More "women's specific" mythologizing

So it seems the women's specific myth isn't going away any time soon, unfortunately.  It doesn't seem to be discriminating between road or mountain bikes either, as a few more femme bikes have been released for the dirt.

I certainly have nothing against bikes made specifically for women....certainly my years spent fitting bikes and building custom rides has made me acutely aware that a bespoke bike (and all it's parts) makes for the most enjoyable ride possible.  I can appreciate wanting a bike a certain color -- not every woman is going to want the black or red or black/red bikes that predominate the industry.

Much of the bike market's marketing for women's specific bikes talks of ladies' special body measurements that require a bike made differently from a man's.  I have seen the different manufacturers reference frequently, and contradictorily, that women have:

•  longer torsos relative to their height, 
•  sometimes shorter torsos as well ;-)
•  shorter arm reach
•  longer reach relative to their torso length (??)
•  longer inseam 
•  surprise!  shorter inseam as well!

Confused yet?  Me too.

Let's look at some facts:

There have been thousands of studies going back hundreds of years, in the field of anthropometrics ( the science dealing with measurement of the size, weight, and proportions of the human body).  Many of the studies will have an "N" value (meaning how many participants were studied -- generally more is better) in the thousands or tens of thousands.  We have really good data on this, and you could (and people do) write thousands of pages on all the comparisons.  

I pulled some data from a University of Rhode Island study back in 2009 that was updated just in the spring of 2012.  To keep it simple, we'll just look at the data from one main table that measures:  Stature (overall height), eye height, mid-shoulder height, waist height, sitting height, buttocks height, eye height (sitting), upper arm length, lower arm + hand length, upper leg length, and lower leg length.  They're broken down into male and female groups with percentiles from the 5th to the 95th -- 95th represents the tallest while the 5th percentile represents the shorties.

Keep in mind that when you're study includes thousands of test subjects you're going to find the best way to measure them so that it's simple, clinically applicable and simple/fast.  So these measurements weren't taken off X-rays, MRI or other super-accurate (and expensive method).  Rather these were taken with simple measuring rigs and tape measures and so the dimensions measured are different sometimes than you would expect....for example torso length is measured with the subject sitting on a flat surface, and the measurement is taken from the seat of the "chair" up to the top of their sternum, so it includes the pelvis and thorax.

Still, we can get a  good idea of what the data shows.

So without belaboring this too much this is what their findings say:

(As a percentage of their overall body height)

Torso length

5th% percentile
males -- 35.5%  - so their torso makes up roughly 35% of their total height
females -- 34.2% 

95th%
males -- 34.5%
females -- 35.3%

Buttocks height

5th%
males -- 46.2%
females -- 45.5%

95th%
males -- 49.1%
females -- 48.3%

Upper Arm length

5th%
males -- 33.8%
females -- 35.0%

95th%
males -- 35.3%
females -- 36.4%

This is by no means a comprehensive list of all the measurements they took -- they had many more.  I just grabbed a smattering of them as a representative sample.

So let's put some of this into perspective....when considering any of these measurements, while there are differences, I'm not seeing any earth-shattering differences that would make me think you could, in any sort of reliable or useful way, manipulate a stock bicycle's frame geometry to match a certain rider, male or female, even if everyone followed the averages expressed in this study, which of course almost no one will (more on this later)

As an example, for upper arm length we see one of the larger differences between the male and female measurements -- 1.2%.  This represents an actual difference of around half a centimeter, or about the thickness of two nickels.

Furthermore the differences are a mixed bag -- when a leg measurement favors on gender in the 5th percentile, that same measurement may be greater (again, slightly) for the other gender in the 95th percentile.....or vice versa.

I looked at the tallest and shortest of the gender, but the results were the same in the middle heights -- consistently close and inconsistently favoring one side then the other.

And as I mentioned before, these are averages and small deviations on any measurement are blended in but will be minimized.  A female may fall into the 50th percentile for height and leg length but have arm lengths that fall into the 65th percentile. 

I recently had a male client, with moderate flexibility, who stood about 6'4" tall (193 cm) with a 37.5" inseam.  I've had a few clients built like this and most of them really did better on a custom geometry bike because their relatively short torso and middling flexibility restricted their handlebar position.  What differed about this client was his arm reach.  He had arm lengths of a man many inches taller, which made it much easier for him to reach his handlebars even if they were in a longer or lower position than we normally see with someone with his torso length. 

Something to consider is that these deviations from the norm -- like his extended arm reach -- aren't uncommon.  Not when you consider that 66% of people fall outside of one-half standard deviation from the average (while 32% fall greater than one full standard deviation away).

So now......given these small variations in the "averages" and the vast potential for deviations from these averages, how useful do you think it would be to alter the geometry of bike in order to fit one sex or the other better?

Add to that all the natural variations we see outside of body segment lengths, like flexibility and strength, and you have a nearly impossible task.  I know this makes it seem like it would be impossible to create a stock bike that fits ANYONE, when in fact standard sizes tend to work out okay for many (but not most) riders out there.  Those riders that they work well for are fortunate to have been born into close proximity of the average measurements.  This fortunate phenomenon is less common if your overall height is on the high or low end of the charts -- bike designs for the very big and very little are still lacking.

So how well do stock bikes fit the masses? 

In my experience about 25% of the population fits them with little or no changes to the bike. 

A full 50% require changes to bike parts that I would consider "significant" in nature. 

What's "significant"? An example would be requiring a stem with a rise above 15 degrees.  Often riders require multiple changes -- bar reach and height accommodations AND cleat and saddle adaptations as well. A simpler definition would be any change that's likely to affect the overall balance or handling adversely.  Now,  a 20 degree rise stem wouldn't render a bike unrideable, but it will be a compromise....the bike won't steer or handle the way the geometry was designed for, and the rider's overall balance and weight distribution will be "off" which can lead to many small issues (for instance, not being able to settle comfortably on a saddle, incomplete engagement of some of the more powerful leg muscles, or more weight on one or more contact points).

Orbea Onix Dama vs Onix -- more on the women's specific myth

Orbea Onix

Orbea Onix Dama

I know I've gone over this before, but more on the "Women's Specific"  myth. 

My primary gripe is that the geometry changes that are actually made to the frame are minimal, and usually very poorly thought out.  Also, yes, some women have longer legs and shorter torsos -- but a lot of them do not.  In fact many men have long legs and short torsos, rather than the shorter legs and longer torsos that the bike manufacturers would have you believe.

For instance, look at the Onix series of bikes from Orbea -- they have their standard version and the Dama, or women's specific version.

The Dama, size 53 is essentially just the size in between the standard Onix sizes 51 and 54 -- possibly a slightly taller scaled head tube.  The Dama size 49, has an effective top tube of 51 cm.  The standard Onix size 51 also has a 51 cm effective TT.  The women's version has a head tube length of 110 mm, the standard version has a 122 mm one. 

If women did have shorter torsos wouldn't they need to make the reach and overall cockpit of the bike more relaxed rather than more aggressive?  Especially since the women's bike has a seat angle that's a full degree steeper (while still maintaining a 51 cm eff. TT), making it's weight bias more forward, upsetting the handling and making it squirrely at high speeds.

Again, I'm not saying that women shouldn't have their geometry tailored to them -- in fact they should, and just as often as the men-folk.  These are not well-thought out changes, they're token, and gimmick and marketing.  These changes are made because they're easy, not because they work.

Don't be fooled; more thought goes into how to "accessorize" a bike in pink and purple bits to make it "Women's Specific" than goes into the fit and the geometry.

The Womens Specific Myth

I get asked a lot from my female clients that come to me for a fitting before they buy a bike (which is the right way to do it -- get a professional sizing done first, THEN buy a new bike and complete the fitting process on it) wondering which "womens specific" bike they should get.

First let me say that, certainly there are many ladies out there that are quite comfortable on their womens specific bike; and they can work out great. But in general, the idea that women need different geometry is a myth.

Let's start by looking at it from an industry standpoint. What are the major bike manufacturers doing? They seem to go one of two ways:

1. They take the men's line of bikes, eliminating the sizes over 57cm, stick narrow handlebars, 170mm cranks, a softer seat, and accent the paint with pink or purple.

A good example of this is Cannondale:



Compare the "like-sized" bikes and you'll find no difference whatsoever in their geometry; same effective top tube, head tube, angles, standover, etc. They use narrower handlebars, presumably a shorter stem or straighter (non-setback) seatpost because they tout a shorter cockpit length, and shorter cranks. (Also girlie colors.)

2. Others do all of the above and then shorten the top tube (and possibly lengthen the head tube).

The truth is that some women do well with option number 1 and others do well with option number 2 .......


........but so do most men.



Taking the 2nd option, where they actually change the length of a few tubes on the bike, assumes that relative to their height women have shorter torsos and/or shorter arms (and possibly less flexibility). While many women do have shorter torsos (and therefore are long legged) their numbers do not outnumber their more proportionate or long-torsoed breathren in great enough numbers to warrant a change in all their bike geometry, I think. Even if you accept that long-legged, short-torsoed women represent the center of the bell curve and have that large of a representation, then changes that the bike companies make to design a "woman's" bike are often not different enough to accommodate the women who actually need it -- on the order of a 1 - 2 centimeter shorter top tube and possibly 1 - 1.5 cm longer on the head tube.

Incidentally, this is the approach that Specialized, Look, Cervelo, among many others take when designing a "higher handlebar position bike" or one they tout to be used in Paris-Roubaix. These are designed for men and women. So it's good that they make these changes, but often I don't think they are completely filling the market niches -- which is why when I build so many custom bikes for people who don't fit these niches.

So I know, now it sounds like that first I was complaining that they make the changes at all and then I complain that they need to make even greater changes. But that's what I think they should do....

.....but they should do the same thing for the men's bikes as well. They should have two or three *grades* of sizing from more aggressive to more relaxed.

Some companies are doing this to a small degree, but, again, usually the changes don't go far enough. Or the more relaxed geometries available are built like Bradley Fighting Vehicles and don't come in a performance package at all. I don't think it's wrong for people to want to ride their bikes hard and have nice components and wheels WHILE being comfortable. Our cycling population is getting older, but a lot of these riders still want to compete or at least continue doing big rides.

So I'm okay with companies NOT changing the geometry specifically for their women's bikes. I'm also okay with them changing the geometry -- it just doesn't need to be "womens specific." Even riders with Y chromosomes need geometry adjustment to optimize their fit.

As long as the stock bike manufacturers continue to err on the side of producing bike geometry with a racing-inspired pedigree, this will continue to be an issue. Unfortunately many cyclists will be sold a bike that does not match their riding strengths, simply because it is all that is available.

Custom bike manufacturers (like Seven Cycles) should continue to benefit from this oversight, especially as the cost of a stock bike and a custom bike continue to get closer and closer together. (Take a look at Seven's Gateway Program and then look at some of the cost of Specialized's Tarmac line, Trek's Madone, Cannondale's SuperSix -- many of those stock bikes get up close to $10,000 in their higher iterations!)

So when anyone (man or woman) is looking for a new bike, find out first what size bike you need and if any special considerations to the geometry of the bike ought to be made. There may be a stock option out there for you. If you think your current bike and fit are pretty good take a look at the setup -- if you have a threaded stem that is set to the "Minimum Insert" line or your stem is short length and/or high rise, then you might be in need of some additional adaptations to your bike geometry.

Why not just have the high rise or short stem on there (or the saddle slid all the way forward or backward on the rails for that matter)?

The problem with making these changes is that the handling of the bike is not built around these set-ups. These changes can work to make the bike fit better and be more comfortable, but they can also begin to affect the handling and the balance of the bike.

It's bad enough that the big stock manufacturers make forks with only 1 or 2 offsets and rakes to use on all their bikes -- from their 62cm down to their 49cm bikes.

(SIDE NOTE: Very small bikes and very big bikes should have forks with different offsets, but this costs money, so there are very limited options in forks out there and the big bike companies try to make up the difference with the head angles of the bikes. When doing this, one end of the spectrum -- either the big or the small -- will have compromised handling. Some of the companies, when listing the geometry for different sizes will even list some of the fork offsets and not list the others, saying they are "proprietary". Having used the Zin to log in the geometry and setup of my client's bikes -- which gives you fork rake and trail among many other measurements -- I can tell you that many times the rake of the fork is not different from the other listed sizes, the manufacturer just chooses to hide the fact that it is the same fork.)

So then when we change the handlebar height or seat fore-aft significantly on these bikes the handling and safety can sometimes suffer.

So do some research, go see a professional bike fitter that can help you find what will work best for you, and if you plan to spend more than $3000, don't discount a custom bike if it suits your needs better than the stock offerings.

Ride well.

Talkin' bike seats

I mentioned in my last post that, for the average woman, and ideal seat design would be wide in the back to support the wider ischial tuberosities, but then needs to quickly narrow to avoid compressing the tissues distal and lateral to the sit bones. 

This narrower space between the femur and sit bones that we tend to rest (which ends up being the proximal hamstring -- medially the semi-membranosus and laterally the biceps femoris) is not the only reason for this saddle shape.  The woman's sit bones are oriented more in the frontal plane (more side to side) than a man's.  The male sit bones are set more in the sagittal plane (front to back).

When you factor in the natural translation of the hips and pelvis downward at the bottom of the pedal stroke, you can visualize that the male sit bones can more readily follow this path of movement -- sort of like a knife blade slicing through the dirt.  The female sit bones can't move as easily in this path -- imagine running the same knife through the dirt now turned to it's side a few degrees, like a plow.  The amount of shear force (or at least the potential for shearing) is much greater.

Essentially, all the angles of the pubic and ischial rami (the structures that form the "loops" on the bottom of the pelvis, and that we sit on) are steeper and sharper and because of this, less contact with saddles is probable.  I think this is the reason women often struggle with saddles -- more contact and shear forces -- and not just the fact that they have wider sit bones.

Saddle position

Of course, the right saddle is nothing without it being fit in the right position.  Many cyclists are on saddles they are unhappy with, but the reason is that they are not sitting on the part of the saddle that is meant to be sat on.  Most are scooted too far forward, even to the point where the sit bones don't rest on the saddle, but rather the saddle is squeezed in between them and the rider is resting more on their soft tissue -- this is a problem, obviously.  A huge mistake I see all too often is having the saddle tilted down --- yes, even a little is generally not a good thing.  

A bike seat needs to be in the right place fore and aft so that the sit bones can contact the wider, more cushioned portion of the saddle, and then it needs to be level so that the sit bones can rest on it.  If you aren't perched on your bike seat, then you aren't effectively stabilized to make full use of your pedal stroke. 

_______________

Think about this: 

If you have a seat slid all the way back on the rails, so that the seatpost clamp is at the front of the seat, and it is level.  What happens when you sit on the saddle?  What if the rails are made of Steel?  Titanium?  What I'm getting at, is that a saddle has a static (or unweighted) position and a dynamic (weighted) position.  The dynamic position is the only one that really matters.  It has been my experience that especially with titanium railed seats if the seatpost clamp is to the back of the rails the seat will flex downward, if towards the front of the rails the seat will flex backward.  Therefore I have allowed some seats to leave my Studio tilted up or down at times to accommodate.

_______________

This leveling of the seat brings me to my last point about a good seat -- for a man or a woman.  The seat should have at least some portion of it's surface should be flat and not fully sloping. 

This FSA saddle is a good example of when some seat designs can cause trouble for people.

The centerline of the seat is the high point and the cover slopes downward to either side.  I am sure there are people who find this saddle comfortable, but I haven't met them yet.

I am intrigued by the new fizik Antares -- the entire saddle looks flat.  I will have to try it out and get back to you on that one.

Next up :  Some top secret stuff going on in the lab.  Well, not really secret, but it should be pretty cool.  We are combining the use of the Retul dynamic "mo-cap" with a very sensitive biofeedback system so we can see what exactly some muscles are doing when we pedal, and using all the information (and there is tons!) to try to determine what the leg muscles are doing when....say, a knee tracks laterally more then the other side. 

From the preliminary findings, I think I can say that many will be surprised at what we are finding.

--J

"Influence of Gender, Power, and Hand Position on Pelvic Motion during Seated Cycling" Sauer et al 2007

Sauer, J.L., J.J. Potter, C.L. Weishaar, H.L. Ploeg, D.G. Thelen.  Influence of Gender, Power and Hand Position on Pelvic Motion during Seated Cycling.  Med. Sci. Sports Exerc., Vol. 39, No. 12, pp. 2204-2211, 2007.

This is the first installment in some interesting research I have been kicking around and using in my bike fitting practice.  I have decided to share a few bits here.

This first study took trained cyclists and they measured movement through the hips and pelvis at three different wattages (100 W, 150W, and 200 W), on three different saddles (Bontrager X-Lite 2006 mens, fizik Vitesse womens, and Bontrager Race Lite mens), and in two different hand positions (tops and drops).

It did not effectively determine much in the way of gender differences.  I think they set out to find out if riding on the drops versus the tops caused more pelvic motion for males or females.  Perhaps they were expecting more aberrant pelvic motion among females, I don't know.  Overall I think they tried to make their scope too broad -- they were trying to figure out too many things at once.  This, I think watered down their results a bit.

They fessed up to their short-comings in their Discussion, which is admirable but still doesn't help to improve the utility of the study.  The short-comings they listed had to do with the fact that the women were tested at the same wattage as the men and therefore at a higher percentage of their maximum - so asymmetries would be more pronounced in the women due to a greater relative workload.  

The women were also tested on the same handlebar (which had 145 mm of drop to it), and given that the women were smaller, they were forced to relatively lean further forward when they went in the drops.

One other thing I wish they had done, was to include more information and clear photos of the saddles they used -- it can be difficult to find saddles outside of their production year.  And saddles can be changed often from year to year, so finding a 2009 fizik Vitesse may not be very instructive.

Things I learned:

The women's ischial tuberosities (sit bones) were (on average) 134 mm apart center to center, while mens were 115 mm.  Nearly 2 cm difference in width of the sit bones -- that's significant.

What does this mean for bike fitting? Well, simply women's bike seats should be wider at the back of the saddle so their sit bones can rest on something properly, right?

Well, maybe.  Remember, these are averages -- some women have hips shaped like a 13 year old boy, so we need to think individualistically.  But also, this study found that the center to center distance between men's and women's hip sockets was NOT significantly different.  

This reinforces to me a long-held idea I look for in women's seats (as it applies to a woman who shares these "average" proportions -- remember, we need to take things on a case by case basis):  Yes, their seat should be wider toward the back to accommodate the wider ischial tuberosities, but it's my opinion that the saddle needs to narrow very quickly in the middle -- or as I call it, the transition --(essentially the part of the saddle below which the seatpost is clamped to the rails).  

To get a visual on the anatomy, check out this link for a view of the pelvis.  The bottom picture gives you a sense of where the femurs attach to the hip socket (acetabulum), so when you look at the male and the female structures above it, you can see there is a difference in how the femur relates to the ischial tuberosities.

Consider the fizik Arione saddles below.  The little hash marks along each side of the saddle are part of their "WingFlex" technology.  This is the transition area that I was referring to.  In the case of the Arione, this is very effective for some people -- mainly men over about 165 pounds seem to benefit.  Perhaps they are heavy enough to take advantage of the Wings and actually cause them to flex out of the way.  I have not found as many women that are comfortable on them.

I believe this is necessary because the gap between where their sit bones contact the seat and the path the femur takes during the pedal stroke is narrower, which can put more shear force on the soft tissue just distal and lateral to the ischial tuberosity.

I feel many women would do better -- and, again, this is a generalization -- on a saddle more like:

Well, not this exact saddle, but it's female equivalent.  Some of you may recognize it as a Selle SMP Stratos, and I think the fact that the saddle narrows down quickly (the angle of this picture does not do it justice) keeps the width where it is needed (in the back) and keeps material out of the way of those distal-lateral soft tissues by our sit  bones.  You can see the actual women's version of this saddle here.

Next post I'll talk about another reason that women's pelvic motions on the saddle differ from men's, since it can't be explained by hip joint or ischial tuberosity widths alone.