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Another seat angle question
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Sorry if this is a dumb question regarding seat angles, but if you shift forward and backward on the seat while riding, don't you change the effective degree at which you are riding? I have my saddle nose 2.5 cm in front of the BB giving me an 80 degree setup, but I don't ride there very long (I'm ordering a saddle cover tomorrow!). So, when I shift my butt back on the saddle to give my taint a break, am I not changing the degree at which I'm riding? Again, sorry if this is a dumb question! Thanks!

Andy

'You'd be surprised how many people violate this simple principle every day of their lives and try to fit square pegs into round holes, ignoring the clear reality that Thinsg Are As They Are.'
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Re: Another seat angle question [Andy] [ In reply to ]
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"So, when I shift my butt back on the saddle to give my taint a break, am I not changing the degree at which I'm riding?"

yes, you are. but road racers are also moving back and forth in their saddles. riding forward allows you to generate pretty good power with a high cadence. riding back in saddle allows you to generate more torque but at a lower cadence. the higher cadence is better if you want to ride with more economy. but moving back and forth in the saddle to gain a particular mechanical advantage depending on the course profile is something all cyclists do.

Dan Empfield
aka Slowman
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Re: Another seat angle question [not a PCer] [ In reply to ]
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"Higher cadences are less, not more, efficient (economical)."

higher than what? 120rpm might be less economical than 95, but generally speaking 90-95 is ridden with a lower metabolic cost than 80rpm, if you're in a race that is no more than several hours long. lots of literature to support this.

Dan Empfield
aka Slowman
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Re: Another seat angle question [Slowman] [ In reply to ]
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Although I'm a high cadence rider myself, don't you have to specify what you are economizing? Some people tell me that I'm spinning too fast and that I will wear myself out. This inevitably comes from power riders who never ride more than short distances. They simply don't have the aerobic engine to support higher cadences.
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Re: Another seat angle question [not a PCer] [ In reply to ]
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"Not true - although the cadence resulting in the lowest 'metabolic cost' (oxygen consumption) increases with absolute power output"

vercruyssen found oxygen consumption was best at 78, but that this is not the important issue. neuromuscular cost -- also metabolic -- was high at 78, and low at 90. ahlquist found no aerobic difference at all in aerobic cost at various cadences, and this is more typical of the literature.

athletes in every single cadence study published that i've read -- quite a few of them -- show that athletes freely choose a cadence very close to 90rpm. why is this, if there is a lower O2 consumption rate below 80rpm, or if there is no difference at all?

studies differ when juxtaposing cadence with rate of oxygen consumption (most studies show no real difference at cadence rate changes). but the rate of glycogen consumption is markedly higher when pedaling at a lower cadence rate, if you're engaged in an event with a relatively high exertion rate. the assumption (backed up by studies in which muscle biopsies were performed during exercise at various cadence rates) is that the higher recruitment of less metabolically efficient fast twitch fibers during lower-cadence exercises caused the athlete to choose a higher, more efficient, cadence rate (89-91rpm was the average rate in every study i found).

this is the basis, btw, of carmichael's "revolutionary" training scheme for armstrong. he knew what he wanted to do, i just don't know that he knew precisely why. studies have demonstrated over the past few years the "why" behind the higher cadence.

this is also the key to why steeper seat angles work, and in how to ride steeper angles. whether the steeper angle only works best when a higher cadence is used, or whether a steeper angle works because it's easier to ride a higher cadence when sitting forward, is probably still not entirely explained. but steeper angles, higher cadences, and a more efficient use of fuel, all appears to go together (which explains why steeper angles yield faster runs off the bike).

i suspect your disagreement with me in this issue is just an issue of terminology. if you are ONLY talking about O2 consumption then i'm happy to concede your point, SOME studies show a lower O2 consumption at lower cadences. but if you're talking about fuel consumption -- and if you'll allow for the less-well-known issue of neuromuscular fatigue to be considered, then it's clear both in the lab and anecdotally that 90rpm is a considerably more efficient way to ride than 78rpm. the only way this is NOT true is if you're riding at an effort level so low (during RAAM, let's say) that the aerobic cost of riding at a higher cadence outweighs the neuromuscular cost.

Dan Empfield
aka Slowman
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Re: Another seat angle question [not a PCer] [ In reply to ]
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I seem to remember you making the opposite claim when arguing with Frank Day about his statement that perhaps lower than 90 rpms (which are common in people using his invention) were more efficient in most people. I believe you cited a study that showed "elite national class cyclists" pedaled at 90 rpms and above, and used that as your arguement that lower than 90 was therefore not as efficient.



Quid quid latine dictum sit altum videtur
(That which is said in Latin sounds profound)
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Re: Another seat angle question [not a PCer] [ In reply to ]
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"I just figure that if you're going to cite the scientific literature, you ought to at least get the terminology correct."

i did get the terminology correct. when a person rides with a lower fuel consumption he rides with a greater economy. but if you prefer to think that consuming less oxygen represents greater economy, even if that means you'll burn more fuel at the same time, then i think you ought to pedal at 78rpm. i just don't think you should anticipate making the podium very often.

Dan Empfield
aka Slowman
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Re: Another seat angle question [not a PCer] [ In reply to ]
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120rpm might be less economical than 95, but generally speaking 90-95 is ridden with a lower metabolic cost than 80rpm.
Not true - although the cadence resulting in the lowest "metabolic cost" (oxygen consumption) increases with absolute power output, even in elite athletes it is still quite low, i.e., less than 80 rpm, which in turn is less than 90-95 rpm.


I guess the bottom line is that one can choose the measure of economy or 'metabolic cost' that is most appropriate to support his/her argument.

In the case of an endurance athlete working for extended periods at sub threshold, sustainable effort levels, oxygen consumption is probably much less a consideration. These athletes are more worried about fatigue or bonking. Oxygen consumption is therefore a much less meaningful measure of economy than other measures such as glycogen consumption.

Bring that effort up to non-sustainable, shorter duration, higher (closer to VO2 max) intensities and O2 cost probably takes on greater meaning. In this case, it doesn't really matter how glycogen 'inefficient' the athlete is. At high power levels, maximizing power per liter of O2 consumed is key as by definition, systemic O2 is limited.

If you're going long, you limit glycogen consumption at the expense of O2 consumption. If you're going short and all out, you sacrifice glycogen and strive to maximize power up and around VO2 max. The appropriate measure of "metabolic cost" depends on the length and intensity of effort.
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Re: Another seat angle question [not a PCer] [ In reply to ]
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"While pedaling slowly may cause more carbohydrate to be burned, it also causes less fat to be burned"

you'll want to go back and review your ex fizz 101 text. "fat burns in a carbohydrate fire," remember that one? next time you bonk, as a result of pedalling at 78rpm instead of 90rpm, you'll remember why it is that you'll wish you'd pedalled with more economy :-)

really, it's in the literature. go to pubmed and search "cadence." then pop $20 per study, download the PDFs, and read. i did. you certainly must've as well. which is why i don't understand your defending a losing argument.

Dan Empfield
aka Slowman
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Re: Another seat angle question [Slowman] [ In reply to ]
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i'm going to reply to my own smart-alecky comment. you are certainly correct, that IN GENERAL, and in both running and cycling jargon, "economy" is generally the term used when considering how much oxygen is consumed per amount of work given.

so when i use the terms "economy" and "economically" i am guilty of using the term imprecisely if you take my terminology to be construed in physiological terms. at the same time, there is certainly a common view among those who run, and who coach running, when using the term "economy." having been primarily a runner in my competitive life for the past 30+ years, running more economically is generally--when you're out on the track doing intervals, not in the lab--considered to refer to one's form.

perhaps it's because of this dual use that i'm given to throwing the term around with less precision than i ought.

that said, it seems that the term is used in a variety of ways by those who know or ought to know. here is the opening three paragraphs in arnie baker's cycling, "economy and efficiency."

"Economy has a specific sport science definition.

"Economy is the power produced (in watts) divided by the volume of oxygen used to produce that power (in liters per minute).

"Economy can be rrelated to mechanics. It is defined as the energy expenditure required for a given workload. In the automotive world, economy refers to miles per gallon."

the problem above is that in three paragraphs economy has been used to express an amount of oxygen consumed, and the amount of fuel consumed. that is probably because almost all of the sports science that relates to what cyclists and runners do refers to aerobic metabolism, and for that reason oxygen and carbohydrate consumption are closely linked.

the problem is, and this is specifically true when considering cadence, the two are not linked. hence, the science appears to indicate that while riding at a lower cadence may consume less oxygen, it consumes more carbs.

Dan Empfield
aka Slowman
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Re: Another seat angle question [not a PCer] [ In reply to ]
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there is little, if any, relationship between a runner's "form" and their running economy.
Because I believe that words do, indeed, mean things, what performance variable DOES "form" affect, if not economy?
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Re: Another seat angle question [not a PCer] [ In reply to ]
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If you're going long, you limit glycogen consumption at the expense of O2 consumption. If you're going short and all out, you sacrifice glycogen and strive to maximize power up and around VO2 max. The appropriate measure of "metabolic cost" depends on the length and intensity of effort.
Well said, except for the fact that "metabolic cost" is synonymous with "oxygen consumption" (there's a very good reason that the measurement of respiratory gas exchange is also called "indirect calorimetry").


You're testing my memory here, but isn't it true that indirect calorimetry is simply used to determine RQ (respiratory quotient - ratio of CO2 produced over O2 consumed)? At the cellular level, when RQ equals 1 all O2 being consumed is being returned as CO2 and therefore metabolism is purely anaerobic? Isn't it simply a way to estimate the proportional contribution of our different metabolic systems and indirectly estimate total calorie consumption?

If memory serves me, there's serious shortcomings in trying to apply this at a systemic level on someone who's exercising (i.e. measured RQ for someone exercising can be greater than the theoretical max of 1).

I guess my point is, do we simply equate O2 consumption with metabolic cost because it's something we can easily measure? What we really want to measure is the number of calories being burned per unit of time... Pretty hard to do. Hence, we look for 'indirect' means to establish metabolic cost which may or may not always be valid.
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Re: Another seat angle question [not a PCer] [ In reply to ]
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If you're going long, you limit glycogen consumption at the expense of O2 consumption. If you're going short and all out, you sacrifice glycogen and strive to maximize power up and around VO2 max. The appropriate measure of "metabolic cost" depends on the length and intensity of effort.
Well said, except for the fact that "metabolic cost" is synonymous with "oxygen consumption" (there's a very good reason that the measurement of respiratory gas exchange is also called "indirect calorimetry").


You're testing my memory here, but isn't it true that indirect calorimetry is simply used to determine RQ (respiratory quotient - ratio of CO2 produced over O2 consumed)? At the cellular level, when RQ equals 1 all O2 being consumed is being returned as CO2 and therefore metabolism is purely anaerobic? Isn't it simply a way to estimate the proportional contribution of our different metabolic systems and indirectly estimate total calorie consumption?

If memory serves me, there's serious shortcomings in trying to apply this at a systemic level on someone who's exercising (i.e. measured RQ for someone exercising can be greater than the theoretical max of 1).

I guess my point is, do we simply equate O2 consumption with metabolic cost because it's something we can easily measure? What we really want to measure is the number of calories being burned per unit of time... Pretty hard to do. Hence, we look for 'indirect' means to establish metabolic cost which may or may not always be valid.
Hence the reason that studies of exercise economy/efficiency are usually constrained to steady-state exercise at intensities below the respiratory compensation threshold (though this precaution may not be as critical as is generally held).
So what you're saying is that all these studies are based on an indirect, imprecise means for measuring metabolic cost at intensities that are probably well below a meaningful "race pace" or intensity level.
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Re: Another seat angle question [not a PCer] [ In reply to ]
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Even above the point that hyperventilation (with respect to CO2 production) invalidates its use as a means of quantifying utilization of specific fuels, it still remains a valid means of estimating overall energy expenditure - this is because the energy equivalent for O2 varies only slightly with the mix of substrates oxidized (i.e., from 100% fat to 100% carbohydrate), and even less over the range above which RER no longer equals RQ.


OK. I'm with you in terms of aerobic metabolic pathways. But at 'race level' intensities isn't there a substantial anaerobic metabolic contribution that by definition would not be reflected by measuring O2 consumption?

Isn't O2 consumption simply proportional to the aerobic metabolic contribution and not the total metabolic cost (i.e. calories consumed)? Wouldn't elevated blood lactate levels at 'race level' intensities indicate that there's a fair amount of energy coming from anaerobic sources?
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Re: Another seat angle question [JustCurious] [ In reply to ]
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so mvig on the saddle definitely changes the effective seat post angle then?
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Re: Another seat angle question [bumface] [ In reply to ]
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Yes, glad we cleared that up for you. I bet you didn't know it was so complicated.
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