8 ms·

Quite a lot of the design inspiration comes from top riders and their coaches - the level of technical knowledge they have is astonishing. We work with bikes li

by zh3 3y ago

Quite a lot of the design inspiration comes from top riders and their coaches - the level of technical knowledge they have is astonishing. We work with bikes like these, covering them with sensors and loadcells (we've had something like 20 ARM processors on a bike at a time, communicating wirelessly), and while the bike is part of the equation most of the drag comes from the rider's body. So a lot of effort also goes into comfort and fit, in order to get the rider into an aero position that they can hold for a period of time (the most aero position may not be possible to hold for very long) so it rapidly becomes an area-under-the-curve thing. We spend a lot of time in the lab, in wind tunnels and in velodromes sorting it all out (now with AI, vision systems, rider position tracking - it's getting really complicated). Also these bikes are not generally roadworthy - every so often we hear a multi-thousand-dollar 'crack!' indicating another frame has had enough.

Eric_WVGG 3y ago
Funny, the last time I read an article about bicycles here, a writer was getting dragged for trying to explain that same point. https://news.ycombinator.com/item?id=39181473 https://news.ycombinator.com/item?id=39181473
- albinowax_ 3y ago
  There's a pretty big gap between the bikes in this post and the kind of carbon road bike most people ride eg, a Giant Defy
- plagiarist 3y ago
  The point that the racing bike is more likely to have a failure during use? The difference seems to be suggesting people not have a toy they want vs. only explaining that there is a serious drawback. Occasionally something happens that makes the attitude really stand out. I once saw an actual electrician tell someone their 3D printed light switch cover was an accelerant. He suggested they re-do one to attach on top of a standard flame-retardant cover. There were like half a dozen "nuh-uh" comments from people who felt attacked by that.
- plorkyeran 3y ago
  The bikes this post is talking about and the bikes that post is talking about have basically nothing in common. Mass market carbon bikes aren't designed to be used for exactly one race and then thrown away in the way that tri bikes sometimes are.
  - lobochrome 3y ago
    No tri bike is designed to be used just once in a race. Not even the GOAT ever used single-use frames. A frame is ridden for a season - unless it breaks.
nottorp 3y ago
> while the bike is part of the equation most of the drag comes from the rider's body So the real solution is to mod the rider?
- InCityDreams 3y ago
  ...hence aero helmets, socks, leg shaving....so, yes.
  - nottorp 3y ago
    Oh I was more thinking of surgical modding. Guess leg shaving is the first step :)
- scott_w 3y ago
  The biggest gain of TT/Triathlon bikes is moving your position from an upright seated position to a lower and narrower position, so "modding" the rider ;-) After that, skinsuits, helmets and overshoes are usually the best bang-for-your-buck (in no particular order) in terms of aero gains.
- zh3 3y ago
  To a large extent, yes. Head position (varies with helmet), back curve, hand and arm positions etc. We measure the number of watts saved by various combinations of rider position/rider equipment (helmets/skinsuits etc) in real time and pop the number up on the on-bike screen in real time. Currently moving to doing this out on the road (following validation on indoor velodromes and wind tunnels), kind of fun being able to see this position saves 10 watts, that one saves 15 watts but is too uncomfortable to hold for long etc.
- prmoustache 3y ago
  There are been a lot of fuss about that in the UK time trial scene with rider mounting 3d printed parts behind their arms and calves to lower their drag.
  - zh3 3y ago
eschneider 3y ago
If racing frames didn't break from extended use, then they could be lighter. You want them to be just barely strong/stiff enough.
- bch 3y ago
  Anybody can build a bridge that works - it takes an engineer to build a bridge that barely works.
  - phanimahesh 3y ago
    So you're saying real engineers are all playing polybridge. Sounds about right.
- jackmott42 3y ago
  The racing frames here don't break as a rule as OP suggests, if one does there was a manufacturing flaw or a crash/impact of some kind. A few grams of weight does not have enough impact TT bike performance enough to make it worth shaving 100 grams if it risks reliability.
eitally 3y ago
Thanks for this comment. For anyone interested in hearing more -- from road/track cyclists who can't use non-UCI compliant equipment -- I highly recommend searching Youtube for content featuring Dan Bigham. He owned the hour record briefly (about a year) until it was broken by Filippo Ganna (late 2022). They're two very different body types and because Dan is the aero & performance engineer working for INEOS (Ganna's pro team), he helped design and optimize the same frame (Pinarello Bolide) to work with a far different rider in a different position. As zh3 notes, the rider & their position has more to do with aero optimization than the frame, and it's interesting to hear someone like Dan talk about how the setup he used for his hour record attempt was so different from Ganna's. Here are a few links to get started: https://www.youtube.com/watch?v=YOLlyKnMz3Y https://www.youtube.com/watch?v=YOLlyKnMz3Y https://www.youtube.com/watch?v=QweOJXRcb0g https://www.youtube.com/watch?v=QweOJXRcb0g https://www.youtube.com/watch?v=WHc52cGz4AA https://www.youtube.com/watch?v=WHc52cGz4AA https://www.youtube.com/watch?v=cgpywSW6t0M https://www.youtube.com/watch?v=cgpywSW6t0M https://www.youtube.com/watch?v=qKT9DsRtuCc https://www.youtube.com/watch?v=qKT9DsRtuCc
- zh3 3y ago
  Dan's name does indeed come up a lot in our circles :) Thanks for the links, even being in the biz there's always more to learn.
- canucker2016 3y ago
  Lionel Sanders (Canadian Triathlete) doing aero testing on the road and the velodrome: https://www.youtube.com/watch?v=6u_Tw3S8KWA https://www.youtube.com/watch?v=6u_Tw3S8KWA https://www.youtube.com/watch?v=O6sqOX1nUIU https://www.youtube.com/watch?v=O6sqOX1nUIU On the road, he was able to reduce his drag coefficient by lowering his hands/arms - (0.23 to just under 0.20), but on the velodrome, he wasn't able to reproduce the improvement despite several variations in hand/body position. In the first video, the testing expert mentions that cycling pros would be in the range 0.16 to 0.18 (smaller/lighter cyclists had the lower coefficients).

by zh3 3y ago

Eric_WVGG 3y ago

Funny, the last time I read an article about bicycles here, a writer was getting dragged for trying to explain that same point. https://news.ycombinator.com/item?id=39181473 https://news.ycombinator.com/item?id=39181473

albinowax_ 3y ago
There's a pretty big gap between the bikes in this post and the kind of carbon road bike most people ride eg, a Giant Defy
plagiarist 3y ago
The point that the racing bike is more likely to have a failure during use? The difference seems to be suggesting people not have a toy they want vs. only explaining that there is a serious drawback. Occasionally something happens that makes the attitude really stand out. I once saw an actual electrician tell someone their 3D printed light switch cover was an accelerant. He suggested they re-do one to attach on top of a standard flame-retardant cover. There were like half a dozen "nuh-uh" comments from people who felt attacked by that.
plorkyeran 3y ago
The bikes this post is talking about and the bikes that post is talking about have basically nothing in common. Mass market carbon bikes aren't designed to be used for exactly one race and then thrown away in the way that tri bikes sometimes are.
- lobochrome 3y ago
  No tri bike is designed to be used just once in a race. Not even the GOAT ever used single-use frames. A frame is ridden for a season - unless it breaks.

nottorp 3y ago

> while the bike is part of the equation most of the drag comes from the rider's body So the real solution is to mod the rider?

InCityDreams 3y ago
...hence aero helmets, socks, leg shaving....so, yes.
- nottorp 3y ago
  Oh I was more thinking of surgical modding. Guess leg shaving is the first step :)
scott_w 3y ago
The biggest gain of TT/Triathlon bikes is moving your position from an upright seated position to a lower and narrower position, so "modding" the rider ;-) After that, skinsuits, helmets and overshoes are usually the best bang-for-your-buck (in no particular order) in terms of aero gains.
zh3 3y ago
To a large extent, yes. Head position (varies with helmet), back curve, hand and arm positions etc. We measure the number of watts saved by various combinations of rider position/rider equipment (helmets/skinsuits etc) in real time and pop the number up on the on-bike screen in real time. Currently moving to doing this out on the road (following validation on indoor velodromes and wind tunnels), kind of fun being able to see this position saves 10 watts, that one saves 15 watts but is too uncomfortable to hold for long etc.
prmoustache 3y ago
There are been a lot of fuss about that in the UK time trial scene with rider mounting 3d printed parts behind their arms and calves to lower their drag.
- zh3 3y ago

eschneider 3y ago

If racing frames didn't break from extended use, then they could be lighter. You want them to be just barely strong/stiff enough.

bch 3y ago
Anybody can build a bridge that works - it takes an engineer to build a bridge that barely works.
- phanimahesh 3y ago
  So you're saying real engineers are all playing polybridge. Sounds about right.
jackmott42 3y ago
The racing frames here don't break as a rule as OP suggests, if one does there was a manufacturing flaw or a crash/impact of some kind. A few grams of weight does not have enough impact TT bike performance enough to make it worth shaving 100 grams if it risks reliability.

eitally 3y ago

Thanks for this comment. For anyone interested in hearing more -- from road/track cyclists who can't use non-UCI compliant equipment -- I highly recommend searching Youtube for content featuring Dan Bigham. He owned the hour record briefly (about a year) until it was broken by Filippo Ganna (late 2022). They're two very different body types and because Dan is the aero & performance engineer working for INEOS (Ganna's pro team), he helped design and optimize the same frame (Pinarello Bolide) to work with a far different rider in a different position. As zh3 notes, the rider & their position has more to do with aero optimization than the frame, and it's interesting to hear someone like Dan talk about how the setup he used for his hour record attempt was so different from Ganna's. Here are a few links to get started: https://www.youtube.com/watch?v=YOLlyKnMz3Y https://www.youtube.com/watch?v=YOLlyKnMz3Y https://www.youtube.com/watch?v=QweOJXRcb0g https://www.youtube.com/watch?v=QweOJXRcb0g https://www.youtube.com/watch?v=WHc52cGz4AA https://www.youtube.com/watch?v=WHc52cGz4AA https://www.youtube.com/watch?v=cgpywSW6t0M https://www.youtube.com/watch?v=cgpywSW6t0M https://www.youtube.com/watch?v=qKT9DsRtuCc https://www.youtube.com/watch?v=qKT9DsRtuCc

zh3 3y ago
Dan's name does indeed come up a lot in our circles :) Thanks for the links, even being in the biz there's always more to learn.
canucker2016 3y ago
Lionel Sanders (Canadian Triathlete) doing aero testing on the road and the velodrome: https://www.youtube.com/watch?v=6u_Tw3S8KWA https://www.youtube.com/watch?v=6u_Tw3S8KWA https://www.youtube.com/watch?v=O6sqOX1nUIU https://www.youtube.com/watch?v=O6sqOX1nUIU On the road, he was able to reduce his drag coefficient by lowering his hands/arms - (0.23 to just under 0.20), but on the velodrome, he wasn't able to reproduce the improvement despite several variations in hand/body position. In the first video, the testing expert mentions that cycling pros would be in the range 0.16 to 0.18 (smaller/lighter cyclists had the lower coefficients).