Sunday, September 8, 2013

Race Experiment: Descending Cum Riding Time

http://ridewithgps.com/routes/3307104

In about one hour my wife will drive me to the top of Iron Springs Road and drop me off. I'll then descend down, at maximum speed, 20.5 miles to Kirkland.

I'm stripping the bike (Bacchetta CA2. blue, carbon fiber) down so that I carry nothing ... no food, water, tools, seatbags, etc. This serves two purposes: ...


a) to assess the descending speed capability of the bike without ballast,

b) to determine the bike handling dynamics of a totally naked bike. A bike with seatbag, water, etc, has variable weight distribution that interferes with air resistance, affects vertical stability at speed, i.e., there is wobble making the bike whippy at high speeds with minor directional forward changes [slight weaving at speed to stay upright, avoid rough road, etc].

I don't expect my maximum speed to exceed 55 mph (which any skilled cyclist - DF or bent) can achieve. But, because of the oversized front chain ring (58t) I'll be able to increase the amount of time/distance I can maintain pedaling (i.e., apply power) at the bottom of descents and beginning of ascents. So, max speed may not be much different but elapsed time between start and finish will certainly be shorter / less.

When I descend so fast that `spinning' generates instability I stop pedaling and become nothing more than a bag of rocks coasting. When I coast less and power pedal more the average speed over distance and time improves.

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