On Bicycles, and.... what else is there?

I've looked at this matter before, but one factor which I've seen continually neglected in all of the climbing power analysis estimates is the effect of grade variability. Road grade on climbs is almost never constant: it varies about a mean in some fashion. Yet the estimates are almost always done assuming constant speed, constant power. Now these estimates end up remarkably accurate anyway. Why? Because the grade variability effect is negligible? Well, no. It's because you're canceling one mistake with another. For example, you neglect grade variability, which always increases power, but you also neglect drafting, which always decreases power. How does grade variability increase power? It's because grade variability typically results in speed variability and speed variability yields variability results in variability in wind resistance and wind resistance, by virtue of being superlinear, is increased more by increases in speed than it is decreased by d...

Last time I analyzed some data from DC Rainmaker, probably riding around Paris, where I was surprised to find that he would have experienced less lateral chain deflection on a 1×11 set-up with a 44-chainring and an 11-25 cassette than he did with a compact 2×11 setup with 34-50 in the front and 11-25 in the back. This is because the 34-50 is a relatively wide chainring range, and one ends up having to chose between cross-chained options on the front: big ring with large cog os small ring with small cog, neither of which is a good choice, just to hit the mid-range of gears. Meanwhile the 1×11 is optimized for the mid-range. But what about rides with extreme terrain, climbing and descending? Here mid-range may be hardly used, spending most of the ride either in low climbing gears are large descending gears. Fortunately the second example I found, this time on the Di2Stats sample page , was highly representative. It's epic: a 60 mile ride with 9600 feet of climbing and descendin...

There's been an almost religious response to SRAM releasing 1×11 for the road. I find this puzzling, as to me it represents a valid choice for riding where super-wide range gearing isn't needed. And in the vast majority of the United States, the idea regularly riding extended steep climbs is at best a fantasy. It's restricted to European bike tours, etc. 1×11 provides basically the same gear spacing as 2×8, which honestly back in the day was fine, although also not for everyone, and those who wanted more went to triple chainrings. Today a lot of those who used triples back then are fine with wide-range 2×10 and 2×11 options. But if you want to avoid dealing with a front shifter, and maybe save a bit of weight, 1×11 can be an attractive choice. I was riding with an old colleague from Stanford Cycling, Mark, who's been riding SRAM 1×11 on hilly San Francisco Bay area rides and he loves it. But then he started racing with 2×6, and so learned to ride at a somewhat w...

After last week's Powertap snafu where I tried pacing myself off the power meter only to later realize it was substantially over-reporting power, I wasn't feeling super-warm-and-fuzzy today about following the same approach in what was essentially a mandatory new attempt at the Wednesday Noon Ride. Using the calibration cycle on the Garmin Edge 500 had appeared to restore the Powertap to the regime where it was able to stay in tune during coasting phases alone, and the numbers I typically saw in the display were more typical of the pre-Switzerland mediocre Dan than the "suddenly blessed with amazing fitness" Dan the Powertap had been assuring me had replaced it. Chris Evans and Brian Schuster of Squadra SF were at the start, two very solid climbers, especially Chris who'd been putting in an impressive string of mid-16-minute Old La Hondas with his approach of starting each week with a leg-ripping effort which I can only imagine matching for more than a mercifull...

Despite an early afternoon meeting for which I risked tardiness if anything went wrong, I felt a strong need to test my fitness on the Noon Ride, Wednesday edition, which climbs my favorite climb anywhere: Old La Honda Road. After the cheap LR44 batteries I'd last installed in my Powertap gave up the ghost a few weeks into my Basel Switzerland experience, I found some superior 357's (silver oxide) in a local combo department store / food store. This should have had me up and running but I didn't have the tool to remove the cover on the hub. I eventually brought it to a local shop, to see if the guy there could remove it with an open-end adjustable wrench, but it was too tight and the metal wrench risked damaging the flats on the hub cover. So I decided I didn't need power all that much in Europe and to wait until I got home. Indeed, the cover was on quite tight for some reason, and after applying some Tri-Flow to the interface between the cover and the hub, applyin...

On Friday afternoon, I decided to try again for a paved climb up to Gempen. I wanted to climb the road I'd descended on Thursday, the one I'd seen so many riders climbing. My nominal goal was a Strava top 10. I thought this should be attainable from the VAMs I saw on the leaderboard if I was feeling good. I decided to head out along the Rhein, crossing the river near where I was staying to the northern shore (German-side, but not Germany here), then heading east, crossing again near where the Birs river feeds into the Rhein from the south. Then I'd head southward to Dornach and begin the climb from there. I once again used Strava route-find, this time putting constraint points at the base of the climb and at the river crossing where I planned to recross the Rhein southward. I was mostly able to follow the thus designed route, and it was again an okay route, but not as scenic as I'd hope. That bridge crossing wasn't great, with some slightly dicey navigation...

Andrew Coggan published the following data on Twitter, showing a cyclist's power-duration data from two separate years: In the above, FTP is power which can be sustained for 1 hour. FRC is "functional reserve capacity" which represents how much work over FTP can be done. I've never myself tried to extract that, but it's a nice concept: similar to anaerobic work capacity in the critical power model. I extracted the data as best I could from the plot using PlotDigitzer, then fit my 4-parameter model using an envelope fit: The philosophy on the envelope fit is that only a limited number of durations represent a rider's best effort; most durations are part of longer efforts and so are sub-optimal for that particularly time duration. The fit only has validity if there are actually as many quality efforts as there are parameters in the model. So a 4-parameter model requires at least 4 quality efforts. The philosophy on the mean fit is to treat all duratio...

The past weeks have been dominated by priorities other than cycling or running -- the occasional ride, including a few in the gorgeous Amalfi Coast of Italy, but a lot of moving to a new neighborhood in San Francisco, travel, recovering from jet lag, and solving problems at work. So after resolving to "make time" for yesterday's Noon Ride Old La Honda, my rational expectations, my self-assessment of fitness, were low. Indeed, after having missed the Red Kite Patterson Pass Time Trial the weekend prior, an event I normally would have been excited about especially since it had a 3-4 master's category in which I'd have the reasonable hope of getting a top 3, I wasn't too disappointed. I'd not even looked at the racing schedule. I don't believe in racing without proper preparation. Long rides? Nope. Interval sessions? Not unless you count one ride in Amalfi. Extended climbs? Virtually none. At least my weight was fairly good, within 1 kg of my ...

After the last comparison, which was a ride with some steep hills in San Francisco, I did a few more rides comparing Vector to Powertap. On that previous ride, my maximal power curve had been somewhat depressed on the Vector. Further investigation showed it appeared to be due to two points where cadence anomalously dropped on the Vector (but not the Powertap). Since Vector multiplied force by cadence by crank length to get power, if any of the three is off, the power is off. The first of these two rides was a spin around Mountain View at lunch, stopping along the way to drop a package at the post office, then pick up some cherries at the local market (Ava's), then after a bit of a loop, a stop at Trader Joe's for figs and apricots. I made good use of my handlebar bag, combing some solid power efforts with fresh summer fruit for the afternoon. Here's the maximal power curve from that ride: The next day I rode into work with SF2G, the Dawn of the Dead variant of Bayway....

Last time I showed a comparison of Powertap to Vector power with a least-square line through the points. I noted this was "hard to interpret". Here's why. A traditional least-square fit begins by assuming that the x-values are perfectly known, the y-values are uncertain. It additionally assumes that the y-values are normally distributed, with a Gaussian probability distribution, with the error distribution the same for all points, or with variances inversely proportional to the weighting factors for a weighted least-square fit. This seems like a lot of technicality, but it introduces subtle biases in the result when comparing two values whcih contribute relatively equally to the error. For example, consider my power comparison for the Garmin Vector to the Powertap: The slope was 0.97. Therefore, if I flip the axis the slope should be 1.03%. If the Vector is 3% lower than Powertap than the Powertap is 3% more than Vector, on average. But that's not what I ...

Last time I compared Powertap to Vector on my Winter Allaban, I had failed to properly set the crank length on the Garmin 800. I'd set it on the Vector, but the menu item on the Garmin is a bit tricky to find, as it only appears when it is in communication with a Vector, so if you scan the menus without activating the Vector and pairing the Edge to the Vector you'll never see it, as I did not. I actually first confirmed my Edge was asserting the wrong cranklength by running the settings.fit file through fitdump. But this is a digression. I basically repeated my first calibration ride, heading steep 14th Street to Buena Vista in San Francisco and doing one-legged climbing on a more gradual grade, then riding home and doing a sprint. I previously did three comparisons where the maximal power curves of the Powertap and Vector were remarkably coincident after I scaled one of the powers by an empirically determined factor close to the 85% value which I later discovered was the r...

Thursday of both last week and this week I did a sprint workout. This involved cruising over the Sunnyvale Trader Joes, buying some rice tortillas, goat chedder, and organic blueberries, stuffing them in my pocket, then cruising residential Sunnyvale streets to the Steven's Creek trail. Along the way, on roads of relatively smooth pavement and with enough length between intersections, I do some sprints (4 each of the weeks). Then I cruise the Steven's Creek trail back across the freeway mess and do a few more (2 the first week, an extra the 2nd week when I sprinted for a green light). I'm not sure how much these help the sort of riding I do. But I think improving the top end potentially offers benefits at lower powers, as well as if I need to put in hard efforts to close gaps. I've not been a position where I was sprinting to win races in quite a long time. But sprint repeats challenge multiple aspects of riding: muscle strength, neuoromuscular coordination, pedal ...

After last week's disappointment on Old La Honda, I did a sprint workout the following day (Thursday), then rode in at tempo on Friday with Jason. But there was no riding through it. I was cooked. I needed some days off. Saturday & Sunday were total "rest" (actually doing home stuff which absolutely needed doing). Monday and Tuesday I was still feeling fatigued, so I took the train to work, riding only to-from the train. Finally, today, I felt energetic again, ready for another try at Old La Honda. Like last week, Greg and Kieran set a ferocious pace from the start, with Mark in tow. I let them go. But unlike last week, I wasn't in a chase pack, but rather solo. But also unlike last week, Mark didn't try to hang with the leaders too long. He dropped off and paced himself very nicely the rest of the way. And the whole rest of the way I chased him. I focused on trying to maintain a steadier pace this time: keep a cap on it at the beginning when I felt ...

I typically use my Powertap on training rides, but when racing, I've not done so since I placed third Ross's Epic Hillclimb up Pine Flat Road in Sonoma back around 2008 or so, At the climb, I'd decided the added weight of my Powertap wheel was worth it for the pacing advantage of power. Unfortunately, my battery died on the start line, so I carried the substantial extra mass of the Powertap up the hill for no advantage. Despite the lack of power, though, I had arguably the best climb of my life, staying with a critical surge I might well have not gone with had I been pacing off the meter. That surge led into a flat/slightly descending part where being with the group was a critical advantage. When the climbing began again, steeply, I felt as if I was going to crack, but then most of the others cracked more. Without the weight of that wheel I may well have been one place better. But power is also useful for post-ride analysis. But for that, I rely on the standard power...

I did the Noon Ride again on Wednesday, up Old La Honda, and I had high hopes. I'd had a recent block of training since the last time I'd done it 6 weeks prior , including the 4-day Memorial Day Tour, always good for a fitness boost. But I'd been feeling fatigued in the 1.5 weeks since the tour. Wednesday, riding out to the Noon Ride start, was the first time I felt legitimately good. Not frisky, race-ready good, but "I can climb Old La Honda" good. At the start, Maciek from SF2G asked what my goal was. "I've got to do 18:30", I told him. I figured just lay it on the line there. 18:30 is a decent time on the Ritchey Breakaway, which I was riding. With Powertap wheel, no bottle, no GPS, no toolbag, but with pump and two cages it's 18.32 lb. That probably made it the heaviest bike on the ride by a decent margin, but still, not too bad. Hitting the base of the climb I was near the front, but got pushed toward the back when we had to wait fo...

The plot thickens... Another day, another ride. This time I made sure to do a static zero test before the ride. I further checked that I had the latest firmware in my Edge units (Mac WebUpdater says I did). I was full of hope that the crank length fix had corrected things. So I set off on a ride to fetch new contact lenses, but where I took "scenic detours" up five significantly steep, significantly painful climbs in San Francisco. For the record: 17th from Market to Twin Peaks (and on to Twin Peaks summit), Sanchez from 17th to 18th, Church from 18th to 21st, 21st from Church to Sanchez (these two are contiguous, but I took a break in between, not initially planning to ride 21st, which is daunting), and finally, just because I felt like I could, the ever-painful 22nd from Vermont to Carolina. No luck. My suspicion now is that the head unit is overriding the crank length setting. Issue is I don't know how to change the crank length in the head units. In the 510 ...

Last time I did a comparison of my Powertap versus Vector. I'd had strong reason to believe the Vector was reporting low, and the test confirmed it. The maximal power curves lined up fairly nicely when I multiplied the Vector power by 0.84 (emphasis on fit to high powers). Since the Vector should measure more power than the Powertap, this indicated an error somewhat greater than this. You'd expect the Vector to measure more power, because the Vector power includes power which doesn't make it to the rear hub and is instead lost in the drivetrain. This power loss includes losses which are proportional to load (like bending the chain under a high-tension state at the top of the run) and losses which are independent of load (like spinning the pulleys). The result is that drive train losses, as a fraction of total power, are higher at lower powers than higher powers. What I saw was consistent with this, which was a good sign. The obvious candidate was that I'd not inse...