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ToolBox
Toolbox: Things To Think About
As the rush of the Olympics slips away it’s easy to forget the detail and attention that goes into each performance. Watching elite athletes is always inspiring and while we often try to emulate their drive and focus in our own workouts and races, it’s easy to forget some of the big and small things that make up a groundbreaking performance.

By Matt McNamara

The quest for perfection has been front and center these past weeks in the visage of Bradley Wiggins, the British track program, and the rest of the Olympians. This drive to get everything right trickles down to most racers, no matter their level. To that end I thought I’d spend my time this month offering a few things to think about as you reach for your own perfection…

Training Is NOT Racing
We coaches write a lot about proper training and preparation for races. We’ll wax poetic about threshold power, correct interval format, and the need for recovery. All of these are true and necessary components of a training plan, but they are not racing. This fact was brought home to me last week in a very real way.

My training has been pretty consistent over the last couple of months, hitting some good numbers and only missing four days in the month of July, so I thought I’d throw in some road racing to help my preparation for cyclocross season. My first race was on a course that included a substantial climb featured in one of the Tour of California stages. It’s a bit of a beast at nearly ?? miles, with sections that top out above15% and a near constant driving headwind. As a not-very-good climber it was intimidating, but I love the challenge of road racing, so why not!?

The field was about 40 riders and the climb starts within the first mile of the race. On the climb I felt good, able to stay at the front without too much effort. Even the steep pitches were manageable in my 26 (I’d considered a 28, but couldn’t pull the trigger, ah ego!). I crested the top 5th. After a quick descent and a sharp right turn we started the second climb. Sitting on the starting line I’d overheard several strong riders talking about how hard they were going to attack the second climb, so I knew what was coming and got myself into the top 10 as the speed ramped up, aided by a crossing tail wind…and here’s where it all came apart. Let’s go to the tape…

FirstClimb: 24:00 @ 319W / 350Wnormalized


The first climb was tough, 24 minutes at 100-110% of threshold was actually kinda fun! The highlighted sections are the more notable surges. The second climb looked like this:



The first minute out of the corner was 400W, then another 1:20 at 400W+…then the wheels fell off. The “BLOWN” section was 2:00 at 309W of me trying to get myself together as the field rolled away. I just couldn’t handle the transition from high speed descending to high power climbing even though the numbers were within my capacity. The transition loaded my legs and I was done.

The take away – I hadn’t included workouts like that in my training and I paid the price. Training is not racing, or better said my training was not specific to the anticipated demands of my race. Back to the crucible to better prep for the next one! How about you?

Time Trial Research
In the quest to quantify and understand individual performances and their underlying elements a group of researchers from Sweden have taken up the question of “Time Trial Positions in Triathlon, Road and Track Cycling – Differences and Similarities.” Their paper looked at a couple of interesting elements: baseline positional differences between each discipline and the much more minutiae based differences in individual position during an effort.

They looked at five different riders and distances:



The researchers used video of each rider imported into analysis software (cSwing) to estimate joint angles at the elbow, shoulder, trunk, hip, knee and foot while traversing a full 360 degree cycle and a minimum of four rotations.

The most interesting aspect of their paper was the differences in each rider’s body position across all revolutions. Perhaps unsurprisingly the track rider, Jack Bobridge, showed the most dynamic position changes, easily attributed to the short duration/maximal power orientation of his ride. He also had the highest cadence. In a similar vein, Fabian Cancellara’s 115 rpm effort resulted in a higher total body movement as well. Hip and Knee angle variations were surprisingly similar across disciplines – consistently ranging between 40 and 80 degrees, and 70 and 140 degrees respectively for all riders. This indicates the overall stability and consistency of each riders pedal stroke, a normal expectation for riders at this World class level. In the end most of the variation in joint angles seems due to anatomical considerations (flexibility) and event duration. For example, longer duration events require modification away from an optimal trunk position in order to produce sustainable power over many minutes to many hours.

While these results are fairly standard the paper does offer a unique insight into the biomechanical adaptations of these top performers and may add insight into your own position decisions

Drivetrain Efficiency
Finally this month we offer a cursory look at the oft maligned question of drivetrain efficiency. Common sense says that power loss due to drivetrain drag is a substantial contributor to overall inefficiency in the system. Fortunately, Spicer et al took a pretty comprehensive look at this issue in 2001. While the intimate details of their research may make it into a future Toolbox article, let’s look at the results and discussion sections to grab the gist of their research in an effort to help you improve your own drivetrain performance.

Friction has long been thought of as the primary point of energy loss in the drivetrain. Spicer et al broke friction into three primary types: the inner link bushing and chain pin, the sprocket tooth, link roller, and inner link bushing assembly, and friction caused by chain line offset. Somewhat surprisingly, the friction loss due to chain line offset was the least significant contributor. The design of the chain allows for a wide range of chain lines and frictional losses are fairly small in comparison to the frictional loss caused by the basic interactions of the chain links with themselves and the much more complex, and substantial losses derived from the interaction between the chain and the sprocket during each revolution.

Another common reference point for lost efficiency is lubrication. Spicer et al sought a comprehensive answer as to the overall advantages of lubrication. Similar to chain line offset, lubrication was deemed a peripheral factor in overall efficiency.

So, what is the source of decreased efficiency? Simply put it is a combination of sprocket size and chain tension. Larger sprockets tend to be more efficient than smaller ones, and more chain tension is generally better than less. This result is even more pronounced as cadence increases at a fixed workload. For example a 52×11 turning 40rpm at 100W is approximately 95% efficient, while a 52×21 at the same cadence and workload is 97.8% efficient. Increase cadence to 90 rpm and the 52×11 drops to 85.4% (-9.6%),while the 52×21 drops to 89.8% (-8.8%). In the end though, the high efficiencies measured under high chain tension account for only a small part of total loss, so it seems that non-thermal effects are the primary culprit in chain efficiency – which is to say that the simple link-to-link and cycle-to-cycle variationsin the chain-to-sprocket interactions are to blame. These variations occur as low frequency vibrations (<100kHz) that are easily damped and produce no heat. So keep changing your chain every few thousand kilometers, keep riding those high chain tension efforts, and work in larger sprockets to maximize efficiency.

Summary
It is easy to focus on a simple few elements in the drive to perform, yet the reality is that a myriad of factors play into performance and many are of such seemingly small significance as to be overlooked. From a comprehensive understanding of the expected events real world demands, to addressing the minutiae of body movement during a maximal time trial effort or chain tension across a range of sprocket options, the essence of true maximal performance is the continual quest for a new level of understanding of all the relationships that matter and contribute.

References:
1. Schafer, Sergej “Time Trial Positions in Triathlon, Track and Road Cycling – Differences and Similarities” Gymnastik-Ochidrottshogskolan Projektarbete 10:2011
2. Spicer Richardson, et al “Effects of Fricitonal Loss On Bicycle Chain Drive Efficiency” Transactions of the ASME, Vol 123, pp 597 – 605, December 2001



About Matt McNamara:
Matt McNamara is a USA Cycling Level 1 coach with over 20 years of racing, coaching and team management experience. He spends inordinate amounts of time reading about cycling and science and not nearly enough time actually riding. You can find him on www.facebook.com.. Facebook, or via email: info@sterlingwins.com.

 

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