Sagan's bike at Paris Roubaix

Discuss light weight issues concerning road bikes & parts.
cunn1n9
Posts: 97
Joined: Sat Jan 15, 2011 1:24 am

by cunn1n9

Its very simple.

Uphill Watts/kg wins.

Flat pure Watts/CdA wins.

RyanH
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by RyanH

cunn1n9 wrote:
Thu Apr 12, 2018 1:57 am
Its very simple.

Uphill Watts/kg wins.

Flat pure Watts/CdA wins.
If it was very simple, then so many in this thread wouldn't be wrong. CdA matters as long as you're moving forward. On a 3% gradient, if rider A weighs 70 kilos and puts out 280w with a CdA of 0.3, they will travel at 28.2 kph. If Rider B weighs 70kg and puts out 265w with a CdA 0.25, then they will also travel at 28.2 kph. Obviously this diminishes as the gradient gets steeper but for many, 3% grade can be considered uphill, even if moderate.
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by Weenie


pdlpsher1
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Location: CO

by pdlpsher1

RyanH wrote:
cunn1n9 wrote:
Thu Apr 12, 2018 1:57 am
Its very simple.

Uphill Watts/kg wins.

Flat pure Watts/CdA wins.
If it was very simple, then so many in this thread wouldn't be wrong. CdA matters as long as you're moving forward. On a 3% gradient, if rider A weighs 70 kilos and puts out 280w with a CdA of 0.3, they will travel at 28.2 kph. If Rider B weighs 70kg and puts out 265w with a CdA 0.25, then they will also travel at 28.2 kph. Obviously this diminishes as the gradient gets steeper but for many, 3% grade can be considered uphill, even if moderate.
Yes. I’m a light rider with a low absolute power. I have a hard time riding against heavier and more powerful riders on shallower grades, because I lack the absolute power needed to overcome wind resistance, even when I’m drafting behind them. Once the road kicks up I leave them in the dust. As a small rider I also do poorly when climbing with a headwind. Again, I lack the absolute power needed to overcome the wind resistance. A heavier and more powerful rider is more likely to do better on a windy climb than a lighter and less powerful rider. I do very well on a steep climb with a tailwind. When the aero drag is zero then my superior power to weight ratio really shines.


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Last edited by pdlpsher1 on Thu Apr 12, 2018 2:30 am, edited 1 time in total.

pdlpsher1
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Location: CO

by pdlpsher1

Duplicate post.

tonytourist
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by tonytourist

I would enjoy riding with the legendary pdlpsher1 and seeing if your theory about leaving me in the dust is true. For some reason I don't think that would be the case :oops: :oops:
Superior power to weight ratio of what, 3.6 w/kg? :lol: :lol:

waltthizzney
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Joined: Mon Jun 20, 2016 6:35 pm

by waltthizzney

tonytourist wrote:
Thu Apr 12, 2018 5:28 am
I would enjoy riding with the legendary pdlpsher1 and seeing if your theory about leaving me in the dust is true. For some reason I don't think that would be the case :oops: :oops:
Superior power to weight ratio of what, 3.6 w/kg? :lol: :lol:
exactly lol this guy has no idea what he is talking about.

My 20 minute power is 360w. I weigh 67kg. My Watts per kilo is pretty strong, but unless I am dealing with a decent grade I am not at a huge advantage compared to guys that can put out 400w which is typical once you get to cat 1 and 2

And if someone is matching your watts per kilo, whoever is doing more actual wattage is probably going faster.

Andrewjn
Posts: 70
Joined: Mon Dec 20, 2010 2:54 am

by Andrewjn

Think something has been missed here>>>>>>> the best rider won on the day irrespective of tyre choice, frontal area, watts and what colour bike he had. Next we will asking what material jersey he was wearing and if he had baked beans in the morning and used expelled wind to improve his actual speed... what won it for him was being a great rider and tactics otherwise Toby Martin should have won and nobody else should have showed up Congats Peter.... great ride

istigatrice
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Location: Australia

by istigatrice

I've only skimmed this thread but I'm pretty sure a lot of what was said was wrong... :noidea:

Watts/kg or Watts/CdA matter to a certain degree, but even in a 3km or 4km pursuit on a closed velodrome things like pacing, the line you ride and your technique still influence the outcome (notice I didn't once mention watts, kg or CdA). There are plenty of different ways to 'average' 300w, or 5w/kg or whatever w/Cda for an effort. By definition there's only 1 fastest way.

Can I just add that, 'simple maths' is almost surely wrong. Especially when the systems we're talking about are 'unstable'. In fact, I wouldn't even call it maths, it's more like 'a rough guess at basic physics'.

Ok, I felt like I needed to get that rant off my chest, please continue :beerchug:
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Disclosure: I'm sponsored by Velocite, but I do give my honest opinion about them (I'm endorsed to race their bikes, not say nice things about them)

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Calnago
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by Calnago

Finally, a simple often forgot voice of reason brings some levity to the discussion. Thank you, @istigatrice.
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pdlpsher1
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by pdlpsher1

tonytourist wrote:
Thu Apr 12, 2018 5:28 am
I would enjoy riding with the legendary pdlpsher1 and seeing if your theory about leaving me in the dust is true. For some reason I don't think that would be the case :oops: :oops:
Superior power to weight ratio of what, 3.6 w/kg? :lol: :lol:
If I race with you I'd lose on the uphills, flats, and downhills. I'm old and slow. But that's beside the point. There's a group that I ride with occasionally that consists of heavy riders. They are probably closer to 200lbs or 90kg. They are more powerful in absolute watts but have subpar W/KG than me due to their high weight. Although they have lower W/KG than me they can still give me trouble on shallow climbs when the speed is high. That's because when the speed is high I'm at a disadvantage in terms of W/CdA. And even with my higher W/KG I still lose on shallow grades because of my W/CdA disadvantage. That's why the gradient level is very important when we talk about W/KG because the gradient also determines how fast one is moving and hence how much air resistance there is.

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themidge
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by themidge

I feel like I am the young pretender to pdlpher1's crown of the classic 'sit in' climber. On the rare occasions that I visit the local group rides I ride behind the widest MAMIL on the flat, get dropped on the downhill, and then smoke them all on the short, steep hills we have round here :twisted:.
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