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Thursday, January 28, 2016

Chris Froome & Team Sky's Secret - How to beat a team of Short Crank Arms

If you haven't already read my original post and studied the crank arm length flow chart posted there, please go to the link below.

http://eatsleeptrainsmart.blogspot.com/2016/01/crank-arm-length-debunked-long-vs-short.html

Chris Froome & Team Sky - The mechanical secret behind their success
The success of Team Sky was the result of a collaborative effort to maximize the benefits of short crank arm lengths, but there are limitations that when exploited, are hard to overcome.  When either variable of the power equation is thrown to extreme levels, the human body will eventually fail to meet the demands.

Power = Torque x RPM

In the case of Richie Porte and Chris Froome, they were on the RPM side of the equation.  Very high cadences achieved only through short cranks have its own pros and cons.  Lets start with how they had the advantage.

The Physical Demands of the TDF
In the Tour De France, everyone has to race consecutive days, so keeping the hips and legs fresh is key to overall success.  The best way to reduce muscle fatigue is to ride with short cranks.  Since short crank arms require less torque, the primary muscles used in cycling are stressed to a lesser extent.  Whereas long cranks cause more long term muscular/ neuromuscular damage, the limitation to short cranks is more temporary fatigue- lactic accumulation.  The acidity can be cleared easily from massage, stretching, food (alkine foods) and sleep.  This meant that each of the Sky riders were fresher than everyone else, especially as the days progressed.

How Team Sky Avoided Revealing their Weakness
A short crank arm allow riders to more easily or naturally maintain a high steady state power output for very long periods of time; something that takes more technique and focus to accomplish on longer cranks.  This explains why Froome always put all of his effort into the first attack, then went immediately into the fastest tempo he could hold.  Standing efforts were also always short lived because standing cadences are much slower.  Contrary to popular belief, a super high cadence isn't the most efficient way to clear lactic acid.  When the cadence is too fast, it creates an effect similar to an isometric hold- the circulation is so fast and the range of motion is so small that the blood takes the path of least resistance.  This means the smaller capillaries miss out on picking up and transporting all of the acidic byproducts.  So as long as a steady state effort could be achieved, Team Sky would always be at an advantage.  This explains why Froome seemed to have his eyes glued to his computer- it was likely to ensure the power was consistent without sacrificing cadence.  It also explains why they often favored to be at the front and were always able to set a fast tempo, but rarely attacked in succession.  Observe stage 10 below and see if you can identify the clues hidden in their riding behavior.



***When Weaknesses were Finally Exploited***
The fast tempos served Froome well to put a psychological buffer on his opponents, but he went past his quota of accelerations in Stage 20.  It's interesting to note through observation that Froome's first attack wasn't very fast compared to how quickly Quintana closed the gap when he finally decided to take action.  It's actually a great example showing the difference in acceleration between short (low torque) and long (high torque) cranks.  The slower acceleration wasn't due to a lack of explosive power on Froome's part, it was mainly due to the fact that he had to shift several times more, and accompanied with each shift is a total loss of power, momentum and reencountered inertia to overcome.  The most expensive components can't avoid this limitation, but only shorten it's effects.


If you can observe who's running long or short cranks, you can use this knowledge to your advantage.  If your opponent is spinning fast, pressure them to attack and get off a steady effort, if they're spinning slow, force them into a hard steady tempo to prevent attacks.  Of course, this also depends on what crank you're using at the time!