Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Pound for pound what makes more of a difference?

General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Pound for pound what makes more of a difference?

Old 08-17-12, 11:51 AM
  #26  
DCB0
Banned.
 
Join Date: Apr 2011
Posts: 937

Bikes: CCM Torino 76

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by JonathanGennick View Post
At least a couple of the earlier responses said just that.
I just re-read the thread and could not find any.
DCB0 is offline  
Old 08-17-12, 12:04 PM
  #27  
JonathanGennick 
Senior Member
 
JonathanGennick's Avatar
 
Join Date: Apr 2007
Location: Munising, Michigan, USA
Posts: 4,008

Bikes: Priority 600, Priority Continuum, Devinci Dexter

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Likes: 0
Liked 4 Times in 3 Posts
Originally Posted by DCB0 View Post
I just re-read the thread and could not find any.
Looking back, there is less than I had remembered:

1. "From what ive seen apparently it doesnt make much of a difference to shed weight on the bike if you are overweight"
2. "Than, when you reach your target weight, reward yourself with a lighter bike." -- implying of course, that one should not buy the lighter bike first

Maybe I was just in a mood when read the thread the first time through.

My answer of "do both" still stands though. There's no reason to see the issue as having to choose between one or the other. If I can buy a lighter weight wheelset today or loose a few pounds over a month, there's no reason not to buy the wheelset today and lose the weight anyway.
JonathanGennick is offline  
Old 08-17-12, 12:39 PM
  #28  
DCB0
Banned.
 
Join Date: Apr 2011
Posts: 937

Bikes: CCM Torino 76

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by JonathanGennick View Post
Looking back, there is less than I had remembered:

1. "From what ive seen apparently it doesnt make much of a difference to shed weight on the bike if you are overweight"
2. "Than, when you reach your target weight, reward yourself with a lighter bike." -- implying of course, that one should not buy the lighter bike first

Maybe I was just in a mood when read the thread the first time through.

My answer of "do both" still stands though. There's no reason to see the issue as having to choose between one or the other. If I can buy a lighter weight wheelset today or loose a few pounds over a month, there's no reason not to buy the wheelset today and lose the weight anyway.
I agree that both are benificial. I read the following in a magazine years ago: 2 lbs off a 20 lb bike is a 10% reduction in weight. Could you make a 10% reduction in weight off your body and still be healthy? If yes, then the bike is not what is holding you back.

There is also the law of diminishing returns: Turning a 35 lb bike into a 30 lb bike is not too difficult, while turning a 30 lb bike into a 25 lb bike is more of a challenge. Turning a 25 lb bike into a 20 lb bike, or a 20 lb bike into a 15 lb bike, is tough, and there may be trade offs in durability or safety as you do it.

Turning my 260 lb body into a 208 lb body won't be too easy, but the side effeects are actaually positive, not negative.
DCB0 is offline  
Old 08-17-12, 12:45 PM
  #29  
bigfred 
Senior Member
 
Join Date: Jan 2009
Location: NZ
Posts: 3,839

Bikes: More than 1, but, less than S-1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked 0 Times in 0 Posts
Originally Posted by JonathanGennick View Post
At least a couple of the earlier responses said just that.
I just reread all 25 posts. I don't see a single instance of anyone even implying that a heavy rider isn't "deserving" of a light bike. The closest anyone comes is this,

"If you are in anyway over weight, concentrate on losing body weight. It will pay all sorts of dividends. Than, when you reach your target weight, reward yourself with a lighter bike."

And, that looks like a very honest and direct response to the OP's question.

If performance is your concern and you have a functional, bike suitable for the rides you're doing, it makes a greater difference to focus on improving the motor/engine of the bike that comprises 90% of the performance equation then worry about the bike.
__________________
Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.
bigfred is offline  
Old 08-17-12, 12:58 PM
  #30  
njkayaker
Senior Member
 
Join Date: Sep 2007
Posts: 11,083
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1698 Post(s)
Liked 18 Times in 13 Posts
Originally Posted by DCB0 View Post
I agree that both are benificial. I read the following in a magazine years ago: 2 lbs off a 20 lb bike is a 10% reduction in weight. Could you make a 10% reduction in weight off your body and still be healthy? If yes, then the bike is not what is holding you back.

There is also the law of diminishing returns: Turning a 35 lb bike into a 30 lb bike is not too difficult, while turning a 30 lb bike into a 25 lb bike is more of a challenge. Turning a 25 lb bike into a 20 lb bike, or a 20 lb bike into a 15 lb bike, is tough, and there may be trade offs in durability or safety as you do it.

Turning my 260 lb body into a 208 lb body won't be too easy, but the side effeects are actaually positive, not negative.
Reducing the weight of a 35 lb bicycle to 30 lbs is a reduction in weight of 14%. If the rider is 160 lbs, the real reduction in weight is only 2.6%. The effect of that small difference in weight on speed is going to be very hard to measure.

The "return" people are interested in is "speed" and a reduction of 5 lbs is only going to have a very small effect on speed. Aerodynamic issues are likely to have a much, much larger effect on people's speed.

It doesn't appear to matter much from where you remove the weight: from the bike, from the rider, or from the "rotating" mass for the direct small benefits of less weight.

Removing weight from the rider is more beneficial because it's (likely) the result of exercising more. The enhancement to speed of being stronger is going to be much larger than the issue of there being a bit less weight.

Last edited by njkayaker; 08-17-12 at 01:04 PM.
njkayaker is offline  
Old 08-17-12, 12:58 PM
  #31  
tagaproject6
Senior Member
 
tagaproject6's Avatar
 
Join Date: Aug 2009
Posts: 8,284

Bikes: Wilier Izoard XP (Record);Cinelli Xperience (Force);Specialized Allez (Rival);Bianchi Via Nirone 7 (Centaur); Colnago AC-R Disc;Colnago V1r Limited Edition;De Rosa King 3 Limited(Force 22);DeRosa Merak(Red):Pinarello Dogma 65.1 Hydro(Di2)

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 452 Post(s)
Liked 47 Times in 33 Posts
Originally Posted by Wait For Me View Post
For all of us that are more then 10% body fat. What makes more of a noticeable difference? Shaving 5lbs of the bike or 5lbs off the rider?
Do both and find out for yourself.
tagaproject6 is offline  
Old 08-17-12, 01:43 PM
  #32  
JonathanGennick 
Senior Member
 
JonathanGennick's Avatar
 
Join Date: Apr 2007
Location: Munising, Michigan, USA
Posts: 4,008

Bikes: Priority 600, Priority Continuum, Devinci Dexter

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 635 Post(s)
Likes: 0
Liked 4 Times in 3 Posts
Originally Posted by DCB0 View Post
Turning a 25 lb bike into a 20 lb bike, or a 20 lb bike into a 15 lb bike, is tough, and there may be trade offs in durability or safety as you do it.
You're right. I'd probably bust up any 15 pound bike that I rode. Or at least, I have not yet been able to afford a 15 pound bike that wouldn't collapse under me.
JonathanGennick is offline  
Old 08-17-12, 02:14 PM
  #33  
Booger1
Senior Member
 
Join Date: Sep 2007
Location: Gaseous Cloud around Uranus
Posts: 3,738
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Uphill or downhill?

Unless you and your bike are going riding at different times,it doesn't matter.

Last edited by Booger1; 08-17-12 at 02:21 PM.
Booger1 is offline  
Old 08-17-12, 02:43 PM
  #34  
rebel1916
Senior Member
 
rebel1916's Avatar
 
Join Date: Aug 2011
Posts: 3,012
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by bigfred View Post
I just reread all 25 posts. I don't see a single instance of anyone even implying that a heavy rider isn't "deserving" of a light bike. The closest anyone comes is this,

"If you are in anyway over weight, concentrate on losing body weight. It will pay all sorts of dividends. Than, when you reach your target weight, reward yourself with a lighter bike."

And, that looks like a very honest and direct response to the OP's question.

If performance is your concern and you have a functional, bike suitable for the rides you're doing, it makes a greater difference to focus on improving the motor/engine of the bike that comprises 90% of the performance equation then worry about the bike.
I said that. I stand by it. Anyone can spend their hard earned money however they want, but spending it on a toy that will help your fitness, as a reward for improving your fitness is just a way to help yourself make good decisions. I am not gonna reread the whole thread, but I'm pretty sure I also mentioned losing weight almost 8 years ago and keeping it off. We all have the potential to be fatties. Most of us just choose not to be crybabies about it.
rebel1916 is offline  
Old 08-17-12, 07:13 PM
  #35  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 21,346

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 92 Post(s)
Tagged: 1 Thread(s)
Quoted: 2463 Post(s)
Likes: 0
Liked 102 Times in 69 Posts
Originally Posted by DCB0 View Post
You are about 15% correct in that post.

HEavier wheels/tires will impact the effort required for acceleration, but not for cruising at a constant speed. On level ground at constant speed, weight of bike, wheels/tires, and rider, play no role.
The switch from studded tires to street tires may make a big difference, but it is impossible to say if it is from the weight, or from the added rolling resistance of the thicker rubber used to keep the studs in place and not poking the tube, and possibly the extra flex in the rubber caused by the rigid studs hitting the pavement. All of these doubtless play some role in slowing you down, but it is impossible to say how much is caused by the weight.
I don't know where you came up with the 15% thing. But you are wrong about cruising at a constant speed. Since we live in an atmosphere and with friction and with variations in altitude, we are never 'cruising at a constant speed'. We are constantly accelerating in response to air resistance and tire friction. Since we are constantly accelerating, the wheels weight has a higher impact on that acceleration.

If you don't like the studded tire example, try the steel wheel vs aluminum wheels. If you can score them, compare the steel to carbon fiber. By the way, my studded tires a knobbed tires that replace knobbed mountain bike tires. Similar rubber, similar tire patterns, similar tire stiffness. The studded tire has a huge impact over the knobbed mountain bike tires.
__________________
Stuart Black
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.
cyccommute is offline  
Old 08-17-12, 07:20 PM
  #36  
downtube42
Senior Member
 
downtube42's Avatar
 
Join Date: Oct 2008
Location: Portland, OR
Posts: 1,940

Bikes: Volae Team, '74ish Windsor Carrera Sport, Priority Eight, Nimbus MUni

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 68 Post(s)
Likes: 0
Liked 25 Times in 16 Posts
Bike won't backslide after it loses 5 pounds.
downtube42 is offline  
Old 08-17-12, 07:35 PM
  #37  
LarDasse74
Guest
 
Join Date: Jul 2008
Location: Grid Reference, SK
Posts: 3,768

Bikes: I never learned to ride a bike. It is my deepest shame.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by cyccommute View Post
I don't know where you came up with the 15% thing. But you are wrong about cruising at a constant speed. Since we live in an atmosphere and with friction and with variations in altitude, we are never 'cruising at a constant speed'. We are constantly accelerating in response to air resistance and tire friction. Since we are constantly accelerating, the wheels weight has a higher impact on that acceleration.

If you don't like the studded tire example, try the steel wheel vs aluminum wheels. If you can score them, compare the steel to carbon fiber. By the way, my studded tires a knobbed tires that replace knobbed mountain bike tires. Similar rubber, similar tire patterns, similar tire stiffness. The studded tire has a huge impact over the knobbed mountain bike tires.
Cruising at a constant speed is totally possible. Your statement that 'we are constantly accelerating' is simply not true. Just because there is drag (rolling, bearing, or aerodynamic resistance) does not mean we are decelerating and need to re-accelerate. IF you rotate your pedals at a constant rate you are moving at a constant speed. If drag increases (a gust of wind, for instance) and you increase the force you are putting into the pedals to keep them turning at the same speed, there is no deceleration and no need to re-accelerate.

In fact, a heavier tire will give you more of a flywheel effect and tend to make your speed more stable on flat ground.

As for your comment about having comparable winter- and summer tires - check again: I have three styles of studded winter tires - a pair of decent quality Nokian 26" mtb tires, a cheap 700C tire, and a good quality 700 tire. All of them feel much stiffer than any non studded tire that I remember having in the 20+ years since I started paying attention to such things. When one of my bikes is mounted with any of these tires, it is definitely slower, but it is a combination of stiff grease in the drivetrain from the cold and heavier clothing on me, as well as higher rolling resistance and weight. And the weight component is close to zero on flat ground.

Even the link you provided in your earlier post does not mention increased effort to ride at constant speed - it specifically talks about acceleration.
LarDasse74 is offline  
Old 08-17-12, 07:39 PM
  #38  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 14,551

Bikes: Nashbar Road

Mentioned: 65 Post(s)
Tagged: 0 Thread(s)
Quoted: 2505 Post(s)
Liked 55 Times in 33 Posts
Originally Posted by cyccommute View Post
... Since we live in an atmosphere and with friction and with variations in altitude, we are never 'cruising at a constant speed'. We are constantly accelerating in response to air resistance and tire friction. Since we are constantly accelerating, the wheels weight has a higher impact on that acceleration.

...
I vote for taking it off the bike first, even for overweight folks. Why not go faster and uphill easier while losing weight?

I don't want to start a nitpick fight, but I disagree with the quoted part. All those small accelerations (and steady force against a resistance doesn't count without a change in velocity) are balanced by the momentum in the small decelerations. No energy is lost ... even if we ignore that part, adding it all up doesn't count for much. Rotating weight counts against you when you first start, after you bleed off energy braking, and possibly in handling, but not really anywhere else.
wphamilton is offline  
Old 08-17-12, 08:11 PM
  #39  
BlazingPedals
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Posts: 10,950

Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 910 Post(s)
Liked 25 Times in 20 Posts
If I drop 5 pounds from the bike, I get the benefits right now. Losing weight takes time and I can always do that later.
BlazingPedals is offline  
Old 08-17-12, 08:45 PM
  #40  
rebel1916
Senior Member
 
rebel1916's Avatar
 
Join Date: Aug 2011
Posts: 3,012
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Lotta people who need to ride their bikes more and their twinkie covered keyboards less in this thread.
rebel1916 is offline  
Old 08-17-12, 10:21 PM
  #41  
BigJeff
Senior Member
 
BigJeff's Avatar
 
Join Date: Jan 2011
Location: Pacific NW
Posts: 563
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Ok... I'll play.

I dropped 5 lbs this past week from me, and about 5 lbs from my bike today.


This past week I went from 249 lbs to 243 lbs. Riding 2 hours a day and doing about 45-75min of cardio workout videos.

My performance and strength over last weeks performance was increasing an average ride speed from 17.2 to 18.6 mph, on the same 40 mile loop with ~1400 elevation gain. On the faster average time we actually just coasted the downhills, since we don't have a need to push ~45-50mph with traffic flying by. (not a pro rider, so why risk it)

My bike is an entry level Focas Variado, weighing in at 26 lbs with all the low end FSA, Concept, Tiagra and (heavy aluminum) Stylus wheels.

Today, we put lipstick on the pig.

We swapped the wheels for Karbona Moonshot 58mm Carbon Clinchers with aluminum rails, carbon bar stem and carbon seat post. Total of shaving around 5lbs off the bike.

I'm doing my first long ride on it tomorrow, but riding around the block and climbing 8%-10% neighborhood streets, the 5lbs from the bike, primarily in rotational mass, has made pedaling quicker and lighter; accelerating is effortless.

DCBO's comments sounds like he's an electrical engineer not a mechanical engineer. Electrical guys have all the math, but lack the connection to the physics of reality. In reality, I'm always adjusting cadence and effort due to drafting, pulling at the front and climbing. Pulls are sometimes 30 seconds at 28mph, or 5 miles at 22mph.... it varies.

Losing 5 lbs off my body, and the strength I gained in doing that enabled us to finish our morning ride 1.2mph average quicker.

Next week, we'll see if the lighter wheels enable an overall quicker average (however, I may still be losing weight next week too... so the experiment isn't perfect).



With "gut feeling" method of testing, riding up a 8%-10% grade after a bike weight reduction is a huge benefit....beyond what I felt from removing weight from myself. My bike is still above 20lbs, but now the only weight savings would be from the group, handlebar and fork. (fork is currently carbon/aluminum)

The Group swap would probably yield a big change due to loss of rotational mass. (if I went from Tiagra to Campy or other top end components)
BigJeff is offline  
Old 08-17-12, 10:49 PM
  #42  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 21,346

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 92 Post(s)
Tagged: 1 Thread(s)
Quoted: 2463 Post(s)
Likes: 0
Liked 102 Times in 69 Posts
Originally Posted by LarDasse74 View Post
Cruising at a constant speed is totally possible. Your statement that 'we are constantly accelerating' is simply not true. Just because there is drag (rolling, bearing, or aerodynamic resistance) does not mean we are decelerating and need to re-accelerate. IF you rotate your pedals at a constant rate you are moving at a constant speed. If drag increases (a gust of wind, for instance) and you increase the force you are putting into the pedals to keep them turning at the same speed, there is no deceleration and no need to re-accelerate.
You can cruise at a constant speed but you can't do it without constant input of energy. Newton's First Law states that an object in motion will stay in motion unless acted on by on outside force. All of those little vampires that slow you down are the outside forces. If you have to increase the force you are putting into the pedals, you are accelerating to counteract the forces that are decelerating you. If you were riding in a frictionless vacuum, you could set the bike on its way and never have to put any more energy into the system to maintain the speed but in a real world situation, you are constantly accelerating even when just maintaining a steady speed.

Now I'm sure you have noticed how a heavier wheel is harder to spin up to speed. Since you are constantly having to accelerate the wheel to maintain speed...remember you said that you have to put more force into the system to maintain speed...a heavier wheel is a detriment. It's why we all want the lightest wheels we can get and don't ride steel wheels. Steel wheels would be stronger but they are a bear to get to speed and to maintain at speed...as anyone who has ever owned a pair can attest.

Originally Posted by LarDasse74 View Post
As for your comment about having comparable winter- and summer tires - check again: I have three styles of studded winter tires - a pair of decent quality Nokian 26" mtb tires, a cheap 700C tire, and a good quality 700 tire. All of them feel much stiffer than any non studded tire that I remember having in the 20+ years since I started paying attention to such things. When one of my bikes is mounted with any of these tires, it is definitely slower, but it is a combination of stiff grease in the drivetrain from the cold and heavier clothing on me, as well as higher rolling resistance and weight. And the weight component is close to zero on flat ground.
I have a Kenda Klondike on the front wheel only and a Panaracer Fire XC on another wheel. The Klondike equipped wheel weighs in at 5 lb 11 oz. The Fire XC wheel weighs in at 4 lbs. The Klondike isn't noticeably stiffer than the Fire XC nor is the tread pattern anymore aggressive...if anything the Klondike is slightly less aggressive than the Fire. For comparison here's the tread pattern from Kenda's website and the Panaracer website. Both tires are 2.1"



I only put the Klondike on the bike when it has snowed and ride the Fire XC when the roads are clearer but under the same temperatures. Thus the drag from grease and clothing are equivalent as is the drag from the tires. The only real difference between the two tires is the weight. The Kenda just isn't a fast tire because of it's excess weight.
Attached Images
File Type: jpg
k1013.jpg (7.8 KB, 2 views)
File Type: gif
firexcpro210.gif (7.3 KB, 62 views)
__________________
Stuart Black
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.
cyccommute is offline  
Old 08-17-12, 11:00 PM
  #43  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 21,346

Bikes: Some silver ones, a red one, an orange one and a few titanium ones

Mentioned: 92 Post(s)
Tagged: 1 Thread(s)
Quoted: 2463 Post(s)
Likes: 0
Liked 102 Times in 69 Posts
Originally Posted by wphamilton View Post
I vote for taking it off the bike first, even for overweight folks. Why not go faster and uphill easier while losing weight?

I don't want to start a nitpick fight, but I disagree with the quoted part. All those small accelerations (and steady force against a resistance doesn't count without a change in velocity) are balanced by the momentum in the small decelerations. No energy is lost ... even if we ignore that part, adding it all up doesn't count for much. Rotating weight counts against you when you first start, after you bleed off energy braking, and possibly in handling, but not really anywhere else.
The problem is that all those small accelerations aren't balanced by the momentum. In a vacuum, without friction and on a perfectly flat surface, momentum will never change. Try getting the bike rolling and then don't pedal. Eventually the bike will stop rolling without continued input of energy...even on a flat surface. And the world, as MechBgon has so wisely stated elsewhere, is seldom flat. Every time you have to put energy into the system to maintain speed, you are accelerating against some force that is slowing your bike down. And every time you push on the pedals, you are spinning the weight of your wheels around while accelerating them.

By the way, you see this is cars as well and motorists are as interested in losing weight off the wheels as much as bicyclists. Motorists, specifically race car teams, are talking about losing weight from all rotating parts...that's the cams, cranks, axles, wheels and anything else that goes spins.
__________________
Stuart Black
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
An Good Ol' Fashion Appalachian Butt Whoopin'.

Last edited by cyccommute; 08-17-12 at 11:06 PM.
cyccommute is offline  
Old 08-18-12, 12:27 AM
  #44  
mechBgon
Senior Member
 
mechBgon's Avatar
 
Join Date: Jul 2002
Posts: 6,957
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I don't know about anyone else, but I happen to be a bit of a gear-mashing fool and it's quite realistic to think that yes, my speed is fluctuating on a small scale even at apparently-steady speeds. The conventional wisdom says that people think they've got a smooth spin until they get onto a fixed-gear bike, and then they get a rude awakening. We're not electric motors.

A couple people have pointed out that it's not easy to drop five pounds from the typical road bike. But the OP didn't ask that. I certainly encourage anyone with five pounds of flab to train until it's gone, but I also reiterate my point: the extra five pounds on the rider could be power-producing muscle mass. But the extra five pounds on the bike...? There'd better be a darn good reason why it's there. Is it making the bike more aero? Is it energy drink that keeps you in the game three or four hours into the ride?
mechBgon is offline  
Old 08-18-12, 01:32 AM
  #45  
daven1986
Senior Member
 
Join Date: Feb 2008
Location: UK
Posts: 2,324
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I'd say remove it from the bike. I removed my trunk bag and rack and changed it for a backpack and my commute times are about 1mph faster - this is averaged over >300 miles and through different weather.
daven1986 is offline  
Old 08-18-12, 02:34 AM
  #46  
contango 
2 Fat 2 Furious
 
contango's Avatar
 
Join Date: Nov 2010
Location: England
Posts: 3,996

Bikes: 2009 Specialized Rockhopper Comp Disc, 2009 Specialized Tricross Sport RIP

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by JonathanGennick View Post
I resent the often less-than-subtle implication that we who are over our target weight somehow are not deserving of a lightweight bike. I happily lose weight from my bike when I can afford to do so. If the OP can afford to drop five pounds from his bike instantly, he should do it. He'll enjoy riding that much more, and he'll lose the body weight in the long run anyway. The right answer then, is to lose weight from both the bike and the body.
Some folks say us fatter types don't deserve a light bike. My concern with a light bike is whether it's strong enough to take a heavy rider. My second concern with a light bike is whether the money it would cost would be money well spent based on what I want out of a bike. If I decide it will take my weight and it's worth the money I'll go and buy it, and give a (expletive) what anyone else thinks about it.
__________________
"For a list of ways technology has failed to improve quality of life, press three"
contango is offline  
Old 08-18-12, 07:33 AM
  #47  
njkayaker
Senior Member
 
Join Date: Sep 2007
Posts: 11,083
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1698 Post(s)
Liked 18 Times in 13 Posts
Originally Posted by cyccommute View Post
We are constantly accelerating in response to air resistance and tire friction. Since we are constantly accelerating, the wheels weight has a higher impact on that acceleration.
http://www.biketechreview.com/review...el-performance
njkayaker is offline  
Old 08-18-12, 07:39 AM
  #48  
gregf83 
Senior Member
 
Join Date: Jun 2008
Location: Vancouver, BC
Posts: 8,751
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 895 Post(s)
Liked 22 Times in 16 Posts
Originally Posted by cyccommute View Post
You can cruise at a constant speed but you can't do it without constant input of energy. Newton's First Law states that an object in motion will stay in motion unless acted on by on outside force. All of those little vampires that slow you down are the outside forces. If you have to increase the force you are putting into the pedals, you are accelerating to counteract the forces that are decelerating you. If you were riding in a frictionless vacuum, you could set the bike on its way and never have to put any more energy into the system to maintain the speed but in a real world situation, you are constantly accelerating even when just maintaining a steady speed.
You're a little confused on your physics here. If you were able to pedal smoothly there would be zero acceleration going on regardless of whether you were riding in a vacuum. As most people don't pedal smoothly there is a very small acceleration when your pedals are at 3 o'clock and you are applying maximum force.

As far as heavier wheels or a heavier bike making a difference, conservation of energy applies and if you read up on it you will find that additional weight on the bike or in the rims will make negligible difference in the power required. The additional power will be due to a slightly higher rolling resistance from the additional weight.

Note that even if you added 10 kg to the bike or wheels it would require less than 3W of additional power at 30kph. The 5 lbs talked about in the OP would add less than 1W which would be very difficult to measure let alone feel.
gregf83 is offline  
Old 08-18-12, 07:44 AM
  #49  
Juan Foote
LBKA (formerly punkncat)
 
Juan Foote's Avatar
 
Join Date: Jan 2010
Location: Jawja
Posts: 3,439

Bikes: Spec Roubaix SL4, GT Traffic 1.0

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 951 Post(s)
Liked 8 Times in 7 Posts
I am of the thought that from a purely performance standpoint, the people who would gain the most advantage from and actually see results from losing weight off the bicycle are those whom are already at a target weight. For instance, a professional athlete commonly keeps body weight to a fairly consistent range even when off training. For them losing weight could lead to issue. Additionally, they are in the form that losing small amounts of weight from the equipment can be appreciated at the end of an event.

For the average slightly overweight American the cheapest option is to lose weight from the body and work towards shape and conditioning. By no means is that to infer that "fatty" doesn't get to have nice bikes...I certainly couldn't justify mine if that was the case.
Juan Foote is offline  
Old 08-18-12, 07:47 AM
  #50  
njkayaker
Senior Member
 
Join Date: Sep 2007
Posts: 11,083
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1698 Post(s)
Liked 18 Times in 13 Posts
Originally Posted by mechBgon View Post
A couple people have pointed out that it's not easy to drop five pounds from the typical road bike. But the OP didn't ask that.
It's a reasonable assumption. For a really heavy bike, loosing 5 pounds would matter even less.

Originally Posted by mechBgon View Post
I certainly encourage anyone with five pounds of flab to train until it's gone, but I also reiterate my point: the extra five pounds on the rider could be power-producing muscle mass. But the extra five pounds on the bike...? There'd better be a darn good reason why it's there. Is it making the bike more aero? Is it energy drink that keeps you in the game three or four hours into the ride?
Obviously, all things being equal, a lighter bike is better. Another reason a bike has "extra weight" is because it's cheaper. The tiny benefit for most riders of spending large amounts to save a hard-to-achieve 5 pounds off of a road bike isn't really worth it.
njkayaker is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.