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Old 05-10-07, 02:31 AM   #1
stbtra
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what's the difference in weight

this may seem like a naive question but why do people want their bikes to weigh less
i.e. what's the diff between a 180lb guy riding a 15lb bike vs a 150lb guy riding a 25lb bike?
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Old 05-10-07, 02:56 AM   #2
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Well more muscle means heavier, obviously. A lighter bike is always going to be a lighter bike, less weight to bring up hills and whatnot, so that's always going to be in your favor no matter how much you weight. Bike weight really isn't a big issue in terms of sheer performance though.
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Old 05-10-07, 07:30 AM   #3
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i heard someplace that 7 pounds on the body equals 1 pound on the bike, but don't know if that's true or what it means.
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Old 05-10-07, 07:38 AM   #4
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A light bike goes uphill faster, accelerates faster (as long as it's not too flexy) and deccelerates faster. It's easier to carry up stairs, get on trains, and lift up to lock to poles. And it feels nice to pick up.
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Old 05-10-07, 07:58 AM   #5
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power to weight ratio

less weight = less work you have to do to make it go faster, farther etc
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Old 05-10-07, 08:01 AM   #6
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Originally Posted by astrx
i heard someplace that 7 pounds on the body equals 1 pound on the bike, but don't know if that's true or what it means.

All such relations are completely nonsense.
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Old 05-10-07, 08:21 AM   #7
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The 180 lb guy is used to carrying around that 180 lbs all day long. The less you add to it the better.

My friend weighs close to 300 lbs. Now if I donned a 120lb backpack, I doubt that I could keep up with her. I don't have the muscles to carry around an extra 120lbs. She obviously does.
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Old 05-10-07, 08:42 AM   #8
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Originally Posted by astrx
i heard someplace that 7 pounds on the body equals 1 pound on the bike, but don't know if that's true or what it means.
Highly doubtful. If you lost 7 pounds you'd probably gain far more advantage than if you got a 1 lb lighter bike.
That cliche probably refers more to luggage than to bike and body weight. If you carry your stuff in a backpack it's more tiring than carrying it on a rack.
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Old 05-10-07, 01:39 PM   #9
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plus it matters where the weight is on the bike. keeping rotational weight (i.e. wheels) down's more important than the stationary stuff.

but yeah, when it comes down to it, it's more about how strong you are than how much your bike weighs.
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Old 05-10-07, 02:05 PM   #10
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A lighter bike responds and reacts to pedal input more effectively than a heavier bike. Saying that- You will only find the light weight bikes at the top end of a range so component quality probably has a lot to do with it. Then again as someone has mentioned- it is where that weight is. Rotating weight on the wheels for example. A light weight wheelset is probably the best upgrade that anyone can make to any bike. That is so as to not complicate the issue as a Heavy set of tyres will ruin all that.

Given the choice- I think most of us would prefer a lightweight bike. They Fly up hills but I would not to take them on a the Belgian cobbles or even roguh roads too often.
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Old 05-10-07, 03:10 PM   #11
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Originally Posted by subhuman
plus it matters where the weight is on the bike. keeping rotational weight (i.e. wheels) down's more important than the stationary stuff.
Yes but how much more? About 1.001 times or less.
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Old 05-10-07, 03:28 PM   #12
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It's the same factor why people buy Ferrari and Porsche to drive in a stop-and-go traffic at a snail speed.
Because of the neighbors!
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Old 05-10-07, 03:41 PM   #13
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My friend weighs close to 300 lbs. I doubt that I could keep up with her.

hahahahhaha
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Old 05-10-07, 03:45 PM   #14
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Quote:
Originally Posted by subhuman
plus it matters where the weight is on the bike. keeping rotational weight (i.e. wheels) down's more important than the stationary stuff. .
This is a common misconception. Light wheels accelerate faster, but unfortunately they also decelerate faster. So you keep surging and lagging. They offer no net advantage compared to lightening some other component of the frame. In fact, for a recent hour record the rider deliberately chose very heavy wheels specifically because their flywheel effect would even out his speed and thus slightly lessen his air resistance.

Last edited by cooker; 05-10-07 at 09:00 PM.
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Old 05-12-07, 05:31 AM   #15
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Originally Posted by asgelle
Yes but how much more? About 1.001 times or less.
Put it this way. I bought a low end road bike with Formula hubs and Alexa rims. I got a set of what the Serious riders would call Training wheels. 105 hubs-36 double butted spokes and Mavic CXP33 rims. Lost 400grammes on the pair of wheels. Then I put on Michelin Pro Race 2 tyres in 23. They added 3 mph to my average speed on a ride- I found slopes did not exist-short hills became slopes and on the hills I was 2 gears higher. That was just a change to Good Wheels. I was then loaned apair of Mavic Krysium's to see if I liked them. an extra 1 mph but I found they transmitted a bit too much road buzz to me as they are a radially spoked wheel. Fast wheel but at 50 miles I was beginning to feel fatigued.

On the MTB- I Use XT hubs- 32 spokes and Mavic 217 rims- (Getting hard to find but I still have 4 rims left) Basically a cheap basic wheel but they are far better than most original fitment wheels. Then I have a set of Mavic crossrides for special occasions- Enduro's etc. Once again they are radial spoking but the tyres and pressute means that I do not feel it as I do on the Road bike. BUT on the MTB I use a 1.8 tyre with a Kevlar bead. They weigh about 200 grammes a pair less than the 2.1 version and that does make a difference uphills. Less drag and no loss of grip.
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Old 05-12-07, 05:44 AM   #16
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I realized how important the difference was when I go to class. A book bag with a couple of college sized texts books (15lbs) on a 2 mi. commute wears my legs out when I am going at moderate speed, but the same commute is nothing when I am rushing to avoid being late for my exam and I am pushing 25 mph on my mtb. The weight makes a difference.

Even a bike lock makes a difference I can feel, especially on little ascents and I'm trying to keep a good credence. I realized that when I went to an exam and I forgot my lock and had to go get it.

Try this for yourself - you'd be surprised.
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Old 05-12-07, 02:23 PM   #17
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They added 3 mph to my average speed on a ride- I found slopes did not exist-short hills became slopes and on the hills I was 2 gears higher. That was just a change to Good Wheels..
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