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.)

--
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Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

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

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

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.

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

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

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.

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

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