A new (I think) rule of thumb regarding bike fit
#1
Banned.
Thread Starter
Join Date: Feb 2013
Location: Brighton UK
Posts: 1,662
Bikes: 20" Folder, Road Bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
A new (I think) rule of thumb regarding bike fit
Hi,
My clothing inside leg is 28"/29", I prefer the latter, but an unusual
size, and 28" fits better than 30", depending on acceptable crumple.
I measured both my bike today, centre of the crank along the tubes
to the top of the saddles, the road bike is 29", the folder 28.5".
Seat height is set so my legs will lock out using my instep over
the pedal. i.e.very near as high as it will go, with no consideration
of being able to touch the ground sat in the saddle for the height.
rgds, sreten.
My clothing inside leg is 28"/29", I prefer the latter, but an unusual
size, and 28" fits better than 30", depending on acceptable crumple.
I measured both my bike today, centre of the crank along the tubes
to the top of the saddles, the road bike is 29", the folder 28.5".
Seat height is set so my legs will lock out using my instep over
the pedal. i.e.very near as high as it will go, with no consideration
of being able to touch the ground sat in the saddle for the height.
rgds, sreten.
#4
Senior Member
Join Date: Sep 2009
Location: USA
Posts: 2,067
Bikes: 84 Pinarello Trevisio, 86 Guerciotti SLX, 96 Specialized Stumpjumper, 2010 Surly Cross Check, 88 Centurion Prestige, 73 Raleigh Sports, GT Force, Bridgestone MB4
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 278 Post(s)
Liked 71 Times
in
56 Posts
I do not think pants size is a good measure for bike fit. There are general rules of fit that provide a close starting point but in an age of saggy pants and weird fitting cloths, I doubt your clothing inseam is a good rule of thumb for anybody but for yourself.
LC
LC
#6
Senior Member
Join Date: Aug 2011
Posts: 3,138
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 67 Post(s)
Liked 83 Times
in
44 Posts
Almost by definition, one man's experience can not be a rule of thumb. Homework assignment - Grab 22 of you closest friends, check your system out on them, and report back.
#7
Banned.
Thread Starter
Join Date: Feb 2013
Location: Brighton UK
Posts: 1,662
Bikes: 20" Folder, Road Bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Hi,
I haven't a hope in hell of getting the people I know
who ride bikes to set their seat heights correctly.
rgds, sreten.
I haven't a hope in hell of getting the people I know
who ride bikes to set their seat heights correctly.
rgds, sreten.
#8
Senior Member
Join Date: Sep 2009
Location: USA
Posts: 2,067
Bikes: 84 Pinarello Trevisio, 86 Guerciotti SLX, 96 Specialized Stumpjumper, 2010 Surly Cross Check, 88 Centurion Prestige, 73 Raleigh Sports, GT Force, Bridgestone MB4
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 278 Post(s)
Liked 71 Times
in
56 Posts
But, as a human engine, seated on a bicycle, there actually has been proven repeatedly optimal configurations for seat height and posture on a bicycle. These "rule of thumb" guides are not perfect but they get most people into the zone where only minor adjustments are needed to account for differing peddling styles, comfort or other practical factors, but PANTS inseam length figures into none of them.
#9
Senior Member
Join Date: Aug 2011
Posts: 3,138
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 67 Post(s)
Liked 83 Times
in
44 Posts
But, as a human engine, seated on a bicycle, there actually has been proven repeatedly optimal configurations for seat height and posture on a bicycle. These "rule of thumb" guides are not perfect but they get most people into the zone where only minor adjustments are needed to account for differing peddling styles, comfort or other practical factors, but PANTS inseam length figures into none of them.
#10
Banned
Seems when reach and stem is right, I get a line of sight straight through the steering axis, looking down.
#11
~>~
Oddly enough the topic of the proper fit on a bicycle has been given more than cursory thought since the Safety Bicycle was invented, often by folk who make a living riding one.
Here's a tome w/ some musings on fit by a World/Multi-TDF champ that might be worth a glance: "Greg Lemond's Complete Book of Bicycling".
You just might want to peruse it and meditate on the attached pic.
-Bandera
Here's a tome w/ some musings on fit by a World/Multi-TDF champ that might be worth a glance: "Greg Lemond's Complete Book of Bicycling".
You just might want to peruse it and meditate on the attached pic.
-Bandera
#12
Banned.
Thread Starter
Join Date: Feb 2013
Location: Brighton UK
Posts: 1,662
Bikes: 20" Folder, Road Bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Hi,
Whilst I would not mind what I suggested being shot to pieces by someone
who knows what they are talking about, I do mind the clueless pointlessly
pontificating about basically nothing, experts on deriding stuff they don't
understand, thinking that somehow makes them appear to be clever.
What I said is clear and simple, but I'm obviously wasting my time.
rgds, sreten.
Whilst I would not mind what I suggested being shot to pieces by someone
who knows what they are talking about, I do mind the clueless pointlessly
pontificating about basically nothing, experts on deriding stuff they don't
understand, thinking that somehow makes them appear to be clever.
What I said is clear and simple, but I'm obviously wasting my time.
rgds, sreten.
#14
Senior Member
Join Date: Mar 2007
Posts: 6,401
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 13 Times
in
13 Posts
Sreten: An interesting observation, but one that does not, sadly, work in general. There is, FWIW, a rule of thumb for saddle height. It is inseam x .883. The inseam, BTW, needs to be accurately measured. Pants inseam is not good enough.
As for the rest, bike fit is an area populated largely by opinionated A-holes who know just enough to have passionately held beliefs but not enough to really know why they're defending them. IOW, welcome to BF.
As for the rest, bike fit is an area populated largely by opinionated A-holes who know just enough to have passionately held beliefs but not enough to really know why they're defending them. IOW, welcome to BF.
#17
Banned.
Thread Starter
Join Date: Feb 2013
Location: Brighton UK
Posts: 1,662
Bikes: 20" Folder, Road Bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Hi,
Some of you are very a sad pointlessly offensive bunch.
Do any of you really think I was taking myself seriously ?
Your attitude problem, not mine.
rgds, sreten.
Some of you are very a sad pointlessly offensive bunch.
Do any of you really think I was taking myself seriously ?
Your attitude problem, not mine.
rgds, sreten.
#19
In Real Life
Join Date: Jan 2003
Location: Down under down under
Posts: 52,152
Bikes: Lots
Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 3203 Post(s)
Liked 596 Times
in
329 Posts
Bicycling Medicine by Arnie Baker
To quote Bicycling Medicine by Arnie Baker
"Seat height is a compromise between aerobic economy, aerodynamics, bicycle handling, injury prevention, muscle fatigue, stroke fluidity, and power.
...
... Base the seat height on the angle from the horizontal formed by the knee at the bottom of the pedal stroke. This angle is measured in degrees of flexion. With the lower leg extended straight out, this angle is zero degrees by convention. As a starting point, many racers are best positioned so that the angle of the knee is 25 degrees. This is a good compromise between aerobic economy, muscle fatigue, stroke fluidity, and power.
...
Aerobic economy and power can be improved with a higher position: a knee angle of 15 to 20 degrees.
...
More control can be obtained with a lower position: a knee angle of 30 degrees. This is important, for example, when riding a bicycle on a steep velodrome.
Riders with pain in the anterior (front) knee - due, for example, to arthritis or patellar tendonitis - do better with a higher seat position and a knee angle of 15 to 20 degrees. Riders with pain in the posterior (back) knee, in the Achilles tendon, or in the back of the calf or thigh do better with a lower seat position and knee angle of 25 to 35 degrees."
(pages 119 - 120)
"A seat height that results in 25 to 30 degrees of knee flexion when the pedal is at the bottom of the stroke tends to result in the least injury but is not optimal for cycling power or aerobic efficiency.
The higher your seat, the more likely you are to have pain in the back of your knee, Achilles tendon pain, or buttock ache. Those with limited flexibility are the most likely to have problems."
(page 148)
I highly recommend reading Bicycling Medicine by Arnie Baker
Personally, I need the slightly lower saddle height described above, and I can find the correct saddle height by doing the following ...
-- getting on my bicycle and riding on flat ground for a few minutes to warm up and get comfortable on the bicycle
-- coasting, placing my heel on the pedal and dropping the pedal to the 6:00 position
-- and if my leg has just a very slight bend in it, that's about right.
"Seat height is a compromise between aerobic economy, aerodynamics, bicycle handling, injury prevention, muscle fatigue, stroke fluidity, and power.
...
... Base the seat height on the angle from the horizontal formed by the knee at the bottom of the pedal stroke. This angle is measured in degrees of flexion. With the lower leg extended straight out, this angle is zero degrees by convention. As a starting point, many racers are best positioned so that the angle of the knee is 25 degrees. This is a good compromise between aerobic economy, muscle fatigue, stroke fluidity, and power.
...
Aerobic economy and power can be improved with a higher position: a knee angle of 15 to 20 degrees.
...
More control can be obtained with a lower position: a knee angle of 30 degrees. This is important, for example, when riding a bicycle on a steep velodrome.
Riders with pain in the anterior (front) knee - due, for example, to arthritis or patellar tendonitis - do better with a higher seat position and a knee angle of 15 to 20 degrees. Riders with pain in the posterior (back) knee, in the Achilles tendon, or in the back of the calf or thigh do better with a lower seat position and knee angle of 25 to 35 degrees."
(pages 119 - 120)
"A seat height that results in 25 to 30 degrees of knee flexion when the pedal is at the bottom of the stroke tends to result in the least injury but is not optimal for cycling power or aerobic efficiency.
The higher your seat, the more likely you are to have pain in the back of your knee, Achilles tendon pain, or buttock ache. Those with limited flexibility are the most likely to have problems."
(page 148)
I highly recommend reading Bicycling Medicine by Arnie Baker
Personally, I need the slightly lower saddle height described above, and I can find the correct saddle height by doing the following ...
-- getting on my bicycle and riding on flat ground for a few minutes to warm up and get comfortable on the bicycle
-- coasting, placing my heel on the pedal and dropping the pedal to the 6:00 position
-- and if my leg has just a very slight bend in it, that's about right.
__________________
Rowan
My fave photo threads on BF
Century A Month Facebook Group
Machka's Website
Photo Gallery
Rowan
My fave photo threads on BF
Century A Month Facebook Group
Machka's Website
Photo Gallery
#20
Senior Member
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 16,869
Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1854 Post(s)
Liked 661 Times
in
504 Posts
Hi,
My clothing inside leg is 28"/29", I prefer the latter, but an unusual
size, and 28" fits better than 30", depending on acceptable crumple.
I measured both my bike today, centre of the crank along the tubes
to the top of the saddles, the road bike is 29", the folder 28.5".
Seat height is set so my legs will lock out using my instep over
the pedal. i.e.very near as high as it will go, with no consideration
of being able to touch the ground sat in the saddle for the height.
rgds, sreten.
My clothing inside leg is 28"/29", I prefer the latter, but an unusual
size, and 28" fits better than 30", depending on acceptable crumple.
I measured both my bike today, centre of the crank along the tubes
to the top of the saddles, the road bike is 29", the folder 28.5".
Seat height is set so my legs will lock out using my instep over
the pedal. i.e.very near as high as it will go, with no consideration
of being able to touch the ground sat in the saddle for the height.
rgds, sreten.
As far as your knee lock technique, that sounds like a fine way to get a starting point. Usually I find it to be only a starting point, and tend to gradually raise it based on stress sensations in the front and side of my knee. But I won't go higher than the location where pelvic rocking and resulting chafing sets in.
This is my personal ROT based on the old traditional "heel on pedal with straight leg" approach. Possible differences with yours:
Heel on pedal versus instep on pedal
Knee "locked" straight versus leg straight and both legs simultaneously hanging relaxed
Similar to the traditional but hard to see the exact correlation.
#21
Senior Member
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 16,869
Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8
Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1854 Post(s)
Liked 661 Times
in
504 Posts
To quote Bicycling Medicine by Arnie Baker
"Seat height is a compromise between aerobic economy, aerodynamics, bicycle handling, injury prevention, muscle fatigue, stroke fluidity, and power.
...
... Base the seat height on the angle from the horizontal formed by the knee at the bottom of the pedal stroke. This angle is measured in degrees of flexion. With the lower leg extended straight out, this angle is zero degrees by convention. As a starting point, many racers are best positioned so that the angle of the knee is 25 degrees. This is a good compromise between aerobic economy, muscle fatigue, stroke fluidity, and power.
...
Aerobic economy and power can be improved with a higher position: a knee angle of 15 to 20 degrees.
...
More control can be obtained with a lower position: a knee angle of 30 degrees. This is important, for example, when riding a bicycle on a steep velodrome.
Riders with pain in the anterior (front) knee - due, for example, to arthritis or patellar tendonitis - do better with a higher seat position and a knee angle of 15 to 20 degrees. Riders with pain in the posterior (back) knee, in the Achilles tendon, or in the back of the calf or thigh do better with a lower seat position and knee angle of 25 to 35 degrees."
(pages 119 - 120)
"A seat height that results in 25 to 30 degrees of knee flexion when the pedal is at the bottom of the stroke tends to result in the least injury but is not optimal for cycling power or aerobic efficiency.
The higher your seat, the more likely you are to have pain in the back of your knee, Achilles tendon pain, or buttock ache. Those with limited flexibility are the most likely to have problems."
(page 148)
I highly recommend reading Bicycling Medicine by Arnie Baker
Personally, I need the slightly lower saddle height described above, and I can find the correct saddle height by doing the following ...
-- getting on my bicycle and riding on flat ground for a few minutes to warm up and get comfortable on the bicycle
-- coasting, placing my heel on the pedal and dropping the pedal to the 6:00 position
-- and if my leg has just a very slight bend in it, that's about right.
"Seat height is a compromise between aerobic economy, aerodynamics, bicycle handling, injury prevention, muscle fatigue, stroke fluidity, and power.
...
... Base the seat height on the angle from the horizontal formed by the knee at the bottom of the pedal stroke. This angle is measured in degrees of flexion. With the lower leg extended straight out, this angle is zero degrees by convention. As a starting point, many racers are best positioned so that the angle of the knee is 25 degrees. This is a good compromise between aerobic economy, muscle fatigue, stroke fluidity, and power.
...
Aerobic economy and power can be improved with a higher position: a knee angle of 15 to 20 degrees.
...
More control can be obtained with a lower position: a knee angle of 30 degrees. This is important, for example, when riding a bicycle on a steep velodrome.
Riders with pain in the anterior (front) knee - due, for example, to arthritis or patellar tendonitis - do better with a higher seat position and a knee angle of 15 to 20 degrees. Riders with pain in the posterior (back) knee, in the Achilles tendon, or in the back of the calf or thigh do better with a lower seat position and knee angle of 25 to 35 degrees."
(pages 119 - 120)
"A seat height that results in 25 to 30 degrees of knee flexion when the pedal is at the bottom of the stroke tends to result in the least injury but is not optimal for cycling power or aerobic efficiency.
The higher your seat, the more likely you are to have pain in the back of your knee, Achilles tendon pain, or buttock ache. Those with limited flexibility are the most likely to have problems."
(page 148)
I highly recommend reading Bicycling Medicine by Arnie Baker
Personally, I need the slightly lower saddle height described above, and I can find the correct saddle height by doing the following ...
-- getting on my bicycle and riding on flat ground for a few minutes to warm up and get comfortable on the bicycle
-- coasting, placing my heel on the pedal and dropping the pedal to the 6:00 position
-- and if my leg has just a very slight bend in it, that's about right.
I share your respect for Baker's writings and procedures, but it's a challenge to measure those angles consistently, or without a similarly dedicated partner. I had a fitting done on that basis (i.e. using a goniometer and based on knee angle) and it worked out quite well for a few years at least. Sadly the gent went out of business ...
#22
In Real Life
Join Date: Jan 2003
Location: Down under down under
Posts: 52,152
Bikes: Lots
Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 3203 Post(s)
Liked 596 Times
in
329 Posts
Machka, in your own technique, do you turn the pedal upside down? Seems to me the design of the pedal and the shoe are significant variables. I usually ride with toe clips or clip-free rattraps. I use the rattraps to set height, and fine tune when I switch over to my touring toeclip pedals.
I share your respect for Baker's writings and procedures, but it's a challenge to measure those angles consistently, or without a similarly dedicated partner. I had a fitting done on that basis (i.e. using a goniometer and based on knee angle) and it worked out quite well for a few years at least. Sadly the gent went out of business ...
I share your respect for Baker's writings and procedures, but it's a challenge to measure those angles consistently, or without a similarly dedicated partner. I had a fitting done on that basis (i.e. using a goniometer and based on knee angle) and it worked out quite well for a few years at least. Sadly the gent went out of business ...
And yes, there may be a little bit of fine tuning required. That is a starting point. From there I might go up or down by millimetres depending on a wide range of factors.
That's the technique I've been using for years, but in 2010, Rowan and I were fit on the tandem we bought, and it turns out that the saddle height we were measured to, using angles etc., is the same saddle height I would have set it to using the heel on pedal, slight bend in knee, method.
__________________
Rowan
My fave photo threads on BF
Century A Month Facebook Group
Machka's Website
Photo Gallery
Rowan
My fave photo threads on BF
Century A Month Facebook Group
Machka's Website
Photo Gallery
#23
Senior Member
Join Date: Aug 2006
Location: Portland OR
Posts: 7,639
Bikes: 61 Bianchi Specialissima 71 Peugeot G50 7? P'geot PX10 74 Raleigh GranSport 75 P'geot UO8 78? Raleigh Team Pro 82 P'geot PSV 86 P'geot PX 91 Bridgestone MB0 92 B'stone XO1 97 Rans VRex 92 Cannondale R1000 94 B'stone MB5 97 Vitus 997
Mentioned: 146 Post(s)
Tagged: 0 Thread(s)
Quoted: 392 Post(s)
Likes: 0
Liked 49 Times
in
31 Posts
Problem with the OP's proposal is that no-one agrees on what an appropriate pants inseam is. One person likes floods, another likes a deep break at the instep. OP says his pants inseam could be from 28" to 30", that is a 2" range which is large enough to make the rule not workable.
#24
Senior Member
Join Date: May 2013
Location: Weston, FL
Posts: 116
Bikes: '92 Merlin Extralight, '19 Giant TCR Advanced Pro 0 Disc
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 9 Times
in
4 Posts
Oddly enough the topic of the proper fit on a bicycle has been given more than cursory thought since the Safety Bicycle was invented, often by folk who make a living riding one.
Here's a tome w/ some musings on fit by a World/Multi-TDF champ that might be worth a glance: "Greg Lemond's Complete Book of Bicycling".
You just might want to peruse it and meditate on the attached pic.
-Bandera
Here's a tome w/ some musings on fit by a World/Multi-TDF champ that might be worth a glance: "Greg Lemond's Complete Book of Bicycling".
You just might want to peruse it and meditate on the attached pic.
-Bandera
#25
Banned.
Thread Starter
Join Date: Feb 2013
Location: Brighton UK
Posts: 1,662
Bikes: 20" Folder, Road Bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
As far as your knee lock technique, that sounds like a fine way to get a starting point.
Usually I find it to be only a starting point, and tend to gradually raise it based on
stress sensations in the front and side of my knee. But I won't go higher than the
location where pelvic rocking and resulting chafing sets in.
Usually I find it to be only a starting point, and tend to gradually raise it based on
stress sensations in the front and side of my knee. But I won't go higher than the
location where pelvic rocking and resulting chafing sets in.
The general rule is to use heel lockout, but if you go to instep lockout
that is not a starting point at all, it is very near the highest you can go.
If you can lockout with the ball of the foot over the pedal then
you are talking inevitable pelvic rocking to avoid full leg locking.
To me it is not complicated regarding standing on one pedal :
Ball of foot you can lift yourself off the saddle.
Instep it should be ~ 50/50, not on or off.
Heel you cannot lift off the saddle.
The above is good enough for me.
rgds, sreten.
Last edited by sreten; 07-08-13 at 06:07 PM.