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#21
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"chris christanis" wrote in message ...
I had a cheap Bell computer that did it for me but it fell off (cheap). So I bought a cateye but it does not tell you calories burned. Anyway to figure this out? This is a very tricky question. Having investigated this in the past, I know there is no agreed, accurate method of determining the calories used. A few observations, though. 1) Any method that does not take account of the speed at which you are cycling is pure rubbish. 2) Unless you are cycling on the flat at a steady speed, any method that does not take account of the total moved mass is pure rubbish. 3) Conversly, any method which ties the calories burned to the moved mass without taking account of the altitude gained/lost and the amount of acceleration/decelerations is pretty much rubbish. 4) Any method that does not take account of the wind speed is likely to be wildly inaccurate if the w/s is over about 5 mph (consider that if you are cycling with a groundspeed of 15mph, your airspeed will vary from 10 to 20 mph tail/head wind at this w/s. At 12 mph, the difference would be 3 to 27 mph) 5) Within a fairly wide range, you can probably find a figure or algrorithm that will give you any result you want, if you research enough sites/books/articles. The method I used to *ESTIMATE* the calorie burn was as follows. a) Find a step aerobics machine which has a calories burned* readout. b) Use an HRM and set the machine to various resistances. For each resistance setting, wait until your heart rate stablises, and note the Hr/Calories readings. c) Plot a graph of these figures d) Use an HRM that will give you a mean Hr for your ride, and use that against your graph to determine your approximate calorie burn. * Try and determine if the calorie readout is the number of calories calculated from the kg/m raised on the machine, or whether the machine introduces a "fudge factor" to account for the inefficiency of human power generation/delivery. If it is the former, it will be a considerable underestimate of the calories burned. All the heat you produce is on top of the energy used to effectively raise your body mass the distance used in the calculation. If you can do the maths, you can use the Hr/Cal figures to produce an equation, but as the relationship is non linear, it's not that easy Apart from the above, I would say that the algorithm given based on mean Hr and weight has the best chance of being accurate, although both this, and the moethod I outline above will not be too good if there is a large variation in Hr during your ride. |
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#22
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On Thu, 02 Sep 2004 11:51:18 GMT, "Peter Cole"
wrote (more or less): "VBadJuJu" none@ wrote Highly accurate too at least as to speed (and therefore distance, avg speed etc). Recently there was one of those automated radar speed things down the street off and on for about 9 weeks. Coming down the hill on my way out to ride I could verify the read out vs the radar thingie. Bike "computers" are simple wheel revolution counters, they're all as accurate as the tire size input. FWIW, 13 - 15 miles works out to about 1000 calories at 10.5 - 11.5 MPH average for me. That sounds off by a factor of 4 or so, it's way too high unless that is up a very steep hill. You can't accurately measure calories without measuring watts, The Analytical Cycling website has a Wattage calculator - nased on frontal area, weight, surface cycled on, speed, etc. and that's a difficult thing to do, the equipment is available to do that (e.g. Powertap), but it's expensive. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#23
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On Thu, 02 Sep 2004 11:51:18 GMT, "Peter Cole"
wrote (more or less): "VBadJuJu" none@ wrote Highly accurate too at least as to speed (and therefore distance, avg speed etc). Recently there was one of those automated radar speed things down the street off and on for about 9 weeks. Coming down the hill on my way out to ride I could verify the read out vs the radar thingie. Bike "computers" are simple wheel revolution counters, they're all as accurate as the tire size input. FWIW, 13 - 15 miles works out to about 1000 calories at 10.5 - 11.5 MPH average for me. That sounds off by a factor of 4 or so, it's way too high unless that is up a very steep hill. You can't accurately measure calories without measuring watts, The Analytical Cycling website has a Wattage calculator - nased on frontal area, weight, surface cycled on, speed, etc. and that's a difficult thing to do, the equipment is available to do that (e.g. Powertap), but it's expensive. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#25
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On 2 Sep 2004 07:11:51 -0700, (Doug Evans) wrote
(more or less): "chris christanis" wrote in message ... I had a cheap Bell computer that did it for me but it fell off (cheap). So I bought a cateye but it does not tell you calories burned. Anyway to figure this out? This is a very tricky question. Having investigated this in the past, I know there is no agreed, accurate method of determining the calories used. A few observations, though. 1) Any method that does not take account of the speed at which you are cycling is pure rubbish. Why is that? The rolling resistance increases linearly with speed,and the wind resistance only starts becoming significant at 15mph, and only increases with a power law for a cyclist/bike of /constant/ shape and frontal area. Most cyclists I know start to crouch and tuck more as the speeds get up to aero-sensitive speeds. 2) Unless you are cycling on the flat at a steady speed, any method that does not take account of the total moved mass is pure rubbish. And even if you are on the flat. 3) Conversly, any method which ties the calories burned to the moved mass without taking account of the altitude gained/lost and the amount of acceleration/decelerations is pretty much rubbish. Particularly true of the latter point. But as for altitude gains, for most routes, and certainly for all circular routes, altitude gains will be balanced by altitude drops. i.e. the distances you put in more effort because you are climbing should be balanced by the distances you can use less effort thanks to the downslope. (And yes, I admit that this assumes that you're a constant-speed rider...) 4) Any method that does not take account of the wind speed is likely to be wildly inaccurate if the w/s is over about 5 mph (consider that if you are cycling with a groundspeed of 15mph, your airspeed will vary from 10 to 20 mph tail/head wind at this w/s. At 12 mph, the difference would be 3 to 27 mph) 5) Within a fairly wide range, you can probably find a figure or algrorithm that will give you any result you want, if you research enough sites/books/articles. The method I used to *ESTIMATE* the calorie burn was as follows. a) Find a step aerobics machine which has a calories burned* readout. b) Use an HRM and set the machine to various resistances. For each resistance setting, wait until your heart rate stablises, and note the Hr/Calories readings. c) Plot a graph of these figures d) Use an HRM that will give you a mean Hr for your ride, and use that against your graph to determine your approximate calorie burn. * Try and determine if the calorie readout is the number of calories calculated from the kg/m raised on the machine, or whether the machine introduces a "fudge factor" to account for the inefficiency of human power generation/delivery. If it is the former, it will be a considerable underestimate of the calories burned. All the heat you produce is on top of the energy used to effectively raise your body mass the distance used in the calculation. If you can do the maths, you can use the Hr/Cal figures to produce an equation, but as the relationship is non linear, it's not that easy Apart from the above, I would say that the algorithm given based on mean Hr and weight has the best chance of being accurate, although both this, and the moethod I outline above will not be too good if there is a large variation in Hr during your ride. Plus if you're training for aerobic fitness, your HR for given effort is going to vary over time. -- Cheers, Euan Gawnsoft: http://www.gawnsoft.co.sr Symbian/Epoc wiki: http://html.dnsalias.net:1122 Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk |
#26
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So my question is "why bother?"
Really, what do you do with this number once you have it? Do you calculate this so that you can justify an extra Twinkie? I think information is a good thing. But I also think that endless amounts of data are a waste of time. Having a good fix on caloric consumption may be useful at high levels of competiton for such long distance events as TDF, the Giro, etc. But what use is it to the recreational rider? Are you really going to count your calories in vs. out? I think it's a bit silly. If you have a scale you can easily monitor 1) short term wt loss (from a ride) which is a measure of dehydration and 2) long term weight change trends which is actual weight loss or gain. Calculating it on the ride seems to be an effort to have a number and little more. |
#27
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So my question is "why bother?"
Really, what do you do with this number once you have it? Do you calculate this so that you can justify an extra Twinkie? I think information is a good thing. But I also think that endless amounts of data are a waste of time. Having a good fix on caloric consumption may be useful at high levels of competiton for such long distance events as TDF, the Giro, etc. But what use is it to the recreational rider? Are you really going to count your calories in vs. out? I think it's a bit silly. If you have a scale you can easily monitor 1) short term wt loss (from a ride) which is a measure of dehydration and 2) long term weight change trends which is actual weight loss or gain. Calculating it on the ride seems to be an effort to have a number and little more. |
#28
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"Peter Cole" wrote:
"VBadJuJu" none@ wrote Highly accurate too at least as to speed (and therefore distance, avg speed etc). Recently there was one of those automated radar speed things down the street off and on for about 9 weeks. Coming down the hill on my way out to ride I could verify the read out vs the radar thingie. Bike "computers" are simple wheel revolution counters, they're all as accurate as the tire size input. No, not "all" of them, which is why I mentioned the accuracy. Counting revs alone will only get you the distance covered. You need the capability to track the time between revs with a degree of accuracy and granularity. I've had more than one very cheapie that had serious trouble tracking that time and therefore the speed readout was inconsistant. On one I suspect the average speed was ok, but the sporadic flashes of 141 MPH left me with little overall confidence. Another only seemed to be accurate as to time factors when the battery was brand new: otherwise after a 2++ hour excursion, the 'ride time' would report as 38 mins. FWIW, 13 - 15 miles works out to about 1000 calories at 10.5 - 11.5 MPH average for me. That sounds off by a factor of 4 or so, it's way too high unless that is up a very steep hill. You can't accurately measure calories without measuring watts, and that's a difficult thing to do, the equipment is available to do that (e.g. Powertap), but it's expensive. Apparently it is pretty accurate, more so than you imagine. It is quite in line with several online fitness calculator/estimates: 1000 vs 997 vs 1060 vs 1297 vs 937 vs 1301. (I forget the exact weight factor I have input on the 'puter, so the max variance of 300 doesnt bother me; the average variance is only 144.) One key element would be the type of bike/tire. Obviously fewer calories are burned on a road bike at 11 MPH than a mountain bike. Using the same factors, the online calculators result in only 600 - 900 calories for generic bicycling - still about double your estimate. Given that the calculator is so in keeping with the other estiamtions, I suspect the computer infers the bike/tire type from the wheel factor input. YMMV |
#29
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"Peter Cole" wrote:
"VBadJuJu" none@ wrote Highly accurate too at least as to speed (and therefore distance, avg speed etc). Recently there was one of those automated radar speed things down the street off and on for about 9 weeks. Coming down the hill on my way out to ride I could verify the read out vs the radar thingie. Bike "computers" are simple wheel revolution counters, they're all as accurate as the tire size input. No, not "all" of them, which is why I mentioned the accuracy. Counting revs alone will only get you the distance covered. You need the capability to track the time between revs with a degree of accuracy and granularity. I've had more than one very cheapie that had serious trouble tracking that time and therefore the speed readout was inconsistant. On one I suspect the average speed was ok, but the sporadic flashes of 141 MPH left me with little overall confidence. Another only seemed to be accurate as to time factors when the battery was brand new: otherwise after a 2++ hour excursion, the 'ride time' would report as 38 mins. FWIW, 13 - 15 miles works out to about 1000 calories at 10.5 - 11.5 MPH average for me. That sounds off by a factor of 4 or so, it's way too high unless that is up a very steep hill. You can't accurately measure calories without measuring watts, and that's a difficult thing to do, the equipment is available to do that (e.g. Powertap), but it's expensive. Apparently it is pretty accurate, more so than you imagine. It is quite in line with several online fitness calculator/estimates: 1000 vs 997 vs 1060 vs 1297 vs 937 vs 1301. (I forget the exact weight factor I have input on the 'puter, so the max variance of 300 doesnt bother me; the average variance is only 144.) One key element would be the type of bike/tire. Obviously fewer calories are burned on a road bike at 11 MPH than a mountain bike. Using the same factors, the online calculators result in only 600 - 900 calories for generic bicycling - still about double your estimate. Given that the calculator is so in keeping with the other estiamtions, I suspect the computer infers the bike/tire type from the wheel factor input. YMMV |
#30
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"VBadJuJu" none@ wrote in message
... "chris christanis" wrote: I had a cheap Bell computer that did it for me but it fell off (cheap). So I bought a cateye but it does not tell you calories burned. Anyway to figure this out? I have one of those and think it is great. The only other cyclocomputer I've seen with calorie consumption estimation was in the $150 range (and *not* cordless IIRC). In that light, I see them as a *value* not "cheap", but also expect that feature will show up on more of the better 'puters next year. Highly accurate too at least as to speed (and therefore distance, avg speed etc). Recently there was one of those automated radar speed things down the street off and on for about 9 weeks. Coming down the hill on my way out to ride I could verify the read out vs the radar thingie. FWIW, 13 - 15 miles works out to about 1000 calories at 10.5 - 11.5 MPH average for me. No way would you burn 1000 calories going that slow, for that short a time, unless the rider is very large. Where did you get that estimate? 1000 calories in 14 miles works out to over 71 calories per mile, which is very high (especially at that speed). Per my CycliStats program's Calorie & Watts Calculator, assuming "Rolling" terrain (422 feet of elevation gain), and a standard road bike configuration (18.5 lb bike, with the rider mostly on the hoods), a 150 lb rider would burn 405 calories, while a 200 lb rider would burn 488 calories. Assuming the ride was done on a mountain bike (24.5 lb bike, with knobby tires and a more upright rider position), the 150 lb rider would burn around 573 calories, and the 200 lb rider would burn 697 calories. By way of comparison, 14 miles at 11 mph would take 1 hr and 16 minutes. Per www.caloriesperhour.com a 150 lb rider would burn 517 calories in that time. A 200 lb rider would burn 689 calories. ~_-* ....G/ \G http://www.CycliStats.com CycliStats - Software for Cyclists |
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