As everyone knows, Q issue is the one who equips tuxedo-clad Particular Brokers with nifty double-0 devices as he chases after villains. Wait, no, that’s not proper… On this planet of biking, the Q issue refers back to the width of the crank arms. Extra particularly, the lateral distance between the surface of the crank arms on the level the place the pedal spindles affix.
The title is definitely derived from the phrase “Quack,” referencing the waddling gait of a duck. And no, I’m not joking this time. Biking legend Grant Peterson coined the time period throughout his time with Bridgestone Bicycles.
Q issue is a part of the equation that dictates the width of 1’s pedalling stance and may impression each pedalling mechanics and total bike match. However the Q issue isn’t the only element of a rider’s stance: it’s a start line. Finally, the width of your ft can be affected by pedal kind, spindle size, cleat place and shoe design.
(Picture credit score: Future)
Differing Dimensions
Earlier than the arrival of mountain and gravel bikes, Q issue was pretty constant throughout cranksets from totally different producers, usually between 145 and 150 mm on street bikes. Now, there are extra variables. Gravel bike-specific parts have barely bigger Q elements, typically within the 150-155 mm vary, and mountain bikes, which should accommodate considerably wider tyres, can have Q elements as huge as 170+ mm.
Bigger Q elements have grown alongside the elevated chainline measurements. Chainline is the gap from the chainring to the centerline of the bike body and is important to a drivetrain’s efficiency. The rise of 1x drivetrains and the ever-increasing arms race to add extra gears has necessitated wider chain traces to work with wide-range cassettes.
(Picture credit score: BMC)
How does this impression using?
Most riders shall be snug with some variability in Q issue dimensions with out situation. A bigger Q issue makes for a wider stance, which promotes stability whereas using, however it additionally decreases cornering clearance and makes pedal strikes extra seemingly when a motorcycle is leaned over.
Aerodynamically talking, narrower is normally sooner. Thus, monitor bikes typically have very slim Q elements. Filippo Ganna’s Pinarello-built Hour-Report bike was designed round an excellent slim 54mm backside bracket and Q issue of simply 134 mm.
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Biomechanically talking, whether or not or not the Q issue has an impression on pedalling relies on one’s physiology. For many riders, there’s a candy spot inside 5-10 mm the place they’re most snug and produce essentially the most energy. Going narrower won’t be sooner if it means a discount in energy output.
For bigger riders, it could be extra snug to have a barely wider stance to match the width of your hips. There are not any exact guidelines in play right here relating to match, reasonably it comes down to every particular person rider’s perceived consolation and desire. For smaller riders, a bigger Q issue might really feel awkward and inefficient, and decreasing your pedalling stance will assist it to really feel extra pure.
Whereas there are riders who’re very attuned to those minute variations, we’re speaking about very refined adjustments, and some millimetres narrower or wider is properly inside most individuals’s consolation vary.
(Picture credit score: Future)
How do you measure Q issue?
Most element producers will checklist Q issue as a part of the specs, however this info isn’t all the time straightforward to search out. Happily, measuring it’s simple sufficient. I like to recommend utilizing a ruler, because it’s simpler to be correct with a inflexible measuring gadget, however a tape will work in a pinch.
First, place the crank arms in order that they’re parallel with the seat tube and considered one of them is straight alongside it. Then, measure from the centre of the seat tube to the surface of the crank arm the place the pedal threads in. On a contemporary street bike, this quantity will seemingly be round 70-73 mm. Doing the identical on the opposite aspect (they need to be symmetrical!) and including them collectively offers you the whole Q issue dimension.
When you personal a number of bicycles, you could discover it helpful to measure Q issue throughout every of them to see if it differs. Element producers will not be according to this dimension throughout product traces and it’s attainable to have shocking quantities of variation between totally different element tiers even from the identical firm. Once more, for most individuals this isn’t a difficulty, but when you end up not jiving with a selected bike for some purpose, this might be the perpetrator.
What are you able to do to alter it?
Happily Q issue isn’t the one piece of the puzzle in relation to pedalling stance. When you want to precisely replicate the match of a selected bike, there are alternatives in relation to translating your pedalling stance.
For instance, in case you just like the stance of your street bike (with a Q issue of say, 146 mm), and need on your gravel-specific drivetrain-equipped gravel bike (Q issue 151 mm) to really feel the identical, then selecting pedals with a shorter axle (Shimano XTR pedals can be found in a slim model) will negate this distinction. Or, in case you want to match the bigger dimension, you may attempt longer pedal axles (Time makes street pedals in three axle lengths; Shimano has two SPD-SL choices; Wahoo has 4 totally different lengths) to make up the distinction.
Most biking sneakers can also accommodate some aspect to aspect adjustment for cleats. When you’re tinkering, this can be a good place to begin, because it doesn’t require buying any further elements. Some sneakers and cleat techniques have extra built-in changes than others. Experimenting with totally different sneakers, cleats and pedals will make it easier to to fine-tune your match if you want to take action.
Conclusion
To some, Q issue might look like simply one other piece of esoteric biking jargon, and, properly, they’re not unsuitable. Nevertheless it is part of the general image of how we trip bicycles. The science behind Q issue has been studied some, nonetheless, extra analysis must happen as a way to develop the physique of data. For sensible functions, most riders will most likely be properly served by merely following the maxim: “If it ain’t broke, don’t repair it.” Both that or, “Quack, quack.”
