5 ms·

To a point, weight is less of a concern in the modern era because aerodynamics dominate at almost all speeds. I’ve always found NDD bikes interesting but I sus

To a point, weight is less of a concern in the modern era because aerodynamics dominate at almost all speeds. I’ve always found NDD bikes interesting but I suspect the advantages are overstated given the top pros are moving away from them. LCB and Sam Laidlow both rode “classic” TT-style bikes to win the Ironman WC last year.

AtlasBarfed 3y ago
Yeah at the pro-ish level of triathlon, I think you need stiffness even in 112 mile bike legs. These aliens are doing 25-27mph, if you have the inevitable sway from the lack of the triangle, you'll lose power to the drivetrain. The Pros might get to piggyback on some of the wind tunnel testers here or there for reasonable amounts, and the "NDD" bikes might not really stack up much in the "total system" aero testing. One might think that ultraskinny 18mm tires would be more aero, but 1) they have bad rolling resistance and 2) they actually aren't, at least for a while the pro teams were using 25mm tires because aero testing said it was better + lower rolling resistance. Point is, aero is weird. But I haven't followed the state of the art of the last three or four years. Finally, modern tri bikes shape themselves for onboard nutrition transport and integrated fluids, sometimes in the tubes. They also have storage boxes for the flat kit. Ironman triathletes care a lot about that. The article makes it seem like these are all fresh off the design board, but these have been around for, what 5-7 years now? I was kind of hoping for more designs in the article, but these are basically what was the cutting edge back then. I would hope the 10,000$ price tags would have come down, but I doubt it. And the other laughable thing is the wheels in those bikes. Where are the disc wheels? A disc wheel is often more important than the frame and helmet. It's funny. You spend 200$ for an aero helmet, that's 1/3 of the gain, another $2000 for aero wheels, that's 1/3 of the gain, and then 10,000$ for a frame, and that's the last 1/3 of the gain. BTW. The lotus was my favorite bike ever. https://www.theproscloset.com/blogs/road-bikes/colby-pearces-1995-lotus-sport-110 https://www.theproscloset.com/blogs/road-bikes/colby-pearces...
- scott_w 3y ago
  > These aliens are doing 25-27mph, if you have the inevitable sway from the lack of the triangle, you'll lose power to the drivetrain. I suspect they're actually really stiff because of the amount of carbon fibre in the construction. What I also suspect is the aerodynamic gains are being overstated in the real-world, which would explain why the pros are going for more standard bikes. The current brands (Canyon, Specialized, Argon-18, Cube) are probably close enough (or faster) in practice that the sponsor money is a better trade-off. > And the other laughable thing is the wheels in those bikes. Where are the disc wheels? A disc wheel is often more important than the frame and helmet. For performance, I 100% agree. That said, disc wheels from the big brands are expensive enough that $10,000 still doesn't cover it. And they probably don't want to put cheaper Chinese wheels on for image purposes (though owning an Elitewheels disc, I'd suspect they're in the same ballpark for aero performance). > then 10,000$ for a frame, and that's the last 1/3 of the gain. It's probably even less than that (going from one TT frame to another) but, hey, if it looks fast, isn't that the real victory? ;-)
- Lio 3y ago
  Totally agree on the Lotus. Although I prefer the original 108 design to the 110. Seeing Chris Boardman win on it at the Barcelona Olympics was like seeing something arrive from another planet. It left quite an impression on a young me. I know a bike shop owner with one of the road versions in his private collection. Seeing it up close is... like being near a religious relic. Yep I am a cycling nerd! :D https://en.wikipedia.org/wiki/Lotus_108 https://en.wikipedia.org/wiki/Lotus_108
- pmontra 3y ago
  Pro teams are going 28 mm or even 30 mm at the front and 32 mm at the back. Some measurements from Tour de France 2023 at [1] One of the reasons why larger tires are better is that the size of the contact patch to the road depends only on the internal pressure of the tire. A 20 mm tire and a 40 mm tire have the same contact patch but their shape is different. The one of narrower tire is aligned back to front so the wheel is less round. The contact patch of the wider tire is aligned right to left, so the wheel is more round and it rolls more easily without dissipating energy in elastic deformations. You'd have to inflate the narrower tire to double pressure to compensate, but then the ride is less comfortable and you can double the pressure only up to a point. That was about rolling resistance, then there is aero. Wind tunnel tests discovered that tires should connect smoothly to the profile of the rim without making the classic shape of everyday bike's wheel: a wide tire in narrow rim. They must have the same width instead and a fatter rim is more aerodynamic than a skinny one. Hence the drive to wider tires. However there is catch. A wider tire adds more mass to wheels and they are the worst place to add mass to because it works against you every time you have to make that wheel spin faster. You add mass to the frame and all the static parts of the bicycle if you really have to. And finally a very large tire (100 mm or 4 inches) is obviously too wide to have a reasonable front surface at high speeds. The sweet spot nowadays seems to be around 30 mm. Note that UCI mandates cyclocross tires to be 33 mm max, and they must work in muddy conditions. Road bikes are at almost those widths. [1] https://escapecollective.com/what-we-learned-by-measuring-tyre-widths-at-the-tour-de-france/ https://escapecollective.com/what-we-learned-by-measuring-ty...
  - scott_w 3y ago
    > A wider tire adds more mass to wheels and they are the worst place to add mass to because it works against you every time you have to make that wheel spin faster. If I recall correctly, this isn't a big deal because accelerating the rotating mass is assisted by the (equal) mass on the other side of the wheel, so adding weight doesn't really make any difference vs adding that same weight on the frame. Where it can hurt is cornering. GCN did a video that suggested increasing width increases grip and cornering... to a point. Once you exceed that point, you spend more time moving the bike "over the tyre" and have a hard time cornering.
- prmoustache 3y ago
  > Yeah at the pro-ish level of triathlon, I think you need stiffness even in 112 mile bike legs. meh it is not that simple. Vibration loss and fatigue is something that is more and more studied these days in cycling. What is fastest in the first 10km might not be the fastest setup 3 hours later.

AtlasBarfed 3y ago

Yeah at the pro-ish level of triathlon, I think you need stiffness even in 112 mile bike legs. These aliens are doing 25-27mph, if you have the inevitable sway from the lack of the triangle, you'll lose power to the drivetrain. The Pros might get to piggyback on some of the wind tunnel testers here or there for reasonable amounts, and the "NDD" bikes might not really stack up much in the "total system" aero testing. One might think that ultraskinny 18mm tires would be more aero, but 1) they have bad rolling resistance and 2) they actually aren't, at least for a while the pro teams were using 25mm tires because aero testing said it was better + lower rolling resistance. Point is, aero is weird. But I haven't followed the state of the art of the last three or four years. Finally, modern tri bikes shape themselves for onboard nutrition transport and integrated fluids, sometimes in the tubes. They also have storage boxes for the flat kit. Ironman triathletes care a lot about that. The article makes it seem like these are all fresh off the design board, but these have been around for, what 5-7 years now? I was kind of hoping for more designs in the article, but these are basically what was the cutting edge back then. I would hope the 10,000$ price tags would have come down, but I doubt it. And the other laughable thing is the wheels in those bikes. Where are the disc wheels? A disc wheel is often more important than the frame and helmet. It's funny. You spend 200$ for an aero helmet, that's 1/3 of the gain, another $2000 for aero wheels, that's 1/3 of the gain, and then 10,000$ for a frame, and that's the last 1/3 of the gain. BTW. The lotus was my favorite bike ever. https://www.theproscloset.com/blogs/road-bikes/colby-pearces-1995-lotus-sport-110 https://www.theproscloset.com/blogs/road-bikes/colby-pearces...

scott_w 3y ago
> These aliens are doing 25-27mph, if you have the inevitable sway from the lack of the triangle, you'll lose power to the drivetrain. I suspect they're actually really stiff because of the amount of carbon fibre in the construction. What I also suspect is the aerodynamic gains are being overstated in the real-world, which would explain why the pros are going for more standard bikes. The current brands (Canyon, Specialized, Argon-18, Cube) are probably close enough (or faster) in practice that the sponsor money is a better trade-off. > And the other laughable thing is the wheels in those bikes. Where are the disc wheels? A disc wheel is often more important than the frame and helmet. For performance, I 100% agree. That said, disc wheels from the big brands are expensive enough that $10,000 still doesn't cover it. And they probably don't want to put cheaper Chinese wheels on for image purposes (though owning an Elitewheels disc, I'd suspect they're in the same ballpark for aero performance). > then 10,000$ for a frame, and that's the last 1/3 of the gain. It's probably even less than that (going from one TT frame to another) but, hey, if it looks fast, isn't that the real victory? ;-)
Lio 3y ago
Totally agree on the Lotus. Although I prefer the original 108 design to the 110. Seeing Chris Boardman win on it at the Barcelona Olympics was like seeing something arrive from another planet. It left quite an impression on a young me. I know a bike shop owner with one of the road versions in his private collection. Seeing it up close is... like being near a religious relic. Yep I am a cycling nerd! :D https://en.wikipedia.org/wiki/Lotus_108 https://en.wikipedia.org/wiki/Lotus_108
pmontra 3y ago
Pro teams are going 28 mm or even 30 mm at the front and 32 mm at the back. Some measurements from Tour de France 2023 at [1] One of the reasons why larger tires are better is that the size of the contact patch to the road depends only on the internal pressure of the tire. A 20 mm tire and a 40 mm tire have the same contact patch but their shape is different. The one of narrower tire is aligned back to front so the wheel is less round. The contact patch of the wider tire is aligned right to left, so the wheel is more round and it rolls more easily without dissipating energy in elastic deformations. You'd have to inflate the narrower tire to double pressure to compensate, but then the ride is less comfortable and you can double the pressure only up to a point. That was about rolling resistance, then there is aero. Wind tunnel tests discovered that tires should connect smoothly to the profile of the rim without making the classic shape of everyday bike's wheel: a wide tire in narrow rim. They must have the same width instead and a fatter rim is more aerodynamic than a skinny one. Hence the drive to wider tires. However there is catch. A wider tire adds more mass to wheels and they are the worst place to add mass to because it works against you every time you have to make that wheel spin faster. You add mass to the frame and all the static parts of the bicycle if you really have to. And finally a very large tire (100 mm or 4 inches) is obviously too wide to have a reasonable front surface at high speeds. The sweet spot nowadays seems to be around 30 mm. Note that UCI mandates cyclocross tires to be 33 mm max, and they must work in muddy conditions. Road bikes are at almost those widths. [1] https://escapecollective.com/what-we-learned-by-measuring-tyre-widths-at-the-tour-de-france/ https://escapecollective.com/what-we-learned-by-measuring-ty...
- scott_w 3y ago
  > A wider tire adds more mass to wheels and they are the worst place to add mass to because it works against you every time you have to make that wheel spin faster. If I recall correctly, this isn't a big deal because accelerating the rotating mass is assisted by the (equal) mass on the other side of the wheel, so adding weight doesn't really make any difference vs adding that same weight on the frame. Where it can hurt is cornering. GCN did a video that suggested increasing width increases grip and cornering... to a point. Once you exceed that point, you spend more time moving the bike "over the tyre" and have a hard time cornering.
prmoustache 3y ago
> Yeah at the pro-ish level of triathlon, I think you need stiffness even in 112 mile bike legs. meh it is not that simple. Vibration loss and fatigue is something that is more and more studied these days in cycling. What is fastest in the first 10km might not be the fastest setup 3 hours later.