Bicycle Stance Width and Q Factor: Origins, Examples, and Solutions

Photo credit www.longhaultrekkers.com

Stance Width Origins

In his early days of track racing, Paul Swift (founder of BikeFit and Director of BikeFit Education) constantly heard the incessant yelling of his coaches, “bring your knees in!” This assumed that there was something inherently wrong with Paul’s form and he needed to force his knees into the “correct” position. Paul is unlikely to admit that his form was anything less than perfection, but the “knees in” adage was fundamentally flawed. At the top of the pedal stroke, the knee was not under the same amount of pressure, and it moved outward naturally to get closer to his ideal position for comfort. The knee then followed the foot faithfully down to discomfort town forcing it inward at the 6 o’clock position.

Paul was not the only person who suffered from this potentially debilitating issue which not only affects alignment but also places significant torque on the knee when it’s forced into an unnatural position. The result: pain and potential injury (not to mention the power loss). Even though 150 years have passed since his racing days and bike fitting is much more popular in cycling culture, the concept of stance width is largely ignored. Our blog article today aims to explain the factors involved, when to make changes, solutions, and our recommendations from years of bike fitting experience. Before we go any further, grab your favorite beverage and let’s go over the terminology we’ll use in this article:

Stance Width – The distance between the center of one pedal to the center of the other pedal. This article will also reference individual leg stance width, which is defined by the distance from the center of the bottom bracket to the center of the pedal.

Q Factor / Crank Width – The distance between the outside portion of each crank arm where the pedal attaches. The term was originally coined by Grant Petersen while he worked for Bridgestone Bicycles. The “Q” stands for “quack” which referenced the wide stance of a duck. This is seemingly contradictory because the argument can be made that q-factor (unchangeable and determined by multiple factors such as bicycle and component manufacturers and the width of the chainstay) is, in many cases, too narrow on a road bike.

Pedal Spindle Width – The distance from the outside of the crank arm to the center of the pedal.

Snowboarding Stance Width Similarities

Now that you’ve thoroughly digested the major terms of the article and you’ve realized you need a signifcantly stronger beverage, let’s completely change gears and talk about snowboarding. When you Google “Stance Width,” a plethora of articles about snowboarding flood the screen. Significant time and energy focus on the adjustment of snowboarding stance width. Their starting point is based on a measurement from the center of the kneecap to the floor, applying that measurement as an initial width starting point, and then specifically adjusting both width and foot angle until the individual achieves maximum comfort. In most of the articles we discovered, a trial and error method was utilized.

Clearly, we are unable to apply the same measuring standards from snowboarding to cycling but there is a striking similarity: the feet need to be set up correctly because once set, the individual is unable to self-select their stance width. Author, bike-fitter, and physical therapist Dr. Katrina Vogel reminds us that “you self-select your stance (width) when you walk, run stand or jump.” Therefore, in sports when you are “locked-in,” achieving the correct stance width is paramount to power delivery, efficiency, and injury prevention.

Determining Factors of Bicycle Stance Width

While snowboarding uses multiple pre-drilled holes in the board to customize the stance width of the bindings, in cycling, we have two determining agents (as well as some customizations that we’ll discuss later): q factor and pedal spindle length.

Q Factor / Crank Width

Q factor is roughly the same within specific categories of bike types i.e. road bikes, mountain bikes, fat bikes…etc.. The cranks need to be wide enough to clear the chainstay and a wider tire will, in turn, affect the chainstay width. We will not spend much time on q factor because it’s largely predetermined (based on bottom bracket width, crank offset, bicycle type, and manufacturer specifications) and since the ultimate goal is to find the most comfortable stance width for the individual, this article will focus on pedal spindle length and stance width customization. With that said, q factor is an odd term and it’s preferable and universal to refer to it as “crank width” in order to not make cycling a sport dominated by coded language. Although we will focus on stance width today, keep in mind these crank width standards based on bike type:

Road Bike: Approximately 150mm. Currently, many Shimano cranks boast a 146mm q factor and the masterminds at Campagnolo prefer 145.5mm, just to mention a few.

Mountain Bikes: Approximately 170mm. Sram XO1 and Shimano XTR both width-in at 168mm.

Fat Bikes: 200-230mm.

Pedal Spindle Width

Largely uniform in the industry (like crank width), this is the best area for stance width customization. Let’s take a look at some of the common pedal spindle widths (we’ll keep adding to this):

Shimano:

• Ultegra 8000 – 52mm (+4mm option–56mm)
• Dura Ace 9100 – 52mm (+4mm option–56mm)
• XTR – 52mm and 55mm

LOOK:

• Blade, Max, Sprint, and Classic (all versions) – 53mm
• *Note – Look Keo pedals have a threaded area that is 2mm longer than other pedals, allowing for the safe installation of up to (2) 1.5mm spacers.

Speedplay:

• Zero Titanium – 50mm
• Zero Chrome-Moly – 53mm
• Zero Stainless – 53mm
• Zero Stainless custom lengths: 50mm, 56mm, 59mm and 65mm

Xpedo:

• Thrust 8 (all types) – 53mm
Thrust 8 custom spindle lengths – 50mm, 56mm, 59mm and 62mm
• *Xpedo, like Look, provides a 2mm longer threaded area.

Issi:

• Road – 50mm and 55mm (+5)
• Flash III: 52.5mm (standard), 58.5mm and 64.5mm
• Trail III: 52.5mm (standard), 58.5mm and 64.5mm
• Flip III: 58.5mm

Crank Bros:

• Eggbeater, Candy, Mallet, 505, Double Shot – 52mm
• Extended Spindle Kit (sold separately) for Candy, Mallet, 505, Double Shot + 5 – 57mm.

Keywin:

• CRM Chrome-Moly 55mm (custom sizes below):
• 49mm
• 52mm
• 58mm
• 61mm
• 65mm

SQ Lab:

• 511, 502, 521
• 50mm (-5)
• 55mm (Standard)
• 63mm (+8)
• 70mm (+15)

When to Modify Stance Width

Although research for this blog post discovered zero articles on common trends in cycling stance width, the consensus of the experienced minds at BikeFit, our trained BikeFit Pros and the popularity of Pedal Extenders, support the need for stance width modification. It’s difficult to believe that the majority of every asymmetrical human male and female size 4’8″ to 7’2″ would be accommodated by a 252mm (about 10 inches) stance width (252mm was obtained by using an average 53mm pedal spindle width on each side and a 146mm q factor). Considering the pedal spindle width and q factor example, cycling is like the “one size fits most” of clothing. We are not sure of who fits the “most” category but in our experience, “most” is more like some. Granted, we already mentioned the possible extended pedal spindle width but think about the amount of emphasis on bike size rather than stance width–every company offers multiple bike sizes but not every company offers an array of stance width options.

With the argument made for customizing stance width, let’s take a gander at a rider who requires modification:

 

Video Courtesy of Quest Therapy Consultants

Take a moment to evaluate each knee. The left and right (more significant) distinctly move outward at the 12 o’clock position and then back in at the 6 o’clock position. Even without the aid of the laser guide, it’s obvious the knee craves a wider stance width but is forced to follow the position of the foot inward during the downstroke. This is incredibly common. We challenge you next time you’re on a lovely weekend ride with others, observe the pedaling of your compatriots. Do you notice knees kicking out at the top of their pedal stroke?

Without delving deeply into the world of bike fitting, the “knees out” rider may also have a saddle height issue or a need for Cleat Wedges. If the saddle is extremely low, a similar pedal stroke will develop. In the case of the video above, saddle height is not the culprit. The client did require wedges, but in order to not confuse the issue, stance width is the main problem.

Stance Width Solutions and Drawbacks

*In case you’re scoring at home (of course you are), this is a quintuple blog repeat score for using “stance width” in every major heading (spoiler alert, they’ll be 8). It exemplifies how we feel about the topic.

To solve the “knees out” issue and achieve maximum comfort, the foot needs to align with the knee–it’s not the other way around. Consequently, the foot must be adjusted/moved out. Here are some solutions:

1. Longer Pedal Spindle

   Feel free to reference some of the pedals mentioned earlier such as Speedplay, Issi, and Keywin. While Shimano Dura Ace pedals now offer a 4mm extension, the “regular” spindle width is already tight at 51mm. As a result, a 55mm spindle width may not be long enough for many riders. When Road Bike Action reviewed the first model (9000) with the extended spindle option, they made this bold statement, “for those looking for a wider stance without bulky extensions, the Shimano cleat has ample lateral adjustment. The pedals also have a 4mm-longer axle option to widen your stance width even more.” To say the cleat has “ample lateral adjustment” is like saying that a Ferrari Portofino has ample seating space. It does, if your only intention is to drive yourself and one other extremely lucky person through the streets in style. The Shimano cleat does have ample lateral adjustment for some people, but most will require more and even a 4mm longer spindle option will often not solve the problem.

2. Cleat in, Foot Out

   Most bicycle cleats and shoes have some room for lateral movement. While some cleats/shoes offer more flexibility than others, this simple change makes a noteworthy difference and is the most affordable adjustment.

   

3. 1.5mm Pedal Spacer Washers

   These small spacers provide an extra 1.5mm to stance width. We do not recommend using more than (1) per pedal. It’s important that there are enough threads to safely install the pedal into the crank. As we mentioned earlier, Look Keo pedals are built with a longer threaded area to accommodate an additional 1.5mm spacer.

4. 20mm Pedal Extenders

   This is not a gratuitous sales ploy by the marketing team at BikeFit. These extenders have helped a multitude of riders. When the lateral movement of the cleat, a longer spindle or the 1.5mm spacers are not enough, the 20mm pedal extender works wonders. Using the previous equation based on the q factor of a Shimano crank, adding a pedal extender to each side would add 40mm to the overall stance width for a total of 292mm or about 11.5 inches. Considering an avg. mountain bike q factor is 170mm, adding 40mm to a road bike at 146mm will likely help many cyclists achieve desired comfort and alignment. BikeFit offers both a Hex+ 20mm Pedal Extender for those pedals that require an 8mm wrench for installation and our regular 20mm Pedal Extender for all other pedal installation types.

   We would also like to note that Road Bike Action’s earlier claim that extensions are “bulky” is the equivalent of calling a pro peloton sprinter overweight. Clearly, they both are the correct size to achieve specific results. The extenders are imperative for many riders and at 37 grams, it’s worth the extra “bulk.”

5. The Combo Move

   Every person requires their own specific stance width. Therefore, combining the different methods together will yield the best results. If you need more space than the 20mm extenders provide, add a 1.5mm spacer. If the 20mm extender is just a bit too long, consider laterally moving the cleat out (foot in) after installation. Many riders even combine the longer spindle of a Speedplay pedal with a pedal extender or a pedal spacer.

Single Leg Stance Width

This one may seem like a head-scratcher but it’s true for most riders. We’ve mentioned this in other articles but a bike is a beautifully crafted, symmetrical machine. The human body is a flawed, somewhat challenged, aging, potentially injured, often uncoordinated, sometimes imbalanced, asymmetrical biped. Consequently, when we are bent over and clipped into a symmetrical machine, problems arise. In order to fit an asymmetrical being to a symmetrical bicycle, it’s important that each leg is evaluated independently. This means that one leg could be perfectly aligned and the other one could have the 12 O’clock kick-out occurring during every stroke. Each leg will potentially require its own modification independent of the other. For example, BikeFit sells more single left-only pedal extenders than the right-only. This doesn’t mean that human nature has a propensity to a wider stance width on the left-hand side (it may, but that’s another blog post), it further supports our assertion (spearheaded by Paul Swift), that “each leg has its own individual stance width.”

After Stance Width is Adjusted

Considering our earlier video of when a stance with modification is needed, here is a view of what alignment looks like after adding a 20mm pedal extender:

The diagram below displays the differences an adjusted stance width offers the rider. Although it shows a “longer pedal axle” as the optimal intervention, the same methodology can be applied using the solutions mentioned previously.

Conclusions and Final Stance Width Thoughts

If research was conducted on cycling stance width, a bell curve of the most prevalent measurements may exist. Even if that information for cycling was available, in our experience, bike fitting is somewhat subjective. Therefore, the perfect formula for cyclist A may be horrific for cyclist B.

Stance width is worth examining for every cyclist on any type of bicycle. As we’ve mentioned in other articles, if a cyclist is out of alignment riding at 85 rpm, that’s 5,100 pedal strokes per leg, per hour. If we carry this scenario out further, let’s say the average cyclist rides 6 hours per week, which is roughly 122,000 pedal strokes per month and over 1 million per year, per leg. With that number of pedal strokes, the strain on the body (especially the knee) is significant.

In cycling, the industry usually grabs us with the flash of style: aero helmets, new colors, more gears, less friction, larger pulleys, more carbon…etc, but none of these are more important than fit. Does it matter how your bike looks or functions if you’re in too much pain to ride it?

If you’re a bike fitter or a bike shop, we implore you to analyze the stance width of every rider you fit or bike you sell. If you’re a cyclist, as much as tinkering with fit may improve your comfort, it also may make it worse. It’s worth every penny to get a professional fit. Before you schedule a bike fit, ask your fitter whether they examine stance width and what modifications or process they use. Glean as much information as possible before you book it or you’ll be unhappy with the results. If you have questions about fitting or stance width, feel free to drop us a line.

Enjoy your ride.

-The BikeFit Team

Paul, Damon and Bill

 

Interested in expanding your knowledge? Bike retailers and shop employees with a QBP account have access to educational resources within the U of Q Training Library. Get started now.

Special thanks to the following sources for photos and information:

Long Haul Trekkers
Slow Twitch
blog.yourstoryboard.com
BC Bike Fit
Quest Therapy Consultants
Rick Schultz–Road Bike Rider
https://en.wikipedia.org/wiki/Q_factor_(bicycles)