ENDURE: July 2012

What’s in a bike?  The short answer....A LOT!  

This month much of Elements has revolved around the proverbial monster of ultra-endurance sports...the Ironman Triathlon.  As you may or may not have known the event consists of a swim, bike and run totalling a distance of 140.6 human powered miles.  The bulk of those miles, 112 to be exact, take place on the bike as athletes hurl themselves through space as fast and efficiently as they can.  In order to achieve both fast and efficient, riders (whether it be an Ironman Triathlete, a pro hammering up the Col du Tourmalet of the Tour de France, the newbie recreational cyclist or anywhere inbetween) spend a lot of time working to make their bike set-up just right.

We thought it would be fun to compare and contrast the differences of these marvelous machines for you the reader from a Physical Therapist’s point of view.  Specifically - how does the set-up of a bike impact the performance of its rider?  So we wandered deep into the darkest realms of the Pro-Activity Performance Laboratories to find someone (Justin Bagley, PT, DPT) with the answers and here’s what we were able to find out.

There are many different types of bikes out there, but if we limit our discussion to the “performance road” category we are left with 2 main styles: The standard road bike and the TT (time trial) bike.

             

The primary difference simply being geometry and how the rider sits on the bike.  The TT bike is built for pure speed and achieves this by allowing the rider to maintain a more aerodynamic position which in turn minimizes wind resistance.  By reducing wind resistance a rider can achieve greater efficiency meaning: A rider can maintain the same speed on a TT bike as they would on  a standard road bike while using considerably less energy, OR...if expending the same amount of energy on each bike the rider on a TT bike would theoretically travel at a higher rate of speed.  

For the Ironman Triathlete this increased efficiency is of utmost importance especially when we consider they need to get off the bike and run a 26.2 mile marathon.  Any energy that can be saved on the bike is welcomed with open arms.  Furthermore, although studies have shown some mixed results, the riding position on the TT bike has been shown to decrease the workload placed on the rectus femoris (quadriceps) muscle as compared to the standard road bike.  Why does this seemingly small piece of information matter? The answer...the rectus femoris is one of the most active muscles used for running.

So why wouldn’t everyone opt for a TT bike?  Well, the TT bike does have its achilles heel.  While it’s built for speed and efficiency it gives up a lot in the way of versatility and stability.   Because it’s designed to go fast the TT bike loses a lot of stability required for riding in a pack, climbing hills and having to start and stop fairly often as most recreational riders find themselves doing.  The bottom line is that standard road bikes are simply easier to handle under normal everyday conditions.

Aside from the question of “what type of bike should I get” the majority of cycling related questions come down to comfort.  Most riders would admit to the annoying experience of numbness and tingling in the the hands, feet or saddle region while riding or perhaps some back, shoulder or knee pain.  These are all signs that things may not be lining up just right.  Covering every detail is of course beyond the scope of this article, but here are a few common  faults we see that you might benefit from knowing.

Hand numbness can be caused by several factors related to bike fit.  The most common is from handle bars that are too far away causing too much weight to be placed through the hands/wrists in an extended position that results in nerve compression where the riders hands meet the handlebar.  Shortening your reach often solves this problem.

Knee pain is often a result of clip in pedals that are not properly aligned causing too much torque between the upper and lower leg or an in properly positioned saddle (typically too far forward) that causes increased stress on the patellar tendon (which crosses the kneecap). This is felt just above or just below the kneecap and can be a very nagging condition for riders if not addressed properly.  

Groin pain/numbness typically results from a saddle that is positioned incorrectly causing the rider to bare most of their weight through the soft tissue (ouch) of the groin instead of the ischial seats (your "sit" bones).

If you have questions regarding your bike fit and its relationship to any symptoms you may be having or are simply looking to improve your performance we have a passionate team of professionals and a growing community of riders to help you get where you’re going...


Happy Riding!


Written by Justin Bagley, PT, DPT  who practices in the areas of general orthopedics and neuromuscular rehabilitation, injury/disease prevention, wellness and human performance.   He has taken special interest in the diagnosis, treatment and prevention of lower extremity and running related injuries