Calculating watts per kilogram
#1
No Pain, No Pizza
Thread Starter
Join Date: Jan 2007
Location: Above Jamestown, CO
Posts: 297
Bikes: 2015 Tarmac Pro Disc, '99 Burley Duet, '10 Velo Vie Vitesse 300R, '94 Trek 2120, '90 Cannondale SR 600, '79 Ross Super Gran Tour, '76 Raleigh Record
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Liked 40 Times
in
23 Posts
Calculating watts per kilogram
When one calculates watts per kilogram. Is the mass only the weight of the rider without clothing, etc.? Or is it the combined weight of rider, their clothing, bicycle, tools, water bottles, etc.?
#2
Senior Member
Join Date: May 2021
Posts: 8,453
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 4416 Post(s)
Liked 4,872 Times
in
3,016 Posts
If you are using it for measuring your fitness then I would just take your undressed weight.
Likes For PeteHski:
#3
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,059
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22600 Post(s)
Liked 8,928 Times
in
4,160 Posts
#5
• —
Join Date: Jun 2015
Location: Land of Pleasant Living
Posts: 12,250
Bikes: Shmikes
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 10176 Post(s)
Liked 5,872 Times
in
3,161 Posts
Before or after pooping?
#6
Should Be More Popular
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 43,059
Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix
Mentioned: 560 Post(s)
Tagged: 2 Thread(s)
Quoted: 22600 Post(s)
Liked 8,928 Times
in
4,160 Posts
Likes For datlas:
#7
• —
Join Date: Jun 2015
Location: Land of Pleasant Living
Posts: 12,250
Bikes: Shmikes
Mentioned: 59 Post(s)
Tagged: 0 Thread(s)
Quoted: 10176 Post(s)
Liked 5,872 Times
in
3,161 Posts
Likes For MoAlpha:
#8
Not actually Tmonk
Join Date: Jun 2007
Location: San Diego, CA
Posts: 14,138
Bikes: road, track, mtb
Mentioned: 140 Post(s)
Tagged: 0 Thread(s)
Quoted: 2640 Post(s)
Liked 3,153 Times
in
1,660 Posts
Wake up, coffee + banana (maybe a small pastry portion), bowel movement, scale, kit up, then on the bike!
__________________
"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste
"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste
Likes For TMonk:
#9
Perceptual Dullard
Join Date: Sep 2009
Posts: 2,421
Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 919 Post(s)
Liked 1,156 Times
in
494 Posts
For supply side, just you, nekkid, post-poop.
For demand side, you, all your kit including water bottles, and your bike.
I would say that most people most of the time mean supply side.
Likes For blacknbluebikes:
#11
serious cyclist
Join Date: Apr 2009
Location: Austin
Posts: 21,147
Bikes: S1, R2, P2
Mentioned: 115 Post(s)
Tagged: 1 Thread(s)
Quoted: 9334 Post(s)
Liked 3,679 Times
in
2,026 Posts
I usually think of it as a trait of the rider, so it's just the rider. Your W/kg doesn't change when you change bikes. And as mentioned, since most bikes are only marginally different in weight when accounting for the bike + rider system, it only matters in very narrow circumstances.
Likes For Bah Humbug:
#12
climber has-been
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,111
Bikes: Scott Addict R1, Felt Z1
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3432 Post(s)
Liked 3,567 Times
in
1,793 Posts
I usually think of it as a trait of the rider, so it's just the rider. Your W/kg doesn't change when you change bikes. And as mentioned, since most bikes are only marginally different in weight when accounting for the bike + rider system, it only matters in very narrow circumstances.
If you're trying to estimate how fast you can climb a steep road, you'll be looking at the W/kg of the whole package (rider + bike + accessories).
Likes For terrymorse:
#13
serious cyclist
Join Date: Apr 2009
Location: Austin
Posts: 21,147
Bikes: S1, R2, P2
Mentioned: 115 Post(s)
Tagged: 1 Thread(s)
Quoted: 9334 Post(s)
Liked 3,679 Times
in
2,026 Posts
Right, but my point is that in that case, the difference between a mid-range and high-end road bike is still very small compared to even a 60kg cyclist, and with two 60kg cyclists the FTP difference is likely larger than the bike weight.
#14
Senior Member
Join Date: May 2021
Posts: 8,453
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 4416 Post(s)
Liked 4,872 Times
in
3,016 Posts
Models that estimate how fast you can climb usually have separate parameters for bike and rider weights. If someone says they have a 4 W/kg FTP they are not including the weight of their bike and kit. Your power in terms of W/kg should be independent of what bike you are riding if you are comparing the performance of riders.
Likes For PeteHski:
#15
Senior Member
Join Date: Apr 2019
Location: UK
Posts: 1,404
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 682 Post(s)
Liked 453 Times
in
338 Posts
Soooo I don’t mean to be controversial but isn’t w/kg usually a measure of strength and fitness? If you make your bike lighter or leave a bidon at home, did you get stronger or fitter?
Likes For choddo:
#16
climber has-been
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 7,111
Bikes: Scott Addict R1, Felt Z1
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3432 Post(s)
Liked 3,567 Times
in
1,793 Posts
The weight difference between a high-end climbing bike and a mid-range road bike is not very small. A decent climbing bike is easily 2 kg lighter than a mid-range bike.
#17
Senior Member
Join Date: May 2021
Posts: 8,453
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 4416 Post(s)
Liked 4,872 Times
in
3,016 Posts
Exactly. When discussing W/kg as a measure of human performance it is literally Watts per kg of bodyweight. The weight of the bike and kit is only relevant in cycling simulation models.
#19
pan y agua
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,304
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1447 Post(s)
Liked 728 Times
in
373 Posts
Fat bottom girls make the rockin world…
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
#21
Super Modest
Join Date: Jun 2002
Location: Central Illinois
Posts: 23,467
Bikes: Trek Emonda, Giant Propel, Colnago V3, Co-Motion Supremo, ICE VTX WC
Mentioned: 107 Post(s)
Tagged: 1 Thread(s)
Quoted: 10963 Post(s)
Liked 4,621 Times
in
2,124 Posts
#22
Grupetto Bob
Join Date: Sep 2020
Location: Seattle-ish
Posts: 6,226
Bikes: Bikey McBike Face
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 2586 Post(s)
Liked 5,648 Times
in
2,924 Posts
#23
Senior Member
Join Date: Jan 2005
Location: Baltimore, MD
Posts: 5,380
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 2488 Post(s)
Liked 2,957 Times
in
1,680 Posts
#24
Super Modest
Join Date: Jun 2002
Location: Central Illinois
Posts: 23,467
Bikes: Trek Emonda, Giant Propel, Colnago V3, Co-Motion Supremo, ICE VTX WC
Mentioned: 107 Post(s)
Tagged: 1 Thread(s)
Quoted: 10963 Post(s)
Liked 4,621 Times
in
2,124 Posts