Low spoke count wheels

Lou Holtman wrote:
On 2013-11-02 16:46:40 +0000, Frank Krygowski said:

On Saturday, November 2, 2013 2:53:46 AM UTC-4, Lou Holtman wrote:
On 2013-11-02 02:54:47 +0000, Frank Krygowski said:
On Friday, November 1, 2013 1:12:54 AM UTC-4, Sir Ridesalot wrote:
Whenever I use my lighter tubular tire wheelset on my vintage bike
I notice a big difference in the amount of effort needed
to climb hills around here. If I keep the speed on the
clinb the same with both wheelsets I do notice a lower
heartrate on the monitor when I'm climbing with the
tubular wheels on the bike. Everything else about the bike
and me is the same whether I'm using the tubular wheelset or
the clincher wheelset.
I'd be really interested in some numbers. Could you climb a
representative hill at least twice, say on successive days,
once with each wheelset, and tell us the heart rates?
More trials would be better of course, but it would be
interesting to see at least one comparison.
You don't need no more trails. If there is one thing you can
calculate accurately that would be the time advantage of lighter
gear when going uphill all the rest being equal.
Of course, some here doubt that can be calculated at all.
The latter is the problem. It is never 'being equal'.
Please explain.
Whether we're talking about increasing speed on a bicycle, insulating a
house to reduce heating costs, changing the route you travel to get to
work, or whatever, before-after conditions are never perfectly equal.
Yet people can and do make rational judgments about expected benefits.

That is what I meant. If I climb a hill 5 days on a row on the same bike
my time will be different every day even if I keep my heart rate the same
The differences will be much larger than the time differences I can
calculate (very simple calculation) from a 200 gr lighter tubular
wheelset. Sir Ridesalot has to deal with the same noise.
Low spoke count has to do with aerodynamics. They need a beefier rim. A
light wheelset has to do with climbing and acceleration, both benefits
you can calculate. This is another stupid wheel discussion. Low spoke
count doesn't mean a lighter wheel or a less reliable wheel. The only

+1

sure thing is that if you break a spoke you can call your wife to pick you
up. However a mate

+2

broke a spoke off a 32 spoke rear wheel and he also had to call his wife.
His frame could not take the wheel wobble with a broken spoke in
combination with his 25 mm rear tire.



--
duane

On Saturday, November 2, 2013 3:34:17 PM UTC-4, Jay Beattie wrote:

That guy needs to pack a spoke wrench(mine is on my key chain).

And/or perhaps buy frames with a little more tire clearance. I've never understood why anyone thinks shaving the clearance between chainstays makes a bike faster.

All these guys who pack extra spokes to fix their conventional wheels can't replace a drive side spoke (which are the spokes that usually break)unless they are also carrying a cassette tool, chain whip and spanner.

Well, there's that trick about bending a "Z" into the end of a longer spoke. That can sometimes work even without removing cogs.

http://www.jimlangley.net/wrench/espoketool.html

- Frank Krygowski

there's a kevlar spoke in the box but unused.

https://www.google.com/webhp?hl=en&t...ide+rear+wheel

a stein cracker ? off course next to the Kevlar spoke ...all obsolete with straight pull spokes.

ROLL ON !

anyone need a set of custom filed headset wrenches ?

On 02/11/13 22:25, John B. wrote:
On Fri, 1 Nov 2013 20:26:32 -0700 (PDT), Frank Krygowski
wrote:

On Friday, November 1, 2013 7:15:24 AM UTC-4, John B. wrote:
On Fri, 01 Nov 2013 14:57:13 +1100, James
wrote:

Tensile strength is not everything.

http://en.wikipedia.org/wiki/Toughness

It pretty much is, for a member that is stressed in tension, made
from conventional materials :-)

Well, there's also "notch sensitivity."

Sure there is, but I don't see much about it in crane cable or
marine rigging cable specifications. Or bow strings :-)


Try aluminium bicycle frames, and I'd presume aluminium spokes.

--
JS

On 03/11/13 05:08, Lou Holtman wrote:
On 2013-11-02 16:46:40 +0000, Frank Krygowski said:

On Saturday, November 2, 2013 2:53:46 AM UTC-4, Lou Holtman wrote:
On 2013-11-02 02:54:47 +0000, Frank Krygowski said:

On Friday, November 1, 2013 1:12:54 AM UTC-4, Sir Ridesalot wrote:

Whenever I use my lighter tubular tire wheelset on my vintage bike
I notice a big difference in the amount of effort needed to
climb hills around here. If I keep the speed on the clinb the
same with both wheelsets I do notice a lower heartrate on the
monitor when I'm climbing with the tubular wheels on the bike.
Everything else about the bike and me is the same whether I'm
using the tubular wheelset or the clincher wheelset.


I'd be really interested in some numbers. Could you climb a
representative hill at least twice, say on successive days, once
with each wheelset, and tell us the heart rates? More trials
would be better of course, but it would be interesting to see at
least one comparison.

You don't need no more trails. If there is one thing you can
calculate accurately that would be the time advantage of lighter
gear when going uphill all the rest being equal.
Of course, some here doubt that can be calculated at all.

The latter is the problem. It is never 'being equal'.

Please explain.
Whether we're talking about increasing speed on a bicycle, insulating
a house to reduce heating costs, changing the route you travel to get
to work, or whatever, before-after conditions are never perfectly
equal. Yet people can and do make rational judgments about expected
benefits.

That is what I meant. If I climb a hill 5 days on a row on the same bike
my time will be different every day even if I keep my heart rate the
same The differences will be much larger than the time differences I can
calculate (very simple calculation) from a 200 gr lighter tubular
wheelset. Sir Ridesalot has to deal with the same noise.
Low spoke count has to do with aerodynamics. They need a beefier rim. A
light wheelset has to do with climbing and acceleration, both benefits
you can calculate. This is another stupid wheel discussion. Low spoke
count doesn't mean a lighter wheel or a less reliable wheel. The only
sure thing is that if you break a spoke you can call your wife to pick
you up. However a mate broke a spoke off a 32 spoke rear wheel and he
also had to call his wife. His frame could not take the wheel wobble
with a broken spoke in combination with his 25 mm rear tire.


I had a spoke break in one of my home brew wheels, not long after I
built it. I suspect I had the spoke tension a bit high, and perhaps the
spoke was faulty because it broke a few turns into the threaded section.
The rims also don't aim the nipple holes at the hub flange.

The wheel has 16 3x spokes on the drive side, and 8 1x spokes on the
left = 24 spokes total. It was one of the left side spokes that broke.

I opened the brakes with the button on the brake lever (Campagnolo) and
rode home, about 20 km on a 23 spoke rear wheel.

I replaced the spoke and reduced the spoke tension a little. All good
since.

--
JS

On Mon, 04 Nov 2013 08:16:12 +1100, James
wrote:

On 02/11/13 22:25, John B. wrote:
On Fri, 1 Nov 2013 20:26:32 -0700 (PDT), Frank Krygowski
wrote:

On Friday, November 1, 2013 7:15:24 AM UTC-4, John B. wrote:
On Fri, 01 Nov 2013 14:57:13 +1100, James
wrote:

Tensile strength is not everything.

http://en.wikipedia.org/wiki/Toughness

It pretty much is, for a member that is stressed in tension, made
from conventional materials :-)

Well, there's also "notch sensitivity."

Sure there is, but I don't see much about it in crane cable or
marine rigging cable specifications. Or bow strings :-)


Try aluminium bicycle frames, and I'd presume aluminium spokes.

Well, I looked at the Columbus tubing specs and they list Rm - which
is the ultimate tensile strength and Rs which is the yield strength
:-)
--
Cheers,

John B.

On Mon, 04 Nov 2013 06:43:07 +0000, Phil W Lee
wrote:

John B. considered Sat, 02 Nov 2013 18:25:17
+0700 the perfect time to write:

On Fri, 1 Nov 2013 20:26:32 -0700 (PDT), Frank Krygowski
wrote:

On Friday, November 1, 2013 7:15:24 AM UTC-4, John B. wrote:
On Fri, 01 Nov 2013 14:57:13 +1100, James
wrote:

Tensile strength is not everything.

http://en.wikipedia.org/wiki/Toughness

It pretty much is, for a member that is stressed in tension, made from
conventional materials :-)

Well, there's also "notch sensitivity."

Sure there is, but I don't see much about it in crane cable or marine
rigging cable specifications. Or bow strings :-)

Discontinuities in shape cause a geometric "stress concentration", which can be estimated by various means.

But materials don't all react the same way to those geometric stress concentrations. Some materials are more sensitive than others. "Notch sensitivity" is a measurement (or estimate) of that sensitivity. Unfortunately, steels that are higher strength tend to have higher notch sensitivities. It eats up some of their advantage.

This doesn't matter much for steady loads or perfectly uniform shapes. But it matters in a fatigue situation or a shock situation. And spokes are definitely a fatigue situation.

Unfortunately, data on notch sensitivity is pretty rare, and specific to given alloys and heat treatments or cold work processes. So it comes down to manufacturers' proprietary testing, on which we'd probably never get details. DT might be drawing and bending their spokes in molten beeswax, while Sapim might use extra virgin olive oil - or even the urine of virgins. Who knows?

I was watching a documentary on Rolls Royce Aero engines the other
night, and the number of things they go into to determine the tensile
strength is FAR in excess of simply what the constituent metals (and
other traces) in the alloy are.
That applies to not just to the most highly stressed and hot parts
deep inside the engine, but some that you might not think would be so
critical, like the engine cowling.

Notch sensitivity was an integral part of that (there ain't much point
in surviving a bird strike on takeoff if it just means the blade which
got notched badly goes on to fail 1 hour into the flight).
Some of the processes are secret, but you can certainly see what makes
such engines so expensive - a scratched component worth rather more
than a small house was binned without a thought, and no component was
placed anywhere without custom made soft protection - even on work
benches that I'd have been quite prepared to undergo surgery on.
Very impressive engineering indeed.

I think there is a little nomenclature problem there. (Ultimate)
Tensile strength is the maximum stress that a material can withstand
while being stretched or pulled before failing or breaking.
The test is made with a large machine that literally pulls carefully
machined samples apart.

This is not to say that tensile strength is the be all and end all of
materials testing but that is all it is, the resistance to being
pulled apart.
--
Cheers,

John B.

On Wednesday, October 30, 2013 6:59:14 AM UTC-5, Graham wrote:
deleted
On the other hand the 32 spoke wheels have had a couple of spoke failures over the past three years both on the rear non-drive side at the elbow over about 7000 miles.

Given the likely cause of failure is fatigue what difference does the spoke material and spoke/hub design make.
deleted
The three cross lacing, low tension, strong pedaling take all the tension out. Sheldon Brown recommends half radial on the non-drive side.
http://sheldonbrown.com/wheelbuild.html

"Mike A Schwab" wrote in message ...
On Wednesday, October 30, 2013 6:59:14 AM UTC-5, Graham wrote:
deleted
On the other hand the 32 spoke wheels have had a couple of spoke failures over the past three years both on the rear non-drive side at the elbow over about 7000 miles.

Given the likely cause of failure is fatigue what difference does the spoke material and spoke/hub design make.
deleted
The three cross lacing, low tension, strong pedaling take all the tension out. Sheldon Brown recommends half radial on the non-drive side.
http://sheldonbrown.com/wheelbuild.html

Mike, I think you might have missed the point of my question. Most of us here know how to build a reliable "traditional" wheel. My question was intended to tease out whether the design of and material choice for hub and spokes for fairly light low spoke count wheels (e.g. shimano dura ace C24s 16/20 spokes 1380gms) could make them more reliable than some posters contend when I and others who own and have ridden such wheels for thousands miles have experience to the contrary. This is a pure tech question not one of personal preferences/predudices.

Graham.