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Showing posts from August, 2009

District Carbon: which district?

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Well, since I got an eye infection around a month ago, I've been feeling up and down, but mostly down. Progress after antibacterial drops from the optometrist , but since then, I've been feeling under the weather again. I needed to pass on the University Road Race, which is a favorite race of mine. My power numbers suggested I should be able to hang on that suffer-fest, and placing at University probably means a top-15 result, which is good for me. So when I'm not riding, my mind invariably drifts to equipment. This bike in particular catches my attention: Trek District Carbon First, the rational self: this thing makes no sense at all. Urban bikes get ridden through potholes, leaned against posts, stacked on bike racks in overcrowded Caltrain cars , wrapped with chains outside Rainbow grocery , and shouldn't stand out in a crowd of possible theft targets. This bit of bike boutiquery begs to be babied: one serious scratch or crack on carbon and it needs to be toss

cost-mass tradeoff on 2010 groups

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I did a few minutes of data mining of the Competitive Cyclist road group configuration page , collecting datapoints in each of the three available full-group manufactures, SRAM, Shimano, and Campagnolo. The page offers convenient totals on mass and price. Their mass numbers aren't always great, and certainly even local shops often beat Competitive Cyclist prices (especially with bike coalition or racing club discounts), but the idea is to compare the relative cost of different groups, and it is assumed discounts are available for each. First, on this comparison, it's clear Shimano is uncompetitive. SRAM comes out the best, with Campy a close second. But second, sticking with complete groups, the jump to the highest end comes with a hefty price tag. Each is over $5/gram. Among the second-tier groups, Force shows itself as the real weight-weenie bargain. With performance essentially equivalent to Red (with exception of the ceramic bearings, which might be important), it sa

House of Tacks

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My last attempt at the House of Pain ended in a minefield of puncture vine , which took out both tires less than a mile after I joined the proto-race. Today, I was back, ready to check off another goal in my riding. I'd already PR'ed Old La Honda , I'd already stuck with the Valley Ride to the sprint . Now I needed to stick with a weekender: Spectrum or the HOP. After that first attempt, as I was in Pegasus purchasing the two tubes I needed to replace the pair which had been perforated well beyond the patchable threshold, another customer in the shop mentioned puncture vine was a common problem on the roads around Danville. But he'd also heard of tacks being spread in the bike lane or shoulder. I didn't think much of it. So today I rolled out of Walnut Creek BART, heading south. As I crossed under 680 on Main Street, a car honked aggressively as it passed, the adjacent lane completely empty. After a brief Spike Bike fantasy, I put it behind me. I continued

Hanging with the Valley Ride

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I hadn't yet done a Valley Ride this year. The Valley Ride is in the same category as the Tue Noon Ride and the Spectrum Ride: a race simulation which if, if you can survive, is a good indication of race readiness. Other than my extended climbing (I recently PR'ed Old La Honda), I've had precious little indication of race readiness this year. Certainly I've shown none at races. The frenzied, lactic acid saturated hammer-mania typical of the shot climbs often encountered in these rides or races is a much different beast than an aerobically dominated climb like Old La Honda Road. And while I'd not done the Valley Ride, my several attempts this year at either the Tue or even the somewhat tamer Thu Nooner had all been failures. Refusing to take short-cuts taken by 2/3 of the packs at Canada College or at Corte Madera, I'd been gapped by the leaders, who are rejoined at the bottom of the associated descents by the low-roaders and are then gone for good. "Un

Powertap analysis of back-to-back Old La Hondas

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On 22 July I did Old La Honda twice. The first time I rode it at a steady, hard tempo. The second time doing 60 second intervals each four minutes, zone 3 between intervals. So this isn't a direct experiment. Yet the interesting thing was my total work reported by the Powertap differed in the two cases: min from ride start km into climb min into climb kilojoules 56.43 5.357 17.96 29.81 94.12 5.383 19.38 28.76 The difference in work is 3.65%. But it makes sense work should be less if I was riding slower, right? Less wind resistance. So I converted each data set into power versus normalized position, and plotted the difference in retarding force (power / speed) versus the difference in the square of speed. The standard model is that in the absence of headwind (and the winds were light that day, especially on sheltered Old La Honda Road's eastern slope) the wind resistance force is proportional to the square of speed. A linear regression yielded a quite reasonable value for

position check

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An eye infection has me sleeping poorly and feeling generally crappy. In these situations, I prefer to take a few days off from worrying about training (except for stretching), get plenty of rest, and focus on getting better. A good chance for a sanity check on my position. CyclingNews did a nice article about the Saxo Bank Squad team getting fitted by Andy Pruitt. Specialized, who sponsors the team, likes to represent itself as experts in ergonomics, and so really play up their relationship with Andy Pruitt, a respected bike fitter who wrote a nice book on the subject (not as "complete" as the title would imply, but definitely worth the read). In the cyclingnews story, there was this side shot of Frank Schleck, showing a side view . I'll take this as an example of, for Frank, a relatively exemplary position. Frank Schleck fitted by Andy Pruitt ( CyclingNews ). So, how do I compare? Leaning the bike against the wall (not the best: a trainer would be better) I took p