Winning an Ironman on 145mm Cranks

While this isn’t really a Powercranks promo, I should give an insight into my love/hate relationship with this training tool.

I first started using Powercranks about 11 years ago, and after about 12 months of exclusive use, I raced them to second place at Ironman Canada 2006.

In this period, I also developed a severe muscle function imbalance about my hip joint and this resulted in an injury that sidelined me for months.

I couldn’t walk pain free for days after the race, and it took quite some time to get on top of the situation. The initial diagnosis was arthritis, but not believing it to be true, I investigated all possibilities before determining it was most likely snapping hip syndrome.

Due to the nature of Powercranks, which facilitate complete unweighting of the leg during the upstroke of the pedalling action, together with my use of 170mm crank length at the time, my hip flexors were being worked to their limit, while the antagonistic muscles, mainly the glutes, were being neglected in extension beyond the neutral position.

This led to the development of hip joint instability and the tendon of Iliopsoas was able to communicate with the hip joint capsule, resulting in irritation, pain and inflammation.

If I had been performing glute function exercises, then the problem may not have materialised, but I didn’t know any better at the time.

The good news was that Powercranks matched my second place prize money for racing on their cranks.

When I finally got back on track and started training consistently again, I was reticent to incorporate Powercranks into my training regime. It was a close to 4 years before I started to seriously consider using them again after a chat with Frank Day in Kona in 2010.

150km into the 180km at 2006 IM Canada - hurting!

150km into the 180km at 2006 IM Canada – hurting!

Part 2

Frank explained that they were experimenting with shorter crank lengths and it was showing some promise, so I thought I would do some investigation myself. In the back of my mind was the prospect of another tilt at racing on Powercranks because for someone in my position, the bonus to race on them was hard to ignore.

I knew, everything else being equal, the shorter crank length would result in a smaller, more efficient range of motion for the hip flexors during the pedal stroke, and, theoretically, improve their endurance capacity.

Frank organised some highly adjustable Powercranks for me, and I started to experiment with different crank lengths to determine which crank length elicited the lowest HR at Ironman specific power outputs.

I did this experimentation on the stationary trainer, and while not 100% specific to the task (we race on the road), it was the most practical option.

To cut a long story short, after many trials, taking into account all the factors that could affect the power/HR relationship, I determined that a crank length of 145mm, cycling with Powercranks, elicited the lowest HR at Ironman specific power outputs – in the 250-260W range for me.

After Hawaii 2010, I had 8 weeks to prepare for my next race, Ironman Western Australia and with 2 weeks taken up with recovery and experimentation, there were 6 weeks left for a specific preparation.

It would be a good time at this point to investigate the theoretical premise behind why shorter cranks, under certain circumstances, can be just as effective as the accepted norm. I have to add, in general, it is hard to argue with the accepted norm, because the norm is the result of decades of experimentation and trial and error.

Getting stuck in - IMWA 2010

Getting stuck in – IMWA 2010

Part 3

Here is an excerpt taken from the Powercranks website – the full article can be found here:


 

Everyone “knows” that longer cranks offer more leverage so should offer more power, correct?

Yes, until one considers crank length affects two confounding factors that also affect power generation. That is knee leverage and pedal speed. Knee leverage? Yes, knee leverage. The more the knee bends the less leverage it has. The knee bends less as the crank shortens so even though some leverage is lost because the crank shortens leverage is gained because the knee is in a more favourable position to apply force so it is a wash pretty much. Then there is pedal speed. The faster the pedal is moving the harder it is to apply force to the pedal. Longer cranks tend to have higher pedal speeds. So, while it takes less force to generate power when cranks are longer it is harder to apply that force to the pedal both because the pedal is moving faster (usually) and the knee is bent more. Change one thing to make it better changes other things to make it worse. This explains why power stays pretty much constant over a wide range of crank lengths.

Another way to look at this is to look at what goes on around the entire pedaling circle. Power generation is more than pushing hard but also involves getting the foot out of the way on the backstroke. The best way to maximize the average power around the pedal stroke is to do what is called “pedal in circles”, where the work performed by the muscles remains pretty much constant. Below is an example of a real world pedaling pattern that can further explain why longer cranks rob the rider of power or why power doesn’t drop (or increases) when cranks are shortened.

icranksexampleleftshortexplanation

So, while one can argue that one can get more pushing leverage with longer cranks we can see that it is likely that you lose more at the top that you gain in pushing advantage. There may be more leverage pushing but what happens around the rest of the stroke is just as important.

Here is some actual data from someone who tested this for himself. This coach for many elites put himself on an Excalibur ergometer, which measures pedal forces around the entire circle, and compared what happened between 170mm and 150 mm crank length, close to what Martin did. Here are his results (the 150 crank length results are on the top, the 170 crank length results on the bottom).

150cranksummary

170cranksummary

 

Note, the total average power for this 90 second test was slightly greater (313 vs 308) on the 150mm cranks despite the fact that the average maximum power was greater (633, 646 vs 610, 620) on the 170 mm cranks. This is hard to explain until one looks at what happens on the upstroke where the negative forces are much less (-73, -145 vs -96, -166) on the 150 mm cranks.


 

In summary, what you lose in the push phase with shorter cranks due to reduced leverage, you gain in the upstroke phase, due to more efficient upstroke musculature function, noting that the negative effective forces only need to be reduced, not eliminated altogether.

This the reason why it is possible to remain competitive using 145mm cranks, when everyone else is using cranks that are far longer.

The key to success is developing the endurance capacity of the upstroke musculature to such a degree that it contributes to reducing the negative effective forces during the upstroke throughout the entire cycle leg of the race.

While the data above would suggest differently, I have found, through practical experience, that the only way to do this effectively is with the use of Powercranks, which necessitate 100% unweighting of the leg by the lifting musculature 100% of the time.

Due to a couple of characteristics of the pedal stroke, which I won’t elaborate on here, there is no guarantee the reduction of the negative effective forces on the upstroke outlined above while cycling with 150mm conventional cranks will persist far beyond the 90 second snapshot shown.

Part 4

Tracking Down 145mm Cranks

After deciding I was going to train and race on 145mm cranks, I was faced with the dilemma of tracking down a decent quality set to install on my bike. At the time, not too many of the major manufacturers were producing anything shorter than 165mm.

After some searching on the internet, I tracked down a set of 145mm cranks manufactured for low end bikes. It was a triple, meaning it has mounting points for three front rings, not the conventional two for road racing cranks, and it mounted to the bike with the use of an outdated square tapered cartridge bottom bracket unit.

The cranks were on special for $22, so I ordered them, ground off the mounting lugs for the smallest chain ring, mounted the two conventional chain rings and bolted them to my bike, hoping they wouldn’t snap during a training ride and leave me stranded miles from home.

IMG_0109

The cranks I used to win two 140.6 events

 

Bike Position

When installing shorter cranks, the first thing you need to do is raise your saddle a distance that is about equal to the difference in length between the original and shorter cranks.

I had to raise my saddle 25 millimetres after moving from 170 to 145 cranks.

Getting too aggressive with aero positioning will defeat the whole purpose of the exercise, ie improving the efficiency of the upstroke musculature by opening the thigh/torso angle with a shorter crank.

This could be overdoing it

This is could be overdoing it

This is my position on the bike during the cycle leg of Metaman 2013, the second race I won using 145mm cranks.

MetamanCycle2013TriZone

There is probably scope to move slightly more forward relative to the bottom bracket and open up the hip angle a little more.

The Training

I realised very early that racing on 145mm Powercranks over the full 180 kilometre cycle leg was going to be virtually impossible. While set up in an acceptable aerodynamic position, it was pretty obvious my upstroke musculature wouldn’t have the capacity to completely unweight the rising leg for 4.5 hours. To this day, I have no idea how I managed to get through the Ironman Canada bike leg in 2006 on 170mm Powercranks.

With any thought of racing to victory and banking a big bonus cheque dashed, I got to work with a combination of Powercranks and conventional crank training to prepare for a tilt at the 2010 Ironman Busselton on conventional 145mm cranks.

To make this work, it is crucial to get the mix of Powercranks and conventional crank training right. The goal is to improve the endurance of the upstroke musculature just enough, while at the same time, lose almost no capacity in the downstroke musculature.

This is trickier than it sounds. While I have had a couple of hits with this training regime, I have had a few misses as well. More is not necessarily better when it comes to the Powercranks side of things and the correct periodisation of the Powercranks work is very important.

My 6 week training block was consisted of two Ironman specific weeks, an easier week, then one final Ironman specific week, before a two week taper.

In this time I did 5 rides most weeks, with 3 on Powercranks (one longer hills cycle and two shorter flatter cycles) and the other 2 on fixed cranks (both with IM power time trialling efforts on the flat).

My crescendo week consisted of 15 kilometres of swimming, 500 kilometres of cycling and 120 kilometres of running.

On race day I felt great on the bike, rode solo virtually the whole way and posted the second fastest bike split of 4.28, about a minute slower than Luke Bell, and had the legs to run a 2.52 marathon afterwards.

If I had done the exact same volume of training using 170mm cranks, would I have raced just as fast? Possibly.

Is 145mm crank length in combination with the Powercranks/Fixed crank training regime suitable for all circumstances, e.g. shorter races and higher power outputs? Possibly not.

The point is though, it is possible to race at the highest level over the Iron distance using a set of cranks usually reserved for a kids BMX bike.

Winners are Grinners

Winners are Grinners

 

 

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