You will be hearing more about "Q Factor" from Spinning® / Star Trac so I thought you may appreciate knowing what it is, in case it comes up in conversation.
Q Factor (also know as Tread) is simply the separation/distance between the two pedal cranks of a bicycle or Indoor Cycle. Here are two articles here and here that discuss this measurement and this picture illustrates how it is measured.
What prompted this post was a conversation I had last week with Josh Taylor from Spinning® about the changes to the latest version of the Spinner® NXT and the new Spinner® Blade. Josh explained to me that one of their design criteria for both cycles was to reduce the Q factor, without reducing the reliability of the Bottom Bracket Wikipedia article. The purpose of the change was to make the new Spinners more Bio-Mechanically efficient. You've no doubt heard about "knee over pedal" that can be adjusted by seat position and shoe cleat alignment. Alignment between Hip Joint > Knee > Feet is also important. For some people bringing your feet closer to their natural spacing will maximize the muscular forces applied to the pedals. Notice I didn't say all people. According to the company who manufactures the KneeSaver there are people (specifically those with wider hips) who benefit from a wider Q-Factor.
You can read more from Josh at his own blog jtcycle.blogspot.com and it includes his descriptions of the new Spinner® NXT and Blade.
I wanted to get a point of comparison so I pulled out my trusty vernier caliper and measured a few Indoor Cycles + two of my road bikes to see how they compared:
- Amy's Trek Women Specific Road bike = 156mm
- Our Trek Tandem Road bike = 165mm
- Spinner® NXT = 170mm
- Schwinn AC Performance = 170mm
- Keiser M3 = 197mm
- New Spinner NXT and Blade will be 158mm per Josh Taylor, which is very narrow.
There are a number of design factors that determine Q Factor on an Indoor Cycling bike:
- Interference from the frame, guarding or other component requires the pedal crank arms be spaced further apart. This is especially obvious on the Keiser M3 and what causes their 197mm Q Factor. The carrier assemble for the Magnetic Resistance on the M3 sticks out on the RH side requiring a special pedal crank assembly.
- Are the pedal cranks off the shelf, or custom made?
- The width of the Bottom Bracket used.
Josh explained to me that once they set a target Q Factor for the new Spinners they realized that they would need to focus their engineering creativity on reducing the width of the Bottom Bracket. Not an easy task. The Bottom Bracket is the most highly stressed part on any pedal driven machine. Think about all the forces that need applied here; the rider's body weight + the twisting force (torque) that's applied to a machine that doesn't move. The Bottom Bracket is made up of an axle that's supported by two roller bearings, one one each end. How far the bearings are apart effects the amount force applied. The wider you space the bearings (and the frame that supports them) = better, which is OK unless you are trying to reduce the Bottom Bracket's width.
Star Trac's solution to this problem was to design a narrow Bottom Bracket with larger bearings and strengthening the frame that supports these bearings. To ensure the crank arms stay securely attached they are using a Morris Taper, instead of the typical interference fit and bolt used in the past. Based on the dimensions Josh is reporting they now have the Indoor Cycles with the narrowest Q Factor on the market.
Why should you care?
I know from experience that the narrower the Q Factor, the closer my feet are to each other, the more comfortable I feel riding a bicycle. This is especially true on a long ride and some cyclists will go to great lengths to reduce their total Q Factor by adjusting shoe cleat position, effectively moving their feet as close together as possible.
But we aren't talking about your personal bicycle here, where changes and adjustments can be made to fine tune the fit of the owner. These are Indoor Cycles. They're designed to ridden by every conceivable variation of human adult; short, tall, wide hips, narrow hips, leg length disparities, etc... Will some in your class notice or appreciate the difference? Maybe. But I personally don't see how a narrower Q-Factor will help our typical students in any measurable way.
I would love your thoughts...
Originally posted 2011-04-24 07:47:55.
John is a member on the AFS (Association of Fitness Studios) Advisory Council.
Holding certifications from; Schwinn, Heart Zones, Team ICG and Life Time Fitness, John's held regularly scheduled cycling classes between 1998 and 2015 when he moved to Florida.
When the weather permits, you'll find him riding and leading outdoor groups by himself or with his Tandem partner (wife) Amy.
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I have mentioned it elsewhere, including workshops for new instructors: I feel like I am riding a horse or have my legs over a barrel when I am on the Keiser M3. It is now the only bike I teach on (two facilities). The increased Q-factor has created bio-mechanical issues for me with the changes forced on the muscles.
It would be interesting to hear from the Bike Fit Guru regarding the bio-mechanics involved. Obviously there is an optimum set up including Q-factor for our personal bikes. I can say that Q-factor was not mentioned during my bike fit… but then i did not spend the big bucks so the question likely did not come up as it was not an option.
The new NXT will have a Q-factor of 158mm, which is narrow compared to Keiser at 197mm. John likes narrow, Stephen apparently does not like wide.
By my math the difference is 39mm or just over 1.5 inches. That equates to 3/4″ per side. Given that most of our indoor riders are still stuffing their sneakers into mostly broken down cages, I would say Q-factor is superfluous on indoor cycles for all but the most devoted outdoor riders.
That said, (assuming the Star Trac bio-mechanics discussion is accurate) it raises the question; Are the Keiser M3’s (my personal favorite) the best bike to be doing serious training on?
As nice as the new bikes with power meters on them are – for teaching indoor cycle classes in general – they’re clearly mission specific. The mission, training to enhance performance.
Moreover, and compatible with Indoor Cycling 2.0, these meters don’t just have power. They combine heart rate and cadence with power. Who benefits most by training on such indoor bikes? I’d say the avid outdoor rider.
If that is the case, then are the Star Trac engineers onto something? Is the new NXT from Star Trac the bike of choice for TRAINING indoors?
For all mentioned above except Keiser, it all come down to a few millimeters.
Me, even at 3/4 of an inch, I’ll take the quiet Keiser over the allegedly more bio mechanically correct noisy alternatives.
Great topic! Don’t forget the RevMaster which has a narrower stance width than all the bikes mentioned until the new StarTrac. The RevMaster stance width was closer to most road bikes since its inception. Unfortunately the latest RevMaster is a little wider than the original.
As we know people come in many different shapes and sizes yet pedal width is not adjustable. However, the most adjustable piece of equipment on a bike is not actually part of the bike. It is the cleats on cycling shoes. It is here that stance width can be adjusted. In simple terms, line up the foot under the knee. It is an old wives tale to say “bring your knees in.” It is however correct to put the foot under the knee, we just need to adjust the cleat in many cases to do so.
Even in outdoor bikes assessing and adjusting stance width is often over looked so no surprise that it is hardly mentioned in indoor cycling.
I also heard Josh talking about the new bike having a narrower Q-factor because it was too wide on the pervious bikes for some cyclists, which is true. However, when you do the comparison to other bikes does that mean they have been wrong all along? Stance width is only wrong when cleats are not set to allow for good knee over toe alignment. Unfortunately that is easier said than done on many bikes. Pedals being narrower allow for more options in setting stance width. There are often ways to add width to a bike when needed but little to nothing can be done when things need to be narrower.
Are you fit or are you BikeFit
Swifty
Update 5/4 by author
Chuck, I agree with you that as interesting as Q-factor (and to a greater extent Q-angle) is, all of this is null and void when we still see that the great majority of our participants don’t even realize the benefits of riding with cycling specific shoes… let alone having a professional adjust their cleats. Heck, I don’t believe that most people know that there are different types of ic bikes out there. Haha!
In case you were wondering the FreeMotion S11 series bikes have a Q-factor of 167mm.
Hi,
I’ve been enthusiastically using a LeMond bike at the gym for several years since it’s the only thing that really gives me a workout, but doesn’t trash my 3-surgeried knee. The gym just replaced these bikes with Freemotion bikes. I think I might hate them. I can’t find a comfortable position: everything I’ve tried has led to knee swelling and pain. It feels like the “Q factor” is wrong and the pedals are too far apart. How do I tell? Is there anything I can do? Grateful for any advice…
chutneygirl – if something causes pain and swelling while riding I would have some one knowledgeable review your setup. I know that riding the same bike, over a long period of time, my knees “learn” the motion > switching to anything different feels weird and need to go through a period of adjustment.
I test rode a Keiser for our Club and while I like many things about it, the Q angle was a NO-GO for me and many of our clients who tried it. Anyone with knee issues, me included (I’ve had 8 knee surgeries and still have my own knees), said it hurt.
I called our Keiser rep and asked him why there was such a large Q angle and he gave me some mumbo jumbo about meeting the needs of the masses. Hmmm, not so sure they hit the mark on this one.
~Robin
Why ist it spinner / star trac? Are this different brands or are all spinning bikes produced by star trac? Just dont get the information about that. Which one invented the first spinning bikes and which brand/series do you recommend for low q-factors?