the purpose of this test, I assume the first 36 s is essentially drag neutral whether shaved or unshaven.  Doing the math… 6.64/(219-36)=3.6% is the relative time reduction due to shaving.  In terms of power…with an average grade of 6.25%, mass of 79.3 kg, and velocity of 55 km/h  shaving was equivalent to ~27 W reduced drag.  Specialized reported something on the order of 15 W drag in the wind tunnel for someone having very hairy legs (#9 on the Chewbacca scale) and wind speed of 25 mph (~40 km/h).  I’m not sure where I fit on the Chewbacca scale, but I’m known as the hairiest Chinese guy alive so I have to believe I’m at least a #9.  My data supports what Specialized reported as drag increases with the square of velocity, 15 W * (55/40)^2 = 28 W.

My daughter, who drove me to the top and followed behind on each run, was traumatized by the whole shaving experience, but she got  a nice dinner out of it and will have a story to tell her friends back at college.

Phill