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How much does weight affect.........

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Old 08-02-18 | 05:19 PM
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How much does weight affect.........

Greetings,

I have a simple question that may get answered in complicated way, or in basic terms. Any help would be appreciated

Im a fixed gear rider in nyc, rides are for fitness and fun ranging from 10-30 miles. Bridges and some parts of Central Park are the extent of my hills and occasionally defeat me. I’m 6 foot 215 and fit, not super cycling fit. I ride a 48x19 gear ratio and some point would like to get a 17 so I’m not spinning like a lunatic at 30mph, but yes I realize I’ll be walking the bike up more bridges when I’m tired.

Heres the big question though. How much effect would it be if I was able to drop 10lbs of my body and get to 205 assuming I maintain relatively same overall fitness level. There must be a calculator out there in terms of watts/speed and weight maybe even with gear ratios and I just can’t find it. If folks are trying to lose grams of their bike I imagine dropping 10lbs has to be significant right?

Thanks
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Old 08-02-18 | 05:28 PM
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Up significant grades, a few percent assuming you're doing similar power.
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Old 08-02-18 | 06:32 PM
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I can tell you that my wife goes up hills way easier and quicker than I do. She weighs 100 pounds less than me, and we’re on the same model bike. I go down quicker . I weigh about the same as you, but I’m old and trying to drop 20, which seems like a major hurdle. I’m guessing it will help me going up hills, if I can drop some weight. Probably not the scientific answer you’re looking for, but I’m guessing somebody will help with more helpful data.
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Old 08-02-18 | 06:43 PM
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If Central Park and NYC bridges are a problem, you should get some gears.
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Old 08-02-18 | 06:44 PM
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Add the weight of the bike to the weight of your body, figure what percentage of that is ten pounds, and that is the percentage lless energy it will take to move the lower mass. Pretty minuscule. if you drop ten pounds of fat ... great. If you drop 15 pounds of fat and ad five in muscle to your legs, better .... but if you ride a lot of high-intensity intervals and hill repeats ... you will actually ride faster and climb hills more easily. Weight loss is never a bad thing .... but it is proportional. Unless you are cutting off your arms ..... not a Huge difference.

Add increased fitness, and ..... well, see what yo see and do what you like .... whatever works for you.
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Old 08-02-18 | 06:49 PM
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Yes losing weight will help but its more practical to think in terms of fat percentage since muscle is functional while fat is just dead weight.
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Old 08-02-18 | 06:56 PM
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Studies have been done indicating 12lbs = 1mph in speed on flat ground. But anything over 20mph the aerodynamics starts having a larger effect.
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Old 08-02-18 | 06:57 PM
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Stop Thinking NYC is Flat.

You love to ride.
You ride hills.
Stop hating them.
The obstacle is the Way.
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Old 08-02-18 | 06:59 PM
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You realize that being heavier doesn't explain why you go down hills faster, right?

Originally Posted by talphie
I can tell you that my wife goes up hills way easier and quicker than I do. She weighs 100 pounds less than me, and we’re on the same model bike. I go down quicker . I weigh about the same as you, but I’m old and trying to drop 20, which seems like a major hurdle. I’m guessing it will help me going up hills, if I can drop some weight. Probably not the scientific answer you’re looking for, but I’m guessing somebody will help with more helpful data.
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Old 08-02-18 | 07:12 PM
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Originally Posted by brianmcg123
Studies have been done indicating 12lbs = 1mph in speed on flat ground. But anything over 20mph the aerodynamics starts having a larger effect.
It seems to me that on a flat ground, it wouldn't matter at all. Ten pounds, that is.
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Old 08-02-18 | 07:18 PM
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Originally Posted by dieselgoat
It seems to me that on a flat ground, it wouldn't matter at all. Ten pounds, that is.
It does.
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Old 08-02-18 | 07:21 PM
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In theory, weight should only affect acceleration/deceleration times unless it adds to friction.
Originally Posted by brianmcg123


It does.
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Old 08-02-18 | 07:23 PM
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Originally Posted by brianmcg123
Studies have been done indicating 12lbs = 1mph in speed on flat ground.
What are you referring to?

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Old 08-02-18 | 07:31 PM
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Originally Posted by HTupolev
What are you referring to?

​​​
I remember reading an old study about this. I can't find the link at it was an old PDF version. The online bike calculators don't seem to back this up. Maybe this was up a certain % grade. But for some reason I have remembered the 12lbs per 1mph rule. But I could be wrong. Not the first time.

Here was some interesting reading though: https://www.velonews.com/2012/05/bik...-matter_220429
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Old 08-02-18 | 08:27 PM
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Originally Posted by Robert A
In theory, weight should only affect acceleration/deceleration times unless it adds to friction.
I don’t know what you mean by friction, but added weight will increase rolling resistance. Also since weight generally increases the size of the rider, in all likelihood, drag will also increase. Both of these resistance forces are present even in the absence of accelerations.
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Old 08-02-18 | 08:39 PM
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There is the statistic of each pound of fat containing seven miles of capillaries. So that's gonna take some energy to keep those miles of blood vessels flowing with every heart beat. And that's just one pound of fat.

Think about that while you're climbing your next hill.
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Old 08-02-18 | 08:40 PM
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Amazing. When I said I was going to drop 10 I didn’t plan on losing muscle. I stated same level of fitness. I’m around 14% body fat, maybe I can cut my calf muscle off for 10lbs lol you avoided the question. Tsk tsk

On the gears comment. You know who you are. Way to not add anything to the discussion. After a few hours riding the bridges just isn’t fun to get home

Now to the intelligent fella who shared the article. Thank you. It’s reasonable to expect with the same effort to go almost 2mph faster and have a much easier time on climbs
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Old 08-02-18 | 08:52 PM
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Dropping 10 lbs is only 5%.It will help but not by much. Not enough to move to 48/17 if 48/19 is already at the limit. Only way to fix it is to get some more gears.
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Old 08-02-18 | 08:59 PM
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Originally Posted by bergerkjh
On the gears comment. You know who you are. Way to not add anything to the discussion. After a few hours riding the bridges just isn’t fun to get home
I lived in BK. I commuted by bike. I've got plenty of five borough (okay, four boroughs - **** SI) miles under my belt. If you're having a hard time with those elevation gains, you should get some gears. This may not be the discussion you want, but it's the discussion you need.
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Old 08-02-18 | 09:14 PM
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Ok I see what’s going on here. We all hate the fixed gear guy because you nerds love your gears and think you’re so cool shifting and clipping in, and wear spandex with sewed in diapers and let’s also point out choosing the easiest gear possible to ride in, I see you out there. Option B youre too stupid to understand my initial statement. At no point did I request advice on my bike.

I specifically asked what effect losing 10lbs would be. Think physics not biology. Maybe show some inkling of proof, maybe even a graph or calculation. Duh get some gears. Never should of mentioned the climbs, I apologize for misleading you. But I also stated I’m going 30ph so do you really think I’m out of shape and can’t get up the hills?

Now......with everyone mentioning 10lbs or 4% lighter not going to help much. Clearly you did not bother reading the article that was so politely shared.

I expected some actual inteligent comments here. Clearly the bulk of you spend more time trolling here than riding.

“Here’s another one. On a hilly loop course, a 20-pound weight difference in bikes yielded a 13.6-percent drop in speed. Extrapolating that to your 12-pound weight difference, you’d be looking at an eight-percent speed loss.

Personally, I would find a six-percent or eight-percent speed loss to be rather unbearable, but if you don’t care about that, then no need to spend the extra money”
― Lennard


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Old 08-02-18 | 09:17 PM
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Right.
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Old 08-02-18 | 09:34 PM
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Dude, the issue is w/kg. Improving that metric by only 5% is not going to help a whole lot. 5% more speed uphill for the same effort and about zero % on the flats.

Bike Calculator
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Old 08-02-18 | 09:45 PM
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I was referring friction in any form -- wind, tires, etc. Still, I don't think 10 pounds changes wind resistance in a meaningful way. Rolling resistance from added weight can be overcome with increased tire pressure.
Originally Posted by asgelle

I don’t know what you mean by friction, but added weight will increase rolling resistance. Also since weight generally increases the size of the rider, in all likelihood, drag will also increase. Both of these resistance forces are present even in the absence of accelerations.
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Old 08-02-18 | 09:53 PM
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Originally Posted by bergerkjh
...

I specifically asked what effect losing 10lbs would be. Think physics not biology. Maybe show some inkling of proof, maybe even a graph or calculation. Duh get some gears. Never should of mentioned the climbs, I apologize for misleading you. But I also stated I’m going 30ph so do you really think I’m out of shape and can’t get up the hills?

...
I don't have the numbers you are looking for. I have been riding up hills on fix gears a long, long time. I can promise you, lose that 10 pounds and those hills will be a lot more fun. And I promise you will go a lot faster when they are more fun. (I am assuming that 10 pounds is weight you don't need.) I weight roughly 155. A 7 pound drop for me, say from 159 to 152 would make riding the fix gear over a hill much more fun! In fact. it is the single best incentive to lose weight for me.

Ben
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Old 08-02-18 | 10:04 PM
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I too found bikecalculator. A bit disheartening on the physics front but then Ben comes in with real life knowledge and there was much rejoicing. The capillaries guy may in fact be closer to right than I thought.

This is all started when I was chasing this twig of a man through some moderate rolling hills. He was unaware I was racing him of course but it makes it fun. When I finally passed him I saw he was average height and maybe 140lbs soaking wet. Also he had to be at least 60 years old

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