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Sep
7
revised Relative efficiency of different commute bike setups
added 588 characters in body
Sep
6
answered Relative efficiency of different commute bike setups
Sep
1
answered Velodrome atmospheric conditions
Aug
21
awarded  Yearling
Aug
10
comment Why is BMX gearing so low
It's exactly because of the acceleration. BMX courses put a premium on being the first to the turn so the start is critical. Recently, UCI rules governing BMX have been amended to allow gearing systems but BMX riders have eschewed them, in part because they put out a max instantaneous power in excess of 2000 watts and few bicycle gearing systems can take that much load without risking a missed shift.
Aug
5
comment when does the pace bike leave in Keirin?
I don't think this is quite exactly right. The UCI regulations specify not a distance to be traveled but rather the distance remaining: no matter the length of the track, the pacer pulls off between 600 and 700 meters before the finish line. Thus, if the track is 250 meters long the pacer pulls off about 2.5 laps before the finish; if the track is 333 meters long the pacer pulls off 2 laps before the finish; and if the track is 400 meters long the pacer pulls off 1.5 laps before the finish.
Aug
1
revised Why aren't Tour de France riders going any faster?
updated for 2012 Tour and Giro results
Jul
31
comment Do higher speed crashes result in less serious injuries.
They reported odds ratios because the study was a case-control with a non-random sample design so the selection bias makes the population-level effect size impossible to estimate.
Jul
25
awarded  Nice Answer
Jul
19
comment Which parameters should I track with bicycle computer so I can analyze changes in my riding?
Right. GPS isn't quite as good for speed as having a dedicated sensor. In addition, if you're going to have to have a cadence sensor anyway, you might want allow for a speed sensor on the rear wheel. If you have speed and cadence, you can usually figure out the chainring and cog, so you don't need to keep track of it directly. Perhaps zetdotpi wanted to use the cadence and gearing to figure out speed -- but when coasting he'd need to rely on the GPS anyway. So it's probably better to have a speed sensor.
Jul
18
comment Is it possible to estimate road grade while riding?
let us continue this discussion in chat
Jul
18
comment Is it possible to estimate road grade while riding?
A virtual elevation module has been built into Golden Cheetah; it's called Aerolab, and can use wind data if its available. As for a wind sensor people are definitely working on them.
Jul
18
comment Is it possible to estimate road grade while riding?
No smoothing kernel needed. We do need accurate speed and power data. There are other examples in that paper of comparing this method with altimetric barometers on big climbs and against public works road plans like here.
Jul
18
comment Is it possible to estimate road grade while riding?
Right, it was a slight headwind out / tailwind back (slight meaning a bit less than 2mph). If we hadn't known the wind speed we could actually have figured it out by guessing various wind speeds until the green and red profiles matched. But notice that the "inaccuracy" of the green profile is exaggerated because the scale is so small -- the vertical scale is in meters while the horizontal scale is in km, and the largest absolute error over the entire course was only about 40 meters and the absolute error in estimated slope was only about 0.25%
Jul
18
answered Is it possible to estimate road grade while riding?
Jul
17
comment What is guttering the peloton
The gatekeeper usually sits at the rear of the echelon at the gutter's edge and doesn't rotate with the others. He allows a little gap to form in front of him so that the rider coming down the echelon has a spot to slip smoothly into, and then can rotate smoothly back up.
Jul
17
awarded  Nice Answer
Jul
17
revised What is guttering the peloton
added 6 characters in body
Jul
16
comment Why is it easier to follow a cyclist up-hill
@DavidJames In that case, Swain has probably miscopied the equation from di Prampero. You can see the correct power equation in Wilson and Papadopoulos' Bicycling Science, or Martin et al Validation of a mathematical model for road cycling power
Jul
16
revised Why is it easier to follow a cyclist up-hill
added 14 characters in body