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Efficiency On a Bike

From reader Peter K in Sweden

My comments follow below.

I also own light wheels, true sub-1000g. But I don't have your hills, so I now prefer deep 1700g-wheels; they're easily faster here. That's not just plain guesstimating.

Actually, as an example, I could analyze your Everest stages and give an estimation just how much difference your wheels made, your own weight loss, and things like a skin suit, aero frame, deep wheels etc could do. Likely, you've done the right things, above all loose weight and gain power. I do need complete power and altitude data of good quality, and preferably a GPS track, which I guess you don't have then. I understand if this data is private.

You might (or might not) want to read things like this;
https://biketechreview.com/reviews/wheels/63-wheel-performance
https://www.analyticcycling.com/DiffEqWindCourse_Page.html

...

Quadrant analysis is used by many teams/coaches for understanding how power is generated.

Splitting power in wind resistance and other parts can help you improve your aerodynamics. That's partly where GPS comes in, for tracking down wind from weather stations.

Seeing what a weight change, a power change, or an aerodynamic change over an actual run you've made, helps in understanding what really matters in cycling performance.

…which is not light bikes by the way, unless you climb, like you do. Light wheels do very little also; a really slight aero improvement has a much bigger impact on everything but the most hilly courses. But this is a secret the industry does not want to be spread; light parts makes the cycling economy go round…

I also get motivated by making my data good looking when I'm out, guess I am a geek. It did improve my FTP in W/kg from 3.3 to 4.8 in one year, though - I'm happy :)

DIGLLOYD WIMF: In an endurance race like the Everest Challenge 2-Day Stage Race, it’s complicated. It is not a lap course, and there is highly variable local weather in each climb. It can be hot and threaten snow on the same day. And mountain weather can change in dramatically in 2-3 hours.

The “unless you climb” hits rather wide of my mark: 70% of the time spent in EC is steep climbing, with another 15% on moderate hills. The last 15% is the flat areas. So it’s all about climbing, steep climbing.

For that matter, I train with lots of climbing. Deep aero wheels are just a drag, literally and figuratively. I have been testing the new Lightweight VR8 eight-spoke wheel, and it’s great for descending and flat ground, but for climbing? No.

Heat and cold

Heat (and sometimes cold) is a major issue; one cannot dress for the morning and hope for the best; some years there is a 65° F temperature swing (36°C). Or it could snow at the summit and be 26° C in the lowlands. More than likely it could be 40° C on a steep climb though 2011 didn’t seem to hit much over 33° C (92° F). A full-zip jersey for maximum cooling is the best choice, because heat is the enemy most years.

Aero wheels

Well, I don’t know everything, but here is my take.

As for aero wheels, I did use my Obermayers which are 987g for the set, and very good aerodynamically. This is the optimal combination for EC: Low weight is a guaranteed win on the climbs, reasonably aero for the descents. Most riders run even shorter rim sections.

Light wheels FEEL great. And psychology plays a major role in all types of racing, a positive feedback loop is no small matter.

Heavier aero wheels are a guaranteed loss on a climb in a race where 70% of the time is spent climbing at speeds under 10mph, and not much faster than that for another 15% of the time. There just isn’t much drag up to 15 mph.

1700g wheels: I calculate a penalty of 4.6 minutes for the climbing sections of EC, relative to my 987g Obermayers. I doubt that any aerodynamic advantage over my Obermayers would make up for that difference. Going 51 mph or 52mph instead of 50 mph on a descent is of dubious value, especially if one can manage a draft of another rider. Also, the wind drag from body and bike is huge relative to the wheels. And aero bars are prohibited for the EC, so I think it’s likely that the body/bike dominates the drag equation.

Deep aero wheels could be dangerous, even deadly if the conditions change down some of the descents: I have personally experienced side gusts in the 30-40 mph range; these side gusts can blast suddenly with little warning, around a corner, etc. It is risky to have a deep dish wheel in such conditions, with death the probable result if one crosses the edge of the road on the fast descents, albeit with a short delay before hitting the rocks.

I braked lightly on some downhills because I encountered some gusts that were pushing me around too much; 40-45 mph was my comfort limit, even though I could have been doing 50+ mph. I am not a pro, and I am not going to risk death to win. So I gave up perhaps a minute on the Glacier Lodge descent. Worth it. Deeper aero wheels would have forced even more speed reduction, since they would have been even more subject to side gusts.

There are some flat sections in the Everest Challenge, but these do not last very long. Aero wheels would be helpful there, but far more useful would be sharing the load by drafting a fellow rider in the same competition group. Better to optimized for climbing, then be strategic on the flats.

Weight and power transfer is what matters when climbing steep stuff

The Everest Challenge is all about steep climbing, most climbs are even beyond the ratings.

The #1 thing that matters is how much total weight (bike, body, gear, water) one carries up 29,000' of climbing. That of course assumes that one rides a bike that efficiently transfers power to the rear wheel, which itself should have minimal power loss (be stiff in terms of power transfer).

Context

Performance data for wheels taken out of context is an issue: a long day riding means some comfort is mandatory. A stiff aero wheel could harm performance far more than a comfortable and just slightly less aero wheel by leaving the rider feeling beaten up.

Analysis: "ysis" = to pull from, you know where. Analysis for a race like EC is silly because so many assumptions have to go into the calculation. EC is a varied course with conditions that can vary wildly hour to hour, let alone year to year. There is no private support allowed (e.g., for a bike or wheel swap), so one has to pick a wheelset and live with it.

My conclusion, seemingly matched by the competitive riders in EC is that a reasonably aero wheel that is as light as possible with good power transfer (rear) is as much as one can hope for. I opted for an extremely light wheel as I think this is a net win over any marginally more aerodynamic and heavier wheel. The Obermayers are 987g for the set, and I ran the feather-light Veloflex Record tires on them.

Cumulative ascent for 2011

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