#31
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Wheel weight
On Tuesday, March 5, 2019 at 2:41:33 PM UTC-8, James wrote:
On 6/3/19 2:48 am, wrote: On Tuesday, March 5, 2019 at 7:45:36 AM UTC-8, wrote: The carbon clinchers: Front; 1.13 Kg Rear with 11-29 cassette; 1.58 Kg. That is with tires and tubes. And the speedo magnet. If you changed to a Garmin or other GPS based speedometer, you could save valuable grams from the front wheel because there's no need for a magnet. -- JS Firstly a GPS based system is not accurate - all of those ups and downs are not counted and on a long ride can add up to several miles. Secondly, the wheel magnets I use weigh less than one gram. I am always amazed that people think that "modern technology" is better than older simply because it is newer. |
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#32
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Wheel weight
On Tuesday, March 5, 2019 at 5:47:46 PM UTC-8, John B. Slocomb wrote:
On Tue, 5 Mar 2019 16:44:03 -0800, "Mark J." wrote: On 3/5/2019 3:20 PM, John B. Slocomb wrote: On Wed, 6 Mar 2019 09:41:29 +1100, James wrote: On 6/3/19 2:48 am, wrote: On Tuesday, March 5, 2019 at 7:45:36 AM UTC-8, wrote: The carbon clinchers: Front; 1.13 Kg Rear with 11-29 cassette; 1.58 Kg. That is with tires and tubes. And the speedo magnet. If you changed to a Garmin or other GPS based speedometer, you could save valuable grams from the front wheel because there's no need for a magnet. I've always been a little skeptical about GPS calculated measurements. I remember back when we lived on the boat the GPS would sometimes measure the altitude at 10 feet which was about twice the height above sea level that the receiving antenna was mounted at. As you should be; GPS has a notoriously large margin of error for measuring altitude. I think it's the trigonometry of the computation; the GPS (as I understand it) measures distance to a collection of satellites whose positions are well known, then computes location from triangulating the results. I'm guessing that since most of the satellites are usually not directly overhead, but rather the line of sight to the satellite is usually be much closer to tangential to the earth, then very small errors in the distance-to-satellite computation turn into much larger errors in the altitude computation. I think this is why higher-end bike GPS's have a pressure-based altimeter as well, to correct the fluctuations in the GPS-computed altitude. I know my Garmin Edge's regularly solicit known altitude input at the start of a course. Mark J. I'm not sure about how accurate GPS really is but back in the day, the seismic folks had a large "Black Box" that they used to locate their seismic lines on the chart that they said was accurate to within feet. -- Cheers, John B. There is a great deal of difference between positional accuracy and actual ground distance traveled. |
#33
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Wheel weight
On 3/6/2019 9:35 AM, Zen Cycle wrote:
I also remember the cornering issue. I bought a rather nice garmin unit about ten years ago, and was frustrated when I found out the averaging was locked at 5 seconds (if there was a way to decrease the sampling interval, I couldn't find it). "Couldn't find it" is a beef I have with lots of electronic devices. About a week ago, the GPS in my car showed me a display I'd never seen befo a complete list of all the satellites it could see. I'd been fumbling with it in the dark (not driving) and I couldn't see how I'd gotten that display. But I needed to get going so I thought "I'll look into it later." A few days later I spent a good five minutes going through every menu I could find. I never located that satellite display again. That GPS is old, sort of primitive, and I seldom update it. For me, the problem is worst for devices for which they push updates. "Oh look, they've updated the interface for that app! _Now_ how do I get it to do what I want?" -- - Frank Krygowski |
#34
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Wheel weight
On 3/6/2019 9:02 AM, AMuzi wrote:
On 3/5/2019 9:55 PM, jbeattie wrote: I have no instrumentation. I like surprises at the end of the ride when I ask my fully instrumented riding buddies how far we went and how much we climbed -- then I round up. No data to prove me wrong. I adopt my son's power data when we're riding together since we're both about the same weight, although he is all muscle and I'm muscle and other things.Â* He gave me a Stages GPS Garmin-ish thing from work, but I haven't put it on my bike. It sends me an e-mail every week reminding me that I haven't ridden any miles.Â* That's super helpful. +1 I don't need to know; it's not why I ride. Back in the mid-1980s I got my first cyclometer. For me, it was useful motivation for training - as in "I'm only going 19 mph? I can go faster than that!" Nowadays the data is just depressing. I try not to look at it too much. -- - Frank Krygowski |
#35
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Wheel weight
On Wednesday, March 6, 2019 at 11:16:38 AM UTC-5, Frank Krygowski wrote:
On 3/6/2019 9:35 AM, Zen Cycle wrote: I also remember the cornering issue. I bought a rather nice garmin unit about ten years ago, and was frustrated when I found out the averaging was locked at 5 seconds (if there was a way to decrease the sampling interval, I couldn't find it). "Couldn't find it" is a beef I have with lots of electronic devices. About a week ago, the GPS in my car showed me a display I'd never seen befo a complete list of all the satellites it could see. I'd been fumbling with it in the dark (not driving) and I couldn't see how I'd gotten that display. But I needed to get going so I thought "I'll look into it later." A few days later I spent a good five minutes going through every menu I could find. I never located that satellite display again. That GPS is old, sort of primitive, and I seldom update it. For me, the problem is worst for devices for which they push updates. "Oh look, they've updated the interface for that app! _Now_ how do I get it to do what I want?" gawd I hate that! |
#36
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Wheel weight
On Wednesday, March 6, 2019 at 3:29:13 PM UTC+1, duane wrote:
On 06/03/2019 9:02 a.m., AMuzi wrote: On 3/5/2019 9:55 PM, jbeattie wrote: On Tuesday, March 5, 2019 at 7:28:17 PM UTC-8, James wrote: On 6/3/19 12:47 pm, John B. Slocomb wrote: On Tue, 5 Mar 2019 16:44:03 -0800, "Mark J." wrote: I think it's the trigonometry of the computation; the GPS (as I understand it) measures distance to a collection of satellites whose positions are well known, then computes location from triangulating the results.Â* I'm guessing that since most of the satellites are usually not directly overhead, but rather the line of sight to the satellite is usually be much closer to tangential to the earth, then very small errors in the distance-to-satellite computation turn into much larger errors in the altitude computation. I think this is why higher-end bike GPS's have a pressure-based altimeter as well, to correct the fluctuations in the GPS-computed altitude.Â* I know my Garmin Edge's regularly solicit known altitude input at the start of a course. I'm not sure about how accurate GPS really is but back in the day, the seismic folks had a large "Black Box" that they used to locate their seismic lines on the chart that they said was accurate to within feet. |
#37
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Wheel weight
On Wednesday, March 6, 2019 at 11:12:05 AM UTC-8, wrote:
On Wednesday, March 6, 2019 at 3:29:13 PM UTC+1, duane wrote: On 06/03/2019 9:02 a.m., AMuzi wrote: On 3/5/2019 9:55 PM, jbeattie wrote: On Tuesday, March 5, 2019 at 7:28:17 PM UTC-8, James wrote: On 6/3/19 12:47 pm, John B. Slocomb wrote: On Tue, 5 Mar 2019 16:44:03 -0800, "Mark J." wrote: I think it's the trigonometry of the computation; the GPS (as I understand it) measures distance to a collection of satellites whose positions are well known, then computes location from triangulating the results.Â* I'm guessing that since most of the satellites are usually not directly overhead, but rather the line of sight to the satellite is usually be much closer to tangential to the earth, then very small errors in the distance-to-satellite computation turn into much larger errors in the altitude computation. I think this is why higher-end bike GPS's have a pressure-based altimeter as well, to correct the fluctuations in the GPS-computed altitude.Â* I know my Garmin Edge's regularly solicit known altitude input at the start of a course. I'm not sure about how accurate GPS really is but back in the day, the seismic folks had a large "Black Box" that they used to locate their seismic lines on the chart that they said was accurate to within feet. Mark is pretty close to the correct reason. Most GPS receivers intentionally track satellites that are close to the horizon as opposed to direct overhead.Â* This is so that the X-Y part of the position information is most accurate, at the expense of less accurate Z position. The overall accuracy depends greatly on the GPS receiver quality.Â* The cheap receivers (say $50 ea) may be within a few meters, while expensive receivers ($500) are 10 times better.Â* If you pay more ($10,000) and incorporate corrections for atmospheric conditions and such, accuracy can be better still. The difference between cheap and expensive is largely down to the stability of the oscillator used to time signals.Â* The antennas can also be an expensive part and play a big role in accuracy and reflected signal rejection. But...Â* Even cheap GPS receivers are relatively stable over a short time.Â* They usually produce a position, speed and heading once per second.Â* The previous position, speed and heading are combined with new measurements in a special filter, that usually results in better accuracy than if the measurements were used alone. The only times I've noticed real problems is when you cycle relatively fast around tight corners.Â* The GPS position effectively cuts a little off the corner each time, modelling it as a series of straight lines. Hence your road speed appears to be slower than it really is and you appear to accelerate again when the road straightens out. More expensive GPS receivers can produce calculated position results more frequently than 1 per second.Â* More powerful processor.Â* More power consumption.Â* Unlikely to be in a battery operated consumer grade bike computer. But I find that they are accurate enough not to miss the magnet and reed switch. I have no instrumentation. I like surprises at the end of the ride when I ask my fully instrumented riding buddies how far we went and how much we climbed -- then I round up. No data to prove me wrong. I adopt my son's power data when we're riding together since we're both about the same weight, although he is all muscle and I'm muscle and other things.Â* He gave me a Stages GPS Garmin-ish thing from work, but I haven't put it on my bike. It sends me an e-mail every week reminding me that I haven't ridden any miles.Â* That's super helpful. -- Jay Beattie. +1 I don't need to know; it's not why I ride. I, on the other hand, am pretty wired up with my Garmin and Strava and RideWithGPS. I like the stats to show my progress. I find the GPS helps me when leading groups on rides that I don't know the route so well. Less problematic than paper maps. What's cool about cycling is that we are both happy with what we have. GPS based cycling computers with navagation capabilities is one of the best and niciest cycling accesory IMO. Everything in one unit, never have to stop to look at a map, automatic logging and uploading, easy swap between bikes, clean cockpit, user definable datafield (number and content). What is there not to like? https://photos.app.goo.gl/R11bCJx9DAaYHuDQA (map, cadence and power) After my last crash we had a discussion with the insurance company of the woman I crashed into about my speed at the time of the crash. She accused me of excessive speed. I knew exactly my speed: https://photos.app.goo.gl/vt8X8cetjpNfotfd9 That was settled then. Lou If you're not sure where you're going and they have a BICYCLE navigation feature they have advantages. But I can do the same thing with my smart phone minus the altitude function. |
#38
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Wheel weight
On Wednesday, March 6, 2019 at 8:41:40 PM UTC+1, wrote:
On Wednesday, March 6, 2019 at 11:12:05 AM UTC-8, wrote: On Wednesday, March 6, 2019 at 3:29:13 PM UTC+1, duane wrote: On 06/03/2019 9:02 a.m., AMuzi wrote: On 3/5/2019 9:55 PM, jbeattie wrote: On Tuesday, March 5, 2019 at 7:28:17 PM UTC-8, James wrote: On 6/3/19 12:47 pm, John B. Slocomb wrote: On Tue, 5 Mar 2019 16:44:03 -0800, "Mark J." wrote: I think it's the trigonometry of the computation; the GPS (as I understand it) measures distance to a collection of satellites whose positions are well known, then computes location from triangulating the results.Â* I'm guessing that since most of the satellites are usually not directly overhead, but rather the line of sight to the satellite is usually be much closer to tangential to the earth, then very small errors in the distance-to-satellite computation turn into much larger errors in the altitude computation. I think this is why higher-end bike GPS's have a pressure-based altimeter as well, to correct the fluctuations in the GPS-computed altitude.Â* I know my Garmin Edge's regularly solicit known altitude input at the start of a course. I'm not sure about how accurate GPS really is but back in the day, the seismic folks had a large "Black Box" that they used to locate their seismic lines on the chart that they said was accurate to within feet. Mark is pretty close to the correct reason. Most GPS receivers intentionally track satellites that are close to the horizon as opposed to direct overhead.Â* This is so that the X-Y part of the position information is most accurate, at the expense of less accurate Z position. The overall accuracy depends greatly on the GPS receiver quality.Â* The cheap receivers (say $50 ea) may be within a few meters, while expensive receivers ($500) are 10 times better.Â* If you pay more ($10,000) and incorporate corrections for atmospheric conditions and such, accuracy can be better still. The difference between cheap and expensive is largely down to the stability of the oscillator used to time signals.Â* The antennas can also be an expensive part and play a big role in accuracy and reflected signal rejection. But...Â* Even cheap GPS receivers are relatively stable over a short time.Â* They usually produce a position, speed and heading once per second.Â* The previous position, speed and heading are combined with new measurements in a special filter, that usually results in better accuracy than if the measurements were used alone. The only times I've noticed real problems is when you cycle relatively fast around tight corners.Â* The GPS position effectively cuts a little off the corner each time, modelling it as a series of straight lines. Hence your road speed appears to be slower than it really is and you appear to accelerate again when the road straightens out. More expensive GPS receivers can produce calculated position results more frequently than 1 per second.Â* More powerful processor.Â* More power consumption.Â* Unlikely to be in a battery operated consumer grade bike computer. But I find that they are accurate enough not to miss the magnet and reed switch. I have no instrumentation. I like surprises at the end of the ride when I ask my fully instrumented riding buddies how far we went and how much we climbed -- then I round up. No data to prove me wrong. I adopt my son's power data when we're riding together since we're both about the same weight, although he is all muscle and I'm muscle and other things.Â* He gave me a Stages GPS Garmin-ish thing from work, but I haven't put it on my bike. It sends me an e-mail every week reminding me that I haven't ridden any miles.Â* That's super helpful. -- Jay Beattie. +1 I don't need to know; it's not why I ride. I, on the other hand, am pretty wired up with my Garmin and Strava and RideWithGPS. I like the stats to show my progress. I find the GPS helps me when leading groups on rides that I don't know the route so well. Less problematic than paper maps. What's cool about cycling is that we are both happy with what we have.. GPS based cycling computers with navagation capabilities is one of the best and niciest cycling accesory IMO. Everything in one unit, never have to stop to look at a map, automatic logging and uploading, easy swap between bikes, clean cockpit, user definable datafield (number and content). What is there not to like? https://photos.app.goo.gl/R11bCJx9DAaYHuDQA (map, cadence and power) After my last crash we had a discussion with the insurance company of the woman I crashed into about my speed at the time of the crash. She accused me of excessive speed. I knew exactly my speed: https://photos.app.goo.gl/vt8X8cetjpNfotfd9 That was settled then. Lou If you're not sure where you're going and they have a BICYCLE navigation feature they have advantages. But I can do the same thing with my smart phone minus the altitude function. I doubt that. Does your phone have a battery life of 15-20 hours with the screen on? Can you use your phone in the rain without a clumsy cover? Lou |
#40
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Wheel weight
On 06/03/2019 2:51 p.m., wrote:
On Wednesday, March 6, 2019 at 8:41:40 PM UTC+1, wrote: On Wednesday, March 6, 2019 at 11:12:05 AM UTC-8, wrote: On Wednesday, March 6, 2019 at 3:29:13 PM UTC+1, duane wrote: On 06/03/2019 9:02 a.m., AMuzi wrote: On 3/5/2019 9:55 PM, jbeattie wrote: On Tuesday, March 5, 2019 at 7:28:17 PM UTC-8, James wrote: On 6/3/19 12:47 pm, John B. Slocomb wrote: On Tue, 5 Mar 2019 16:44:03 -0800, "Mark J." wrote: I think it's the trigonometry of the computation; the GPS (as I understand it) measures distance to a collection of satellites whose positions are well known, then computes location from triangulating the results.Â* I'm guessing that since most of the satellites are usually not directly overhead, but rather the line of sight to the satellite is usually be much closer to tangential to the earth, then very small errors in the distance-to-satellite computation turn into much larger errors in the altitude computation. I think this is why higher-end bike GPS's have a pressure-based altimeter as well, to correct the fluctuations in the GPS-computed altitude.Â* I know my Garmin Edge's regularly solicit known altitude input at the start of a course. I'm not sure about how accurate GPS really is but back in the day, the seismic folks had a large "Black Box" that they used to locate their seismic lines on the chart that they said was accurate to within feet. Mark is pretty close to the correct reason. Most GPS receivers intentionally track satellites that are close to the horizon as opposed to direct overhead.Â* This is so that the X-Y part of the position information is most accurate, at the expense of less accurate Z position. The overall accuracy depends greatly on the GPS receiver quality.Â* The cheap receivers (say $50 ea) may be within a few meters, while expensive receivers ($500) are 10 times better.Â* If you pay more ($10,000) and incorporate corrections for atmospheric conditions and such, accuracy can be better still. The difference between cheap and expensive is largely down to the stability of the oscillator used to time signals.Â* The antennas can also be an expensive part and play a big role in accuracy and reflected signal rejection. But...Â* Even cheap GPS receivers are relatively stable over a short time.Â* They usually produce a position, speed and heading once per second.Â* The previous position, speed and heading are combined with new measurements in a special filter, that usually results in better accuracy than if the measurements were used alone. The only times I've noticed real problems is when you cycle relatively fast around tight corners.Â* The GPS position effectively cuts a little off the corner each time, modelling it as a series of straight lines. Hence your road speed appears to be slower than it really is and you appear to accelerate again when the road straightens out. More expensive GPS receivers can produce calculated position results more frequently than 1 per second.Â* More powerful processor.Â* More power consumption.Â* Unlikely to be in a battery operated consumer grade bike computer. But I find that they are accurate enough not to miss the magnet and reed switch. I have no instrumentation. I like surprises at the end of the ride when I ask my fully instrumented riding buddies how far we went and how much we climbed -- then I round up. No data to prove me wrong. I adopt my son's power data when we're riding together since we're both about the same weight, although he is all muscle and I'm muscle and other things.Â* He gave me a Stages GPS Garmin-ish thing from work, but I haven't put it on my bike. It sends me an e-mail every week reminding me that I haven't ridden any miles.Â* That's super helpful. -- Jay Beattie. +1 I don't need to know; it's not why I ride. I, on the other hand, am pretty wired up with my Garmin and Strava and RideWithGPS. I like the stats to show my progress. I find the GPS helps me when leading groups on rides that I don't know the route so well. Less problematic than paper maps. What's cool about cycling is that we are both happy with what we have. GPS based cycling computers with navagation capabilities is one of the best and niciest cycling accesory IMO. Everything in one unit, never have to stop to look at a map, automatic logging and uploading, easy swap between bikes, clean cockpit, user definable datafield (number and content). What is there not to like? https://photos.app.goo.gl/R11bCJx9DAaYHuDQA (map, cadence and power) After my last crash we had a discussion with the insurance company of the woman I crashed into about my speed at the time of the crash. She accused me of excessive speed. I knew exactly my speed: https://photos.app.goo.gl/vt8X8cetjpNfotfd9 That was settled then. Lou If you're not sure where you're going and they have a BICYCLE navigation feature they have advantages. But I can do the same thing with my smart phone minus the altitude function. I doubt that. Does your phone have a battery life of 15-20 hours with the screen on? Can you use your phone in the rain without a clumsy cover? Lou I tried with my iPhone as well using RideWithGPS. In addition to your points, I was rarely able to see the screen on sunny days. |
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