Snow Bike Fit - playing with q-factor is fun!

One look at the bike above and you know this won't be a "normal" bike fitting.

I'm certainly not new to the world of snow bikes: I've worked and ridden with Mike Curiak for the better part of the last decade, so I've certainly been subjected to a few cold "over-night" rides on the groomed surfaces of the Grand Mesa.  I have consulted with Mike (BTW he owns the record for the fastest human-powered traverse of the Iditarod Trail, by bike of course, all 1100 miles in a little over 15 days), as well during this time for certain aspects of his training, any time he gets a wild hair to try something that should be nearly impossible by human standards.  

I've seen the numerous iterations and changes made to his current snow rig -- the indomitable Snoots made by the good people of Moots Cycles in Steamboat Springs, Colorado.  So I vaguely know the ins and outs of a true snow bike.

To say that this bike is "custom" is an understatement of the largest order.  Every single tube, feature, and add-on has been painstakingly developed in a partnership of ideas between Mike and master welder Brad up in Steamboat (Brad has his own snow bike as well). I think the low five figure price tag Curiak has estimated is exactly that -- a very low estimate.

A quick rundown of the features: 

• The whole bike is (in Moots tradition) built of titanium
  
• Only the front rack is on there.  The rear rack has been removed for simplicity during the bike fit.
• The tires are 4 inches wide (Surly Endomorphs) built to snow-specific rims, of course.
• The cassette and freehub body are 9-speed but only 8 gears are on there due to space requirements.
  
• The rear hub is 165 mm spacing instead of the normal 135 mm for mountain bikes.
• For that matter, the front hub is also spaced 165 mm so front and rear wheels are inter-changeable.

• The bottom bracket (a Phil Wood square taper) is 155 mm end to end (instead of ~110 to 120mm  for road and mountain bikes).
• In some of the pictures you will see brass fittings on the bottom of the bottom bracket and the back of the fork legs -- these are pet-cocks for fuel dispensation.  The fork legs and the seat tube (along with the big "box" above the crankset) hold fuel for his stove.
• Custom made bar ends grace the cockpit, but they are usually hidden under large hand covers called Pogies to protect hands from the severe cold

All told, the bike weighs.... well, a lot, even unloaded. 

So for obvious reasons, Mike wanted to check out some position issues that had come up in a 300 mile "shake-down" race.  I mean, when your going to be pedaling and pushing  a bike for three straight weeks, peace of mind is a big deal.

So now to the fitting....

Numerous problems presented themselves.  First, I had never put a bike with that large of a rear-axle spacing on the Compu-trainer stand.  A 150mm spaced tandem was the biggest up to this point.  After lining things up and having the right skewer on there, it was clear that with a little finagling it might JUST fit, but the enormous tire would not clear any part of the flywheel.  So we decided to remove the flywheel completely and we could set resistance on the rear wheel by dragging the rear disc brake.  

With this settled, I began to work on the flywheel, only to find that it requires a T25 torx wrench for one side (fine, I got that) and, more problematic, a 4.5 mm size Allen key for the other.  My complete Park Tool Allen kit does not have a 4.5 -- UGH!!

Such is the frustration one frequently encounters with a Compu-trainer:  Spotty software compatibility.  Ear-clip heart rate monitors.  When you really have no competition I guess you just never have to work to improve anything in your product.  Hopefully, someday soon, someone will come up with a better set-up and I can ditch that thing on Ebay.  Cyclops?  Anyone, please?

So on to the next idea.  Curiak brought an old set of rollers with him for just such an occasion.  

This, I thought, was going to be interesting:  4 inch wide tires on rollers.  

For safety reason we did away with the handy Retul platform that rotates -- no need to introduce more potential energy into the situation -- and set the rollers up, quite literally, in the corner of the Studio.  This way Mike had an "out" when it came to balancing and trying to stop - he could just lean into  the wall.  Also, placing the front wheel in contact with the wall in front, compensated for the bikes desire to run itself right off the rollers, especially as he tried to start pedaling.

There was plenty of inherent resistance in the tire/roller interface, so we were able to leave the tension belt off the rollers completely.

With the logistical hard part out of the way, all we had to do was hook him up to the Retul LED harness and test him out.  No problem here except at the feet.  Mike uses Lake winter shoes that are 8 sizes too big and puts in extra liners and vapor barriers (the funny looking loose gray "socks" you see in the pictures).  

Finding landmarks of the ankle and toes was next to impossible, and the water-proofing gunk ("schmeg" according to Mike) all over his shoes made it difficult for the LEDs to stay in place.

(Wood screws help with traction when pushing a 150 pound bike into a headwind on glare ice)

Everything held up and after two back to back scans of his right side, we moved the whole set-up to the opposite wall and repeated the scans for his left side

So what we found was quite helpful.  Here is an example of the Retul file from his right side.

We actually performed 5 different capture periods to get all the information we wanted.  I determined, first, that his seat was much too low -- I could actually just look at him pedal early on in the fitting and see this, but the Retul really helps to  quantify the asymmetries that a trained eye picks up.  What the system was integral in picking up was that Mike sits off to the left of his saddle and with the left hip scooted forward as well.  It was not severe - I have seen much worse positioning, but it was certainly worth paying attention to.

As I expected, Mike's lower extremities were very "quiet" even when pedaling with some effort.  His knees tracked very little in the medial-lateral direction, and they did so only at about a 1 degree angle off the vertical. His hips had only minimal to moderate movement vertically as well.  No surprise, since he often races many days in a row and has only had mild issues in the past.

After doing some further measurements on the bike it was determined that Mike's pedals were spaced unequally - his q-factor was increased on the right by a few millimeters.  This was feeding into his current left-skewed hip position.  

(Incidentally, Mike also noticed his rear wheel was 3 mm out of dish - this determination I left to him, since he is a master wheel builder and has built every wheelset I currently own.  By correcting this, his bike will track better in the snow -- every little bit helps especially when the bike is loaded.)

Normally, given the deficits noted by the Retul system, I would think about spacing the clients left pedal out temporarily with some washers to provide for a better proprioception to both legs.  ("Temporarily", because I don't believe in purely compensating for a functional deficit [Read here] )  Not a great idea for Mike's purposes - when you are riding for this long under the extreme cold conditions he'll face, you want to have as much interface with threaded surfaces as you can.

In this case, though, we are able to space the bottom bracket spindle back to center.  

****

A brief detour.....

As the bike industry strives for narrower and narrower q-factors on their bikes (just about to the point now where it can be a detriment to the average cyclist), this bike fitting reinforces to me that we sometimes have to ask ourselves "Why?".  Is a narrower q-factor better?  For everyone?  For anyone?

It is helpful to some, but my experience has been that about 3/4 of the cycling population does not benefit and are often harmed by it.  You have to ask yourself, 

"How does placing my feet closer together affect my back, hips and knees?"  

"Are my ankles going to act differently?"

"In what foot position (off the bike) is my hip flexor going to be the most coordinated (to get out of the way of the downstroke of the opposite leg)?"

There are a number of proposed reasons for having narrow q-factors out there (on the inter-web and otherwise) and they smack of the same type of reasoning that has pervaded (and perverted) bike set-up and fit for years:  

• When we walk our feet have a narrow step width (they track in line with one another) then so should our feet on the pedals ..... the problem with this reasoning is 1. normal step width during gait is actually between 2 and 4 inches and 2. during gait one foot is completely unattached to the ground for slightly more than half the cycle.
  
• measuring between the iliac crests (bumps on the front of our pelvis near the belt line) can give you an idea of what q-factor you should look for in a bike setup ..... we can't even guarantee an accurate seat height based solely on our inseam, so this one doesn't hold much water.  It's like determining spoke length for a wheel by measuring the diameter of the rim -- it might get you in the general ballpark for the correct length, but there are numerous other factors to consider (like hub flange diameter, hub spacing, lacing pattern, etc)
• most of the references I have read begin, "Logic suggests...." or "...it seems intuitive that... a narrow q-factor would be optimal." .... As someone with a scientific heart, I really cringe when I read pronouncements like this.  

There is no research out there to tell us what is optimal, but what my years of bike fitting have taught me is that when we do get the research it will likely be very similar to the crank length argument (some articles show improvement with much longer cranks, some with much shorter - translation = everyone is different and needs to be addressed individually).  Many asymmetries see improvement with spacing the pedal out - I see it help every day.

One point I will stipulate is that a narrow q-factor makes pedaling out of the saddle easier since you don't have to leverage the handlebars as much since less bike "rocking" is necessary.  

A narrow q-factor often "pinches" the biomechanical cycle, rendering many cyclists more inefficient.  The simple case of Mike's (and many other's) bike, makes a simple argument that you shan't spontaneously combust if you have a wider stance on the bike.  (It may even help.)

****

A computational error when he was outfitting the bike with a new seat led to the low saddle height, and when we changed both these things, his symmetry improved significantly.

All told, it was a worthwhile endeavor -- the changes we made were small (as they so often are), but 10 years of doing this has taught me that even small changes can make a dramatic difference for a "normal" cyclist.  For Mike, dialing it's absolutely critical.

We were finished, and none too soon... within a 48 hours the bike was broken down, packed up, and on it's way to Alaska.

Happy riding (and pushing) Mike.

Bike Fit: change the bike or the body?

I am writing this to elucidate further my thoughts on bike fitting and how it can successfully be accomplished.  I always learn anytime I write.

Undoubtedly, this whole post (along with my entire thought process with regard to fitting bikes) stems from my education and clinical work as a physical therapist.  

When I browse the internet or talk with bike fitters (from all over the world), most of the time I am a bit surprised that most bike fittings are approached as static events.  A rider comes in, position is assessed as "off", position is altered to make them "neutral", said rider goes off to ride their bike happily ever after.  I have just found this to not be true to how the human body acts or how cyclists progress (or digress).

First of all, we all have asymmetries.  Some greater than others.  Bicycles, if constructed well, are nearly perfectly symmetrical.  So if you try to take this asymmetric person and plop them on a symmetric bike, the ball of twine begins to unravel.  Obviously the bike doesn't move much -- a seat may become depressed on one side from increased pressure of a sit bone, for example -- but our body drapes itself on the bike any way it can to exert maximum force through the pedals for the longest period possible.  

A common demonstration of this is when a cyclist's right sit bone sits too far right of center on the saddle and it also sits further forward on the saddle than the left.  This leads to the right knee being further forward relative to our pedal, meaning this right leg "acts" longer while the left is now functionally shortened.  The body wants to keep the head facing directly forward so a counter-rotation occurs through the spine, and since the hands are forced to be in the same place the left shoulder blade has to elevate and the left shoulder is flexed to a greater degree.

The above is a common and very clean demonstration of how an asymmetric sitting position can translate up and down the body.  Unfortunately things aren't always this "clean."  At times a body part may not be oriented how you'd expect it (i.e. if both knees sat in opposite positions to those described above despite hard evidence of a right anterior and lateral sit bone position), but this is another post for another time.

So now you have assessed all these joints and how they are positioned, it's important to try to figure out where these alignment issues are coming from.  If you don't know what the root cause is for them, you can't correct them.  Many people do have structural or "fixed" deformities -- a longer right tibia, an anteverted hip, a scoliosis in the spine -- but I have found that most are quite small -- less than a quarter of all leg length discrepancies are greater than 1 cm.  

(Incidentally, the ONLY way to get a true measurement of a leg length difference is to have full length leg X-rays done and have the radiologist take measurements off that.  Anyone who looks at you in standing or takes measurements with a tape measure and then tells you with certainty you have a 2.2 cm leg length difference is blowing smoke - it can't be done; not well at least.)

More often than not, most of the deficits and asymmetries I come across are functional in nature.  This means they aren't related to underlying bony deformities.  For example, most of the leg length differences I find are related to tight hip musculature, or a tight sacro-iliac (SI) joint.  Differences of up to 2 inches can be perceived with the standard assessments, but it is clear from further investigation that the femur or tibia are not off by this large margin.  If we correct the underlying problem -- by mobilizing their SI, for instance -- often their "leg length difference" disappears.  This same phenomenon can be seen in just about any joint in the body:

- one rotator cuff can be significantly more restricted than another causing a discrepancy in how far that arm can reach in a given direction, 

-one hip flexor may be inhibited (neuromuscularly) causing a difference in step length during walking. 

The possibilities are endless.

So you might think, "what does it matter if a difference is functional or structural.  It's still a difference and should be adjusted for."  I can appreciate this line of thinking.  It does make some sense....until, you realize that a functional discrepancy can be CHANGED.  It can get better.  If you are willing to work at it a little bit then it can cease to be a problem .  

You have a functional leg length difference due to a tight psoas muscle, and this causes you to sit unequally on your bike.  You lengthen the psoas through a stretching regimen and over time you can begin to sit squarely on the seat again (and get rid of that saddle sore in the process).

The other problem with adjusting or compensating for a functional difference is that, left alone, they will get worse.  When we have a deficit, say a tight right hip flexor, it affects how we do other tasks, like while running it can increase the amount we rotate our trunk to the left to balance ourselves as we stride.  This becomes a functional deficit in trunk right rotation.  These patterns develop synchronously and they feed into one another.  Meaning, one leads to another, one worsens and leads the other to worsen.

Long story short: if you take a functional limitation and leave it alone (you don't stretch or strengthen the area appropriately) it will get worse.

This may be a good time to explain the difference between Correction and Compensation.

A correction is taking the deficit or underlying problem and working to fix or remedy it to return the body to a previous standard of function. 

A compensation is accepting a deficit and working on other avenues to work around the deficit and return the body to as close to the previous standard of function as possible. 

For example, when a right-handed person has a stroke leaving the right arm paralyzed, the rehabilitation therapist has to make a decision:  should they work on returning function to the right arm (correction) or work on teaching the left hand to do all the things the right hand did (like eat, write, drive etc.)?

So to get back to the realm of bike fitting....

Again most of the deficits that present themselves during bike fits are functional, not structural.  They can be corrected to at least some degree.

Most bike fittings done are adjusting and tweaking the bike to correct for these functional deficits, which is fine except almost no attention s payed to how the rider can affect their body to help it fit their bike better.

So most bike fits are compensating for (rather than correcting) functional deficits.  The glaring problem here is that these functional deficits are likely to get worse and the changes made to tghe bike will no longer be adequate.

Without working on our problem areas, we fit our bikes worse every year.

So, what's the answer?

I think it's clear that we need to adjust the bike to make it more comfortable during a fitting, but equal time needs to be paid to instructing the client on  how they can ensure that their bike will fit them well for years to come. 

New technology

In the past year I have invested in some new technology for bike fitting.  It is the Retul System from the guys in Boulder.  This is the same system you have seen on www.cyclingnews.com and velonews.com showing fittings of various athletes (like Christian VandeVelde, Tim DeBoom, and Craig Alexander among others).

Prior to this I had been doing very comprehensive (they really resembled physical therapy evaluations quite a lot) bike fittings, but the Retul system added a very important aspect:  objective measurement.

You see, when you evaluate movement in a dozen people a day (or more) for 10+ years you get really good at picking out asymetries.  (I was told in PT school that it would take about 4 years to REALLY begin to know what you were doing and what you were looking at - and they were right - but more on that later)  I can't help it anymore, it is second nature to me, like it is to many therapists, that I watch everyone walk and I evaluate their gait.  It's like a reflex now.  I'll be riding down Main Street and, there is a lady with a weak hip abductor, there's a teenage girl with hypermobile knee joints; that guys left hip flexor is too tight -- you get the idea.

With the Retul, I can take all those things I can *see* - like a knee doing a small figure-8, a mid-foot pronating,a shoulder elevating, a hip dropping or just sitting too far forward - and it quantifies them for me.  It tells me *how much* for just about every measurement I could ever want or need.  This really takes the guess-work out of deciding how much to correct (how many cleat shims, how much to raise/lower the seat, and more importantly, how much the client needs to do [read as exercises] to help themselves to continue to fit their bike.)

The best part of the system (for me) besides the fact it is so accurate, is that it does nothing to tell you how to fix the problem.  To do this would be an attempt at turning the whole process formulaic.  Yuck!  Especially to a physical therapist, *formulaic* is a dirty word.  I firmly believe that individuals are just that...individuals, and what may be acceptable for one person may be completely inappropriate for another, and vice versa.  I realize that many people doing bike fits do not feel the same way - something to tell them what to do is exactly what they are looking for and what they would invest in.  This tells me that they don't know what they are doing and/or do not have the background to make sound decisions on an individual basis.

Rest assured, you will hear more and more about the Retul system in weeks and months to come.  I will share specific examples and data when I'm able.

Thanks for reading.

-J

The Commuter

This is the commuter.  It's a Surly Big Dummy.  It weighs 52# - unloaded - but it lets me carry everything I need (up to 200#).  I can even transport other bikes.  Sweet.

The Statement

I thought a while before deciding to start this site.  I don't want this to turn into a bunch of verbal diarrhea where I spout vitriole or mundane daily occurences.  (I had enough of that in the cycling forums)  

My hope is that I can use this as a cathartic documentation of the things I have been passionate (in my professional life) about the last decade or so.  Those things are:

• Bike fitting
• physical therapy and training
• bicycle commuting

I am a physical therapist by trade and have been performing bike fits for the better part of the last 10 years (I have been a PT for 12 years).  

Some things (about bikes) that I believe:

• Bikes should be a primary means of transportation.  Period.
• PTs, ATCs, Biomechanists (MS or higher), sports medicine physicians are better equipped than just about anyone else to properly fit you to your bike.
• Stock bike manufacturers are dropping the ball with respect to bike fit when they spec the geometry for their frames.

More, of course, on all of this later.  But welcome and happy riding.