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Jul
31
comment How much speed can I buy
If money were no object, you could spend it on a streamlined vehicle like the Delft VeloX. It has CdA < .02 m^2 and special $400 tires (that are good for perhaps 20 km of use) with Crr < .002. On a flat road and zero wind, at 140 watts and a total mass of 105 kg you ought to be able to achieve ~ 80 km/h.
Jul
31
comment How much speed can I buy
We have long known what it takes to go faster: either increase the power you can make or reduce the power you must make. If your power output is fixed, you're looking at reducing the power needed to overcome drag. That means reducing rolling resistance, aerodynamic drag, and efficiency losses. Compared to typical tires/tubes the best can reduce the coeff of rolling resistance from perhaps .006 to perhaps .0025. Drivetrain efficiency can be improved from typical 95 or 96% up to maybe 97%. Aero drag on a standard bike can be reduced from perhaps .4 m^2 to under .3 m^2.
Jul
28
comment Are Osymetric chainring and power2max Classic power meter compatible?
That was just an example -- there are other times when absolute accuracy matters. It's just that training typically isn't one of the uses for a power meter that requires very high data fidelity; that's why people have been able to train effectively without one. There are, however, things that would be very difficult to do without a power meter, and these generally require accuracy. An example is VO2Max testing with a ramp protocol, since the ramps need to be of known and equal size.
Jul
28
comment Are Osymetric chainring and power2max Classic power meter compatible?
Absolute accuracy (rather than relative accuracy) can matter depending on what you're doing. For example, if you are trying to estimate aerodynamic or rolling resistance, you'll need absolute accuracy across the range of speeds you're likely to experience.
Jul
20
comment Descending without braking: where's the sweet spot?
@StephanMatthiesen In almost all cases what matters is CdA rather than the separate components Cd and A. In general, you measure the total drag in Newtons or lbf, then convert that to CdA, then if you're really interested you measure A and divide to get Cd.
Jul
18
comment Is there a standard equivalent for effort between distance and elevation?
@TomSterkenburg We discussed how to calculate drag resistance in this stackexchange question: bicycles.stackexchange.com/questions/9938/…
Jul
16
comment Why are so many technical aspects of cycling so subjective?
There is testing but mostly it's not widely known. For your particular example, see here and here.
Jul
10
comment Swain Power-HR relation
Exactly, though you'll want to exhaust your anaerobic capacity or else you'll overestimate VO2Max. That's why VO2Max tests are usually done with a ramped protocol, and the estimates are done off the final step before failure. In your example, you don't want to use the average of 97kJ for 5 minutes, instead you might want to use the max power over the last minute of a ramped protocol (or another similar protocol where you've exhausted the anaerobic component).
Jul
10
comment Swain Power-HR relation
Ah, okay. The issue is that even if you have HR, you don't have stroke volume which is what you need to get cardiac output. However, if you know metabolic efficiency (net or delta or work efficiency are better than gross efficiency, but sometimes all you have is gross efficiency) you can go from work to get L of O2 consumed, so if you have total mass you can estimate VO2Max. So you don't really need HR -- Swain was using that because he didn't have power, but you do. So do a VO2Max-level power effort and convert directly to estimate VO2Max.
Jul
10
comment Swain Power-HR relation
Can you clarify your question? The Swain model is used to estimate power when you know heart rate, VO2Max, and metabolic efficiency. You appear to have power and HR. Are you trying to go backwards to estimate VO2Max, or metabolic efficiency, or something else?
Jul
3
comment Is there a standard equivalent for effort between distance and elevation?
It's complicated but not terribly so if you know power and speed. That's the basis for the "virtual elevation" approach for estimating cycling drag -- it converts effort (in terms of power and speed) into elevation gain.
Jul
3
comment Is there a standard equivalent for effort between distance and elevation?
Sure there's a way to convert % climb into level miles. All you need to know are a handful of things: your total all-up mass (including you, your bike, and all your equipment), your coefficient of rolling resistance, your coefficient of aerodynamic drag, the wind speed, and your ground speed.
Jul
3
comment Is there a standard equivalent for effort between distance and elevation?
@DanielRHicks If you use a power meter you can estimate "fatigue profiles" that show how power decreases with duration of effort. People who have done so have shown individual consistency under wide (but not extreme) ranges of pedal force and pedal speed conditions. That is, your fatigue profile may differ from mine, and each can change with fitness and training, but otherwise, yes, there is some science to calculating fatigue and recovery rates.
Jul
2
comment Is there a standard equivalent for effort between distance and elevation?
A third option is to track "session RPE" using the 10-point (or 20-point) Borg scale, which doesn't require any hardware investment at all -- and, once you know how to use it and get some experience, is roughly about as accurate as looking at average heart rate.
Jun
21
comment Knee position while on the aero bar
It's hard to tell from these photos so take these as comments and questions rather than an answer -- but it seems like that frame may be a bit big for you. Putting aero bars on a road bike isn't ideal -- if you're doing draft-legal you may want to investigate ITU-legal mini-aero bars. Where is the tip of the saddle in comparison to the BB? I'm not a big fan of KOPS or related fitting systems but if you are, then when you drop a plumb line the bike has to be horizontal, and it appears that your bike is being held in the rear on a trainer but the front wheel is on the floor.
Jun
10
comment Why exactly did Boardman manage a further distance than Wiggins?
It's actually not that uncomfortable -- I've experimented with it. That said, it's definitely harder to control the bike so I wouldn't recommend it unless you were on a straight flat road or a velodrome. Alone.
May
21
comment What is a power meter and why do I need one?
@ChrisCleeland I sort of disagree. I've never been much of an athlete on a bike and a power meter has helped me quite a bit. I got one before I had a TT bike, and this answer, while good in general, mostly addresses the idea that a power meter is only good for training FTP. Power meters can also be used for other things than training FTP -- in fact, training is one of the least demanding things one can do with a power meter.
May
5
comment what power did alex dowsett put out during his hour record?
The rider is allowed to receive very limited information, according to UCI rules: pace, distance covered, or time. If the velodrome is quiet you can shout out lap times but generally for record attempts you use a chalkboard -- though of course more recently teams have been using iPads or other tablets. You don't want to give the rider too much distracting information.
May
5
comment what power did alex dowsett put out during his hour record?
A power meter was mounted on the bicycle but according to UCI rules no visible display is allowed so the data are either for review post-ride or can be transmitted to a track side computer for real-time analysis.
Apr
5
comment How many miles of riding require the same effort as one mile of running?
@StephenTouset, I've done a similar thing for short duathlons, where you have a bike leg in-between two run legs. Here's an example of the splits: anonymous.coward.free.fr/wattage/duath-splits.png