The following is a paper I wrote at the conclusion of a year long mentorship through the International Bike Fitting Institute with Curtis Cramblett. The process involved many conversations and research into concepts and techniques not all of which are included in this final paper. The idea is to further the knowledge of a fitter in a focused area of study, in this case Saddle Position. It has been an enlightening and informative year and has changed the way I look at saddle position forever. Like that amazing fitter from “down under” says “How hard can it be?” The answer is simply, it depends, on so many factors.
The Backside of Bike Fitting: Saddle Position
The subject of saddle position in bike fitting seems like such a simple and basic concept. Any fitter should be able to master this basic contact point. There are so many different methods and processes of establishing correct position of a saddle, it can actually be quite overwhelming. Each method has pros and cons and learning what these are has been fascinating to me through this mentorship process. Determining what the drivers are to dictate changes in saddle position is the hallmark of this mentorship. In the following discussion, I will cover the methods, challenges, and solutions of establishing proper saddle position in bike fitting.
There are several methods of determining saddle height currently in use. Some fitters learned the flexibility restriction method taught by instructors like Michael Sylvester and the Serotta International Cycling Institute (SICI). This method employs the range of motion of both the hip extensors (Glutes and Hamstrings) and the hip flexors (Psoas and Iliacus) to determine a saddle height that does not exceed the bodies ability to pedal comfortably with muscle control throughout the pedal stroke. Steve Hogg uses a similar method of observing the knee as the leg passes through the bottom of the stroke to ensure control of the muscles of the leg as power is applied through the stroke 1. BikeFit/CyclePoint and Retul/Specialized teach a method that relies on measurement of the knee angle at the bottom of the pedal stroke. Other fitters measure this angle dynamically with motion capture equipment, and some take the angle statically with the rider’s leg stopped at bottom dead center 2. Still other fitters use the older methods like the one developed by French coach Cyrille Guimard and made popular by Greg Lemond in the United States. This method uses a rider’s inseam measurement in centimeters multiplied by .883 to determine optimum saddle height 3. There are several other methods dating back to the late 1960’s including “the Hamely Method”4 using 109% of inseam and “The Burke Method”5 that determines height with heel on pedal and leg extended at bottom of stroke.
Each of these methods has pros and cons based on the person who is using the method. Measurements can be problematic by practitioners who lack experience finding angles with a goniometer off the body, or fitters who are not familiar with bony landmarks to apply markers for motion capture equipment. Without sufficient experience observing a cyclist pedal, some might struggle to discover the subtle changes in muscle patterns and limb control through the pedal stroke. Using the inseam length and a predetermined formula to establish saddle height has obvious issues for anyone falling outside of the middle of the classic bell curve of human anatomy types, regardless of the fitter’s experience level. Whenever a measurement is taken statically, there can be errors based on the limb is not moving, and saddle height is more importantly determined while actually pedalling and not coasting or stopped.
In my research of these different methods, I found a combination of methods more effective than any single one in practice. While flexibility and range of motion always play a role in saddle position, there are other factors that are easier to observe and control in the fit process. Pelvic stability is easier to observe while a rider is pedalling. This method aligns closely with the philosophy of Sylvester and Hogg in observing control of muscle firing patterns. When a rider can control the muscle firing pattern with better central nervous system communication, stability is usually the observable result. This might result in a knee angle below the suggested range of certain schools for riders with limited flexibility or range of motion. For some, it might even be above that range if their control is better. There are other factors that might influence these differences like heel droppers and toe pointers that will be discussed later. Pelvic stability is a primary goal of saddle position no matter the process of achieving that goal.
How might a leg length discrepancy (LLD) effect saddle position? Discerning a true leg length discrepancy can be difficult for a seasoned medical professional let alone a bike fitter. Generally speaking from a fitting perspective, LLD of under 5mm are not “usually” considered a problem needing attention. Sometimes a shim might be used, but usually after other changes have been considered without improved observable stability. Leg length discrepancy can be both accommodated and sometimes corrected depending on the severity and type. Severity as mentioned above, below 5mm can sometimes be absorbed by the rider with mobile adapters like the ankle and hip. Above 5mm, some attention must be focused on shim installation, orthosis, crank arm length or all of the above. The type of LLD is probably the most important consideration when it comes to saddle position. These types are structural and functional 6.
1.) Defined as the bones of a limb being longer than the other.
2.) Best found with a standing AP radiograph (x ray).
3.) Some feel it’s important to know where (above or below) the knee the LLD is located.
4.) Not usually correctable and will need to be accommodated.
1.) Not a bone length issue as much as a bone position issue.
2.) More common than structural.
3.) Often correctable in the long term.
4.) Most often accommodated in the short term until long term solutions are achieved.
5.) Can be more tricky to evaluate from a fitting perspective.
Accommodation is most often the approach for fitters, especially those without a medical background with knowledge of identifying and then manually correcting issues like a rotated innominate or pelvic upslip. There are many medical sources for treatment of these common “functional” LLD issues 7. Because these manual methods to the body don’t always “stick” or remain a corrected solution for various reasons in the short term, it makes an accommodation the more common fit decision. As a fitter, it’s extremely helpful to know these methods and understand when to refer a client out for a more thorough examination by a medical professional.
Many fitters will simply adjust saddle height for the short leg and not consider accommodating for the length issue. Often the long leg will then experience issues at the top of the pedal stroke because of a closed hip angle or knee angle that makes the long leg more of a problem than the original problematic short leg. When this is the case a shorter set of crank arms will limit if not remedy this issue. Often a compromise must be made between the two limbs to acquire the best stability and muscle activation from both involved. Whenever there is an accommodation there is a sacrifice. The solution is to limit the sacrifice for the ultimate goal whether it be less pain, more power, better efficiency, or more stability. Trying to achieve all of these goals is unrealistic and therefore something must be sacrificed.
It is important to consider how much the rider adapts to the LLD on their own before any accommodation is added. It is rare to try to make “both legs the same length.” Most shimming for LLD is in search of stability as the goal. Don’t be afraid to go too far in the accommodation then come “back” to stability in order to locate a solution 8. Another option: try a supportive arch in the shoe to help with overpronation and perhaps lower the saddle at the same time until both legs feel engaged and pelvic stability is achieved.
It can sometimes be difficult with these changes because negative consequences often occur as a result of accommodation. It is common understanding that the short leg will have issues at the bottom of the pedal stroke. Enough issues usually for it to be the focus of the saddle position question instead of the long leg issues at the top of the stroke. The key is to get both legs involved and stable at the optimum ability given the difference in length regardless of the accommodations made at the time of the fitting. In the case of a client receiving sufficient therapy to correct a functional LLD, a follow up will be needed to re-evaluate position after accommodation is no longer needed.
One of the other drivers for saddle position changes can be riders who are referred to as toe-pointers and heel-droppers.
While there can be many drivers for this type of pedal stroke observation, most common is the tight gastroc/soleus complex. It can be the result of a locked up talocrural joint instead of tight muscles. It may also be the result of the saddle being too high and be observed as instability in the pelvis or foot/pedal interface. It is possible the rider might lack innervation of the muscles responsible for dorsiflexion (anterior tibialis, extensor hallucis longus and the extensor digitorum longus). Even tight hamstrings can play a role in control of the ankle. When unable to extend the knee because of limited hamstring flexibility a rider often compensates at the ankle presenting increased plantarflexion.
Most often heel-drop is the result of instability in the pelvis or foot/pedal interface. Sometimes people drop the heel as a result of a hypermobile talocrural joint. These folks often lack the strength to control the joint under load. It is also possible, like the toe-pointer, there is a lack of central nervous system communication with the muscles responsible for plantar flexion (gastroc complex, flexor hallucis longus and flexor digitorum longus). Certain riders may proprioceptively wish to apply force to the heel instead of the ball of the foot during the power phase of the stroke. Without a stable surface at the heel like when standing on flat ground the heel drops during the pedal stroke. Finally, it is of course possible heel-dropping can be the result of the saddle being too low.
The solutions for most of these issues are fairly straight forward. Often physical therapy can address tightness and instability issues for clients in just a few visits. Sometimes a little foam rolling or manual manipulation can immediately achieve results during the fit session. Innervation issues need to be addressed by a medical professional and are beyond the scope of most bike fitting professionals. There are some vascular return limitations associated with both types of riders. Generally with good ankle movement throughout the pedal stroke (plantarflexion in the downstroke and less plantarflexion in the upstroke), there will be sufficient vascular return from the foot to limit significant swelling of the feet within the shoes. With limited ankle movement, due to constant toe pointing or heel dropping throughout the stroke, blood can “pool” in the feet and cause a host of issues including, but not limited to, numbness and hot spots. Most importantly, both toe pointers and heel droppers are ultimately controlled by the stability of the pelvis. Some toe pointers will end up with a higher than “typical” saddle height for their increased reach due to plantarflexion through the pedal stroke and vice versa with heel droppers.
All of these factors help determine saddle position in the space under the rider. Saddle position across road, cross, and track disciplines can be narrowed down to a fairly small point in space in relation to the bottom bracket. This concept is often referred to as “The Fit Window”. If thought of in terms of a circle, it is about the size of a US dime. This circle is bigger for some people who are better adapters and smaller for others who are not. In metric terms, it is roughly 3mm round on the small side and 15mm on the large side. The disciplines where this does not always hold true are Mountain bikes (MTB) and Triathlon (TRI) bikes. With the infiltration of dropper seatposts, MTB saddle position is more mobile than ever before. The full extension position can be very close to the “dime” size circle we see in other disciplines but is often setback more than we might see on the road bike. The big change is usually in saddle angle. Road bikes are typically in the +/- 2 to 3 degree range and MTB saddles are often up to 7-9 degrees nose down to accommodate both steep climbing terrain and suspension sag setup. TRI bikes are not encumbered with strict UCI regulations like Time Trial bikes (TT). TRI bikes often go well forward of this point to even positive “setback” or set forward. This allows saddle positions well outside of the “dime” size point often well forward and up from there. If measuring Knee Over Pedal Spindle (KOPS)9 as a reference and not a guide, we might see a knee as far as 90mm to 120mm in front with a saddle “set forward” of as much as 50mm depending on the saddle of choice.
My research on the subject of saddle position unearthed many concepts and methodologies I did not encounter previously. Regardless of discipline, the ultimate control factor in position returns to muscle control, sustainability and stability at power. If these 3 factors are the primary controlling influences in your decision process for making changes to saddle height, the results will almost always be positive. It is critical to remember that every person is different and every fitting is unique in the limitations, goals and historical background that drive the saddle to the optimal location for each rider.
1.)Steve Hogg Bike Fitting February 3, 2011 https://www.stevehoggbikefitting.com/bikefit/2011/02/seat-height-how-hard-can-it-be/
2.)“When the Foot Meets the Pedal” by Paul Swift and Katrina Z. Vogel MS DPT. CreateSpace Independent Publishing Platform March 20, 2015
3.)My World from a Bicycle , Lemond Sizing Method http://myworldfromabicycle.blogspot.com/2010/05/lemonds-sizing-chart.html
4.)Effects of Bicycle Saddle Height on Knee Injury Risk and Cycling Performance
Rodrigo R. Bini, Patria Hume, James L. Croft ; June 2011
5.)”High-Tech Cycling 2nd Edition” by Edmund R. Burke PhD,
Published by Human Kinetics 2003
6.)Evaluation of functional and structural leg length discrepancy in patients with adolescent idiopathic scoliosis using the EOS imaging system: a prospective comparative study
7.)Stone Athletic Medicine- Pelvic Upslip and Rotation: Evaluation and Treatment May 15, 2014
8.)Steve Hogg Bike Fitting April 3, 2011
9.)The Myth of KOPS An Alternative Method of Bike Fit : by Keith Bontrager