Kennedy Trail dirt: Mixing things up for Low-Key Hillclimbs

A big motivation for Kennedy was that it would mix things up a bit: not only the experience, but also the scoring. While the results in typical climbs can get almost frustratingly predictable, on the dirt skill, confidence, and balance can play a substantial role.

I like to compare the scores for riders who did climbs in any given pair of weeks, to see how their scores different (RMS average difference). Here's the result: 

climbs:
w1: Montebello
w2: Quimby Road (Murillo start)
w3: Morgan Territory Road (S)
w4: Hwy 9 from Boulder Creek
w5: Hwy 84 - West Alpine
w6: Soda Springs
w7: Kennedy Trail

-----------------------------------
rms score delta (riders doing each)
-----------------------------------
       w1    w2    w3    w4    w5    w6    w7
w1      .  4.73  2.99  5.29  6.04  3.40  6.88   w1 
w2   4.73     .  4.96  7.91  5.77  3.33  6.48   w2 
w3   2.99  4.96     .  4.07  6.41  3.09  6.72   w3 
w4   5.29  7.91  4.07     .  5.66  5.59  7.46   w4 
w5   6.04  5.77  6.41  5.66     .  4.59  8.02   w5 
w6   3.40  3.33  3.09  5.59  4.59     .  6.70   w6 
w7   6.88  6.48  6.72  7.46  8.02  6.70     .   w7 
       w1    w2    w3    w4    w5    w6    w7

The week-pairs for which scores were the closest match were Montebello and Morgan Territory. A close second was Morgan Territory and Soda Springs. The biggest difference was between Kennedy Fire Trail and W Hwy 84 - W Alpine, while Kennedy Fire Trail vs West Highway 9 was also a large difference. Scores between Kennedy and any other week differed RMS by at least 6.48 points. There's other weeks which also had mismatch, for example Quimby versus W Hwy 9, but in general Kennedy proved the most unique.

Here's a plot of the W 84 scores versus Kennedy scores for riders who did both. The scoring algorithm clumped the scores around the line y = x, so there's no evident strong bias to faster or more endurance-oriented riders. The only bias is towards riders relatively better or worse at climbing on dirt, as it should be:

week 5 vs 7

So the scoring worked well. As I've described before I calculate a parameter I call the "slope factor" which corrects for riders being relatively closely or relatively widely spaced in time on a given climb. Steeper hills tend to spread riders out more than flatter rides. But dirt also spreads people out more than pavement. It is curious to see if the result matches this expectation. Here's the scoring factor plotted, where each point relating road grade to slope factor is indicated with the week's number:

slope factors

Kennedy, indicated with the brown 7, is indeed an outlier, and separated the riders more than any other climb. This year's scoring code helps limit the relative influence of Kennedy versus, for example, Mount Hamilton on Thursday which traditionally yields far less separation due to its modest grades and intermediate descents.

Comments

Post a Comment

Popular posts from this blog

Marin Avenue (Berkeley)

Image
On Saturday, I got an email from Tim telling letting me know that Murphy's Spring Classics was going to start up Marin Ave. I'd missed that. Murphy announces his courses the day before, and indeed it was already well into the night before when the course announcement went out. I'd skipped over the details, jumping straight to middle and end games. Marin? I laughed at the irony, because not long before when he'd told me he was choosing to repeat the Nifty Twn Fifty which we'd done together last year versus selecting Murphy Mack's Stage Mullett two-day, I responded I didn't think I had it in me to ride Marin Ave two years in succession. Well, so much for that. I was committed, so I went downstairs to swap my 11-26 cassette for my Recon 12-27. The name is easily overlooked: "Marin Ave" fails to strike the same impression as, for example, "Redwood Gulch" or "China Grade". But among those in the know, Marin Ave is infamous i
Read more

hummingbird feeder physics

Image
I couldn't figure out how the hummingbird feeder worked. Why didn't it overflow? Forces need to balance, of course. Neglecting surface tension, there liquid level is higher in the inner reservoir than in the feeding chamber, so there must be a corresponding pressure difference. Suppose the pressure in the inner chamber were zero. Then the column height difference would need to be atmospheric pressure / (density of liquid × gravity). But this is over 9 meters! Obviously the height difference is only approximately 1% of this. So the pressure difference inside versus outside is only approximately 1%. The inside is only slightly below atmosphere. So air is getting in. How? Does it diffuse through the liquid? If this were the dominant mechanism, it wouldn't take long for the pressure inside to go from 99% to 99.3%, for example, which should be plenty to push the column of liquid down in the inside chamber and thus push liquid out through the holes. It would over
Read more

Gallium Pro geometry

Image
On Caltrain yesterday, I was surprised to see among the usual set of commuting bikes a SRAM Red-equipped Argon Gallium Pro. The bike immediately stole your attention. The design was one which has been trending: clear-coated carbon with plenty of text detail so the viewer is sure to realize he's gazing upon the result of advanced, proprietary engineering and not at yet another paint job on the same old OEM frames being pumped out of the same old Taiwanese factories. But it worked: the bottom bracket area was huge, the downtube a large-diameter "inverted Kamm tail" design seemingly designed to maximize wind resistance, the top tube a broad, eccentric shape which screamed "vertically compliant yet torsionally stiff". All it lacked were the pencil-think seat stays Cervelo popularized, but this was a machine designed for stiffness over anything else. It seemed dramatic overkill, since the bike was small (the Argon "XS" I suspect). There wasn't muc
Read more