7 ms·
> whose performance bottlenecks are imposed by the bike instead of themselves I'm a fluid dynamics researcher, and I'll tell you the money these people spend o
by semi-extrinsic 6y ago
> whose performance bottlenecks are imposed by the bike instead of themselves
I'm a fluid dynamics researcher, and I'll tell you the money these people spend on "aero" and "weight saving" and "higher drivetrain efficiency" stuff is 99.9% snake oil. Unless you are among the top 1000 road bike racers in the world.
Increasing your exercise load by half an hour per week, or spending a little time understanding and implementing aerodynamically efficient body posture or other forms of technique, will both yield improvements that are several orders of magnitude higher than the marginal improvements achieved by spending $$$ on "aero" and carbon fiber.
I've seen detailed calculations of rider performance that indicate a 500 g saving in frame weight (which is huge), over the course of a 120 km race with 1200 m climb, will save you a whopping total of 15 seconds on ~4 hours of race time.
- masklinn 6y ago> I'm a fluid dynamics researcher, and I'll tell you the money these people spend on "aero" and "weight saving" and "higher drivetrain efficiency" stuff is 99.9% snake oil. Unless you are among the top 1000 road bike racers in the world. So, biking audiophilia.
- tigen 6y agoAt least weight saving is easily measurable and indisputable. Audiophilia focuses mostly on areas that are not so easily quantifiable.
- darkerside 6y agoI've heard audiophilia derided as the practice of listening to the noise instead of the music, sand that was enough for me to get off the train and never think twice.
- locusm 6y agoCarbon frames are worth it for the damping factor alone if you ride for more than an hour a week IMHO.
- hazeii 6y ago>spending a little time understanding and implementing aerodynamically efficient body posture You might be interested in what we're up to [0], get in touch if it interests you. [0] https://bodyrocket.cc https://bodyrocket.cc
- semi-extrinsic 6y agoOoo, nice. This is quite clever - still will require insight and effort from the rider, but it should be less of a shot in the dark, if it works. I'm not in your target market personally, but I like the approach. Are you going all out with triaxial load in the seat post, or uniaxial (posterior)?
- hazeii 6y agoYou're asking the right sort of question :) Seatpost is actually one of the simpler sensors, without giving too much away it's sensing force in 4 different directions.
- ncmncm 6y agoI don't understand why you need to measure anything but instantaneous crank torque, speed, and (for completeness) pitch angle. Integrating power in vs acceleration out, the difference is loss. What am I missing? Does bad posture waste energy before it reaches the crank?
- mariodiana 6y agoMy understanding is that weight saved on anything that rotates has an even bigger impact, but that doesn't change what you've said. The vast majority of posers bragging about the 500 grams they've saved in parts are carrying an extra 10 pounds on their own frame.
- gameswithgo 6y agothe rotating weight thing is mostly myth, while true that rotating mass costs more to accelerate, cyclists don’t accelerate hard enough for it to amount to anything substantive. source: i did the math in excel
- wyre 6y agoWhat do you mean by “accelerate hard enough?” Can I see your math?
- AtlasBarfed 6y agoThe TdF pros disagree with you. Yes they can be traditionalist and have "pack mentality", but these people spend literally 6-10 hours on a bike straight. In particular, when you are bonking and trying to keep up with a group or get up a mountain, you become PAINFULLY aware of the deficiencies in your equipment. An extra pound on your bike when trying to keep up with your group up a 8% grade will feel like you're carrying an anvil.
- gameswithgo 6y agoaero changes can be quite substantive even for amateurs. on the order of a minute or so per 40k tt aero equipment and position and training are all orthogonal so it isn’t a question of picking just one.
- PragmaticPulp 6y agoI'm an engineer and a biker. If you only look at the numbers or try to run simplistic calculations, it's easy to think that bikers are just deluding themselves. But there's more to it than just numbers on paper, and there's more to biking than just riding in a straight line from point A to point B. Carbon fiber frames aren't just about saving weight. The Carbon Fiber has different flexibility and damping properties that result in a different feel, for example. My engineer friends make fun of me for spending $1K on a set of carbon fiber wheels, until I let them ride the bike. It only takes a few pedal strokes to feel how the reduced rotational inertia translates to faster acceleration. The advantages are even more significant when jumping or throwing the bike around, because the bike's moment of inertia is reduced significantly. Carbon fiber handlebars don't save much weight, but the damping properties make for a minor reduction in fatigue. Carbon fiber Derailleur arms will again only save a few grams, but they're more likely to spring back from impacts than metal pieces that will simply bend. More expensive shifters have better bearings and cables that make for more precise shifts, meaning less fiddling over time and less mental effort to make sure I'm only changing 2 gears instead of 3. The list goes on and on. Casual observers think we're just being silly and fooling ourselves with expensive parts. Meanwhile, I'm still buying the expensive stuff, enjoying it, and having zero regrets. At this point I just don't talk about it with any non-bikers because so many of them think they've got it all figured out.
- hyperpallium2 6y ago> reduced rotational inertia translates to faster acceleration \aside why not smaller (radius) wheels? Use higher gearing, and accept the bumpiness. Though for touring aot commuting, there's something pleasant about higher inertia.
- PragmaticPulp 6y agoLarger wheels roll over obstacles better. That's why most mountain bikes are 27.5" or 29", which is about as big as you can go without causing too many other compromises. Bumpiness isn't just a comfort issue. Your body ends up absorbing a lot of the up and down motion, which drains your forward momentum.
- 6y ago
- rgbrenner 6y agoIn theory, theory and practice are the same. In practice, they are not. Your post is what theory looks like when people forget the difference. Your theory leaves out tons of variables, including the condition of the road, and the differences in how materials deform under pressure. I've seen the stats you're referring to, and that's what it looks like in a lab with perfect conditions. Go ride a $400 bike and a nice carbon fiber bike. The difference is much more substantial than 15 seconds per 4 hours. It's less fatiguing, the pedals feel stiffer (cheap bikes feel mushy in the pedals), my speedometer has a higher average speed, it's easier to climb hills (flat surfaces like in the lab are rare on real world streets--flat roads are almost never 0% grade), etc. Sometimes you need to put down excel and actually do the thing you're theorizing about.
- gwicks56 6y ago"Ride up grades, not buy upgrades"
- audiometry 6y agoI am involved in the distribution of very expensive bicycle components. The demand is massive. From my commercial experience, this sort of stuff has lots of similarities with other branded goods (bags, watches, designer clothes). It probably is built to a higher standard than mass-merchandise, but people buy it for more reasons than the tiny theoretical improvement in performance. I reckon more people buy a Rolex as a signaling device than because it more closely to Swiss Chronometer accuracy standards. I think the same for lots of bike stuff. Not really a value-judgement (I'm thankful for my customers) but in many cases, it's not a pure performance-per-dollar value calculation that they're making.
- koonsolo 6y agoCycling is huge here in Belgium, definitely as a hobby. A semi-professional once told me how crazy it is that people with a beer belly spend a huge amout of money on their bike, just to get a few grams off. A proper diet could save them a few kilos for free.
- thechao 6y agoMy brother used to run a aftermarket Ducati performance parts company. “Racers” would swap out every bolt on the bike from steel to titanium (which is actually a terrible idea for a high end sports bike), yet leave the 15 lbs “toolbox” (which was a useless joke of a toolset) under the seat. Also, there’s a reason most jockeys (for horses) are tiny...