From: jobst.brandt@stanfordalumni.org
Subject: Re: Why 36 and not 32?
Newsgroups: rec.bicycles.tech
Message-ID: <W1u%7.8244$TI3.65532@typhoon.sonic.net>
Date: Fri, 11 Jan 2002 04:41:26 GMT

John Forrest Tomlinson writes:

> And how can 32 be skimping if it's reliable?  I've got a 28 hole
> front wheel for training (and 36 in back) that I have been using for
> years and the rim is going to wear out from braking before a spoke
> goes.  That's not skimping.

You could say the same of a Campagnolo Shamal wheel if no spokes
broke, definitely a possibility, but if one broke you wouldn't have
much to go on just as this thread discussed.

If you break one of 32, wheel misalignment is usually to bad to ride.
This is doubly so with "modern" frames that have no clearance anyway,
but tweaking a 32 or 28 spoke wheel after a break is not nearly as
easy as with 36.  I days of yore I rode plenty of miles on 35 spokes
in the days before DT spokes and others that are competitive.

Jobst Brandt  <jobst.brandt@stanfordalumni.org>  Palo Alto CA

From: jobst.brandt@stanfordalumni.org
Subject: Re: Why 36 and not 32?
Newsgroups: rec.bicycles.tech
Message-ID: <R4M%7.8507$TI3.68640@typhoon.sonic.net>
Date: Sat, 12 Jan 2002 01:13:21 GMT

John Forrest Tomlinson writes:

>> You could say the same of a Campagnolo Shamal wheel if no spokes
>> broke, definitely a possibility, but if one broke you wouldn't have
>> much to go on just as this thread discussed.  >> If you break one
>> of 32, wheel misalignment is usually to bad to > ride.  This is
>> doubly so with "modern" frames that have no clearance > anyway, but
>> tweaking a 32 or 28 spoke wheel after a break is not nearly as easy
>> as with 36.  I days of yore I rode plenty of miles on 35 spokes in
>> the days before DT spokes and others that are competitive.

> But I've _never_ broken a front spoke (several got bent one when a
> pedal went into the front wheel at the end of a race) and it's so
> extremely unlikely that it will happen.  So what you're saying is
> irrelevant.  The wheel has been used a lot and now I'm looking
> carefully at the sidewalls.

> Have you seen _any_ spokes breaking on front wheels of
> properly-built 28 or 32 hole rims? For a 155 pound rider on bad
> (paved) roads?  Ever?  If not, what is possibly wrong with it?

Well, the wealth of riders today is such that having the same rim
front and back is out the window.  In that case, 32 might be excusable
as would 28.  Just the same, at high speed, descending on mountain
roads where a crash means going over the side, I'm glad to be riding
36 front and rear as my entire weight goes to the front wheel going
into corners.

If I rode mainly on the local loops, I wouldn't worry about it.

Jobst Brandt  <jobst.brandt@stanfordalumni.org>  Palo Alto CA

From: jobst.brandt@stanfordalumni.org
Subject: Re: 18 hole rims?
Newsgroups: rec.bicycles.tech
Message-ID: <bDPR9.59419$Ik.2013605@typhoon.sonic.net>
Date: Sun, 05 Jan 2003 05:44:39 GMT

Sheldon Brown <captbike@sheldonbrown.com> writes:

>>> Sheldon "If You Have The Same Number Of Spokes Front And Rear,
>>> Either Your Rear Wheel Is Weaker Than It Should Be, Or Your Front
>>> Wheel Is Heavier Than It Needs To Be" Brown

>> I don't believe so.  The front wheel is subjected to higher side
>> loads and, while braking, the entire load of the rider and bicycle.

> The front wheel has much wider flange spacing and also has the
> enormous advantage of not being dished.

The dish affects primarily lateral strength and as I said, lateral
loads on rear wheels are far smaller than front wheels.

> If you'd ever worked in a bike shop you'd know that spoke failures
> on rear wheels are very common, while spoke failures on front wheels
> are almost unheard of.

Aha!  Spoke failure is not the only criterion for the number of spokes
and resulting wheel strength.  Peak loads, ones not statistically
frequent enough to cause spoke failure, collapse wheels of which I
have seen more front wheel collapses than rear.  Although these
observations only prove that there may be a difference, they don't
conclusively show that front wheels statistically fail from overload
more than rear wheels, wheels that have distinctly more spoke failures
that front wheels.

>> I think 36 spokes front and rear is still an optimal wheel if you
>> can find a rim designed with that in mind.

> As an old anglophile, I think the Brits had the right idea years ago
> when all of their bikes were 32/40.

I think they were wrong.  This concept struck me as odd when I first
started bicycling because I observed wheel collapses among my bikie
friends.  I think the initiators of this concept were sedentary riders
who never collapsed wheels.  For them it was probably correct.

> For a bike with 64 spokes, I'd greatly prefer 28/36 to 32/32.

Had you not said that my previous comment would not have clashed as it
does in retrospect.  Please don't derive that you are a sedentary
rider from that but rather that you hadn't considered the concept of
wheel collapse that I observe in my riding.  As my mother used to say,
"Can't you play with kids your own age?"  to which I replied, "kids my
age don't do stuff that I like to do."  In that vein, we still
collapse wheels and jump our road bicycles too high on dirt roads,
36-36 spokes and all.

Jobst Brandt
jobst.brandt@stanfordalumni.org
Palo Alto CA

From: jobst.brandt@stanfordalumni.org
Subject: Re: 18 hole rims?
Newsgroups: rec.bicycles.tech
Message-ID: <Ep8S9.59525$Ik.2023857@typhoon.sonic.net>
Date: Mon, 06 Jan 2003 05:23:48 GMT

Pete Biggs writes:

>>> If you'd ever worked in a bike shop you'd know that spoke failures
>>> on rear wheels are very common, while spoke failures on front wheels
>>> are almost unheard of.

>> Aha!  Spoke failure is not the only criterion for the number of
>> spokes and resulting wheel strength.  Peak loads, ones not
>> statistically frequent enough to cause spoke failure, collapse
>> wheels of which I have seen more front wheel collapses than rear.
>> Although these observations only prove that there may be a
>> difference, they don't conclusively show that front wheels
>> statistically fail from overload more than rear wheels, wheels that
>> have distinctly more spoke failures that front wheels.

> In what circumstances do these front wheels collapse, and what rims
> did they have?

Common tubular rims like Fiamme red and Mavic MA-2's.  In a race, and
on the road people get crossed up and collapse wheels.  Talk to the
bicycle shops that minister to such riders and they ought to tell you
a lot about wheel collapses.  On the track, the most common, non-crash
occurrence is lifting a front wheel in a sprint.  The wheel comes down
moving laterally with respect to its axis.

> I've done plenty of hard braking but have never managed to collapse a
> front wheel by putting all my weight on it.

If you brake hard on rough paved roads so that all weight is on the
front wheel, it should be at least as strong radially as the rear
wheel.  I think if you descend hard on, for instance the east slope of
the Stelvio, where most hairpin turns are left over concrete from the
1930's, you'll be glad that your wheel can take it under these loads.
There are nearly 50 such turns on that slope.  There are other roads
with similar surfaces and grades.

> In my experience (and observations with many used bikes when I used
> to buy & sell them), as well as spoke failures, buckled, dented and
> cracked rims* are much more common on rear wheels.  Potholes are the
> cause of the worst damage, and my rear wheels have always come off
> worse than the fronts after hitting them.  Doesn't having more
> spokes make the wheel more resistant to this kind of damage?

That depends on what sort of riders you are servicing.  I'm not talking
about ding'd rims but lateral wheel collapse.  That is affected by the
number of spokes.

> * Open Pro, MA2, various common cheap aluminium and steel clinchers
> of the last 20 years.

I don't know what clientele you were seeing.

Jobst Brandt
jobst.brandt@stanfordalumni.org
Palo Alto CA

From: jobst.brandt@stanfordalumni.org
Subject: Re: 18 hole rims?
Newsgroups: rec.bicycles.tech
Message-ID: <Iu8S9.59526$Ik.2023518@typhoon.sonic.net>
Date: Mon, 06 Jan 2003 05:29:12 GMT

Matt J anonymous writes:

> Sorry to sound ignorant, but what constitutes a collapsed wheel?
> Tacoing? Is this true of mountain bikers too - collapsing front more
> than rear wheels? Or do suspension forks help that? How, if at all,
> do these spoke count idea relate to mountain bike wheels? Thanks -
> just curious

Yes a collapsed wheel resembles a taco or in scientific terms, a
saddle.  I mentioned how this occurs in an earlier response.  When a
wheel is so heavily loaded that spokes are nearly or completely
untensioned, only slight lateral loads suffice to fold the wheel.
This is not from riding over a rock or through a sharp edged hole in
the road.

Jobst Brandt
jobst.brandt@stanfordalumni.org
Palo Alto CA

From: jobst.brandt@stanfordalumni.org
Subject: Re: 14/15/14 vs. straight-gauge 15
Newsgroups: rec.bicycles.tech
Message-ID: <mbr3b.16168$dk4.534562@typhoon.sonic.net>
Date: Thu, 28 Aug 2003 17:43:46 GMT

Michael Press writes:

>>> Why 36 holes?

>> It's the most robust equipment that is available without a
>> significant price penalty.  Why _not_ 36 holes, eh?

> Why not 24 holes?  Why not 48 holes?  etc.

I'm glad you asked.  There is a best ratio between rim cross section,
spoke diameter and number of spokes.  As the spoke count is reduced,
spoke tension must be increased to prevent slackening in use.  This
demands a greater rim strength in bending to bridge between spokes and
it requires a stronger rim bed to prevent spoke pull-outs.  At the
other end, hubs must be made stronger to retain higher spoke tension.

Since spoke tension is limited by the circumferential compressive
strength of the rim, more spokes don't hurt although they cannot be as
tight as fewer spokes, but they can support a greater load because it
is distributed among more spokes.  That is why 48 spokes have served
tandems well for those willing to ignore the fad of fewer spokes.  It
boils down to how many spokes per length of rim and for 700c rims it
comes down to 36.

All this was developed from over 100 years of trial and error, back in
the days when the bicycle was an important transportation vehicle and
racers were not rich professional athletes who could afford replacing
wheels that failed readily.  Of course this doesn't affect riders who
ride mainly new wheels and several sets of them.

> I look for components that perform well while being as light as
> possible while being sufficiently durable for my application.  It's
> also nice if they are standard sizes for easy replacement and/or
> swapping between my bikes.  If that means a wheel with 24 or 32 or
> 36 or 48 spokes, I don't care, but I was asking if anyone has valid
> analytical or anecdotal reasons for one over the other.

I'm glad to see you qualify that with "for my application".
That puts a different spin on it.

Jobst Brandt
jobst.brandt@stanfordalumni.org
Palo Alto CA