DIY Bike fitting
Seat Set Back for road bike ?
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For some reason, Australia has the highest number of commercial bike fitters per capita in the world. I'm not able to explain the phenomenon, but DIY bike fitting is part of the cycling experience
and I would like to share some of my knowledge with you. I was once a cycling coach. Bike fitting constituted less than 1% of the scope of my job. This is a generalized guideline for high performance
riding set up (not applicable to TT bike or down hill racing). If you have any sort of injury or health issues, please consult your G.P., and do not attempt to conduct any bike fitting with the sole
intent of making those issues go away.
On Wall Street, his name was legendary. Now it is infamous. Bernard Madoff promised his clients with extraordinarily high returns, before the Ponzi plan blew up. There is NO free lunch.
Likewise for a bike set-up, someone might promise you that they could set you up with the best position in the whole planet & it will enhance your performance without altering any other
aspects of your cycling. It is a total waste of his & your time.
Although some may suggest how neurologically & functionally dysfunctional you are, it would usually take 25 to 50 hours of training to adapt to a totally new position regardless of your
fitness level, age & gender. There is almost no deviation between an average "Dave" & a world champion. Localized muscle soreness is very likely due to enlistment of different muscles. Don't look down on your body; it is the most
amazing machine on the planet. You could turn it from a diesel engine into a V10 F1 engine through proper training & set up.
There are some basic principles that have to be followed. Adjust your bike in the following sequence, as one set-up leads to another, and you will have a very good neutral starting point to play
with. Don't be afraid to change your positions. It is fun. Forget about your existing position, it is not relevant. I will explain the steps to you one by one.
1. Cleat Position
To find the neutral position, start with positioning the good old ball of your feet inline with the pedal axle. Once that is done, try moving it forwards/backwards + 15 - 5mm to see which setting
you like. The Cleat position is the foundation of bike fitting, as almost everything after that is dependent on it (setback, saddle height etc). Ultimately, cleat position is your personal
preference, depending on the type of riding you do.
Note: -ve (cleat closer to toes) is for track sprinter set up only
+ve (cleat closer to ankle) is good for ultra long distance, like Audax. (less leverage = more stable, less calf muscle use = less power/less
energy consumption, less hot feet )
2. Saddle Height.
A. Visual method: Your leg should be slightly bent when at the bottom of the stroke. How bent? Just refer to the latest professional cycling race videos (the type of event that you're
B. The Lemond formula (inseam x 0.883 = the distance from the center of the bottom bracket to the upper part of the saddle)
Claude Genzling developed this method during the Tour de France of 1978. He measured saddle heights and the length of cyclist’s inner legs to derive this average formula. The formula is not
applicable to modern bike set-ups though. It is 2 - 4cm too low. So where does the 2 - 4 cm discrepancy come from?
- 2cm from the top: Saddles in the late 70's had no padding, and had stiff steel rails, whereas today's saddles have thicker padding, and more shock absorbing rails. As a result, there is
more 'sag' in today's saddle, placing you closer to the bottom bracket. Also, the average rider weight, for whom the formula was designed for, is a lot less than a modern recreation cyclist, which
again means that saddle sag was not taken into consideration.
- 2cm from the bottom: Shoes from the 70's have less heel lift, and metal cleats from that era are much thinner than modern plastic cleats.
I would suggest a revised formula of inseam x 0.883 + 2 - 4 cm depending on the variables I mentioned earlier. That is a good starting point, and the position will be within 3 cm of your preferred
An increase in absolute power would be noticed from a higher saddle (your muscles contract more in the same pedal revolution) but higher energy consumption will be noticed. There is NO Free
Lunch. Therefore a higher saddle position would be good for short distance races, eg sprinting. On the other hand, you get more control & stability on the bike with a lower saddle
height, as the center of gravity is lower, which is good for mountain biking. There ain't no such thing as a correct saddle height. It all comes down to your personal preference. If your preference
changes over time, so will your saddle height.
Eddy Merckx changed his saddle height before the final down hill sprint of the 1973 Championnat du monde. ( World Championship ).
It take almost 40 years for the PRO to start experiment the idea this summer
Should I use knee velocity to determine saddle height? No, It is a practical joke.
Pedaling is a multiple linkage skeletal/muscular motion, which involve slow & fast twitch muscle fibres. The vertical & horizontal velocities of the knee, hip, ankle & toe are not
constant, no matter the intensity or how good or bad the pedaling technique is. Knee velocity is a like sine wave movement, a cycle of peak and troughs of intensity.
Should I use bottom of the stroke fluency to determine saddle height? No, it is another practical joke.
Trained riders, Toe Dippers, Heel Droppers or Pedal Scrapers all have different pedaling styles. If all things were equal, they’d all have different levels of fluency at the bottom of the down
3. Saddle Back & Fore
A renowned motocross racer turned mountain bike guru Keith Bontrager had doubts about the validity and accuracy of the K.O.P.S (Knee Over Pedal Spindle) system in the early 80's. He came up with a different bike fit system, and the most famous work/result was a down size of
the Mavic MA2 700c rim into a 26" MTB rim. Trek acquired "Bontrager" in the mid 90's. And there are some bike fitter recycle Keith's theory partially.
America was still in its initial MTB development phase in the early 80’s. Road cycling was almost non-existent. My mate "Jock" Jonathan
Boyer, the top US rider at the time and was the first American to finish the TDF, yet was totally unknown in the US. Bontrager tried his hand at bike fitting, and used a purely physics based
approach. The reason he had doubts about the KOPS system was due to the incorporation of it in the FIT KIT. Early Fit Kit was very inaccurate. The Fit Kit was
a mathematically based system, and purely relied on formulas & calculations. It was a very strict implementation of the Claude Genzling (Lemond) formula & KOPS, and relied on the assumption
that riders’ upper/lower leg length ratio was 50/50 and had fixed size feet. More than 99% of it output was not K.O.P.S. !!!
Other fitting systems used a statistics approach, which incorporated the mean value of the riders’ historic physical fitting data to determine the riding position. Interestingly enough, I found
that the output of such systems were a little bit more meaningful than mathematically based systems. We don’t come out of the factory as mass produced items, and therefore Bontrager's pure
mechanical approach has its fatal faults.
Bontrager overlooked the following crucial elements:
1. Gravity :
His 5-linkage system works like a 2 stroke engine, which almost works independently from gravity and becomes inefficient when gravity is taken into account. But, the human bio-engine is very
sensitive to gravity, even as little as a 1° change of seat angle will affect the way your body works ( a few percent in terms of power output. )
2. Sport physiology & technique :
Bontrager’s worries, that ‘out of the saddle’ riding affects a bike fit position, are not a concern for modern cycling. That’s how the PRO’s climb the extremely steep Zoncolan ( with Max maximum gradient of 22% ) in the 2011 Giro.
Tourmalet = 7%
Galibier = 7.5%
Alpe D'Huez = 8.6%
Mont Ventoux = 7.1%.
Out of saddle hill climb scenario: one should never ride out of the saddle during a climb! However, there are 5 exceptions to this general rule of thumb.
a. If your bike runs out of gears, you have to ride out of the saddle with the help of the upper body. But it’s happened a lot less since last year in the professional racing scene.
The lower gear the PRO’s would use is 34 x 32, but installing a 32 teeth sprocket with a mid-cage rear derailleur would be socially unacceptable, one would get crucified in the café!
b. On the bike stretch
c/d. Sprint or acceleration phase, one chooses to use their upper body muscles to enhance the acceleration. Upper body muscle enlistment is not necessarily a bad thing, as long as the
effort can transfer to the pedals and onto the road.
e. Use of it as a metabolic credit card, which has to be paid off later. Out of saddle climbing has higher metabolic cost. Sometimes PRO riders choose to use their upper body
muscle to extract extra power, however it is not as efficient overall as seated. That is the last resort for them to get the extra kick.
Out of saddle spring scenario: one shall never ride out of the saddle to sprint in a flat finish! Again, there are 2 exceptions to this general rule of thumb.
a. Acceleration phase, one chooses to use their upper body muscles to enhance the acceleration. Upper body muscle enlistment is synonymous with inefficiency these days for no reason. Some
bike fitters even label it as a crime ! As a matter of fact, Upper body muscle enlistment play a major role in cycling.
b. In the finish of a long road race, one's legs are totally XXXX. One needs to use different muscle groups to sprint. The use of upper body muscles that also result in enlistment of
different leg muscle groups, is usually adopted by a person to power the pedals during this phase.
Keith did not count the pedaling technique into the formula, he assumed pedaling motion similar to a two stroke engine piston (up & down), but it is not so in the human bio-engine.
Keith's out of saddle Sprint scenario: the moment (torque) @ the Lower Dead Center (LDC) is actually desirable. It helps sprinters pedal through the dead spot! Is it the same theory as to
why 100m runners start in the crouched position before a race. Sprinters also chose to use their upper body muscle to power the pedal.
Keith did not count the aerodynamics into the formula.
Keith's Out of saddle hill climb scenario: You should not climb out of the saddle when the speed is over 20 km/h. If you run out of gears & drop below that speed, you need to ride out
of the saddle with the help of the upper body. Aerodynamics is not a concern anymore at that low speed. Riding upright is more desirable, since you can transfer all your body weight onto the pedal
more directly. The bike becomes a mobile stepping machine (ie the decrease of effective cockpit length is not a worry anymore).
There are a few bike fitters around the world who recycle Bontrager's theory. They fabricate their own theory through ‘cut and paste’ of partially true articles from the Internet in their fitting
room. The ‘bashing’ of K.O.P.S. has become fashionable as it creates controversy. Shock marketing can sometimes be extremely effective and successful. Some fitters have become the " Bike
Fitting God " through this. They have to use paradoxes to cover their previous paradox until it blows up. Usually they don't know better than their fitting clients ! Their a new generation of
bike fitters are devert by them. Commercial bike fiiting become Chinese whispers !
Museum piece as it may seem, K.O.P.S has been around & well proven on the road for over a century. Modern products’ life cycle is becoming shorter and shorter and many products in mature
industries are revitalized by product differentiation and market segmentation. Marketers have applied it to K.O.P.S. They created a niche market.
K.O.P.S. is not the Holy Grail of bike setup, It is the neutral reference point for setting up a bicycle saddle's back & fore
position. Fusto Coppi & Contador both using KOPS
Here is an extreme example with maximum setback. If you were riding a recumbent, your knee is not on top of the pedal anymore. The pedaling phase is shifted by 90 degrees anti-clockwise. Push
phase will start from 9 o'clock & end at 3 o'clock. The pedaling style & force also changes. (Force is a vector. i.e. it has both magnitude and direction). There will be almost zero
utilization of gravitational force in the pedaling motion. That is why recumbent & TT bike always suffer even in a small hill. On the
flat, the aerodynamic advantage will out weigh the low power output. But building a road frame with setback position will cause 20 issues.
According to Newton’s 3rd law (The mutual forces of action and reaction between two bodies are equal, opposite and collinear). The pedaling push force will be cancelled out by the recumbent
chair's back. Riding a bike is quite different from riding a recumbent. The recumbent has a chair with a back. The bike does not.
UCI banned it after Thierry Marie won the 1986 TDF prologue, unfortunately.
UCI also banned the cable attachment device after the Italian national team won the 1987 100km Team Time Trial World
Championship in Villach, Austria.
Fignon's Systeme U team used saddles with a back
The only UCI legal option left is riding like Magni in the 1956 Giro with a broken collarbone. He couldn't pull on the bars so he gripped a length of inner tube in
his teeth. Saddle with high back won't do the job !
What are the contending forces to cancel out the pedaling force on a UCI legal bike?
1. Body weight
2. Pull force from the opposite pedal
3. Upper body muscular force
For low levels of activity, body weight is good enough to counter the pedal force, and if it’s an un-trained rider, there is virtually no pull pedal action. In high levels of activity, riders
usually solely use their upper body strength to counter the higher pedaling force. To reduce the usage of upper body strength, a combination of a proper saddle ‘back & fore’ position, pedaling
technique and shifting the upper body weight to the front is required. It will use a lot less upper body strength. One will become more aerodynamic as well. Moving the saddle backwards will make
matters worse. Instead of cantilevering the torso out from their pelvis to counter the extra pedaling up thrust, excessive enlistment of the upper body muscles is required. It is more
like riding a recumbent without the chair's back! Never mind though, if you are just cruising along.
There is nothing new under the sun. STEVE tried it many years ago, but he failed BIG TIME!!!
K.O.P.S is not just a coincidence. It coherence the 3 most important elements of pedaling. ( given that you have correct saddle height, neutral anterior pelvic tilt, endurance cadence
& proper pedaling technique. )
1. The crank Max leverage zone
2. Leg muscles activation phase
3. Gravitational force
During that period, the mean pedaling reaction force is collinear & opposite to gravitational force. Any phase shift will produce corresponding horizontal force component. (i.e.
setback position will push your body backwards & up front position will push your body forwards) Excessive enlistment of the upper body muscles is required in both cases. Also Quad
activation phase is not located in the optimal zone anymore, which leads decrease in efficiency.
K.O.P.S is the most efficient position to pedal with optimal endurance cadence for a trained rider. It getting the most work done ( power x time ) for a given energy input ( not Max power that some bike fitter suggested
It also guides you to developing into a real cyclist. There will be localized quad soreness in the initial training period.
Quad deactivation is the order of modern society. If you observe any shopping mall's stairs & lifts, the anti gravity usage ratio will tell you something. We still stand & walk to the
garage, which means that the gluteus muscles (bum) are still enlisted everyday. Their bike fitting philosophy is based on quad deactivation & uninitiated consumers swear by it. They have
successes in their own right. ( The human body is incredibly adaptable ) They would have been more successful, if they dialed the seat angle more aggressively & installed a saddle with a back.
Then it will have been a potential threat to the world record breaking CRUZBIKE, a real piece of OZ ingenuity. I am pround of them.
Not everyone will get the benefit from K.O.P.S. though. Most of the un-trained riders will chose high gears to ride their bike, involuntary, since their fast twitch quad muscle fibres have not
been trained & developed. They pedal with very low cadence ( under 75 rpm ), which is similar to driving a car in 5th gear all the time. It is the main cause of their unstable pelvis, swollen patella, numbness, pains, injuries, low power output, chronic fatigue, heart disease & other chronic health issues.
Believe it or not. Their commercial bike fitters specilized in low cadence optimization ! Some do their job very well indeed. If you like the idea, you should stop reading here.
Pedaling with low cadence, the high power fast twitch fibres in the quad muscle are prohibited. The low power slow twitch fibres in the gluteus muscles need to be enlisted further. It
fires at the initial phase of the down stroke (12 to 3 o'clock). The pedaling phase needs to be shifted a few degrees in advance to make them ride more effectively. With the phase shift (setback
position) The TDC will be @ 11 O'clock, LDC will be @ 5 O'clock., the slow twitch gluteus muscle is optimized. ( replacing knee extension phase by enhanced hip extension ! ) But low
cadence with setback position is a vicious cycle of low performance cycling.
Setback position is optimized for low rpm (low output) pedal pushing. It is also an instant enhancement for an untrained person to simply push the pedals @ low
rpm. It is a butt enhancement ‘drug’, overdose may also cause addiction & long term performance decline!
A lot of people have the misconception that pushing higher gear is better, stronger & faster. As a matter of fact, higher cadence x higher gear will produce more power. (Power = TORQUE x RPM)
For human body & motor engine, rpm optimization is the only way to obtain optimal power for a given capacity. My acquaintance
sprint legend Gary Neiwand can rev up to 300 rpm with no chain attached to the crank. F1 engines rev close to 20,000 rpm. In contrast, most
recreational riders pedal less than 75 rpm & truck engine rev around 1500 rpm. In a combustion engine or human body, high rpm can burn more air/ fuel mixture to produce more
power. Engine need bigger fuel injection nozzle / air intake system, while humans need a bigger heart & lungs. If a rider has been pushing high gears all the time, their heart & lungs
will be under developed in relative terms. When they try to ride with high cadence, they will run of breath (carburetor is too small), and it will slow them down dramatically.
Q It seem you are a cycling lore from days of yore, you want us all ride like a PRO ?
A. You should riding the same candence as the modern PRO for your health, general well being & performance. But you would riding a much lower gear. That what
the gear design for !
Here is another extreme example with maximum up front position. Body sliding forward on the seat under load is normal respond. World-class
sprinters can pedal very fast. They produce well over 2000w MAX as opposed to 200w average output of a recreational rider (some say Sir Chris Hoy could produce 3000W). They shift their body weight all the way to the front to counter the tremendous pedaling force that they produce
while sprinting. At the same time, they can use their upper body muscle more effectively & also become more aerodynamic. They change their pedaling force direction as well. TDC will be @ 1
O'clock. LDC will be @ 7 O'clock. The weight shift also helps them to accelerate when they are out of the saddle (increase in the effective crank length!). It is not the most economical way to pedal,
but is the best way to achieve Maximum power output. (Virtual) up front position is optimized for high rpm/high output all out effort. There is NO free lunch,
you need to enlist your upper body muscle to get the extra kick.
In a match sprint, it only lasts for a couple of minutes. Sprinters usually sprint for 10 seconds, yet they still set up the bike up with K.O.P.S. position.
Q: Why don't they move the saddle up front?
A: Because they want to pedal efficiently & sit comfortably for the majority of the time of the race (90%). When they are in action, they pick & stick their xxx into the tip of the saddle.
Only for a few seconds though, thank god!
Q: Should I use upper body center of gravity (BCG) to determine saddle setback?
A: It is a mistake. No, you should not.
The BCG bike fitters will set the less flexible rider with up front position even the sprinter won't use, and the more flexible rider with low performance setback position to achieve
the so called "balance point". It should be the other way round, in most cases.
BCG fitting protocols are very inaccurate. BCG it is not a static point, it's constantly changing in a 3D environment on the road. The pedaling reaction force is also changing in
What contributes to the BCG change?
a. Lumbar flexion change, when you change your body lean angle
b. Seating position change, when you slide your body back & fore on the saddle
c. Weight distribution change, when you place your hand on different parts of the handlebar
What contributes to the Pedaling Reaction force change ?
a. Your cadence
b. The amount of force being applied to the pedals
c. Pedaling technique
There are also other variables that need to be taken into consideration in the formula as well.
a. Upper body flexibility
b. Core strength
c. Duration of the ride
d. Change of speed (aerodynamics)
e. Change of terrain
Cycling is a dynamic activity. Performing a single drill in a home trainer at a given load to speculate the balance point is quite often dangerous. You should not determine the BCG in a static
apparatus like a stationary trainer. It is a static quantification of only one aspect of a person engaged in a dynamic activity. Although the drill seem to be dynamic.
How could I find the real " balance point "?
Use the stem length. Is it as simple as this. Bike parts are cheap these days. You could buy a reasonable quality stem on eBay for a few $. Test the different stem lengths on the road in real
world riding conditions. If you are a sprinter, test it in a 200m sprint on the velodrom. If you are an Audax rider, test it in your 1200km epic ride.
4. Saddle angle
Start with neutral (horizontal) position & try + - one to 5 degree & see which angle is more comfortable. This is again your personal preference, but the horizontal position is a good
neutral one that you can start with.
The following are ‘secondary’ set-ups. You should perform the above set-up in sequence, before you proceed further.
5. Handlebar Width
Your personal preference, but general rule of thumb is to use a handlebar that is similar in width to your shoulders (left to right). It is a trade off between aerodynamics & comfort. Never
trade off comfort for anything. World-class track sprinters all use 38 / 39 cm handlebar. A pro tour rider with half of their size would use 42cm handlebar.
6. Stem length.
Your personal preference, it is a trade off between aerodynamic & comfort. No rule to apply, but can be determined by your "effective torso length" (i.e. your upper body length, flexibility
& core strength). Make sure the stem is not too long that you are not able to control the bike properly, and not too short that the cockpit is too congested.
If you are a performance-based cyclist, average pedaling up thrust force & aerodynamics need to be taken into consideration. For example, hypothetically, there are a set of identical
twins. One is a criterium racer, the other is an Audax expert. The racer needs a longer stem to counter his higher output, while a shorter stem would be more appropriate for the Audax expert, who is
always cruising around zone 2 @ lower speed. Never trade off comfort for anything.
7. Handlebar height
Your personal preference again, it is a trade off between aerodynamics & comfort. Never trade off comfort for anything. No rule to apply. Intensity & duration of the
ride, upper body flexibility & core strength need to be considered.
If you have back or upper body pain, there are 2 main reasons.
A. You are not using your handlebar in the correct manner
B. You are not sitting upright enough: Some bike fitters would suggest you to sit further back in order to take away the force of your upper body weight on your hands from the handle bar.
As a matter of fact, it would transfer most of your upper body weight to your lower back, which would induce more back problems. There is NO Free Lunch, the transferred weight has to go
somewhere. It will also change the position of the BB in relation to your body, and force you to engage low performance pedaling. No matter how hard you train, there will be no localized
quad soreness (it has been DEACTIVATED), and you will get nowhere performance wise. You do not improve as a cyclist, and you marginalize yourself as a low performance rider.
If you have upper body or lower back pain, you should be sitting more upright. i.e. you should raise your handle bar up, instead of moving your saddle back with a shorter stem. Raising the
handlebar up will reduce the lumbar flexion. You could relax & rest your hands on the handlebar to transfer part of the upper body weight from the spine. The weight distribution remains almost
the same. Simple as this! It won't cost you a cent in most cases. No expensive setback carbon seat post, no shorter stem. The trade off is that you are less aerodynamic. On the topic of aerodynamics,
it is not a marketing hype. Resistance comes in the form of drag (air resistance), which progressively increases in relation to your
velocity. Therefore if you travel less than certain speed, drag resistance is not a concern.
8. Handlebar angle & hood position. Your personal
Always start with neutral position,
Handlebar neutral position is about 5 degrees off (down) horizontal axle
Hood neutral position
1. For newer Campagnolo, Shimano & Sram, the flat section of the hood should be up 5 degree
2. For older Campagnolo & Shimano , the initial flat section of the hood should be down 5 degree
I have to admit that I am a BIG SUCKER of high performance cycling. Whenever I see a high-end bike with low performance setup on the road, I intuitively want to stop & point it out to them.
But the owners of high performance bikes can set up the bike however way they want. If they’ve paid money for commercial bike fitter to setup their bike with low performance manner in pursuit of high
performance, then the practice is questionable.
I do ride with setback position sometime, or I should say virtual setback position. When I negotiate with very steep hills, my bike usually runs out of gears. The cadence drops below 70rpm. In
that situation, I would hang my butt out of the end of the saddle & start to power the pedals with my gluteus & upper body. (hybrid powered vehicle) After I finish the hill, I will go
back to neutral position again. In an all out sprint towards the yellow ‘soon to be red’ light, I will do what the sprinter does. But it constitutes less than 1% of my total riding time. That is
why K.O.P.S is my choice of setup. With neutral K.O.P.S. setup, I could ride with setback or up front position anytime I want. There are more & more saddle manufacturers producing long &
flat saddles to cater for multiple riding positions. ( I like it so mich, I produce a multi riding position saddle myself ) In contrast, there are some saddles with high back & dip noise that tend to lock
you in one single position.
In essence, all parameters of bike set up are your personal preference. The saddle back & fore position is more like the cam profile of a car engine, since human bio-engine have variable
valve lift & cam timing ( body move back & fore on the saddle according to the load apply to the pedals ), and most importantly have mapping ( technique ) to accommodate
Up front or set back? You can choose and adapt while you riding. If you have a neutral K.O.P.S. setup with an appropriate saddle.
There are no theories, no hypothesis, no anecdotal evidence, no assumptions, no scare tactics, no asymmetric information, no product placement, no price tag, no donation, no moral hazards here.
It’s all about high school physics, biomechanics, sport physiology & most importantly, commom sense.
I hope you could get some inspiration from this article & keep improving your bike fitting & riding. Lastly, I wish you will all become your own perfect bike fitter. Nobody knows your body
better than you do.
5th May 2011
There will be no addendum until UCI change the bike regulation