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#11
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Sheldon "I ain't dead yet" Brown appreciation thread!
On Tue, 11 Dec 2007 22:02:58 -0800 (PST), "
may have said: http://www.motherearthnews.com/DIY/1...bent-Bike.aspx http://www.motherearthnews.com/uploa...4-02_01-01.jpg http://www.motherearthnews.com/uploa...-162-01tab.jpg http://www.motherearthnews.com/uploa...162-01tab1.jpg http://www.motherearthnews.com/uploa...081-162-03.jpg http://www.motherearthnews.com/uploa...081-162-02.jpg Interesting, and there might be something in that which I could adapt. My big obstacles have been the steering knuckles and front axles; everything I've seen that looks strong enough has either been beyond budget or beyond tooling. This one, as executed, fails on the flimsiness test, but it contains the seed of something that might work if I can find a stub axle material that will reliably carry the load after being attached to the kingpin (analog of fork tube) using the welding techniques that I can apply. I also have to some up with a pair of wheels that will fill the bill. I might have located them, in the form of 20" wheels from a large lawnmower, however. (It uses a 1/2" straight axle, and the wheels have sealed catridge ball bearings of a common size. I think I know where to get these wheel at a reasonable price.) -- My email address is antispammed; pull WEEDS if replying via e-mail. Typoes are not a bug, they're a feature. Words processed in a facility that contains nuts. |
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#12
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Sheldon "I ain't dead yet" Brown appreciation thread!
Quoth landotter:
Come on'Sheldon, you say the disease is just waist down--so your noggin is good, what kind of cool new crazy ya got going on now?? Well, I upgraded the tires to Scorcher slicks, made a special mount for a video camera and other accessories. Most recent mod was the installation of a NuVinci continuously- variable "gear" hub in place of the rear derailer setup. I've only had the opportunity to ride it a couple of miles since this upgrade, but it seems pretty nice so far! Sheldon "How Many Speeds?" Brown +---------------------------------------+ | There's nothing like not being dead | | to improve a fellow's outlook. | | -- Michael Flynn | +---------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com Useful articles about bicycles and cycling http://sheldonbrown.com |
#13
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Sheldon "I ain't dead yet" Brown appreciation thread!
In article
, Sheldon Brown wrote: Quoth landotter: Come on'Sheldon, you say the disease is just waist down--so your noggin is good, what kind of cool new crazy ya got going on now?? Well, I upgraded the tires to Scorcher slicks, made a special mount for a video camera and other accessories. Most recent mod was the installation of a NuVinci continuously- variable "gear" hub in place of the rear derailer setup. I've only had the opportunity to ride it a couple of miles since this upgrade, but it seems pretty nice so far! Sheldon "How Many Speeds?" Brown If the NuVinci catches on, cyclists will start to think of their gearing in terms of ratio of the lowest to highest gears (ie, 305% gearing indicating that the top gear has about three times the development as the low gear). And then maybe we'll finally get a 55/26 combined with a 11-34 3-speed rear end. -- Ryan Cousineau http://www.wiredcola.com/ "My scenarios may give the impression I could be an excellent crook. Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing |
#14
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Sheldon "I ain't dead yet" Brown appreciation thread!
On Wed, 12 Dec 2007 18:09:33, Ryan Cousineau wrote:
If the NuVinci catches on, cyclists will start to think of their gearing in terms of ratio of the lowest to highest gears (ie, 305% gearing indicating that the top gear has about three times the development as the low gear). You'll still need to worry about the absolute development of either the high or low gear. E.g. an otherwise identical 305% drivetrain on both a 700C wheelset and a 16" wheelset, won't give nearly the same experience to the rider. -alan -- Alan Hoyle - - http://www.alanhoyle.com/ "I don't want the world, I just want your half." -TMBG Get Horizontal, Play Ultimate. |
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Gear range designation
Ryan Cousineau a écrit:
If the NuVinci catches on, cyclists will start to think of their gearing in terms of ratio of the lowest to highest gears (ie, 305% gearing indicating that the top gear has about three times the development as the low gear). That's one way to calculate it, but I don't think it's the _best_ way to calculate it. My gear calculators provide not only values for the individual gears, but also show the percentage difference between adjacent gears. There has been some confusion about this, so here's the skinny: The percentages are mainly of use with derailer or hybrid gearing, where they help the rider determine the most efficient shift pattern, where there are two or three different shifters to be considered. The algorithm is pretty simple. Look at two adjacent gears, then express the higher one as a percentage _increase_ over the lower of the two. For instance, if one gear is 80 inches and the next gear up is 88 inches, that's a 10% increase. The higher gear is 110% of the lower gear, but the increment is only 10%. Manufacturers of internal gear hubs tend to tout the total gear range of their hubs, but they commonly calculate it in a different way. For instance, if there was an internal-gear hub that only covered a range from 80 inches to 88 inches, the manufacturer could say this was a range of 110%. This is a legitimate way to represent the overall range of a gear system, though I prefer the incremental approach, and would call it 10%. Using the overall percentage is not really a good basis for comparison. For example, take this hypothetical gear that gives 80 and 88 inches with some particular set of sprockets. Compare it with, say, a SRAM 7-speed or Sturmey-Archer 8-speed. If you use the "overall" gear to express the range, they're 110% and 305%, so it seems that the 7- or 8-speed has a bit less than 3 times the "range" of the other system. My algorithm would list these hubs as having "ranges" of 10% and 205% respectively, which I think is a more reasonable expression of the gear ranges. I have a work-in-progress Web page that shows the ranges of various hub gears and derailer systems expressed graphically. Check it out at http://sheldonbrown.com/gear-range.html Sheldon "Numbers" Brown |
#16
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Gear range designation
On 13 Dic, 20:59, Sheldon Brown
My gear calculators provide not only values for the individual gears, but also show the percentage difference between adjacent gears. To visualise the progression wouldn't it be better to graph it on a logarithmic scale? Sergio Pisa |
#17
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Gear range designation
On Thu, 13 Dec 2007 11:59:51 -0800 (PST), Sheldon Brown
wrote: Ryan Cousineau a écrit: If the NuVinci catches on, cyclists will start to think of their gearing in terms of ratio of the lowest to highest gears (ie, 305% gearing indicating that the top gear has about three times the development as the low gear). That's one way to calculate it, but I don't think it's the _best_ way to calculate it. My gear calculators provide not only values for the individual gears, but also show the percentage difference between adjacent gears. There has been some confusion about this, so here's the skinny: The percentages are mainly of use with derailer or hybrid gearing, where they help the rider determine the most efficient shift pattern, where there are two or three different shifters to be considered. The algorithm is pretty simple. Look at two adjacent gears, then express the higher one as a percentage _increase_ over the lower of the two. For instance, if one gear is 80 inches and the next gear up is 88 inches, that's a 10% increase. The higher gear is 110% of the lower gear, but the increment is only 10%. Manufacturers of internal gear hubs tend to tout the total gear range of their hubs, but they commonly calculate it in a different way. For instance, if there was an internal-gear hub that only covered a range from 80 inches to 88 inches, the manufacturer could say this was a range of 110%. This is a legitimate way to represent the overall range of a gear system, though I prefer the incremental approach, and would call it 10%. Using the overall percentage is not really a good basis for comparison. For example, take this hypothetical gear that gives 80 and 88 inches with some particular set of sprockets. Compare it with, say, a SRAM 7-speed or Sturmey-Archer 8-speed. If you use the "overall" gear to express the range, they're 110% and 305%, so it seems that the 7- or 8-speed has a bit less than 3 times the "range" of the other system. My algorithm would list these hubs as having "ranges" of 10% and 205% respectively, which I think is a more reasonable expression of the gear ranges. I have a work-in-progress Web page that shows the ranges of various hub gears and derailer systems expressed graphically. Check it out at http://sheldonbrown.com/gear-range.html Sheldon "Numbers" Brown What you're running into is similar to the discussion of whether one needs to look at mark-up or margin in pricing; a 67% mark-up (i.e., the selling price is 167% of the cost) provides a 40% margin. In the real world of retail, however, it's often neither of these which determines whether a product is profitable to sell, but rather the relationship between the cost of the item's presence (which includes the cost of space to display it) vs. the dollar volume directly and indirectly generated by the sales of that item. The bike analogy to *that* discussion would be "does this range of gear ratios adequately fill the needs of the rider in question?", which requires evaluation of factors beyond mere tooth counts and internal gear ratios. I happen to favor the "margin"-analog figure as a means of comparison, since for me it better characterizes the spread between the upper and lower limits, as you implied. For some people, the "markup"-analog (with the initial 100% removed) is easier for them to wrap their heads around. Much of the determinant of preference in this area depends on the kind of math one is accustomed to doing...if any. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#18
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Gear range designation
In article
groups.com, sergio wrote: On 13 Dic, 20:59, Sheldon Brown My gear calculators provide not only values for the individual gears, but also show the percentage difference between adjacent gears. To visualise the progression wouldn't it be better to graph it on a logarithmic scale? For personal use I put the differences in decibels, a logarithmic scale. 0.3 db is about 1.07 times, or a 7% change. For example: 46 49 14 88.7 94.5 16 77.6 82.7 18 69.0 73.5 21 59.1 63.0 24 51.8 55.1 28 44.4 47.2 32 38.8 41.3 38.8 41.3 0.27438 44.4 0.30554 47.2 0.27438 51.8 0.39509 55.1 0.27438 59.1 0.30554 63.0 0.27438 69.0 0.39509 73.5 0.27438 77.6 0.23714 82.7 0.27438 88.7 0.30554 94.5 0.27438 Here is a conversion table for ratio to decibel. 1.00 0.0000 1.01 0.0432 1.02 0.0860 1.03 0.1284 1.04 0.1703 1.05 0.2119 1.06 0.2531 1.07 0.2938 1.08 0.3342 1.09 0.3743 1.10 0.4139 1.11 0.4532 1.12 0.4922 1.13 0.5308 1.14 0.5690 1.15 0.6070 -- Michael Press |
#19
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Gear range designation
In article
, Werehatrack wrote: On Thu, 13 Dec 2007 11:59:51 -0800 (PST), Sheldon Brown wrote: Ryan Cousineau a écrit: If the NuVinci catches on, cyclists will start to think of their gearing in terms of ratio of the lowest to highest gears (ie, 305% gearing indicating that the top gear has about three times the development as the low gear). That's one way to calculate it, but I don't think it's the _best_ way to calculate it. My gear calculators provide not only values for the individual gears, but also show the percentage difference between adjacent gears. There has been some confusion about this, so here's the skinny: The percentages are mainly of use with derailer or hybrid gearing, where they help the rider determine the most efficient shift pattern, where there are two or three different shifters to be considered. The algorithm is pretty simple. Look at two adjacent gears, then express the higher one as a percentage _increase_ over the lower of the two. For instance, if one gear is 80 inches and the next gear up is 88 inches, that's a 10% increase. The higher gear is 110% of the lower gear, but the increment is only 10%. Manufacturers of internal gear hubs tend to tout the total gear range of their hubs, but they commonly calculate it in a different way. For instance, if there was an internal-gear hub that only covered a range from 80 inches to 88 inches, the manufacturer could say this was a range of 110%. This is a legitimate way to represent the overall range of a gear system, though I prefer the incremental approach, and would call it 10%. Using the overall percentage is not really a good basis for comparison. For example, take this hypothetical gear that gives 80 and 88 inches with some particular set of sprockets. Compare it with, say, a SRAM 7-speed or Sturmey-Archer 8-speed. If you use the "overall" gear to express the range, they're 110% and 305%, so it seems that the 7- or 8-speed has a bit less than 3 times the "range" of the other system. My algorithm would list these hubs as having "ranges" of 10% and 205% respectively, which I think is a more reasonable expression of the gear ranges. I have a work-in-progress Web page that shows the ranges of various hub gears and derailer systems expressed graphically. Check it out at http://sheldonbrown.com/gear-range.html Sheldon "Numbers" Brown What you're running into is similar to the discussion of whether one needs to look at mark-up or margin in pricing; a 67% mark-up (i.e., the selling price is 167% of the cost) provides a 40% margin. In the real world of retail, however, it's often neither of these which determines whether a product is profitable to sell, but rather the relationship between the cost of the item's presence (which includes the cost of space to display it) vs. the dollar volume directly and indirectly generated by the sales of that item. The bike analogy to *that* discussion would be "does this range of gear ratios adequately fill the needs of the rider in question?", which requires evaluation of factors beyond mere tooth counts and internal gear ratios. I happen to favor the "margin"-analog figure as a means of comparison, since for me it better characterizes the spread between the upper and lower limits, as you implied. For some people, the "markup"-analog (with the initial 100% removed) is easier for them to wrap their heads around. Much of the determinant of preference in this area depends on the kind of math one is accustomed to doing...if any. Most uses of percentage are intended to deceive: 93.7% of them. -- Michael Press |
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