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Coasting down hill

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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Coasting down hill

Old 05-27-22, 10:29 AM
  #51  
burnthesheep
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Originally Posted by PeteHski
If it's a hilly TT, your target power on the climbs will be higher than it is on the descents or flat. At least if you want to win. It's simple physics/maths. Any pacing algorithm (eg. Best Bike Splits) will always set higher power targets on the climbs (obviously taking account of your personal limits).
You will, but not as much as many people often post about it. Hence why I said about 10% over, max. The reason is physiologically, you cannot "bank" that much extra of your critical power for an effort of a duration of an hour or so. If you can do 300 for an hour your best standalone 20min might be as high as 318 or so. But if you do 318 once for 20min up a hill, go down the hill at a LOT lower.......you won't be able to still average 300w. That's not how ftp and critical power works.

So, you have to game the physics and physiology to maximize how many KJ's you can put out for the effort........while minimizing the time spend going slowest.

So, assuming it isn't a mountain climb and descent TT......but just hills you can still pedal down. A good bet would be 105% up and 95% down and as damn close to 100% as you can bear it on the flats.

FYI.........I have more than one regional gold (in category) for USAC TT. And it's not due to monstrous power either, mostly efficiency.
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Old 05-27-22, 10:34 AM
  #52  
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Originally Posted by LarrySellerz
I think of it more as moderating the pressure you put into your pedals to better make small changes in speed to follow a wheel without hitting the breaks. If you need to pedal at like 150 rpm or something just to keep up soft pedaling takes a lot of effort
If you're pedalling at 150 rpm without actually putting down any power, you're WASTING effort.
Again - Hence, gears.
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Old 05-27-22, 11:03 AM
  #53  
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Originally Posted by genejockey
If you're pedalling at 150 rpm without actually putting down any power, you're WASTING effort.
Again - Hence, gears.
The reason one would pedal like that is to avoid coasting, ty reduce the accordian. Just being a good wheel. Ive been riding a 42x18 ss so this happens when trying to follow fast guys on flat ground
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Old 05-27-22, 11:09 AM
  #54  
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Originally Posted by ofajen
No external work is being done, but if you recall my posts regarding the internal work of pedaling, there is a work load on your CV system just from moving your legs and feet at a given cadence before any external work can be applied to the pedals.
I don't have a catalog of all your previous posts so, no, I don't recall them.
This internal work is a sharply increasing function of cadence and the power requirement runs about 1.0 Watts/kg at 110 rpm. Formenti at Kings College has published several papers on measuring this within the last decade.
That's fine and dandy, but it still means a 100kg cyclist would have to spin at 220 RPM to reach 200 W, which barely touches the "hundreds of watts" stated by the OP.

Originally Posted by genejockey
If you're pedalling at 150 rpm without actually putting down any power, you're WASTING effort.
Again - Hence, gears.
Yep, spinning at 150 RPM without putting out any useful power is incredibly pointless.
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Old 05-27-22, 11:10 AM
  #55  
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Originally Posted by genejockey
If you're pedalling at 150 rpm without actually putting down any power, you're WASTING effort.
Again - Hence, gears.
The reason one would pedal like that is to avoid coasting, to reduce the accordian. Just being a good wheel. Ive been riding a 42x18 ss so this happens when trying to follow fast guys on flat ground
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Old 05-27-22, 11:25 AM
  #56  
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Originally Posted by ofajen
The article I linked agrees and gives the same guidance.
The article is correct on it's general points but, personally, I have a hard time putting faith in the computer simulations done by anyone that states "Air resistance increases exponentially with speed."
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Old 05-27-22, 11:48 AM
  #57  
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Originally Posted by bampilot06
This.
You are a pilot. Did you stay at a Holiday Inn Express last night?
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Old 05-27-22, 12:05 PM
  #58  
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Originally Posted by indyfabz
You are a pilot. Did you stay at a Holiday Inn Express last night?

Airport Crew room is about the same experience, so, yes I did.
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Old 05-27-22, 02:18 PM
  #59  
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Originally Posted by bampilot06
Airport Crew room is about the same experience, so, yes I did.
I didn’t know that was a thing for pilots. I do know that some railroads that operate in remote areas have somewhat similar accommodations. When I spent 2 nights in Edgemont, SD, I saw crews being shuttled to what looked like a dorm building.
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Old 05-27-22, 02:22 PM
  #60  
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Originally Posted by indyfabz
I didn’t know that was a thing for pilots. I do know that some railroads that operate in remote areas have somewhat similar accommodations. When I spent 2 nights in Edgemont, SD, I saw crews being shuttled to what looked like a dorm building.

Oh, that sounds better. This is a room with some recliners thrown in.
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Old 05-27-22, 02:51 PM
  #61  
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Originally Posted by burnthesheep
You will, but not as much as many people often post about it. Hence why I said about 10% over, max. The reason is physiologically, you cannot "bank" that much extra of your critical power for an effort of a duration of an hour or so. If you can do 300 for an hour your best standalone 20min might be as high as 318 or so. But if you do 318 once for 20min up a hill, go down the hill at a LOT lower.......you won't be able to still average 300w. That's not how ftp and critical power works.

So, you have to game the physics and physiology to maximize how many KJ's you can put out for the effort........while minimizing the time spend going slowest.

So, assuming it isn't a mountain climb and descent TT......but just hills you can still pedal down. A good bet would be 105% up and 95% down and as damn close to 100% as you can bear it on the flats.

FYI.........I have more than one regional gold (in category) for USAC TT. And it's not due to monstrous power either, mostly efficiency.
Yes of course the variation in power has to be within your performance envelope. It's no good if you blow up on the climbs. But the general principle is that you bias power in proportion to the gradient. I often use Best Bike Spilt software to generate a target power profile for a course and with an FTP of around 300W, it typically recommends around 150W on descents, 200W on the flat, 250W on medium grade climbs and 300W on steep climbs. This would be over a typical 100 mile hilly course with an IF of around 0.75, so Normalized Power around 225W. If I targeted a constant 225W on the same course I would be much slower. In practice I don't follow the power targets religiously, but I certainly follow this principle and I'm pretty competitive in local events. Our local region is all rolling hills with countless punchy climbs and hardly any sustained flat. So managing power variation is critical. It's actually impossible to ride at a constant power output on these roads.
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Old 05-27-22, 04:37 PM
  #62  
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Originally Posted by bampilot06
Oh, that sounds better. This is a room with some recliners thrown in.
At least you don’t have to sleep on the floor like us peasants.
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Old 05-27-22, 04:45 PM
  #63  
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Originally Posted by tomato coupe
The article is correct on it's general points but, personally, I have a hard time putting faith in the computer simulations done by anyone that states "Air resistance increases exponentially with speed."

but it does. How would you like it to be said?
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Old 05-27-22, 04:46 PM
  #64  
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Originally Posted by Mojo31
At least you don’t have to sleep on the floor like us peasants.
Something has to separate us.
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Old 05-27-22, 04:47 PM
  #65  
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Originally Posted by bampilot06
but it does. How would you like it to be said?

Drag increases exponentially with speed.
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Old 05-27-22, 04:54 PM
  #66  
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Originally Posted by bampilot06
Drag increases exponentially with speed.
The Rolling Stones said "What a drag it is getting old." So, does drag increase exponentially with age, or is it more of a linear function?
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Last edited by genejockey; 05-27-22 at 05:00 PM.
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Old 05-27-22, 04:54 PM
  #67  
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Originally Posted by bampilot06
Drag increases exponentially with speed.
No, it increases quadratically with speed.
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Old 05-27-22, 04:57 PM
  #68  
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Originally Posted by tomato coupe
No, it increases quadratically with speed.

Now we’re splitting hairs, but you can have your podium back.
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Old 05-27-22, 05:00 PM
  #69  
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Originally Posted by genejockey
The Rolling Stones said "What a drag it is getting old." So, does drag increase expontially with age, or is it more of a linear function?

Thats a good song, I have not heard that one in a long time.

Mothers little helper.
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Old 05-27-22, 05:02 PM
  #70  
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Originally Posted by bampilot06
Now we’re splitting hairs, but you can have your podium back.
It may be splitting hairs to you, but it doesn't help the credibility of someone claiming to do computer simulations.
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Old 05-27-22, 05:03 PM
  #71  
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Originally Posted by bampilot06
Now we’re splitting hairs, but you can have your podium back.
Pedants R Us!

(Though a true pedant would point out that 'R' is not a word, and you really should use the subjective case, not the objective, and the word order is wrong.)
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Old 05-27-22, 05:08 PM
  #72  
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Originally Posted by bampilot06
Something has to separate us.
Quite an elitist attitude.
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Old 05-27-22, 05:19 PM
  #73  
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Originally Posted by Mojo31
Quite an elitist attitude.
I wasn’t being serious.
I suspect you are not either.
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Old 05-27-22, 05:29 PM
  #74  
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Originally Posted by bampilot06
I wasn’t being serious.
I suspect you are not either.
No, not at all.
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Old 05-27-22, 05:42 PM
  #75  
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Was this thread ever serious?
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