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  1. #1
    Retired dabbler hobkirk's Avatar
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    It'is all about the climbing - esp. for us - Lose 440 yds going up, gain 15 doown

    I don't do much in this forum even though I fit the definition - I'm currently 233# at 6'2" - much too heavy by any chart and vastly too heavy for this sport. I hope you find the following info interesting.

    Ascent

    When I started riding, I used to ask my only cycling friend a lot of questions. His most memorable quote was "it's all about the climbing." This from a guy who chose to ride centuries (100 miles) over the Kangamangs pass in the White Mountains.

    But I didn't just harass friends, I also read about cycling.

    Joe Friel depressed me with his claim that:

    • Every kilogram costs 3 seconds over a kilometer on a 5% ascent


    I weigh 38# more than my minimum goal, 48# over my preferred goal. If I round that to 20 Kg (1 Kg = 2.2#), that means my fat costs me 90 seconds over one mile at 5% (I think "miles," not "kilometers").

    • At 10 MPH, it's 0.25 miles.


    No wonder I get dropped on group rides at every climb.

    Coasting

    Gravity is a fat rider's friend on downhills, but the advantage is a small fraction of the climbing penalty. Based on a year of riding, almost entirely with fit people, I would guess my downhill advantage is 1-2 MPH - it's a subtle edge. Downhill speeds are faster, of course, and I am using educated guesses for average descent speed.

    • 30 MPH would gain 9 seconds (15 yards, roughly 0.01 miles) over 28 MPH over a mile. Argh!


    Net

    • Lose 0.25 miles going up, gain 0.01 miles going down


    -----------

    On a recent group ride there was a very long and very steep hill around the 25 mile mark. The fit riders (there are very few fat riders in my cycling clubs) had grouped at the top. I yelled "curse you skinny people" as I rode by. They should grasp my sarcasm by now. I kept going because I knew they would catch me on the next climb.

    -----------

    Feel free to point out any errors! Have a great ride.
    2007 Specialized Roubaix, 105 Triple
    Started cycling 6/1/2010 at 64 - lethargy, bad knees, & 247# triggered my foray into cycling
    200# as of 9/9/2012 (mostly from diet, 40# in 5 mo)
    2010 (1st 7 mo) = 4.7K miles (a little nuts), 2011 = 6K

  2. #2
    Senior Member volosong's Avatar
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    Sheech! I knew I couldn't climb, but didn't know it was that bad. The new bike has helped a lot, but it looks like I need to get my weight down to where your goal is. I am 6'3", (well, actually 6' 2 and 3/4", depending on the time of day), and currently holding at 206. I too would like to maintain 195, and would really feel comfortable at 185. Got there a few years ago, but a heavy work schedule and using food as an emotional comfort "outlet" took me back up to 215 or so earlier this year. I seem to be holding steady at 205-206 the past few weeks.

    And ... uugh! I don't like hills, but that seems to be the best way for us to burn off the excess calories. Oh, and going downhill? I'm a "chicken" on the downhills. An experience with the "death wobble" has scared me enough to keep my coasting speeds below 35 or so. On flats, no problems ... just downhlls.

    Thanks for your analysis.
    Deut 6:5

    ---

    "Ha ha! You fool! You fell victim to one of the classic blunders - The most famous of which is 'never get involved in a land war in Asia'".
    - Vizzini during his "battle of wits" with the Man in Black

  3. #3
    Senior Member Homeyba's Avatar
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    That's pretty much it. Us big guys have to be stronger to go just as fast up hills as the little guys. The advantage of being bigger/stronger is that with our strength we can also put a serious hurt on them in the flats.
    It doesn't get harder, you just go slower.

  4. #4
    Senior Member Mithrandir's Avatar
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    Quote Originally Posted by Homeyba View Post
    That's pretty much it. Us big guys have to be stronger to go just as fast up hills as the little guys. The advantage of being bigger/stronger is that with our strength we can also put a serious hurt on them in the flats.

    I'm noticing this. I can't climb worth crap, as I discovered much to my chagrin last week, but on level ground I can scream by guys who are easily 200 pounds lighter than me.

    I'll keep tackling hills for practice, but these calculations make me slightly disheartened

  5. #5
    Getting a clue engstrom's Avatar
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    I'm fortunate that I'm in a very big bicycle club. As a result we have 9 different Saturday morning rides (at 9 varying levels of speed and distance). The ride I do has several clydes. Pretty much all of them are faster than me up the hills, but I'm getting better. And eventually I'll lose 50 lbs. (already lost 30) and be down to my goal weight. Between weight loss and continued training I figure I'll be great on those hills (of course by then I'll be riding one of the more advanced rides and still be slow compared to the rest of the guys ).

  6. #6
    Senior Member Seattle Forrest's Avatar
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    Quote Originally Posted by hobkirk View Post
    Gravity is a fat rider's friend on downhills, but the advantage is a small fraction of the climbing penalty. Based on a year of riding, almost entirely with fit people, I would guess my downhill advantage is 1-2 MPH - it's a subtle edge. Downhill speeds are faster, of course, and I am using educated guesses for average descent speed.


    • 30 MPH would gain 9 seconds (15 yards, roughly 0.01 miles) over 28 MPH over a mile. Argh!
    I think if they're both on the same bike, a skinny person tucked in will go down the hill faster than a hefty person riding on the tops. Remember, aerodynamics is the only reason a bowling ball falls more quickly than a feather.
    Don't believe everything you think.

  7. #7
    Senior Member nkfrench's Avatar
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    Quote Originally Posted by Seattle Forrest View Post
    I think if they're both on the same bike, a skinny person tucked in will go down the hill faster than a hefty person riding on the tops. Remember, aerodynamics is the only reason a bowling ball falls more quickly than a feather.
    It's not an exact analogy. We're riding downhill, not dropping off cliffs. The physics are a little beyond me, but clydes have more potential mass at hilltop. athenas too.

  8. #8
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    Quote Originally Posted by nkfrench View Post
    It's not an exact analogy. We're riding downhill, not dropping off cliffs. The physics are a little beyond me, but clydes have more potential mass at hilltop. athenas too.
    I believe you mean potential energy, not potential mass. From a pure potential energy becoming kinetic energy, the mass is irrelevant - yes, a heavy rider has more potential energy at the top of the hill, but he also needs more kinetic energy to move at a given speed when at the bottom of the hill: The formula is Potential energy (at the top) = Kinetic energy (at the bottom). PE=mgh, KE=.5mv^2m so mgh=.5mv^2 (m is mass, g is acceleration due to gravity, h is height, v^2 is the velocity squared) - the mass term cancels out. This would be enough to describe the behavior of items falling in a vacuum.

    However, there are two major factors that complicate things - we don't ride in a vacuum, so we need to handle air friction, we aren't falling straight down, so we have to account for a much more complex rolling movement.

    Air friction is insanely complicated to actually compute for something as weird-shaped as a rider on a bike, but the biggest factor is frontal area - a smaller (or more tucked in) rider will have less air friction than a larger one. No help to us Clydes.

    The rolling movement is a bit beyond my long-ago and nearly-forgotten physics knowledge, but I don't think there's any help to us big guys there either - though I may be wrong.
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  9. #9
    Senior Member Seattle Forrest's Avatar
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    Quote Originally Posted by nkfrench View Post
    It's not an exact analogy. We're riding downhill, not dropping off cliffs. The physics are a little beyond me, but clydes have more potential mass at hilltop. athenas too.
    Potential mass? We're either there or we aren't; it's not like another 50 pounds will materialize on our way down the hill.

    You're right that we're rolling, and not free-falling, and what that means is that slick tires will get you down the hill faster than knobbies. That's going to be good for a few miles per hour. Honestly, I think switching from Gatorskins (not Ultras) to GP4000s got me about 1 or 2 mph going down a hill at around 30 mph, because they have less rolling resistance. I could be off, but that's my gut feeling.

    But, really, the difference is we aren't in a vacuum, so we have air resistance. And it goes up with the cube of your speed, for whatever frontal area you have. This is why the bowling ball falls more quickly than the feather, not because of their weight. Doing the aero-tuck so that less of your body is pushing against the wind will help you speed down the hill more than gaining weight ever will.

    None of this changes the point in the OP, that hills slow Clydes down, compared to equally strong but skinnier riders. Oh well.
    Don't believe everything you think.

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