What is the truth behind bike weight? Does it really help THAT much?



Travis44

New Member
Jul 28, 2007
57
2
0
Carbon, titanium, grams and weight shaving: does it really make a difference? Will you really be able to tell the difference between a 16 lb bike and a 17 lb bike? I ride a 25 lb steel Scwhinn, so you can see that I am yet to experience this carbon obsession and such. I always hear people discussing how good a bike is just because of how much it weighs. My question: does it really matter? Does it effect riding on the flats as well as mountains? Or is it just a placebo, something that has a very minor effect but you "think" that your bike is lighter? Please respond, I want to get down to the bottom of this.
 

wiredued

New Member
Aug 17, 2004
1,300
0
0
Using www.analyticcycling.com I found that on the mountain road I climb 10lbs extra weight requires about 24 watts more power to maintain the same speed. The steeper and longer the climb the more it matters in a race but I'm just doing it to calculate watts.

Travis44 said:
Carbon, titanium, grams and weight shaving: does it really make a difference? Will you really be able to tell the difference between a 16 lb bike and a 17 lb bike? I ride a 25 lb steel Scwhinn, so you can see that I am yet to experience this carbon obsession and such. I always hear people discussing how good a bike is just because of how much it weighs. My question: does it really matter? Does it effect riding on the flats as well as mountains? Or is it just a placebo, something that has a very minor effect but you "think" that your bike is lighter? Please respond, I want to get down to the bottom of this.
 

dhk2

Well-Known Member
Aug 8, 2006
2,214
74
48
74
Travis44 said:
Carbon, titanium, grams and weight shaving: does it really make a difference? Will you really be able to tell the difference between a 16 lb bike and a 17 lb bike? I ride a 25 lb steel Scwhinn, so you can see that I am yet to experience this carbon obsession and such. I always hear people discussing how good a bike is just because of how much it weighs. My question: does it really matter? Does it effect riding on the flats as well as mountains? Or is it just a placebo, something that has a very minor effect but you "think" that your bike is lighter? Please respond, I want to get down to the bottom of this.
What matters is the total weight of bike and rider. Acceleration and vertical ascent rate on hills is almost proportional to total weight (at constant power). Total weight really doesn't matter on the flats at steady speed. EG, if you, your clothes, shoes, water and bike now weigh 200 lbs, saving 8 lbs on a new bike will leave your "system" at 192 lbs. That means you'll climb steep hills and accelerate ~4% faster. On a low-speed 10 minute climb, 4% is 24 seconds, which is a few bike lengths advantage.
"Does it really matter?" For most of us non-racers the answer is really no, but lots of us spend big money to get that small advantage. Guess it all depends how badly you want to beat up on your buddies.

Apart from the math, a lighter bike feels "quicker" and more responsive under you. When you step down on a stiff new 16-17 lb wonderbike, it will feel like it's a lot quicker to jump than your old lead sled. Despite what you hear about old-school steel, bet you'll like the ride feel on the lighter bike better too.

Try some test rides and see for yourself. It's been said many times that dieting is a lot cheaper way to save pounds than buying a new bike, but that's another topic :)
 

sogood

New Member
Aug 24, 2006
2,148
0
36
25lb to 16lb is 36% reduction in weight. Put on a 14lb bag on your present 25lb bike and ride it for a while, then take that weight off for a comparable percentage in weight reduction and ride it again. I think you'll be able to answer your own question in a factual way. One parameter you may not be able to discern is frame stiffness. Most of the CF frames these days have improved considerably in terms overall stiffness. You'll just have to imagine that one.

BTW, don't forget to come back and let us know what you've found and conclusion. And should you test downhills, then your heavily laden bike will go faster.
 
Dec 30, 2007
2,111
8
0
Travis44 said:
Carbon, titanium, grams and weight shaving: does it really make a difference? Will you really be able to tell the difference between a 16 lb bike and a 17 lb bike? I ride a 25 lb steel Scwhinn, so you can see that I am yet to experience this carbon obsession and such. I always hear people discussing how good a bike is just because of how much it weighs. My question: does it really matter? Does it effect riding on the flats as well as mountains? Or is it just a placebo, something that has a very minor effect but you "think" that your bike is lighter? Please respond, I want to get down to the bottom of this.

Do the arithmetic. Saving 2 pounds on a 200 pound package, rider and bike, is 1%. Not significant, not meaningful, not really anything of note. WAY to much emphasis on the bike and trying to lose grams, not pounds. 4 things make a SIGNIFICANT difference in cycling performance.
-Fit-does your bike fit ya
-Fitness-are you fit?
-Fat-lackthereof on you where you may be able to lose a SBW(standard bike weight-20 pounds)
-Finesse-riding and racing smart

Not the frame, not the wheels, not the machine really at all. Whether the bike is 18 pounds or 16 pounds, the bike only has a significant impact on riding performance is if something breaks, then it slows your ride down a lot.

But will somebody spec 32h wheels, even if they are .1 offa ton++? Just to save those 28 grams, yep. Will somebody buy a chain with holes in the plates and pins to save grams, yep.....so it goes, the daffy bike market.

Latest 'craze' is ceramic balls. Most engineers that have tested this say 1-2% more power..if it's worth the $400 or so for ceramics all the way thru-go ahead. I don't think so.
 
Dec 30, 2007
2,111
8
0
sogood said:
25lb to 16lb is 36% reduction in weight. Put on a 14lb bag on your present 25lb bike and ride it for a while, then take that weight off for a comparable percentage in weight reduction and ride it again. I think you'll be able to answer your own question in a factual way. One parameter you may not be able to discern is frame stiffness. Most of the CF frames these days have improved considerably in terms overall stiffness. You'll just have to imagine that one.

BTW, don't forget to come back and let us know what you've found and conclusion.

Not really 36% of the bike and rider, of course. Plus 25 to 16 is 9 pounds, and on a 175 pound rider is 5%, not 36%.

Will the gent be 5% faster with a 16 pound bike?
 

TheDarkLord

New Member
Dec 24, 2007
3,887
0
0
sogood said:
25lb to 16lb is 36% reduction in weight. Put on a 14lb bag on your present 25lb bike and ride it for a while, then take that weight off for a comparable percentage in weight reduction and ride it again. I think you'll be able to answer your own question in a factual way. One parameter you may not be able to discern is frame stiffness. Most of the CF frames these days have improved considerably in terms overall stiffness. You'll just have to imagine that one.

BTW, don't forget to come back and let us know what you've found and conclusion.
That's highly misleading. It is the weight of bike plus rider that counts. The rider is moving along with the bike, and it is the entire mass that has to be accelerated. But there are other considerations when comparing a road bike and mountain bike, such as the effect of the knobby tires.

Coming to the OP's question, the weight savings probably makes a difference in pro-racing, but when it comes to typical riders, the placebo effect may contribute more than that of the weight savings itself.
 

sogood

New Member
Aug 24, 2006
2,148
0
36
Not really 36% of the bike and rider, of course. Plus 25 to 16 is 9 pounds, and on a 175 pound rider is 5%, not 36%.
Doesn't matter. The issue is whether a rider can feel a 36% reduction in the bike's weight. He'll just have to try it.

As for the math. 39lb (25+14) to 25lb is a 36% weight reduction, comparable to 25lb to 16lb. Of course, he can also try a 9lb variation (25lb to 16lb), but that's by absolute weight difference rather than by percentage.
 

sogood

New Member
Aug 24, 2006
2,148
0
36
TheDarkLord said:
That's highly misleading.
Not really. It may be the worst case scenario but it sure will tell the OP whether he can feel a difference (ride speed/time isn't everything). If he can't, then he can stay with his 25lb bike. If he can, then he may need to explore a bit more, possibly test ride a 16lb bike.
 
Dec 30, 2007
2,111
8
0
sogood said:
Doesn't matter. The issue is whether a rider can feel a 36% reduction in the bike's weight. He'll just have to try it.

As for the math. 39lb (25+14) to 25lb is a 36% weight reduction, comparable to 25lb to 16lb. Of course, he can also try a 9lb variation (25lb to 16lb), but that's by absolute weight difference rather than by percentage.

Well, not gonna wrestle over this but the energy to accelerate a bike is the mass of the bike and rider. So to 'feel' something you have to take into account the total, not just the bike weight. The only place weight of the bike makes a difference alone is when he's lifting it onto the roof of his car.

Also having everything be equal except 9-11 pounds is gonna be tough. I think a control would be add say 10 pounds to the package, like add weighted vest, then ride the same hill, to see but lots of variables.

So I think by isolating the weight of the bike increase is skewed a bit.
 

sogood

New Member
Aug 24, 2006
2,148
0
36
Well, not gonna wrestle over this but the energy to accelerate a bike is the mass of the bike and rider. So to 'feel' something you have to take into account the total, not just the bike weight. The only place weight of the bike makes a difference alone is when he's lifting it onto the roof of his car.

Also having everything be equal except 9-11 pounds is gonna be tough. I think a control would be add say 10 pounds to the package, like add weighted vest, then ride the same hill, to see but lots of variables.

So I think by isolating the weight of the bike increase is skewed a bit.
The OP needs to convince himself. So a simple experiment on his turf would allow him to "get to the bottom of it". So why not? All these physics probably doesn't mean very much for the OP.
 

alienator

Well-Known Member
Jun 10, 2004
12,596
310
0
rudycyclist said:
Alienator can definitely answer this one for ya!!:D

It's been answered here and in just about every other forum or whatever...er....elsewhere. The fact is that bike weight, be it on the frame, the wheels, the crank, or lodged in the crevices in the brakes or in your butt, it won't make much of a difference at all. A bike might feel a bit more spunky as you throw it backa and forth, but that doesn't equal quantum leaps in performance.

You can believe the facts or not.
 

JTE83

Member
Jan 28, 2004
1,390
18
0
This is a bit unscientific because I was in different form for these top speeds, and I don't remember the exact weight of my bikes.

Top Speed in the flats no wind sprint & weight of bike -
2004 Cervelo Soloist Team 32.9 mph 17.4 lbs
2005 Kestrel Talon 31.1 mph 18.6 ? lbs
2002 Giant TCR Aero 2 30.2 mph 18.6 lbs
2005 Giant OCR 1 with 2 Jandd Commuter Panniers 29.8 mph 29? lbs

Haven't tried top speed on my best bike - 2006 CF Cervelo Soloist Team with Zipp 404s and Zero Gravitys!
 

sogood

New Member
Aug 24, 2006
2,148
0
36
JTE83 said:
This is a bit unscientific because I was in different form for these top speeds, and I don't remember the exact weight of my bikes.

Top Speed in the flats no wind sprint & weight of bike -
2004 Cervelo Soloist Team 32.9 mph 17.4 lbs
2005 Kestrel Talon 31.1 mph 18.6 ? lbs
2002 Giant TCR Aero 2 30.2 mph 18.6 lbs
2005 Giant OCR 1 with 2 Jandd Commuter Panniers 29.8 mph 29? lbs

Haven't tried top speed on my best bike - 2006 CF Cervelo Soloist Team with Zipp 404s and Zero Gravitys!
I have a feeling this one will get shot down. :D
 

ScienceIsCool

New Member
Jun 25, 2006
333
0
0
sogood said:
I have a feeling this one will get shot down. :D
KERBLAM! There ya go...

If you think of the factors that affect drag, and therefore top speed, mass doesn't come into it. Unless you are going up or down a hill of course. Well, there's a miniscule variation in bearing drag and rolling resistance due to weight, but whatever...

Since aerodynamics is the biggest component of drag, I'd say the variation in riding positions between the bikes is what's causing the difference in top speeds.

John Swanson
www.bikephysics.com
 

alienator

Well-Known Member
Jun 10, 2004
12,596
310
0
ScienceIsCool said:
KERBLAM! There ya go...

If you think of the factors that affect drag, and therefore top speed, mass doesn't come into it. Unless you are going up or down a hill of course. Well, there's a miniscule variation in bearing drag and rolling resistance due to weight, but whatever...

Since aerodynamics is the biggest component of drag, I'd say the variation in riding positions between the bikes is what's causing the difference in top speeds.

John Swanson
www.bikephysics.com

Why do you hate Cervelo so much? And why do you hate America?
 

Crankyfeet

New Member
Jun 5, 2007
10,817
0
36
sogood said:
Doesn't matter. The issue is whether a rider can feel a 36% reduction in the bike's weight. He'll just have to try it.

As for the math. 39lb (25+14) to 25lb is a 36% weight reduction, comparable to 25lb to 16lb. Of course, he can also try a 9lb variation (25lb to 16lb), but that's by absolute weight difference rather than by percentage.
With due respect... the percentage weight reduction of the stand alone bike is irrelevant. It is the nine pounds difference that is relevant.
 

sogood

New Member
Aug 24, 2006
2,148
0
36
Crankyfeet said:
With due respect... the percentage weight reduction of the stand alone bike is irrelevant. It is the nine pounds difference that is relevant.
Relevant to what? Speed? Feel? Look?

As I said, using that 36% weight reduction as a parameter is probably a worst case scenario. If the OP can't feel a difference, then he won't feel the difference b/n 25lb to 16lb. If he does, then he can go and test ride a physical 16lb bike. In any case, it's a close to zero cost experiment.
 

Phill P

New Member
Jul 9, 2006
513
0
0
45
Saving a good chunk of weight (off bike or rider) can make a noticable difference off climbing performance. I'd like to climb 5% faster.
So the theory that has been driven into cyclists is that even a small difference in weight will make a small difference. You might not notice each small difference but they add up.

And thats where our ego and marketing kicks in. Racing or otherwise we want to be able to keep up or push ahead, and every advantage is desired.
The marketing departments are always telling you people win on thier products, your competitors/mates have this advantage, you need it too.
Plus there is prestige to owning a "quality" bike, jut like owning a "quality" car.

For me personally, I'd looooove a high end bike that weights 7.5kg and looks pretty. But the extra it costs to go from mid range solid dependable and resonable looking to high end flashy light weight does not result in enough performance increase for my type of riding. Beides a $10,000 bike crashes just the same as a $3000 bike, maybe even worse!
For some people what they percieve in gain is worth the extra money TO THEM, so let them spend it. The rest of us get the trickle down effect of the developement that goes into these over priced items.
 

Similar threads

R
Replies
0
Views
402
R