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  #11  
Old June 4th 18, 06:11 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 2,767
Default MTB randonneur

On Sun, 03 Jun 2018 20:06:31 +0200, Emanuel Berg
wrote:

Jeff Liebermann wrote:

How wide a tire do you need?


I don't need especially wide tires. Just not 32
and preferably wider than 35. Shooting from the
holster, I'd say my prefered tire size is
622-40, 622-42, or 622-47.


Methinks they are the same as 28x1.50, 28x1.60, and 28x1.75.
Looking at Schwalbe touring tires, they're available in those sizes in
a variety of tread patterns.
https://www.schwalbetires.com/bike_tires/road_tires

Perhaps custom rims might be a solution. Something like this:
http://www.spontaneousfire.com/trikeofdeath.htm
For normal riding, you only install one tire on the extra wide rim.
For heavy loads or touring, you install two tires. This arrangement
might also provide useful redundancy in the event you get a flat tire.
I think 3 side by side tires might be better than two. Soon, everyone
will be riding on extra wide rims and multiple tires.

But this is me just projecting the project
based on my general experience and what
I've read. I never did any randonneuring
whatsoever on any bike!


Neither have I, and it shows. However, I have done some touring and
bicycle camping in the distant past. Prior to these adventures, I did
read some books and magazine articles on touring. I then ignored most
of the advice and did what I thought best, with predictable results.

Incidentally, I also used my touring bicycle to do local service calls
in my computer repair business. At the time, computers were still too
big and heavy to be effectively transported on a bicycle. I also had
to carry several filing boxes full of floppy disks and a mess of
tools. Leaving anything on a parked bicycle was a security problem. I
might try it again as the computers are much smaller today and all the
software I need are now on about five USB flash drives.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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  #12  
Old June 4th 18, 10:31 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 829
Default MTB randonneur

Jeff Liebermann wrote:

I don't need especially wide tires. Just not
32 and preferably wider than 35.
Shooting from the holster, I'd say my
prefered tire size is 622-40, 622-42, or
622-47.


Methinks they are the same as 28x1.50,
28x1.60, and 28x1.75.


I think you are right:

47-622 28 x 1.75 x 2
47-622 28 x 1-5/8 x 1-3/4 700x45C 28x1.75
47-622 27 x 1.75 700x45C
42-622 28 x 1-5/8 700x40C
40-622 28 x 1-5/8 x 1-1/2 700x38C

These digits BTW are simply what I have found
on tires so there is no attempt at normalizing
the English sizes. It seems sometimes they say
1-3/4 and sometimes 1.75.

I also have these:

37-622 28 x 15/8 x 13/8 700x35C
32-622 28 x 14/8 x 10/8

Perhaps just lack of
standardization/normalization behind those
"more than 8 eights" fractions...? Some of the
decimals seem to be unexpressable (cleanly) as
eights or sixteenths tho?

--
underground experts united
http://user.it.uu.se/~embe8573
  #13  
Old June 4th 18, 11:08 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 829
Default MTB randonneur

Perhaps just lack of
standardization/normalization behind those
"more than 8 eights" fractions...? Some of
the decimals seem to be unexpressable
(cleanly) as eights or sixteenths tho?


Is this [1] the correct algorithm?
It translates 1.75 into 1-3/4 at least :P

ths () {
local value=$1
local denom=${2:-16}
local whole=$(( int(floor($value)) ))
local rest=$(( $value - $whole ))
local frac=$(( int(rint($rest * $denom)) ))
if (( $(( $frac % 2 )) == 0 )); then
local new_denom=$(( denom / 2 ))
ths $value $new_denom
else
echo $whole-${frac}/${denom}
fi
}
# $ ths 1.75
# 1-3/4

[1] http://user.it.uu.se/~embe8573/conf/.zsh/math

--
underground experts united
http://user.it.uu.se/~embe8573
  #14  
Old June 5th 18, 06:25 AM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 2,767
Default MTB randonneur

On Tue, 05 Jun 2018 00:08:22 +0200, Emanuel Berg
wrote:

Perhaps just lack of
standardization/normalization behind those
"more than 8 eights" fractions...? Some of
the decimals seem to be unexpressable
(cleanly) as eights or sixteenths tho?


Is this [1] the correct algorithm?
It translates 1.75 into 1-3/4 at least :P


Wrong. A 26x1.5 tire and a 26x1-1/2 tire are different tire sizing
systems:
http://www.sheldonbrown.com/tire-sizing.html
See charts of fractional and decimal sizes.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #15  
Old June 5th 18, 01:01 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 829
Default MTB randonneur

Jeff Liebermann wrote:

A 26x1.5 tire and a 26x1-1/2 tire are
different tire sizing systems:
http://www.sheldonbrown.com/tire-sizing.html
See charts of fractional and decimal sizes.


It says this [1], but doesn't explain how the
systems work what I can see. If you compare one
2x1.5 and a 26x1-1/2, why are they not
interchangeable, and what tire is wider?

In my experience the width is less important
than the diameter. One can make it work with
different widths. But perhaps that is different
in the road bike and MTB worlds?

BTW is this also a "different tire sizing
system"

37-622 28 x 15/8 x 13/8 700x35C
32-622 28 x 14/8 x 10/8

?

[1] Does Point Seven Five Equal Three Quarters?

Inch-based designations sometimes express the
width in a decimal (26 x 1.75) and sometimes as
a common fraction (26 x 1 3/4). This is the
most common cause of mismatches. Although these
size designations are mathematically equal,
they refer to different size tires, which are
NOT interchangeable. It is dangerous to
generalize when talking about tire sizing, but
I would confidently state the following:

Brown's Law Of Tire Sizing:

If two tires are marked with sizes that are
mathematically equal, but one is expressed as
a decimal and the other as a fraction, these
two tires will not be interchangeable.

--
underground experts united
http://user.it.uu.se/~embe8573
  #16  
Old June 5th 18, 04:04 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 2,767
Default MTB randonneur

On Tue, 05 Jun 2018 14:01:19 +0200, Emanuel Berg
wrote:

Jeff Liebermann wrote:

A 26x1.5 tire and a 26x1-1/2 tire are
different tire sizing systems:
http://www.sheldonbrown.com/tire-sizing.html
See charts of fractional and decimal sizes.


It says this [1], but doesn't explain how the
systems work what I can see.


For those who believe, no explanation is necessary.
For those who do not believe, no explanation is possible.

Brown's Law Of Tire Sizing:

If two tires are marked with sizes that are
mathematically equal, but one is expressed as
a decimal and the other as a fraction, these
two tires will not be interchangeable.


So the prophet has written, so it must be.

Google a little for some history on the topic. You'll get a wide
variety of explanations and conspiracy theories.
https://www.google.com/search?q=history+of+bicycle+tire+sizes

For example:

The History of Mountain Bike Wheel Size (Gary Fisher)
https://www.youtube.com/watch?v=8syt59gK65o (4:07)

https://mariposabicycles.ca/blog/2015/01/26/tire-and-rim-sizes/
"Since the article was written, 650B wheels and tires have
become popular and more easily available. But to confuse
matters, they are now being called 27.5’s which makes no
sense as they are far smaller than 27? wheels. And, 29’ers
are in fact 700c wheels with larger section tires, adding
a little more confusion to an already nonsensical subject."

To insure maximum confusion, 1 inch = 25 mm.
A guide to tyre sizes.
http://www.users.globalnet.co.uk/~pattle/ddgcs/tyres.htm
I'm not sure if they use Pi = 3.14159 or 3.0 in the calculations.

In my never humble opinion, you can't specify bicycle tires with just
two numbers. See how automobile tires are specified for an example of
how it could and should be done. If that means yet another numbering
system, so be it.
https://tiresize.com/conversion-chart/


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #17  
Old June 5th 18, 04:11 PM posted to rec.bicycles.tech
David Scheidt
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Posts: 1,233
Default MTB randonneur

Emanuel Berg wrote:
:Jeff Liebermann wrote:

: A 26x1.5 tire and a 26x1-1/2 tire are
: different tire sizing systems:
: http://www.sheldonbrown.com/tire-sizing.html
: See charts of fractional and decimal sizes.

:It says this [1], but doesn't explain how the
:systems work what I can see. If you compare one

What "System"? They're tire sizes. They were invented by some
manufacturer, who thought there was a market, at different times and
different places. 26x 1 3/4 is the same
as 650C, which was commonly used on triathalon bikes. 26 x 1.75 is a
US size that was used for beach cruisers with wide tires; those bikes
became the first mountain bikes, whcih is why 26" ruled the mountain
bike world until someone thought we needed 29ers and 27.5 ers.

:2x1.5 and a 26x1-1/2, why are they not
:interchangeable, and what tire is wider?

2xdecimal are 571 mm diameter, 25X1 1/2 is 559. Unless I have that
backwards, which I probably do. Then it's the other way around.
Either way, it's clear why tires are not interchangable. Bike tire
widths are all a fantasy, so who knows which is wider.


--
sig 72
  #18  
Old June 5th 18, 04:26 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 829
Default MTB randonneur

David Scheidt wrote:

2x1.5 and a 26x1-1/2, why are they not
interchangeable, and what tire is wider?


2xdecimal are 571 mm diameter, 25X1 1/2 is 559.
Unless I have that backwards, which I probably
do. Then it's the other way around. Either way,
it's clear why tires are not interchangable.
Bike tire widths are all a fantasy, so who
knows which is wider.


26xdecimal is 571 and 26x1-1/2 is 559?
But I have 26x1-1/2 that are 584. I also have
26xdecimal that are 559! Or did you really
mean 25?

44-584 26 x 1-5/8 x 1-1/2
40-584 26 x 1-1/2 650x35B
[...]
56-559 26 x 2.10
559 26 x 2 MTB and derivatives
26 x 2 trailer, 2 - 19-3/4
50-559 26 x 2.0
50-559 26 x 1.95

But OK, it *is* the diameter that is different
after all! And you know this by examining not
the digits but the notational styles of the
tire width indication?

Wow, it makes sense even to me!

--
underground experts united
http://user.it.uu.se/~embe8573
  #19  
Old June 5th 18, 11:10 PM posted to rec.bicycles.tech
JBeattie
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Posts: 3,098
Default MTB randonneur

On Tuesday, June 5, 2018 at 8:11:10 AM UTC-7, David Scheidt wrote:
Emanuel Berg wrote:
:Jeff Liebermann wrote:

: A 26x1.5 tire and a 26x1-1/2 tire are
: different tire sizing systems:
: http://www.sheldonbrown.com/tire-sizing.html
: See charts of fractional and decimal sizes.

:It says this [1], but doesn't explain how the
:systems work what I can see. If you compare one

What "System"? They're tire sizes. They were invented by some
manufacturer, who thought there was a market, at different times and
different places. 26x 1 3/4 is the same
as 650C, which was commonly used on triathalon bikes. 26 x 1.75 is a
US size that was used for beach cruisers with wide tires; those bikes
became the first mountain bikes, whcih is why 26" ruled the mountain
bike world until someone thought we needed 29ers and 27.5 ers.

:2x1.5 and a 26x1-1/2, why are they not
:interchangeable, and what tire is wider?

2xdecimal are 571 mm diameter, 25X1 1/2 is 559. Unless I have that
backwards, which I probably do. Then it's the other way around.
Either way, it's clear why tires are not interchangable. Bike tire
widths are all a fantasy, so who knows which is wider.


Why is an inch an inch? Why isn't it like an inch and a quarter -- or a quarter inch. They did that with millimeters. Have you seen how small those are? I bet that some guy came up with a millimeter and showed it to his boss who said, "no, too big . . . make it smaller." It's the same deal with tires.
Did I mention mountain lions? Why do they have three names -- cougars, pumas and mountain lions. Is one larger than the other? Is one a metric size? Can you use a puma when the manufacturer specifies a cougar? Can you? Can you? Hey, mister . . .

-- Jay Beattie.
  #20  
Old June 6th 18, 10:01 PM posted to rec.bicycles.tech
SMS
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Posts: 8,214
Default MTB randonneur

On 6/3/2018 10:20 AM, Emanuel Berg wrote:
Perhaps this was approached from the wrong
angle, if one desires wide tires, perhaps one
should get a 28" MTB steel frame and only have
the gear loaded the same way?


I've certainly seen a lot of people touring on a hardtail mountain bike,
using narrower tires than the bike came with. But good luck finding a
steel mountain bike these days. They exist, but they are expensive.

 




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