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

Which way the bike is faster: more weight in front or back?

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!

Which way the bike is faster: more weight in front or back?

Old 05-31-14, 11:33 AM
  #1  
vol
Senior Member
Thread Starter
 
Join Date: Jul 2010
Posts: 3,750
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Which way the bike is faster: more weight in front or back?

I know suspension fork adds weight to the bike. But for the same total weight of a bike, does it make different in speed or ease of pedaling whether the weight is more in the front (such as a suspension fork) or in the back (such as a bike without suspension fork but has some load on the rear rack)?
vol is offline  
Old 05-31-14, 12:36 PM
  #2  
knobster
.
 
Join Date: May 2006
Location: Hillsboro, Oregon
Posts: 3,981

Bikes: Specialized Roubaix Comp, Soma ES

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
No scientific data on this, but I would think that it wouldn't matter as long as it's not rotational weight.
__________________
Demented internet tail wagging imbicile.
knobster is offline  
Old 05-31-14, 12:55 PM
  #3  
gregf83 
Senior Member
 
Join Date: Jun 2008
Location: Vancouver, BC
Posts: 8,719
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 876 Post(s)
Liked 10 Times in 9 Posts
It doesn't matter where you put the weight. Extra weight will have a small impact on climbing and negligible impact on flat ground.
gregf83 is offline  
Old 05-31-14, 03:08 PM
  #4  
erig007
Senior Member
 
Join Date: Sep 2012
Location: 6367 km away from the center of the Earth
Posts: 1,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I've noticed a big difference when i put my 17lb security chain in front rather than back. Must be due to the fact that most weight is on the rear tire already.
erig007 is offline  
Old 05-31-14, 03:25 PM
  #5  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,481

Bikes: 8

Mentioned: 183 Post(s)
Tagged: 0 Thread(s)
Quoted: 6724 Post(s)
Likes: 0
Liked 141 Times in 119 Posts
Suspension is there to keep the tire on the ground in spite of its roughness , weight is just a side effect. ..


Weight carried on the fork does steady the steering a Bit.

More so if the weight is balanced and low.. panniers ..


Pogoing suspension does slow climbing ..

Last edited by fietsbob; 05-31-14 at 03:32 PM.
fietsbob is offline  
Old 05-31-14, 03:26 PM
  #6  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 14,447

Bikes: Nashbar Road

Mentioned: 60 Post(s)
Tagged: 0 Thread(s)
Quoted: 2462 Post(s)
Liked 29 Times in 22 Posts
I think that the bike might handle better if the weight is balanced. That's all I've got on that question.
wphamilton is offline  
Old 05-31-14, 04:09 PM
  #7  
cplager
The Recumbent Quant
 
cplager's Avatar
 
Join Date: Jan 2012
Location: Fairfield, CT
Posts: 3,078

Bikes: 2012 Cruzbike Sofrider, 2013 Cruzigami Mantis, 2016 Folding CruziTandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by wphamilton View Post
I think that the bike might handle better if the weight is balanced. That's all I've got on that question.
For speed, it won't make any difference. For handling, it could make a big difference.
cplager is offline  
Old 05-31-14, 04:17 PM
  #8  
erig007
Senior Member
 
Join Date: Sep 2012
Location: 6367 km away from the center of the Earth
Posts: 1,666
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by cplager View Post
For speed, it won't make any difference. For handling, it could make a big difference.
It does for me.











Last edited by erig007; 05-31-14 at 04:51 PM.
erig007 is offline  
Old 05-31-14, 05:12 PM
  #9  
cplager
The Recumbent Quant
 
cplager's Avatar
 
Join Date: Jan 2012
Location: Fairfield, CT
Posts: 3,078

Bikes: 2012 Cruzbike Sofrider, 2013 Cruzigami Mantis, 2016 Folding CruziTandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by erig007 View Post
It does for me.
Ok. Let me be more clear: Assuming you correctly inflate your tires to reflect your load, it won't made any difference on your speed.
cplager is offline  
Old 05-31-14, 05:51 PM
  #10  
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Posts: 7,262
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 657 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I'd expect the suspension fork to have effects on speed other than just due to weight. If the riding surface is very uneven it might have a beneficial effect by allowing the rider to stay in control and with more comfort. But on smoother surfaces it's more likely to have a negative effect on speed by absorbing some energy as the rider periodically presses down compressing the fork and only some of that stored energy is recovered when the fork expands later in the pedal stroke.
prathmann is offline  
Old 05-31-14, 09:18 PM
  #11  
Machka 
In Real Life
 
Machka's Avatar
 
Join Date: Jan 2003
Location: Down under down under
Posts: 51,393

Bikes: Lots

Mentioned: 128 Post(s)
Tagged: 0 Thread(s)
Quoted: 2848 Post(s)
Liked 46 Times in 32 Posts
Less weight = faster bike
Machka is offline  
Old 05-31-14, 09:45 PM
  #12  
carnivroar
Senior Member
 
carnivroar's Avatar
 
Join Date: Mar 2012
Posts: 154

Bikes: NOT a fixie

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Machka View Post
Less weight = faster bike
Maybe only uphill.

More weight:
  • more momentum = more inertia = less work needed to keep bike moving
  • harder to accelerate = more work required to accelerate


Less weight:
  • less momentum = less inertia = more work needed to keep bike moving
  • easier to accelerate = less work required to accelerate


Given two bikes (one heavier and one lighter) of equal quality, a flat road, and the same amount of work per bike on any given time (work = force * distance = forceOnThePedal * distanceThePedalMoved), I reason that:
  • On shorter distances, a lighter bike will win, since acceleration takes a significant amount of time.
  • On longer distances, a heavier bike will catch up and win since it requires less work to keep it moving at the same speed as the light bike. Since both bikes are being moved by the same amount of work, the heavier bike will be able to pedal faster, which translates to more revolutions and thus more distance covered.

As for downhill, the same as above applies except that the heavier bike has the benefit that the force of gravity is stronger (f = mg), therefore less work is needed to keep the heavier bike moving at the same speed as the lighter bike. And again, since both bikes are being moved by the same amount of work, the heavier bike will be able to pedal faster, which translates to more revolutions and thus more distance covered.


(Physics major)

Would an engineer/physicist correct me?

Last edited by carnivroar; 05-31-14 at 09:51 PM.
carnivroar is offline  
Old 05-31-14, 10:36 PM
  #13  
knobster
.
 
Join Date: May 2006
Location: Hillsboro, Oregon
Posts: 3,981

Bikes: Specialized Roubaix Comp, Soma ES

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
His question was does it matter where the weight is. Not if weight matters to speed.

I did notice that though, my Trek 520 touring bike, if I was riding on flats, I could maintain 20 mph without much effort, but hills sucked. Opposite for my light bike.
__________________
Demented internet tail wagging imbicile.
knobster is offline  
Old 05-31-14, 11:20 PM
  #14  
vol
Senior Member
Thread Starter
 
Join Date: Jul 2010
Posts: 3,750
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by knobster View Post
His question was does it matter where the weight is. Not if weight matters to speed.
Thank you. "or ease of pedaling".
vol is offline  
Old 05-31-14, 11:47 PM
  #15  
Sixty Fiver
Bicycle Repair Man !!!
 
Sixty Fiver's Avatar
 
Join Date: Sep 2007
Location: YEG
Posts: 27,266

Bikes: See my sig...

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 43 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Go and put a load on a rear rack and go for a ride, and then take it off and go for another ride... this is enough added weight that it will affect acceleration.

A well designed front suspension fork should not add that much weight and not suck up very much power at all, bikes equipped with suspension forks tend to have some rear bias for position and come with an aero penalty to favour performance on rougher roads.

The fork on my mountain bike weighs a speck under 3 pounds, an average steel fork is going to weight close to 2 pounds and maybe more... the mountain bike is set up for XC and really flies along and I forget that the fork is there.
Sixty Fiver is offline  
Old 06-01-14, 08:57 AM
  #16  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 21,277

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

Mentioned: 91 Post(s)
Tagged: 1 Thread(s)
Quoted: 2409 Post(s)
Likes: 0
Liked 78 Times in 55 Posts
Originally Posted by carnivroar View Post
Maybe only uphill.

More weight:
  • more momentum = more inertia = less work needed to keep bike moving
  • harder to accelerate = more work required to accelerate


Less weight:
  • less momentum = less inertia = more work needed to keep bike moving
  • easier to accelerate = less work required to accelerate


Given two bikes (one heavier and one lighter) of equal quality, a flat road, and the same amount of work per bike on any given time (work = force * distance = forceOnThePedal * distanceThePedalMoved), I reason that:
  • On shorter distances, a lighter bike will win, since acceleration takes a significant amount of time.
  • On longer distances, a heavier bike will catch up and win since it requires less work to keep it moving at the same speed as the light bike. Since both bikes are being moved by the same amount of work, the heavier bike will be able to pedal faster, which translates to more revolutions and thus more distance covered.

As for downhill, the same as above applies except that the heavier bike has the benefit that the force of gravity is stronger (f = mg), therefore less work is needed to keep the heavier bike moving at the same speed as the lighter bike. And again, since both bikes are being moved by the same amount of work, the heavier bike will be able to pedal faster, which translates to more revolutions and thus more distance covered.


(Physics major)

Would an engineer/physicist correct me?
I agree with knobster that vol's question isn't about the total weight but the weight distribution. How the weight is distributed doesn't have much impact on speed but it does on handling.

That said, you need to reconsider your original premise. According to the Newton's Laws of Motion what you say is true. The heavier bike has more momentum and will require less work to keep it at speed in the absence of any external forces. The problem lies in the external forces. Bicycles, or any object, moving in an atmosphere over a surface with friction on wheels that have friction in the bearings isn't isolated from external forces. Bicycles are constantly accelerating to overcome air resistance, road friction, bearing friction, tire hysteresis which causes friction, etc. Even a "flat road" surface isn't "flat" because there are constant elevation changes. So a heavier bike seldom gets to experience the benefits of the greater momentum. Their larger inertia has a greater influence.
__________________
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 06-01-14, 09:14 AM
  #17  
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 29,256

Bikes: Catrike 559 I own some others but they don't get ridden very much.

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 1143 Post(s)
Liked 21 Times in 16 Posts
What about tire rolling resistance?

As I understand it, the more a tire deforms as you ride the higher the rolling resistance. If everything else was equal, equalizing the weight on front and rear tires would minimize the tire rolling resistance factor.
__________________
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
Retro Grouch is offline  
Old 06-01-14, 11:28 AM
  #18  
Jeff Wills
Insane Bicycle Mechanic
 
Jeff Wills's Avatar
 
Join Date: Mar 2008
Location: other Vancouver
Posts: 8,942
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 418 Post(s)
Liked 14 Times in 10 Posts
Originally Posted by cyccommute View Post
...

That said, you need to reconsider your original premise. According to the Newton's Laws of Motion what you say is true. The heavier bike has more momentum and will require less work to keep it at speed in the absence of any external forces. The problem lies in the external forces. Bicycles, or any object, moving in an atmosphere over a surface with friction on wheels that have friction in the bearings isn't isolated from external forces. Bicycles are constantly accelerating to overcome air resistance, road friction, bearing friction, tire hysteresis which causes friction, etc. Even a "flat road" surface isn't "flat" because there are constant elevation changes. So a heavier bike seldom gets to experience the benefits of the greater momentum. Their larger inertia has a greater influence.
Umm... picky point: when riding, you're exerting yourself in order to overcome air resistance and other forms of drag to maintain constant speed. On a conventional bicycle, about 50% of your effort is used to overcome aero drag. The trick to this is that rolling resistance and bearing drag increase in proportion to speed while aero drag increases in proportion to the square of the speed.

There's a neat quote on this calculator page: An interactive, model-based calculator of cycling power vs. speed (play with the calculator, too!)
"One of the scary implications of this equation is that at high speed, the power you have to produce is proportional to the cube of your velocity. So, to increase your speed by 25%, you need to nearly double your wattage!"
__________________
Jeff Wills

Comcast nuked my web page. It will return soon..
Jeff Wills is offline  
Old 06-01-14, 12:15 PM
  #19  
cplager
The Recumbent Quant
 
cplager's Avatar
 
Join Date: Jan 2012
Location: Fairfield, CT
Posts: 3,078

Bikes: 2012 Cruzbike Sofrider, 2013 Cruzigami Mantis, 2016 Folding CruziTandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Retro Grouch View Post
What about tire rolling resistance?

As I understand it, the more a tire deforms as you ride the higher the rolling resistance. If everything else was equal, equalizing the weight on front and rear tires would minimize the tire rolling resistance factor.
This is why you need to adjust the pressure in your tires to match the weight distribution. Change distribution, change pressure, almost identical total rolling resistance.
cplager is offline  
Old 06-01-14, 12:20 PM
  #20  
cplager
The Recumbent Quant
 
cplager's Avatar
 
Join Date: Jan 2012
Location: Fairfield, CT
Posts: 3,078

Bikes: 2012 Cruzbike Sofrider, 2013 Cruzigami Mantis, 2016 Folding CruziTandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Jeff Wills View Post
Umm... picky point: when riding, you're exerting yourself in order to overcome air resistance and other forms of drag to maintain constant speed. On a conventional bicycle, about 50% of your effort is used to overcome aero drag. The trick to this is that rolling resistance and bearing drag increase in proportion to speed while aero drag increases in proportion to the square of the speed.

There's a neat quote on this calculator page: An interactive, model-based calculator of cycling power vs. speed (play with the calculator, too!)
"One of the scary implications of this equation is that at high speed, the power you have to produce is proportional to the cube of your velocity. So, to increase your speed by 25%, you need to nearly double your wattage!"
The calculator is a great tool for answering these questions.

Rolling resistance is (modeled as) constant with respect to speed (not as a linear function) . In cars, this is true to some speed after which it does grow with speed.
cplager is offline  
Old 06-01-14, 12:25 PM
  #21  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,481

Bikes: 8

Mentioned: 183 Post(s)
Tagged: 0 Thread(s)
Quoted: 6724 Post(s)
Likes: 0
Liked 141 Times in 119 Posts
If the weight you add to the front is a fairing to smooth the airflow over and around the rider ,

those aerodynamic improvements will give you a little more speed

of course if the bike is a Low Racer recumbent and the body around the rider is fully streamlined , nose to tail,

then you can go Even faster..
fietsbob is offline  
Old 06-01-14, 02:44 PM
  #22  
Jax Rhapsody
Rhapsodic Laviathan
 
Jax Rhapsody's Avatar
 
Join Date: Jan 2013
Location: Louisville KY
Posts: 581

Bikes: Rideable; 83 Schwinn High Sierra. Two cruiser, bmx bike, one other mtb, three road frames, one citybike.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 69 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I've thought about this before, in the end bikes are always heavier in the back. I've seen bikes with carbon seat stays to try and lighten the rear up some. I figured it's really nothing to worry over, especially since unlike cars, the wheelbase is always longer that the "body." As far as coasting and things, I think tires have a lot to do with that.
Jax Rhapsody is offline  
Old 06-01-14, 03:07 PM
  #23  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 14,447

Bikes: Nashbar Road

Mentioned: 60 Post(s)
Tagged: 0 Thread(s)
Quoted: 2462 Post(s)
Liked 29 Times in 22 Posts
Originally Posted by carnivroar View Post
More weight: more momentum = more inertia = less work needed to keep bike moving

Less weight: less momentum = less inertia = more work needed to keep bike moving
You should re-examine this part.
wphamilton is offline  
Old 06-01-14, 03:55 PM
  #24  
vol
Senior Member
Thread Starter
 
Join Date: Jul 2010
Posts: 3,750
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Jax Rhapsody View Post
I've thought about this before, in the end bikes are always heavier in the back.
Not my new bike, which is what prompted me to ask the question. My new bike has a suspension fork, otherwise would be much lighter. the rear is very light. I felt this strongly when I tried to carry it up the 3 or 4 steps of stairs to enter a building: it's difficult, because the front would fall downward while the back goes up, totally different from my older bike. But the new bike rides so much more smoothly and pedaling takes much less effort. Before this I was so content with my older bike. (I realize you must be talking about when the person is on the bike, but since I'm not heavy and I didn't have anything on the rear of the bike, the rear is not heavier.)
vol is offline  
Old 06-01-14, 04:26 PM
  #25  
Sullalto
Senior Member
 
Join Date: Mar 2014
Location: Cascadia
Posts: 1,206

Bikes: Jamis Quest Comp

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 168 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by erig007 View Post
I've noticed a big difference when i put my 17lb security chain in front rather than back. Must be due to the fact that most weight is on the rear tire already.
17 lb chain?

What are you carrying, boat anchor links?
Sullalto 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.