But one of the trickiest measurements to change and to get right is a bike\u2019s Q-factor \u2013 or more correctly its stance width.\u00a0<\/p>
Below, we\u2019ll explain what Q-factor is, why it\u2019s important, the effects of it being incorrect and what you can do to adjust yours.<\/p>
What is Q-factor on a bike and why is it important?<\/h2>Stance width is a combination of the pedal spindle length and the crank arm Q-factor. – Scott Windsor \/ Liam Cahill \/ Our Media<\/figcaption><\/figure>Q-factor is the lateral distance between the outside edges of the two crank arms. As such, it\u2019s a feature of your crankset<\/a>; you\u2019ll find the Q-factor quoted by many brands on their websites. So, technically, it\u2019s not possible to change it without changing your crankset.<\/p>But when Q-factor is discussed, the measurement being referred to is often your stance width<\/a>.\u00a0<\/p>This is the lateral distance between your feet when pedalling. This takes account of where your feet are positioned on the pedals, the shape and size of the pedals and the length of the pedal spindles.\u00a0<\/p>
There are ways to alter your stance width, as discussed below. Getting the optimum stance width for your anatomy could make your pedalling more efficient, reduce the risk of injury<\/a> and help prevent your heels rubbing on your crank arms or chainstays.<\/p>Q-factor doesn\u2019t just affect your pedalling though. A wider Q-factor will reduce the amount by which you can lean a bike into a corner without the risk of grounding a pedal.<\/p>
How does Q-factor affect your pedalling?<\/h2>![\"Front-on](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/09\/Pedalling-Impact-Q-Factor-1-scaled.jpg\")
An incorrect stance width can result in misaligned leg joints and leg pain. – Scott Windsor \/ Liam Cahill \/ Our Media<\/figcaption><\/figure>If you think about how it feels to walk with your feet wide apart, a wider Q-factor has the same effect when riding your bike.\u00a0<\/p>
If your feet are wide apart, it\u2019s less mechanically efficient and works your muscles in an unusual way, possibly leading to muscle and joint problems.\u00a0<\/p>
Research<\/a> at the University of Birmingham in the UK around 10 years ago by Dr Xavier Disley showed pedalling to be more efficient at narrower Q-factors than at wider ones. There may be a slight aerodynamic advantage to a narrower Q-factor as well.<\/p>![\"Picture](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2019\/03\/cleats-4-1497603751678-a9pdvs616ugi-cc34fc6-e1584102749677.jpg\")
Your natural off-bike stance width provides a guide to how wide your bike pedal setup should be. – Thomas McDaniel \/ Immediate Media<\/figcaption><\/figure>Another related measurement is your stance angle, which is the angle your lower limbs make when pedalling. You want this to be as close to how you would walk as possible. Part of a bike fit<\/a> is often to determine your natural stance width off the bike and adjust your fit on the bike to reflect this.<\/p>If your Q-factor is incorrect, this can manifest in discomfort, often at the knees but also sometimes in the feet or hips.<\/p>
The different Q-factors on road, mountain, gravel and electric bikes<\/h2>![\"Top-down](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/09\/Crank-Q-Factor-1-scaled.jpg\")
A splay to the crank will lead to an increased Q-factor. – Scott Windsor \/ Liam Cahill \/ Our Media<\/figcaption><\/figure>Road bikes<\/a> and gravel bikes<\/a> have a narrower bottom bracket than mountain bikes<\/a> and straighter crank arms, which gives them a narrower Q-factor of around 148mm.\u00a0<\/p>In contrast, most mountain bikes have a Q-factor that\u2019s around 20mm wider at 170mm, due to a longer crank axle and crank arms that splay out more from the axle.\u00a0<\/p>
The wider Q-factor makes it easier to provide clearance in the bike\u2019s frame for the wider mountain bike tyres<\/a> that are typically found on these bikes.<\/p>Fat bikes<\/a> have a wider Q-factor again, often 235mm, to accommodate their very wide tyres, and this can have a pronounced effect on pedalling efficiency.<\/p>Many mid-mounted electric bike motors<\/a> are wider than standard cranksets, resulting in a wider Q-factor.\u00a0<\/p>To compensate, Rotor<\/a>, for example, sells lower Q-factor cranks, which bring the overall Q-factor more in line with a non-assisted MTB. Its eKapic cranks for Bosch<\/a> motors, for example, result in a 171mm Q-factor.<\/p>![\"Mondraker](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/04\/DSC7694.jpg\")
Newer motors such as the Bosch Performance Line SX are built narrower for a Q-factor more like a non-assisted bike. – Mondraker<\/figcaption><\/figure>The newer Shimano EP6 and EP8<\/a> series motors are built narrower than many older electric bike motors to give a Q-factor more like a standard mountain bike at 177mm and the Bosch Performance Line SX<\/a> reduces this to 160mm.<\/p>It\u2019s worth noting that a bike\u2019s Q-factor doesn\u2019t vary with its frame size. The same crank model is fitted to all sizes of a bike model, and it will have the same Q-factor even if it has longer crank arms.\u00a0<\/p>
Higher-quality children\u2019s bikes<\/a>, such as those from Frog, often have cranks with a narrower Q-factor to better suit smaller, younger riders.\u00a0<\/p>Track bikes<\/a> also have a lower Q-factor than road bikes to improve riders\u2019 aerodynamics.<\/p>What should my Q-factor be?<\/h2>![\"Liam](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2023\/03\/Best-value-aero-upgrades040-2af0630.jpg\")
A bike fit should take into account your Q-factor. – Joseph Branston \/ Our Media<\/figcaption><\/figure>Your optimum Q-factor is highly dependent on your anatomy, in particular the width of your pelvis.\u00a0<\/p>
Most people can adapt to a pedal position with a Q-factor that\u2019s suboptimal for them. However, this may result in the centre of your knees being misaligned with your hips and ankles during your pedal stroke.<\/p>
If your knees are moving inboard, it\u2019s a sign that your Q-factor could be too wide for you. If they are moving outboard it may be too narrow.\u00a0<\/p>
It\u2019s worth noting that this can also be the result of an incorrect saddle height<\/a>, so it\u2019s important to check your saddle height before taking measures to adjust your Q-factor.<\/p>Taller people\u2019s natural stance width is typically wider than shorter people\u2019s, so they may need to adjust their Q-factor to reflect this.<\/p>
A bike fit should address all the factors that could affect your pedalling comfort and efficiency, including your Q-factor.\u00a0<\/p>
How do I change my Q-factor?<\/h2>
There are a few ways in which you can alter your Q-factor if you think your current setup isn\u2019t quite right for you, which we\u2019ll now run through.<\/p>
Change your cleat position<\/h3>![\"Photo](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/09\/Cleat-Postion-Change-scaled.jpg\")
Moving your cleat in or out on your shoe’s sole is a first step to change your stance width. – Scott Windsor \/ Our Media<\/figcaption><\/figure>The majority of cycling cleats<\/a> and their respective pedal systems allow some degree of inboard\/outboard adjustment, which will alter how far apart your feet are placed.\u00a0<\/p>Shimano SPD-SL road cleats, for example, allow 6mm of lateral movement (per cleat), so you can move your feet up to 12mm further apart or closer together. Look Keo cleats offer less lateral position alteration at 4mm. <\/p>
Look and Shimano\u2019s two-bolt SPD cleats<\/a> only allow you 2mm of lateral adjustment, however.<\/p>Wahoo Speedplay<\/a> is the road bike pedal system that gives you the greatest lateral cleat position adjustability, with 8mm of adjustment possible.\u00a0<\/p>Of course, you could always use flat pedals<\/a>. Many flats have very wide platforms, which enable you to place your feet pretty much where you like.<\/p>Add spacer washers<\/h3>![\"\"](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2019\/03\/stance-width-11-1533124089082-19ghflyuqb0n3-b4a19bf.jpg\")
Spacer washers can increase stance width by a few millimetres, but reduce the amount of thread engaged with your cranks. – Thomas McDaniel \/ Immediate Media<\/figcaption><\/figure>Placing spacer washers on your pedal spindles can add another 1 to 3mm to your Q-factor.\u00a0<\/p>
You should be careful with this because you\u2019re reducing the amount of pedal thread in the crank arm. Crank threads are typically made of aluminium alloy and quite soft, so there\u2019s a risk of stripping the crank \u2013 an expensive mistake.<\/p>
Buy pedals with longer spindles<\/h3>![\"\"](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/09\/Pedal-and-Crank-Q-Factor-1.jpg\")
Wahoo Speedplay Zero pedals are available with four different spindle lengths. – Our Media<\/figcaption><\/figure>If your cleats don\u2019t allow you to set a wide enough Q-factor, some pedals are available with longer axles.\u00a0\u00a0<\/p>
Both Shimano Dura-Ace and Ultegra road bike pedals<\/a> are sold with 4mm longer axles, as well as the standard width, enabling you to increase your Q-factor.<\/p>Shimano XTR M9120<\/a> pedals can be bought with 3mm shorter axles to lower your Q-factor.<\/p>
Q-factor is the lateral distance between the outside edges of the two crank arms. As such, it\u2019s a feature of your crankset<\/a>; you\u2019ll find the Q-factor quoted by many brands on their websites. So, technically, it\u2019s not possible to change it without changing your crankset.<\/p> But when Q-factor is discussed, the measurement being referred to is often your stance width<\/a>.\u00a0<\/p> This is the lateral distance between your feet when pedalling. This takes account of where your feet are positioned on the pedals, the shape and size of the pedals and the length of the pedal spindles.\u00a0<\/p> There are ways to alter your stance width, as discussed below. Getting the optimum stance width for your anatomy could make your pedalling more efficient, reduce the risk of injury<\/a> and help prevent your heels rubbing on your crank arms or chainstays.<\/p> Q-factor doesn\u2019t just affect your pedalling though. A wider Q-factor will reduce the amount by which you can lean a bike into a corner without the risk of grounding a pedal.<\/p> If you think about how it feels to walk with your feet wide apart, a wider Q-factor has the same effect when riding your bike.\u00a0<\/p> If your feet are wide apart, it\u2019s less mechanically efficient and works your muscles in an unusual way, possibly leading to muscle and joint problems.\u00a0<\/p> Research<\/a> at the University of Birmingham in the UK around 10 years ago by Dr Xavier Disley showed pedalling to be more efficient at narrower Q-factors than at wider ones. There may be a slight aerodynamic advantage to a narrower Q-factor as well.<\/p> Another related measurement is your stance angle, which is the angle your lower limbs make when pedalling. You want this to be as close to how you would walk as possible. Part of a bike fit<\/a> is often to determine your natural stance width off the bike and adjust your fit on the bike to reflect this.<\/p> If your Q-factor is incorrect, this can manifest in discomfort, often at the knees but also sometimes in the feet or hips.<\/p> Road bikes<\/a> and gravel bikes<\/a> have a narrower bottom bracket than mountain bikes<\/a> and straighter crank arms, which gives them a narrower Q-factor of around 148mm.\u00a0<\/p> In contrast, most mountain bikes have a Q-factor that\u2019s around 20mm wider at 170mm, due to a longer crank axle and crank arms that splay out more from the axle.\u00a0<\/p> The wider Q-factor makes it easier to provide clearance in the bike\u2019s frame for the wider mountain bike tyres<\/a> that are typically found on these bikes.<\/p> Fat bikes<\/a> have a wider Q-factor again, often 235mm, to accommodate their very wide tyres, and this can have a pronounced effect on pedalling efficiency.<\/p> Many mid-mounted electric bike motors<\/a> are wider than standard cranksets, resulting in a wider Q-factor.\u00a0<\/p> To compensate, Rotor<\/a>, for example, sells lower Q-factor cranks, which bring the overall Q-factor more in line with a non-assisted MTB. Its eKapic cranks for Bosch<\/a> motors, for example, result in a 171mm Q-factor.<\/p> The newer Shimano EP6 and EP8<\/a> series motors are built narrower than many older electric bike motors to give a Q-factor more like a standard mountain bike at 177mm and the Bosch Performance Line SX<\/a> reduces this to 160mm.<\/p> It\u2019s worth noting that a bike\u2019s Q-factor doesn\u2019t vary with its frame size. The same crank model is fitted to all sizes of a bike model, and it will have the same Q-factor even if it has longer crank arms.\u00a0<\/p> Higher-quality children\u2019s bikes<\/a>, such as those from Frog, often have cranks with a narrower Q-factor to better suit smaller, younger riders.\u00a0<\/p> Track bikes<\/a> also have a lower Q-factor than road bikes to improve riders\u2019 aerodynamics.<\/p> Your optimum Q-factor is highly dependent on your anatomy, in particular the width of your pelvis.\u00a0<\/p> Most people can adapt to a pedal position with a Q-factor that\u2019s suboptimal for them. However, this may result in the centre of your knees being misaligned with your hips and ankles during your pedal stroke.<\/p> If your knees are moving inboard, it\u2019s a sign that your Q-factor could be too wide for you. If they are moving outboard it may be too narrow.\u00a0<\/p> It\u2019s worth noting that this can also be the result of an incorrect saddle height<\/a>, so it\u2019s important to check your saddle height before taking measures to adjust your Q-factor.<\/p> Taller people\u2019s natural stance width is typically wider than shorter people\u2019s, so they may need to adjust their Q-factor to reflect this.<\/p> A bike fit should address all the factors that could affect your pedalling comfort and efficiency, including your Q-factor.\u00a0<\/p> There are a few ways in which you can alter your Q-factor if you think your current setup isn\u2019t quite right for you, which we\u2019ll now run through.<\/p> The majority of cycling cleats<\/a> and their respective pedal systems allow some degree of inboard\/outboard adjustment, which will alter how far apart your feet are placed.\u00a0<\/p> Shimano SPD-SL road cleats, for example, allow 6mm of lateral movement (per cleat), so you can move your feet up to 12mm further apart or closer together. Look Keo cleats offer less lateral position alteration at 4mm. <\/p> Look and Shimano\u2019s two-bolt SPD cleats<\/a> only allow you 2mm of lateral adjustment, however.<\/p> Wahoo Speedplay<\/a> is the road bike pedal system that gives you the greatest lateral cleat position adjustability, with 8mm of adjustment possible.\u00a0<\/p> Of course, you could always use flat pedals<\/a>. Many flats have very wide platforms, which enable you to place your feet pretty much where you like.<\/p> Placing spacer washers on your pedal spindles can add another 1 to 3mm to your Q-factor.\u00a0<\/p> You should be careful with this because you\u2019re reducing the amount of pedal thread in the crank arm. Crank threads are typically made of aluminium alloy and quite soft, so there\u2019s a risk of stripping the crank \u2013 an expensive mistake.<\/p> If your cleats don\u2019t allow you to set a wide enough Q-factor, some pedals are available with longer axles.\u00a0\u00a0<\/p> Both Shimano Dura-Ace and Ultegra road bike pedals<\/a> are sold with 4mm longer axles, as well as the standard width, enabling you to increase your Q-factor.<\/p> Shimano XTR M9120<\/a> pedals can be bought with 3mm shorter axles to lower your Q-factor.<\/p>How does Q-factor affect your pedalling?<\/h2>
The different Q-factors on road, mountain, gravel and electric bikes<\/h2>
What should my Q-factor be?<\/h2>
How do I change my Q-factor?<\/h2>
Change your cleat position<\/h3>
Add spacer washers<\/h3>
Buy pedals with longer spindles<\/h3>
![\"\"](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2019\/03\/stance-width-10-1533124089078-tq3wqtkd5oq5-6d4a3db.jpg\")
![\"\"](\"https:\/\/c02.purpledshub.com\/uploads\/sites\/39\/2024\/09\/Pedal-and-Crank-Q-Factor-2.jpg\")