A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Physics for marketing professionals



 
 
Thread Tools Display Modes
  #51  
Old March 30th 15, 08:24 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default Physics for marketing professionals

On 3/30/2015 2:22 PM, James wrote:
On 31/03/15 01:32, jbeattie wrote:
On Sunday, March 29, 2015 at 8:20:25 PM UTC-7, James wrote:
On 30/03/15 11:08, John B. Slocomb wrote:

But Brandt, in "The Bicycle Wheel", recommended spoke
tension to
be just a tiny bit below "Taco Tension" which would seem
to imply
that loss of a spoke or two would cause the wheel to
distort
severely and thus be unrideable. So a broken Kevlar
lacing would
be only slightly less robust.

That book was written at a time that normal rims for
Jobst were
about 20mm wide and 10mm deep (for tubulars).

The rims were not very strong by themselves. If you try
to taco an
aero aluminium or CF rim today, you will more likely rip
the spoke
through the rim before it tacos, or break spokes, or the
hub.

A better description of good spoke tension is something
like 1/3 of
the yield strength of a spoke.


His favorite rim was the Mod E2/MA2, which was a pretty
robust 450g
rim. You could do the soft-taco thing and the rim would
recover, and
with the double eyelets, you didn't get rim cracking --
usually. I
had some MA2s where the sockets came right through the rim
wall.
Those tensions were also hard on hub flanges and
unworkable for
modern, 130mm high-dish, low weight, lower spoke count
clinchers.
IMO, a better description of spoke tension is the rim
manufacturers'
recommended tension along with some mild thread-lock like
Teflon
paste or linseed oil. I have the first edition of the
book and don't
know if later editions changed the basic formula for
determining
spoke tension, but I always thought that was one part of
the book
that needed revision.


Perhaps my use of the word "strong" did not convey quite
what I meant. I should have written "The rims (Mod E2/MA2)
were not very stiff by themselves."

I still don't believe the MA2 rim is "robust" though, by
today's standards. Modern deep aero rims are far stronger
and stiffer. This is obvious because they don't need 32 or
more spokes to build a reliable wheel.


All that and made of much better material now as well.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


Ads
  #52  
Old March 31st 15, 02:14 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default Physics for marketing professionals

On Monday, March 30, 2015 at 12:24:05 PM UTC-7, AMuzi wrote:
On 3/30/2015 2:22 PM, James wrote:
On 31/03/15 01:32, jbeattie wrote:
On Sunday, March 29, 2015 at 8:20:25 PM UTC-7, James wrote:
On 30/03/15 11:08, John B. Slocomb wrote:

But Brandt, in "The Bicycle Wheel", recommended spoke
tension to
be just a tiny bit below "Taco Tension" which would seem
to imply
that loss of a spoke or two would cause the wheel to
distort
severely and thus be unrideable. So a broken Kevlar
lacing would
be only slightly less robust.

That book was written at a time that normal rims for
Jobst were
about 20mm wide and 10mm deep (for tubulars).

The rims were not very strong by themselves. If you try
to taco an
aero aluminium or CF rim today, you will more likely rip
the spoke
through the rim before it tacos, or break spokes, or the
hub.

A better description of good spoke tension is something
like 1/3 of
the yield strength of a spoke.

His favorite rim was the Mod E2/MA2, which was a pretty
robust 450g
rim. You could do the soft-taco thing and the rim would
recover, and
with the double eyelets, you didn't get rim cracking --
usually. I
had some MA2s where the sockets came right through the rim
wall.
Those tensions were also hard on hub flanges and
unworkable for
modern, 130mm high-dish, low weight, lower spoke count
clinchers.
IMO, a better description of spoke tension is the rim
manufacturers'
recommended tension along with some mild thread-lock like
Teflon
paste or linseed oil. I have the first edition of the
book and don't
know if later editions changed the basic formula for
determining
spoke tension, but I always thought that was one part of
the book
that needed revision.


Perhaps my use of the word "strong" did not convey quite
what I meant. I should have written "The rims (Mod E2/MA2)
were not very stiff by themselves."

I still don't believe the MA2 rim is "robust" though, by
today's standards. Modern deep aero rims are far stronger
and stiffer. This is obvious because they don't need 32 or
more spokes to build a reliable wheel.


All that and made of much better material now as well.


But, alas, the new rims are more prone to spoke hole cracking. The spoke sockets on the E2/MA2 were nice. I cracked a few Aeorheads in the transition from old-style wheel building to new (i.e. building with a tensiometer and a manufacturer's spec tension instead of near-taco tension).

I've never built a pair of deep aero rims, so I don't know how those behave..

-- Jay Beattie.

  #53  
Old March 31st 15, 02:36 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 6,374
Default Physics for marketing professionals

the street level Tiwan/Japanese 10 speed/27" rims were forgiving in trueing up, trueing after bending. malleable 'junk'. World Class not Euro Class. Washers were in vogue.

replaced by the double wall at that extreme.
  #54  
Old March 31st 15, 05:27 AM posted to rec.bicycles.tech
Tim McNamara
external usenet poster
 
Posts: 6,945
Default Physics for marketing professionals

On Mon, 30 Mar 2015 08:32:28 -0700 (PDT), jbeattie
wrote:

His favorite rim was the Mod E2/MA2, which was a pretty robust 450g
rim. You could do the soft-taco thing and the rim would recover, and
with the double eyelets, you didn't get rim cracking -- usually. I
had some MA2s where the sockets came right through the rim wall.
Those tensions were also hard on hub flanges and unworkable for
modern, 130mm high-dish, low weight, lower spoke count clinchers. IMO,
a better description of spoke tension is the rim manufacturers'
recommended tension along with some mild thread-lock like Teflon paste
or linseed oil. I have the first edition of the book and don't know
if later editions changed the basic formula for determining spoke
tension, but I always thought that was one part of the book that
needed revision.


It was written for learning to build wheels without a tensiometer, since
those were rare at the time. The "soft taco" method, while lacking
precision, at least worked. Times have changed with weird rim designs,
alternative spokes, etc. Well, if you're keeping up with things- I'm
still riding MA2s and Sun CR 18s and have downtube shifters on the two
bikes I ride the most (friction, no less, but I am up to 8 speed on one
and have 9 sp STI on the tandem... I dislike STI, but there are no
downtube shifter bosses to upgrade to DT shifters).
  #55  
Old April 1st 15, 10:11 AM posted to rec.bicycles.tech
John B. Slocomb
external usenet poster
 
Posts: 606
Default Physics for marketing professionals

On Sun, 29 Mar 2015 23:54:33 -0400, Frank Krygowski
wrote:

On 3/29/2015 10:34 PM, Jeff Liebermann wrote:
On Sun, 29 Mar 2015 12:29:25 -0400, Frank Krygowski
wrote:

Does non-twisting rope exist?


Climbing rope.
https://www.google.com/search?q=climbing+rope&tbm=isch
Kernmantle construction. Braided (kern) nylon core. Woven outer
sheath (mantle) for protection.


As in
https://www.google.com/search?q=clim...i h=606&dpr=1
?

Pretty pricey for hanging a kayak. I was hoping for, oh, under $10.


The old cotton woven "cloths line" rope if they still sell it.
http://www.homedepot.com/p/Unbranded...4097/202048188
$6.50 for a hundred feet.
--
Cheers,

John B.
  #56  
Old April 1st 15, 11:52 AM posted to rec.bicycles.tech
LF
external usenet poster
 
Posts: 131
Default Physics for marketing professionals

Hooray! Now I can upgrade to low spoke count boutique wheels, and ditch the 36-spoke hand built wheels I've been riding for a couple decades, without a problem.
Best, Larry
  #57  
Old April 3rd 15, 02:55 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 6,374
Default Physics for marketing professionals

On Wednesday, April 1, 2015 at 6:52:36 AM UTC-4, LF wrote:
Hooray! Now I can upgrade to low spoke count boutique wheels, and ditch the 36-spoke hand built wheels I've been riding for a couple decades, without a problem.
Best, Larry


Dear Larry...look thru http://goo.gl/1zK1Y4
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Remember, these are professionals! Ryan Cousineau Racing 4 April 16th 08 05:19 AM
Urgent!!! Switch Professionals for UAE VAM SYSTEMS Marketplace 1 January 26th 08 03:28 AM
Urgent!!! Tandem Cobol Professionals for UAE vam General 4 June 12th 07 06:09 PM
email extractor , site , solutions , email based marketing , email marketing solution , email extractor , newsletter software , mass email , e-mail marketing , email marketing solutions , bulk email software , web advertising , email marketing , mark Nuclear Incorporation. www.nuclear-inc.com UK 0 April 5th 07 09:36 PM
i want to do my A2 physics coursework about the physics of a unicycle... annaats Unicycling 2 June 15th 04 10:39 PM


All times are GMT +1. The time now is 11:21 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.