Dura Ace Q & A

[Johan Bornman]

Sorry to say it but the adjustable crank are back!

 

 

... and what problem does it solve?

 

[JasonW]

 

 

 

Ok' date=' so contrary to what I thought, you would acually need a stronger set of muscles, but they could be less fit! Or am I completely off track now?

[/quote']

 

Jason, we often associate fitness with aerobic capacity. However, it is more than that and generally defined as a combination of flexibility, strength and stamina (aerobic capacity).

 

Us cyclists are therefore not quite as fit as we think, since we're weak and stiff. I proved this to myself some years back when I climbed a gum tree with a chainsaw and attempted to bring the tree down. On the bike I was a machine. In the tree like Tarzan I was a 90 pound weakling.

 

So, in your example above, the guy that prefers the shorter crank scenario will be stonger than you since you are more inclined to activities that requires stamina.

 

But please don't take this and attempt to quantify it. I'm talking delicate mixes and balances here.

 

Good athletes understand their natural predispositions and train accordingly. They will delicately balance strengh, endurance and speed training to achieve the body type they require for their activity.

 

You'll notice that the average Joe who trains for the Epic trains disproportonately at an aerobic level whereas the track guy works on anaerobic strength.

 

 

 

Thanks, was really just of academic rather than practcial interest! Given that (most) cyclists have an (in principle) infinite number of gearing options, there would seem to be even less relevance to the debate.

 

 

[cycleq]

 

BB' date=' I don't understand the phrase "metabolic cost". However, lets for the sake of this argument simplify grossly and assume there are two types of energy systems involved in turning a crank.

 

Anaerobic and Aerobic.

 

Lets also assume that the act of applying a force to something requires only anaerobically supplied energy and the act of dragging that force around the circle only aerobic energy.

 

Now, you'll see that your twins are expendifferent types of energy. The one with the short crank is supplying more anaerobic energy and the one with the long crank is working more aerobically.

 

Since they are twins and genetically identical and, one is typically more pre-disposed to one energy system than the other (a shotputter vs a marathon athlete), one of the twins will be suffering a little and the other finding the ride a bit easier.

 

This in spite of them doing the same work.

 

Which one is suffering and how much more? There's the thumbsuck. It has to do with your muscle composition. A simple biopsy can indicate your predisposition but I for one stay away from donating chunks of muscle to lab technicians.

 

Back to metabolic cost. You can't say the metabolic cost of an anaerobic activity is higher than the cost of an aerobic activity, so the "Cost" is moot.

 

Depending on the hill's incline and the rate of ascent, we could probably figure out which one is metabolcally paying more, metaphorically speaking, of course but I think it is a silly statement to make.

 

I just ride with whatever crank the bike has on it.

 

 

 

[/quote']

 

If you don't understand 'metabolic cost' why not do some reading on the reams of information available on it? However, Johan, your ignorance of metabolic cost is not an excuse to bootstrap a silly argument about grossly simplified energy systems involved in turning a crank. Fact is, like riding the cranks the bike has on, turning cranks is not really capable of gross simplification. Wow, we missed all those other available energy systems, joint articulation, active muscle volumes, selective muscle recruitment and just a whole lot more. So for the purposes, everything you opined after your first bit of bootstrapping rendered itself spurious. I'm prompted to ask; "So what problem did all that solve?"

 

Crank length, as you mentioned earlier, can be selective predisposition, habit, ignorance, efficient or inefficient. The human body is hugely capable of adapting (in a short time) to crank length discrepancies of up to 10cm! Until the jury comes in with a definitive assessment of the vagaries of crank length, for mere mortals it isn't so bad just to ride the cranks on the bike. If you're happy with that, whatever floats your boat. Selective predisposition in some individuals, however, means not everyone will be happy with that. So be it.

Meanwhile, no problem, no solution obviously.

Determinants of metabolic cost during submaximal cycling J. McDaniel, J. L. Durstine, G. A. Hand, and J. C. Martin Department of Exercise Science, University of South Carolina, Columbia, South Carolina 29208

The metabolic cost of producing submaximal cycling power has been reported to vary with pedaling rate. Pedaling rate, however, governs two physiological phenomena known to influence metabolic cost and efficiency: muscle shortening velocity and the frequency of muscle activation and relaxation. The purpose of this investigation was to determine the relative influence of those two phenomena on metabolic cost during submaximal cycling. Nine trained male cyclists performed submaximal cycling at power outputs intended to elicit 30, 60, and 90% of their individual lactate threshold at four pedaling rates (40, 60, 80, 100 rpm) with three different crank lengths (145, 170, and 195 mm). The combination of four pedaling rates and three crank lengths produced 12 pedal speeds ranging from 0.61 to 2.04 m/s. Metabolic cost was determined by indirect calorimetery, and power output and pedaling rate were recorded. A stepwise multiple linear regression procedure selected mechanical power output, pedal speed, and pedal speed squared as the main determinants of metabolic cost (R² = 0.99 ? 0.01). Neither pedaling rate nor crank length significantly contributed to the regression model. The cost of unloaded cycling and delta efficiency were 150 metabolic watts and 24.7%, respectively, when data from all crank lengths and pedal speeds were included in a regression. Those values increased with increasing pedal speed and ranged from a low of 73 ? 7 metabolic watts and 22.1 ? 0.3% (145-mm cranks, 40 rpm) to a high of 297 ? 23 metabolic watts and 26.6 ? 0.7% (195-mm cranks, 100 rpm). These results suggest that mechanical power output and pedal speed, a marker for muscle shortening velocity, are the main determinants of metabolic cost during submaximal cycling, whereas pedaling rate (i.e., activation-relaxation rate) does not significantly contribute to metabolic cost.

 

[Johan Bornman]

 

Dear Cycleq????

 

Some issues you'd like to air?  I think you wasted too many words trying to say that I'm bulsh*tting. Say it, point to the offending sentence and lets deal with it.

 

Metabolic cost is in fact not widely used. My Penguin Dictionary of Biology doesn't have such an entry and neitehr has my trusty back-up, Wikipedia. I am one of those people who say I don't know what something means when I don't know what something means. Maybe that's a value that's alien to you.

 

If I look at your citation, I can only deduce that the word means "efficiency".  I deduced that initially and went on to explain. I warned that I'm simplifying but demonstrated why - save here but pay there. Anything wrong with that argument?

 

Perhaps you feel you can do a better analogy using all the available energy systems. Please go ahead. The topic is interesting, don't spoil it.

 

Finally, I prefer debating with people who don't snipe from behind nicknames.

 

[cycleq]

Please read my post. I didn't say you're bullsh1tting - I said you're bootstrapping. But that is your way, this is mine. I avoid opportunities to debate with you - frankly the homespun-homily mantle you proudly wear is a little tedious and its worthless debating with know-it-alls anyway.

 

In the world of physiology/exercise physiology "metabolic cosy" is quite widely used. Perhaps not in the yellow saddle halls, but that was my point.

 

BTW, this is not sniping any more than the stuff you engage in every day with posters on the web. I don't have a TV persona I'm trying to defend so my anonymity is my business. If you can't take criticism, perhaps try being a tad more accurate.

cycleq2008-09-02 22:40:43