6 ms·

Why don't you actually do some math, or experiments, rather than just telling us you have doubts? This is all really easy stuff to answer. For instance. 75kg

Why don't you actually do some math, or experiments, rather than just telling us you have doubts? This is all really easy stuff to answer. For instance. 75kg rider + bike. Make the bike 1kg lighter. Go up a 8% grade for 1 kilometers at 300 watts Time saved by 1kg weight reduction? 30 seconds out of 40 minutes. Or suppose we add 300grams to the frame to make it aero, which is typical. If that reduces the CdA by .02 out of .25, you are at about a breakeven point. JUST during the 1km climb. Then you save time on all the flats and non technical downhills. Acceleration is even less affected by bike mass. People forget that bike mass is a tiny % of total system mass (our fat asses). And mass is only one of 4 major components that affect acceleration. I'm happy to run through some acceleration scenarios if you like.

gergely 4y ago
You are correct on the watt, weight computes but I think the aerodynamic saving is worthless on a gravel race. People are not going that fast on gravel to gain anything from aerodynamical optimisations. You need to keep going at least 40 km/h to have any advancement without up-down movement which is obviously not something that you can achieve on gravel.
- prmoustache 4y ago
  Aero also helps at 25 or 30kph. It is quite easy to check out actually on a road bike. Ride at a steady pace without pushing hard, hands on top, then put your hands in the hoods of the brake lever, elbows at 90° without pushing more, you will gain easily 1kph just by changing position. More if it is windy.
  - newaccount74 4y ago
    I assume the poster meant aerodynamic optimisation of the bike itself (eg. aero wheels, aero saddle post, etc). Riding position obviously makes a huge difference.
cycomanic 4y ago
The issue is that a lot of the aerodynamic frame advances only work in ideal laminar conditions. However wind is gusty, there are trees and other obstacles next to the course etc. In those cases the advantages largely disappear as Hambini has shown.
- jackmott42 4y ago
  I'm not sure what testing Hambini has been up to, last I saw him he was calling for the death of Damon Rinard (who is a really nice guy, by the way! and great cycling engineer) However I have plenty of first hand field testing data showing that this is very obviously not true, as do hundreds of other people. We ride in the real world with power meters and timers and we can detect these things even in gusty real world conditions. Just two examples: http://www.trainingandracingwithapowermeter.com/2010/10/challenge-to-cycling-aerodynamicists.html http://www.trainingandracingwithapowermeter.com/2010/10/chal... and https://betterbicycles.org/science/speed/validation-of-bicycle-power-equation/ https://betterbicycles.org/science/speed/validation-of-bicyc...
metadat 4y ago
> I'm happy to run through some acceleration scenarios if you like. Yes, please continue! I'm digging your analysis.
vikingerik 4y ago
I know nothing about typical bike timings, but I was struck by that. Does it really take 40 minutes to go 1 km at an 8% grade? Would it be faster to get off the bike and walk? When you're not rolling, you don't have to output power to fight your own weight trying to roll back - the friction between your shoes and the ground counteracts that. (I assume a real race doesn't allow you to walk, just batting around thoughts hypothetically here.)
- elektronaut 4y ago
  I suspect the parent is referring to elevation, not distance. 1km in distance would only take a few minutes.
- toss1 4y ago
  One racecourse I know about that has both running and bicycle races is the Mt Washington Auto Road in New Hampshire USA. It is the tallest mountain east of the continent. The top is at 6288ft/1917m above sea level. The road is 7.6 miles / 12.2 km long and the climb is 4650 vertical feet / 1420m. The footrace has been run since 1936 and the bicycle race since 1973. The road used to be paved only half way and gravel the rest, but it is now largely paved. Now, the Men's bicycle record is 0:50:38 (2022) and the women's record is 58:14 (2000). The running race records are 0:56:41 (2004) and 1:09:25 (2012). So, pretty clearly, even at a 12% grade, the bicycle still has an advantage. I'd say this is still true even though the bicycle race consistently attracts US Cycling Team and other international class competitors, and the running race seems to less frequently attract that caliber. [0] https://en.wikipedia.org/wiki/Mount_Washington_Road_Race https://en.wikipedia.org/wiki/Mount_Washington_Road_Race [1] https://en.wikipedia.org/wiki/Mount_Washington_Auto_Road_Bicycle_Hillclimb https://en.wikipedia.org/wiki/Mount_Washington_Auto_Road_Bic...
  - vikingerik 4y ago
    Very interesting information, thanks. The sibling comment pointed out that the parent probably meant 40 minutes for 1km of elevation gain, not linear distance, which makes sense too. Maybe I'm just trying to justify my own struggles where it's faster to walk the bike up any significant grade :)
bbarn 4y ago
You're forgetting the effect of exertion on the rider under heavy loads like climbing. I've ridden heavy bikes, and I've ridden light bikes. Light bikes feel better, rotational weight mattering more than anything else.
- fnbr 4y ago
  They’re not- 300W of effort is 300W of effort, it doesn’t have a bigger impact if the bike is heavier or not.
  - deleted 4y ago
    [deleted]
  - darkerside 4y ago
    I wonder if that's really true on hills. Most people ride hills with more effort, pushing down on one pedal at a time. The bike speeds up and slows down much more with each pedal stroke. Compare to the flats where you have a smooth stroke and very consistent output. I could see all the mini accelerations adding up to a much larger energy expenditure than would be indicated by a spherical cow in a vacuum.
    - wiredfool 4y ago
      Eh, it's really quite small, unless you have stupid heavy wheels (meaning, that the wheels are a significant percentage of the mass of the entire system). If the mass of the wheel is 100% located at the rim, the energy goes 1/2 into straight line energy and half into rotational. But -- if you slow down, you don't lose that energy, it just redistributes to gravitational potential. The flywheel effect from heavy wheels may actually help, as it tends to smooth out pedal strokes. The energy to go up a hill is just mgh - friction. Some cadences are less efficient than others (e.g. for me, standing is more power but lower efficiency), and bikes that are too stiff may not help you get the best rhythm. In a totally unscientific test -- I've got a 12kg Aluminum gravel bike, wide tires, rack, fenders. I've also got an 8kg carbon racing bike, skinny tires, aero rims, etc. They have similar riding positions (reach/drop), though the gravel bike has a wider seat, which is better for one climbing cadence. I usually ride the gravel bike these days, because comfort. Two weekends in a row, I did a 12x rep climbing workout (2.5 hours), one on each bike. First weekend, Road bike. It felt _fast_. Quick, lively, accelerated from the stoplights on the way to the hill. Second week, back on the gravel bike, grinding up the hill. Total ET difference: 5 seconds. Sure there are differences.
ben7799 4y ago
I'm a former racer too and this constant equipment arms race and arguing is just so fatiguing. People can argue about analytics around equipment till pigs fly. It's all still just an order of magnitude smaller than the differences between being fit and not fit and a stronger rider versus a weaker rider or a coached rider versus un-coached rider. The sport has separated into riding enthusiasts and equipment enthusiasts and the bike companies have completely brainwashed equipment enthusiasts. Your times don't make any sense either... 8% for 1km takes vastly less time than you're talking about at the power levels you're talking about. You're probably off an order of magnitude there. A rider with an FTP of around 300 will probably climb closer to 10km @ 8% in 40 minutes. Nothing is more tiring than being at the start of a race and there's someone with a $10k+ bike and a gut talking smack about bikes to someone everyone else knows is going to win the race and the guy with the $10k bike is getting dropped & pulled from the race. One person spent all their time on training and the other spent all their time researching & buying equipment.
- jackmott42 4y ago
  You are right I had the gradient off by 10x, sorry that should have been obvious, it has been a while Actual time savings of 1kg of weight reduction: 1 second And personally I've used aeroweenieing to podium in a cat 3 road race, and my wife has set state records and won pro races. You can make fun of fat guys doing a professional job if you like but it isn't just them.
  - ben7799 4y ago
    If spending lots of money to win a Cat 3 race and knowing you did it with money and equipment instead of fitness and smarts is OK with you more power to you. But if it means thousands of dollars spent on a race that likely paid < $50 to the winner the whole thing can also look ridiculous too depending on perspective. This isn't really funny, it's a fundamental problem with cycling as a sport that limits who participates in the sport and hurts the sports ability to find and develop the best riders. It seems particularly bad in the US. Rules which helped control the equipment arms race would be good for the sport at the competitive level. Many promising athletes never try the sport because the costs are so prohibitive. On top of that in road racing if expensive equipment raises the speed of everyone in the field it accomplishes nothing other than increasing the risk of severe injury as speeds go up. If someone made $10k shoes that gave a competitive advantage in soccer or basketball, or a $10k baseball bat that offered significant advantages, etc.. that equipment would very likely be outlawed right away. Cycling has let everything get very out of control. Baseball obviously has already banned lots of bats that offer competitive advantage, whether it's banning metal bats after a certain level or limiting the power of metal bats below that level.
ActorNightly 4y ago
You are assuming that rider can output X watts continuously. This is not how humans work. Riders have different profiles in terms of torque vs rpm from their legs. A lighter bike means that a rider is outputing less torque, which he/she can sustain without downshifting to a lower gear, leading to overall increase in time not only during the climb, but also how much energy the rider has left in the tank after the climb for the rest of the course.

gergely 4y ago

You are correct on the watt, weight computes but I think the aerodynamic saving is worthless on a gravel race. People are not going that fast on gravel to gain anything from aerodynamical optimisations. You need to keep going at least 40 km/h to have any advancement without up-down movement which is obviously not something that you can achieve on gravel.

prmoustache 4y ago
Aero also helps at 25 or 30kph. It is quite easy to check out actually on a road bike. Ride at a steady pace without pushing hard, hands on top, then put your hands in the hoods of the brake lever, elbows at 90° without pushing more, you will gain easily 1kph just by changing position. More if it is windy.
- newaccount74 4y ago
  I assume the poster meant aerodynamic optimisation of the bike itself (eg. aero wheels, aero saddle post, etc). Riding position obviously makes a huge difference.

cycomanic 4y ago

The issue is that a lot of the aerodynamic frame advances only work in ideal laminar conditions. However wind is gusty, there are trees and other obstacles next to the course etc. In those cases the advantages largely disappear as Hambini has shown.

jackmott42 4y ago
I'm not sure what testing Hambini has been up to, last I saw him he was calling for the death of Damon Rinard (who is a really nice guy, by the way! and great cycling engineer) However I have plenty of first hand field testing data showing that this is very obviously not true, as do hundreds of other people. We ride in the real world with power meters and timers and we can detect these things even in gusty real world conditions. Just two examples: http://www.trainingandracingwithapowermeter.com/2010/10/challenge-to-cycling-aerodynamicists.html http://www.trainingandracingwithapowermeter.com/2010/10/chal... and https://betterbicycles.org/science/speed/validation-of-bicycle-power-equation/ https://betterbicycles.org/science/speed/validation-of-bicyc...

metadat 4y ago

> I'm happy to run through some acceleration scenarios if you like. Yes, please continue! I'm digging your analysis.

vikingerik 4y ago

I know nothing about typical bike timings, but I was struck by that. Does it really take 40 minutes to go 1 km at an 8% grade? Would it be faster to get off the bike and walk? When you're not rolling, you don't have to output power to fight your own weight trying to roll back - the friction between your shoes and the ground counteracts that. (I assume a real race doesn't allow you to walk, just batting around thoughts hypothetically here.)

elektronaut 4y ago
I suspect the parent is referring to elevation, not distance. 1km in distance would only take a few minutes.
toss1 4y ago
One racecourse I know about that has both running and bicycle races is the Mt Washington Auto Road in New Hampshire USA. It is the tallest mountain east of the continent. The top is at 6288ft/1917m above sea level. The road is 7.6 miles / 12.2 km long and the climb is 4650 vertical feet / 1420m. The footrace has been run since 1936 and the bicycle race since 1973. The road used to be paved only half way and gravel the rest, but it is now largely paved. Now, the Men's bicycle record is 0:50:38 (2022) and the women's record is 58:14 (2000). The running race records are 0:56:41 (2004) and 1:09:25 (2012). So, pretty clearly, even at a 12% grade, the bicycle still has an advantage. I'd say this is still true even though the bicycle race consistently attracts US Cycling Team and other international class competitors, and the running race seems to less frequently attract that caliber. [0] https://en.wikipedia.org/wiki/Mount_Washington_Road_Race https://en.wikipedia.org/wiki/Mount_Washington_Road_Race [1] https://en.wikipedia.org/wiki/Mount_Washington_Auto_Road_Bicycle_Hillclimb https://en.wikipedia.org/wiki/Mount_Washington_Auto_Road_Bic...
- vikingerik 4y ago
  Very interesting information, thanks. The sibling comment pointed out that the parent probably meant 40 minutes for 1km of elevation gain, not linear distance, which makes sense too. Maybe I'm just trying to justify my own struggles where it's faster to walk the bike up any significant grade :)

bbarn 4y ago

You're forgetting the effect of exertion on the rider under heavy loads like climbing. I've ridden heavy bikes, and I've ridden light bikes. Light bikes feel better, rotational weight mattering more than anything else.

fnbr 4y ago
They’re not- 300W of effort is 300W of effort, it doesn’t have a bigger impact if the bike is heavier or not.
- deleted 4y ago
  [deleted]
- darkerside 4y ago
  I wonder if that's really true on hills. Most people ride hills with more effort, pushing down on one pedal at a time. The bike speeds up and slows down much more with each pedal stroke. Compare to the flats where you have a smooth stroke and very consistent output. I could see all the mini accelerations adding up to a much larger energy expenditure than would be indicated by a spherical cow in a vacuum.
  - wiredfool 4y ago
    Eh, it's really quite small, unless you have stupid heavy wheels (meaning, that the wheels are a significant percentage of the mass of the entire system). If the mass of the wheel is 100% located at the rim, the energy goes 1/2 into straight line energy and half into rotational. But -- if you slow down, you don't lose that energy, it just redistributes to gravitational potential. The flywheel effect from heavy wheels may actually help, as it tends to smooth out pedal strokes. The energy to go up a hill is just mgh - friction. Some cadences are less efficient than others (e.g. for me, standing is more power but lower efficiency), and bikes that are too stiff may not help you get the best rhythm. In a totally unscientific test -- I've got a 12kg Aluminum gravel bike, wide tires, rack, fenders. I've also got an 8kg carbon racing bike, skinny tires, aero rims, etc. They have similar riding positions (reach/drop), though the gravel bike has a wider seat, which is better for one climbing cadence. I usually ride the gravel bike these days, because comfort. Two weekends in a row, I did a 12x rep climbing workout (2.5 hours), one on each bike. First weekend, Road bike. It felt _fast_. Quick, lively, accelerated from the stoplights on the way to the hill. Second week, back on the gravel bike, grinding up the hill. Total ET difference: 5 seconds. Sure there are differences.

ben7799 4y ago

I'm a former racer too and this constant equipment arms race and arguing is just so fatiguing. People can argue about analytics around equipment till pigs fly. It's all still just an order of magnitude smaller than the differences between being fit and not fit and a stronger rider versus a weaker rider or a coached rider versus un-coached rider. The sport has separated into riding enthusiasts and equipment enthusiasts and the bike companies have completely brainwashed equipment enthusiasts. Your times don't make any sense either... 8% for 1km takes vastly less time than you're talking about at the power levels you're talking about. You're probably off an order of magnitude there. A rider with an FTP of around 300 will probably climb closer to 10km @ 8% in 40 minutes. Nothing is more tiring than being at the start of a race and there's someone with a $10k+ bike and a gut talking smack about bikes to someone everyone else knows is going to win the race and the guy with the $10k bike is getting dropped & pulled from the race. One person spent all their time on training and the other spent all their time researching & buying equipment.

jackmott42 4y ago
You are right I had the gradient off by 10x, sorry that should have been obvious, it has been a while Actual time savings of 1kg of weight reduction: 1 second And personally I've used aeroweenieing to podium in a cat 3 road race, and my wife has set state records and won pro races. You can make fun of fat guys doing a professional job if you like but it isn't just them.
- ben7799 4y ago
  If spending lots of money to win a Cat 3 race and knowing you did it with money and equipment instead of fitness and smarts is OK with you more power to you. But if it means thousands of dollars spent on a race that likely paid < $50 to the winner the whole thing can also look ridiculous too depending on perspective. This isn't really funny, it's a fundamental problem with cycling as a sport that limits who participates in the sport and hurts the sports ability to find and develop the best riders. It seems particularly bad in the US. Rules which helped control the equipment arms race would be good for the sport at the competitive level. Many promising athletes never try the sport because the costs are so prohibitive. On top of that in road racing if expensive equipment raises the speed of everyone in the field it accomplishes nothing other than increasing the risk of severe injury as speeds go up. If someone made $10k shoes that gave a competitive advantage in soccer or basketball, or a $10k baseball bat that offered significant advantages, etc.. that equipment would very likely be outlawed right away. Cycling has let everything get very out of control. Baseball obviously has already banned lots of bats that offer competitive advantage, whether it's banning metal bats after a certain level or limiting the power of metal bats below that level.

ActorNightly 4y ago

You are assuming that rider can output X watts continuously. This is not how humans work. Riders have different profiles in terms of torque vs rpm from their legs. A lighter bike means that a rider is outputing less torque, which he/she can sustain without downshifting to a lower gear, leading to overall increase in time not only during the climb, but also how much energy the rider has left in the tank after the climb for the rest of the course.