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Tuesday, March 31, 2009

"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.

Friday, March 27, 2009

Cycling Research?

Unfortunately there is not as much science entrenched in the culture of cycling.  For years, Euro pros abstained from sex before races because it was feared that it would rob them of some essential power, for god's sake.  (Although Mario Cippolini worked hard to make us think he did not follow this logic.)  

Certainly this is changing, what with pro teams and amateurs alike making use of physiologic testing, wind-tunnels, and accurate power data.

The arena of bike fitting has had a few stabs at this, but many (like Specialized's BG Fit) are tainted by a corporate and retail driven focus.  

So I guess fads and marketing need to be treated with some apprehension.

In the realm of physical therapy and sports rehabilitation, certainly there are fads and marketing within the industry, but good therapists tend to use what works -- which is, most often, sound exercise regimens and manual treatment techniques -- not the Tony Little Gazelle, the Ab-Lounger, or that electrical stimulation belt for 6-pack abs.  

For this reason, I tend to default to good old published research, whenever I wish a fresh angle on some idea.  It's more work - information isn't already broken up into sound-bite worthy tidbits by some marketing department, it's not immune to corporate influence (many studies ARE funded by corporations with an angle to support), and some studies are just not set up very well, so they may or may not really tell us anything with any degree of certainty.  But that is why getting good information from them is more satisfying - because it does take a little work and you have to be discerning in your reading.

So as often as I can, I will share some of the more interesting things that are out there -- I think many will be surprised (I know I am constantly) at what some of the research shows.  Here's a taste:

Did you know that a study was done about 3 years ago looking at the most efficient crank length for trained cyclists?  They tested riders with crank lengths varying from 130mm up to 220mm, and found no significant difference for even some of the most extreme differences.  Granted the test was a very short and intense (I believe it may have been as brief as 3 or 4 minutes) but the fact that a cyclist could score anywhere close with 130mm cranks as they did with 200mm cranks, on any test, is amazing.  It certainly puts into perspective how futile the hand-wringing regarding 175 vs 172.5 cranks, that many cyclists do, may be. 

Wednesday, March 4, 2009

Custom Studio Build #1

This year I decided to try something new with my "demo" bike fleet.

Generally, manufacturers work with their retailers in the late summer and fall to plan what bikes and how many the retailer wants to have on the floor that year.  Most manufacturers (especially the big guys) require very large orders, and offer terms or a grace period before full payment of the inventory is due.  I am extremely fortunate to work with custom builders who understand intimately the needs of a Studio my size.  

My studio works on a different business plan then most (larger) shops.  I am not about selling a whole bunch of stock bikes -- in fact I don't really sell but a couple the entire year.  Almost all of the work I do is full custom, and as such, it doesn't pay to have 20 stock bikes laying around as inventory or demos.  

In past years, I have picked a couple of common sized bikes of varying "bling" between the builders i use and placed an order with a good parts build and one of the basic paint schemes.  This has served me well.  The bikes I order, represent the builders well (which is the point after all) they look great, and I can sell them pretty readily throughout the year.

This year I thought of really making each of my floor bikes unique.  Custom paint.  Better kit.  Better grouppo.  Better wheels.  I even steered away from the "stock" size that these builders provide for floor model bikes and customized the geometry in a way that I have found fits a wider range of individuals better -- especially in my market.

So with that in mind, here is what my first "Custom Studio Build" looks like:

Here is a breakdown:

  • Custom sized Seven VII in "Cue Ball White" paint, bare carbon decals, and raspberry hibiscus accents.  Custom Seven 5E fork (rake matched for geometry, of course).

  • SRAM Red group, except for Force substitutes in the brakes and the front derailleur.  Compact crank with an 11-26 Red cassette.
  • Oval Concepts R910 Aergo road bar, matching Oval Concepts stem, and r900 carbon seat post
  • DT Swiss Mon Chasseral 1450 wheels
  • Alpha Q carbon water bottle cages
I can't say enough about the frame.  It is clean and precise.  Every bike I have ever gotten from the good folks at Seven has been flawless.  The paint is exacting, and it is 100% ready to build right out of the box -- I like that.

I am a big fan of the SRAM Red, but I have started doing the Force substitution  on the brakes, for a modest cost improvement, and no compromise on function, and the front derailleur --again for a modest cost reduction, and the fact that I think the Force front derailleur is a little snappier in it's shifting.  Possibly due to it's aluminum and steel rather than aluminum and titanium construction.  

Weight penalty for the derailleur?  1 oz.

The DT Swiss Mon Chasserals may be one of the best deals out there.  The wheels are light (1450g), strong, and have the most bomb-proof hubs in the world.  Included in the cost are padded wheel bags and DT Swiss' RWS skewers.  Best of all, they're assembled right here in Grand Junction, Colorado.

The Oval Concepts kit is a relatively new addition here at the Studio.  I like the ergonomics of the Aergo handlebar, and the strong feel of the stem.  The reverse bolts are a mild pain in the butt to get some wrenches on, so on-the-ride adjustments could be tedious.  Really the only thing I took issue with is the complete lack of instructions or torque settings.  I don't appear to be the only person to belly-ache about this, as I found a few fellow sufferers during a quick Google search.  If a bar manufacturer  REQUIRES the use of their stem to maintain the warranty on the ($365) bar (which Oval Concepts does) then torque settings (at least!) should be supplied.

The bike turned out great -- I couldn't be happier.  At a recent Open House, this bike garnered much "oohing" and "aahhing" in the gallery.  I don't think it is long for the sales floor.