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Monday, January 23, 2012

Do I need a mountain bike fit?

As I've mentioned before, I do a lot of bike fits, and have done, for about a decade.  I didn't get interested in bike fits, and then seek out classes to teach me to do it, I went through physical therapy school, practiced for a few years, and when my biking and biomechanics interests collided, realized that I could identify many bike fit, and movement issues merely as a result of my training that other "expert bike fitters" (at the time who were exclusively bike shop employees) had missed.

I've long said, you would likely get a much better bike fit from a PT who knows a little about bikes, than you would from an expert cyclist/mechanic/trainer who has little actual knowledge in movement science.

I've heard many bike shop employees, and general cycling "experts" say that you don't need a bike fit on a mountain bike -- it's just not worth your time.

I would have to, respectfully of course, disagree.

I will stipulate the following:
Mountain bike fits are different than road bike fits.
That's it.
If I approached a mountain bike fit as a road bike, I wouldn't have a very happy client.  It's a bit like a physician treating viral and bacterial infections exactly the same.  They share some similarities to treating the two -- lots of rest, good hydration, yadda yadda.  But other aspects, like antibiotics, don't really apply to both.
I look at different factors when I have someone on a mountain bike.  They are nearly two distinct sports that happen to share a few common movement patterns.
Pro cyclist Ross Schnell

Movement Patterns
Starting with those movement patterns, it's obvious that I'm talking about pedaling.  Seated, standing, whatever.  You have to pedal on the dirt and on the tarmac.  This is not a revelation to anyone.  The amount we stand and sit is different, though, between the two.  Generally,  the mountain bike gets us up off the saddle more often because of obstacles, terrain changes, steeper grades, avoiding furry creatures etc.  This up and down from the saddle is something I consider when I'm fitting a mountain bike, because the ability to maneuver your butt off the seat and then forward, back, and side to side as we manipulate the bike is paramount to riding cleanly.
A different saddle position is almost a given between the mountain bike and the road bike.  I don't think I have ever set someone up on their road bike the same as their mountain bike in the 11 years I've been doing this
On a flat road ride, we can often go long stretches with nothing to force us into a different position, which is why I say road biking is like a repetitive stress injury (RSI) waiting to happen.  It is for this reason that I work with my clients on changing their position frequently.  This often involves standing frequently on a ride even when there aren't hills or other obstacles to make us get up.  
It also involves more subtle changes: for example, with my triathletes, and time trialists I will set the entire bike fit up so that they can have 3 hand positions on their aerobars.  A short, middle, and long position.  They spend a lot of time in the middle, but if they approach a shallow incline they may move to their short position, or if they hit a long, slightly downhill, they may move to their long position to stretch their back and hip muscles.
Overall, I think almost every cyclist could benefit from standing up a little more, just to mix things up.  If we lived in a world where cyclists stood all the time, I would be giving the opposite advice -- to sit down a little more often.  That's just the way our body is -- it needs position changes.  
Balance
In a bike fit, I believe balance and upper body positioning are even more important on the mountain bike, again due to the fact that we have to manipulate the bike to move underneath us so much.
How is the rider's weight distributed over the bike?  How about when they climb?  Then, these questions beg the answer of what type of rider and what type of terrain do they frequent?  All these factors will determine where we end up positioning the cyclist.
Cockpit
One of the most subtle areas of mountain bike fit are the placement and orientation of the controls.  What is the best position for the shifters and brakes?  How big are their hands?  Do they prefer braking with one finger or two?  Grip shift or triggers?

The simple cockpit of my beloved single speed


Incorrectly placed controls can throw a riders upper body positioning out of whack, and create issues with discomfort or safety.  Too many people doing bike fits will just consider how they feel on a bike and then project that (often unwittingly) on their client.  I have frequently re-done bike fits where a petite woman had her controls placed and adjusted on the bike by a bigger male, and he didn't take into account that his shoulders are wider, his grip is stronger, and he has much better reach with his fingers than she does.  The changes we make in these situations are small and profound -- suddenly she has full control of her steed.

Suspension
The last consideration is the suspension setup.  Are they set at the correct pressure?  Is there enough sag?  Rebound isn't set too fast?  How do their leg mechanics change in the sprung and unsprung position?

So many people have their suspensions set up incorrectly.  But it's not like there is only one correct answer here.  Depending on the terrain they ride and whether they race or not, I may set two similarly sized riders up differently on their suspension.  As always, we have to take into account all the individual differences.


So, do I think that everyone on a mountain bike needs a bike fit?  Absolutely not.  
Just like, not everyone on a road bike needs a bike fit.  But if you're having any issues with staying comfortable or powerful on the bike, or if you think you just aren't sure you're getting as much efficiency as you can, then you might seek out an expert bike fitter.  
You can't believe everything you hear, and when people call mountain bike fits "worthless" -- I can't fault them.

You can't blame someone who just doesn't have the knowledge to speak intelligently on the subject.

--John

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