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Aug
30
comment Accurately replicating the resistance felt whilst riding via a resistance fan diy turbo trainer
@DanielRHicks, Alex is familiar with the inertial load. Here is his home-built resistance trainer and its flywheel. User95786, here are some estimates of the drag parameters (the "virtual" CdA and Crr) for the Lemond Revolution. Perhaps that will help you in building your own.
Aug
11
comment How do I use my power meter file to improve my time up this steep hill climb tt?
In general, constant power output gives you the best times when the conditions (slope and wind, mostly) are constant. So pacing is an obvious place to look, but that depends on having a power meter that is accurate (not just consistent) over a wide range of pedal force and pedal speed. So it might be important to check your PM before relying on it to pace or to isolate gearing choices.
Aug
11
comment How do I use my power meter file to improve my time up this steep hill climb tt?
And, btw, there is a way to calculate the gear ratios you used -- but not necessarily the gear ratios you should have used. That's an entirely different question.
Aug
11
comment How do I use my power meter file to improve my time up this steep hill climb tt?
I'm sorta surprised you could hit 500 watts near the end of this TT since you did the first 3 minutes at ~370ish. So, you may be able to improve your time with better pacing. However, you'll also want to be sure your PM is working properly. From your other question it appears this is from a Stages, right?
Jul
22
comment What's the lowest safe cadence on a climb?
@DanielRHicks: you're right that max pedal force isn't constant across all cyclists but the classic dataset collected by Kautz (isbweb.org/data/kautz, or anonymous.coward.free.fr/rbr/kautz.png) shows that max pedal force is roughly twice avg. pedal force (in the Kautz data, max is 1.85x avg), whence the rule of thumb cited above. This has been verified by more recent pedal-based power meters like the Garmin Vector.
Jul
22
comment What's the lowest safe cadence on a climb?
It's easy to calculate the maximum force at the pedal but it's hard to calculate the "safe" force at the knee since that depends on your knee. A reasonable rule of thumb is that max pedal force is around 12*watts/rpm, and that applies whether riding on the flat, gentle climbs, or brutal climbs. Of course, on brutal climbs you'll need the right gearing to keep your power down -- with your current gearing up a 15% slope your power at 90 rpm wouldn't be 225 watts.
Jul
21
comment What's the lowest safe cadence on a climb?
BTW, from the information given in your question, it appears your max pedal force will be around three-quarters of your body mass (i.e., less than your body mass).
Jul
21
comment What's the lowest safe cadence on a climb?
Does the section labeled "Cadence and knee strain" in this bicycles.stackexchange answer address your question? bicycles.stackexchange.com/questions/12518/…
Jul
13
comment How do I train for climbing in a relatively flat area?
There is insufficient information to give a good answer. Are you trying to race up these climbs, or are you just trying to survive up these climbs? How long and how steep are the most difficult climbs you anticipate doing? Will you be riding with others with whom you're trying to keep up, or can you set your own pace?
Jul
12
comment When Mark Cavendish says he's sprints at 1500 watts how long is that for?
Cavendish was the subject of Menaspa's 2013 article in IJSPP so it is particularly on point for this question.
Jul
9
comment Analysis of Stages high-speed data
Welcome to bicycles.stackexchange, Andy.
Jul
7
comment Analysis of Stages high-speed data
@Oscar The negative parts do reflect counter-acting torque but it appears dbr may have been coasting at the time rather than pedaling. I included the calculation just to show the anomaly. If I were were doing this in "production mode" I would almost certainly record that as zero power, and tine-tune the analytical algorithm to produce average power over a second rather than over a crank revolution.
Jul
7
comment What is the effect of changing length of crank arms?
It's been studied quite a bit but usually from the perspective of muscle shortening speed so searching for "crank length" won't always find the right studies. But perhaps this little empirical experiment is closer to what you had in mind: bikeblather.blogspot.fr/2014/07/…
Jul
6
comment Analysis of Stages high-speed data
He may not have pedal angle but he does have a timestamp and thus elapsed time between peaks of the force or torque curve. Since the Stages only measures forces on the left crank, you could integrate over the cycle and do what Stages does: double it to get total power. If you were obsessive, you could do what has been proposed elsewhere: use the difference in trough-to-peak time to peak-to-trough time as an estimate of L/R balance to get a refined estimate of total power.
Jul
5
comment Analysis of Stages high-speed data
Here's my concern and hesitation: I'm puzzled because the patterns of those torque or force values aren't what I expected to see. Here is a plot of torque measured from special force-sensing pedals from the classic Kautz study on pedaling dynamics. anonymous.coward.free.fr/rbr/kautz.png In particular, single-sided torque (such as I would expect from the Stages) isn't as even as what I'm seeing in your data.
Jul
5
comment Analysis of Stages high-speed data
@dbr, here's a plot of the kgf and timestamp from your "full" data file: anonymous.coward.free.fr/wattage/stages/dbr2.png (and here's a plot of the first 128 kgf samples: anonymous.coward.free.fr/wattage/stages/dbr1.png)
Jul
5
comment Analysis of Stages high-speed data
Can you say a bit more about the full data set? Could it be that you did about 20 seconds worth of pedal strokes at roughly 60rpm, then coasted down, then did another 15 seconds or so at a slower cadence? Or am I completely off?
Jul
2
comment What is the effect of changing length of crank arms?
The Martin et al. study looked only at max power but the results have been the same for submaximal power: over a wide range of crank lengths, submaximal power does not appear to be affected. That means you can choose crank length on other criteria, including personal preference, clearance or cornering issues, fitting or range of motion issues, or even because a crank is on sale, without worrying that it will decrease sustainable power. It also means that changing crank length won't increase sustainable power. Which is to say, it's been studied a lot.
Jun
28
comment Is it worth it to get a bike computer with cadence?
What was it about the Cateye Micro that it gave excellent cadence, and how do all current cadence measurements fall short of that? For what purposes does one need Cateye-level cadence accuracy that one cannot achieve with other levels of accuracy?
Jun
27
comment Allen Coggan power profile table for Cyclo cross riders?
Closer to an all-rounder but there's a slight difference depending on the type of cyclocross you race on. Generally speaking, European cyclocross runs are a little longer, North American cyclocross runs are a shorter and steeper. Also, it appears Coggan is de-emphasizing power profiles and is switching to FRC profiles.