What's really important..
10-03-06, 06:35 PM
#1
Senior Member
Thread Starter
Join Date: Oct 2005
Location: Salem, MA
Posts: 2,188
Bikes: Land Shark, Level Professional, Tsunami singlespeed, Giant Reign 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
What's really important..
I came across an interesting article at biketechreview regarding how bicycle wheel design relates to performance. The long and short of it is:
Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into:
1) 60% rider drag
2) 12% rolling resistance
3) 8% frame drag
4) 8% wheel drag
5) 8% bike/rider inertia.
6) .5% wheel inertia forces
~3% attributed to drivetrain and component flexing
I'm by no means suggesting this is gospel, but I find it to be an interesting perspective on what really matters. when bike and rider (sans wheels) are treated as one even a few pounds of weight make a pretty miniscule difference....until you're climbing.
Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into:
1) 60% rider drag
2) 12% rolling resistance
3) 8% frame drag
4) 8% wheel drag
5) 8% bike/rider inertia.
6) .5% wheel inertia forces
~3% attributed to drivetrain and component flexing
I'm by no means suggesting this is gospel, but I find it to be an interesting perspective on what really matters. when bike and rider (sans wheels) are treated as one even a few pounds of weight make a pretty miniscule difference....until you're climbing.
10-03-06, 06:40 PM
#2
Postmodern Beauty King
Join Date: Oct 2004
Location: Corvallis, OR
Posts: 154
Bikes: Centurion Fix, Jamis Nova, Jamis Crosscountry
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Are you trying to say it would be more worthwhile to try to look like a fish than to have light and aero wheels?
10-04-06, 05:28 AM
#3
LF for the accentdeprived
Join Date: May 2005
Location: Budapest, Hungary
Posts: 3,549
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Originally Posted by sers
2) 12% rolling resistance
10-04-06, 05:57 AM
#4
jack of one or two trades
Join Date: Jun 2005
Location: Suburbia, CT
Posts: 5,640
Bikes: Old-ass gearie hardtail MTB, fix-converted Centurion LeMans commuter, SS hardtail monster MTB
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Originally Posted by LóFarkas
Sounds too high. Of course, if by "average rider" he means a guy using an MTB with knobbies doing 12mph, then okay. A guy on 700*23 slicks doing 18mph will probably not have rolling resistance that high.
Also, I'm not a physicist, but I would guess that rolling resistance decreases very little as speed increases. I think that since drag becomes much more pronounced at higher speeds you can't tell that the rolling resistance is there, but I think it still is. Just thinking out loud here.
10-04-06, 06:02 AM
#5
LF for the accentdeprived
Join Date: May 2005
Location: Budapest, Hungary
Posts: 3,549
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
^^^
Thing is, rolling resistance is directly proportional to speed. Drag grows exponentially (2x speed=> 2x roling res., but 4x aero drag) So at higher speeds rolling resistance becomes lower as a % part of the whole resistance package.
Thing is, rolling resistance is directly proportional to speed. Drag grows exponentially (2x speed=> 2x roling res., but 4x aero drag) So at higher speeds rolling resistance becomes lower as a % part of the whole resistance package.
10-04-06, 08:55 AM
#7
Biggity-bam
Join Date: Apr 2006
Location: West Lafayette IN, Ann Arbor MI
Posts: 698
Bikes: Pista Concept, Fetish beater, Fuji road
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I agree that the rolling resistance seems high, but everything else seems in line.
10-04-06, 10:41 AM
#8
Senior Member
Join Date: Jun 2006
Location: Philadelphia
Posts: 849
Bikes: 1985 Pinarello Catena Lusso / 1983 Pinarello Montello / Raleigh Marathon / Camel Cigarettes conversion / 1957 Worksman cruiser / Puch 140 / Raleigh Grand Prix
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
that QR lever isn't that aero...they're kind of angled like elevators of an airplane...maybe that puts the rolling resistance to 11.8% instead of 12%...then again normal force would exert equal amounts right back...
10-04-06, 10:42 AM
#9
Senior Member
Join Date: Jun 2006
Location: Philadelphia
Posts: 849
Bikes: 1985 Pinarello Catena Lusso / 1983 Pinarello Montello / Raleigh Marathon / Camel Cigarettes conversion / 1957 Worksman cruiser / Puch 140 / Raleigh Grand Prix
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
"sometimes I pedal my bike so fast, it's like I'm on the air...above the floor." -Kid
10-04-06, 11:51 AM
#10
Senior Member
Join Date: Jul 2006
Location: Berlin
Posts: 99
Bikes: Canyon Ultimate CF, Moto LeChamp SL, Raleigh Rush Hour, Crescent MTB, Swedish Army issue bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
even though the course was zero net elevation, wouldn't it matter if it was hilly or completely flat?
10-04-06, 12:27 PM
#11
Senior Member
Thread Starter
Join Date: Oct 2005
Location: Salem, MA
Posts: 2,188
Bikes: Land Shark, Level Professional, Tsunami singlespeed, Giant Reign 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Originally Posted by pidda
even though the course was zero net elevation, wouldn't it matter if it was hilly or completely flat?
