Back to the future!!

On Sat, 07 Jul 2007 01:31:04 -0000, Chalo <[email hidden]>

Quoted message said:

Michael Press said:

Michael Warner said:

I ride with someone who hasn't fixed a creaking bottom bracket because
(so he claims) if it's not creaking he knows he's not working hard enough.
It's a training aid!

Does he positively, absolutely know,
exactly why it creaks?
Some creaks signal imminent fracture.

That's true; some things creak while they are in the process of
growing a crack. In my long experience of breaking stuff, my
observation is that most things that break don't make noticeable noise
before they snap off. But some do.

However, I have found a myriad of things that can and do creak at any
time whatsoever. For me, the most likely culprit is a sprung saddle.
Drops of oil banish these creaks for only a frustratingly short time.
Mostly I just live with them.

Second most likely is a steel-to-aluminum interface at the bottom
bracket shell. When I hear this sort of ticking or creaking, I know
it's time to disassemble, inspect, grease, tighten all fasteners, and
reinstall. It's during such service that I often find a worn
cartridge bearing before it gets noisy or sloppy.

After those two sources of creaks are eliminated, I find that any
remaining creaking or ticking could be _anything on the bike_, with no
clear order of probability. Pedal spindles, pedal cages, stem quill
or clamp, luggage rack, crack in the frame, cracked headset crown
race, rim joint, saddle clamp, dry seatpost... just about anything.
Worst of all, the sound can seem to come from an area of the bike
that's nowhere near the problem part. I hate that.

Chalo

Dear Chalo,

Riders like you often hate and fear small things that squeak:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/tricycle/eletri1a.jpg

🙂

Cheers,

Carl Fogel

Marcus Coles said:

still me said:

none said:

I've never seen a center-pull brake without dual pivots, although I'm
pretty sure there must be a single pivot center-pull or two out there.

I'm having problems visualizing that.

Quoted message said:

Try to picture a cable operated pair of pliers or rim grabbing tongs.

Maybe Mr. Fogel knows of a example, my cybervoyage to Joel Metz'
collection http://www.blackbirdsf.org/brake_obscura/ failed to turn up
anything.

Maybe this:
http://www.blackbirdsf.org/brake_obscura/images/road/campy_delta2.jpg

--

John ([email hidden])

Carl Fogel said:

Dear Chalo,

Riders like you often hate and fear small things that squeak:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/tricycle/eletri1a.jpg

🙂

I showed that to my wife and she immediately noticed the resemblance,
right down to the unorthodox three-wheeler comparable to the ones in
my shed.

I think that this picture is also relevant to the discussion we were
just having about tire diameter, contact patches and tire casing
deflection.

Chalo

On Sat, 07 Jul 2007 05:12:51 -0000, Chalo <[email hidden]>

Quoted message said:

Carl Fogel said:

Dear Chalo,

Riders like you often hate and fear small things that squeak:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/tricycle/eletri1a.jpg

🙂

I showed that to my wife and she immediately noticed the resemblance,
right down to the unorthodox three-wheeler comparable to the ones in
my shed.

I think that this picture is also relevant to the discussion we were
just having about tire diameter, contact patches and tire casing
deflection.

Chalo

Dear Chalo,

Well . . .

A mature small-eared Asian elephant weighs around three to five tons.

Presumably our example is a highly-trained TDF sort of elephant,
mostly lean muscle mass and on the light side for better performance
on long climbs, so we're entitled to assume a svelte 6,000-pound beast
loading the three tires of the tricycle.

A wild guess suggests motorcycle rims with tires at least 3 inches
wide, possibly 4--let's settle for the spurious precision of 3.5
inches for the width.

Six thousand pounds is about 2,000 pounds per wheel. The rear tires
are probably more heavily loaded than the front, but let's not fuss
too much--a ton per 3.5-inch wide tire seems reasonable.

Elephants rarely ride sidecar trials (at least I never saw one), so we
can safely say that they shun 4 psi inflations and prefer higher
street-style tire pressures. Sixty psi is higher than I recall anyone
using on ordinary motorycycle tires, so let's plug that in and see
what we get . . .

6,000 pounds / 3 tires = 2,000 pounds per tire

2,000 pounds per tire / 60 psi = 33.3 square inches per tire

33.3 square inches / 3.5 inches wide = ~10 inch contact patch

It's hard to tell how much the tires are flattened, since they're
partly hidden by the wrinkling of the heavy cloth, but a 10-inch long
contact patch seems plausible:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/tricycle/eletri1a.jpg

Alas, we just don't have enough data to see what's going on here. If
the elephant is mid-size 4-ton model, then we get:

8,000 lbs / 3 tires = 2,667 lbs / tire

2,667 pounds / 60 psi = 44.5 square inches per tire

44.5 square inches / 3.5 inches wide = 12.7 inch contact patch

Still plausible, but almost 30% longer.

I'm afraid that this leaves us in the dark until we learn more about
what tire widths and pressures pro elephants prefer. Such mysteries
are common--it's very hard to find out how many pros are riding
tubulars versus clinchers in the Tour, much less what pressure they
use.

As a technical aside, trial motorcycle tires are not strictly similar
to 700c road bicycle tires. The bicycle tires are pretty much round,
while the trials tread motorcycle tires have hefty square blocks that
stick off the round carcass to form an almost flat surface. The outer
rubber blocks effectively raise and brace the lower curve of the round
carcass, making the sidewall "spring" shorter and perhaps stiffer.

The periods below are meant to show the curve of the inflated carcass,
propped on either side by high rubber blocks:

|. <----rim---> .|
|. .|
. .
. .
. .
. .
. .
| . . |
| | . . | |
|___| |___| |___|

Cheers,

Carl Fogel

Chalo said:

DirtRoadie said:

"Universal 61" or "Mafac Racers" are examples of the centerpull
brakes back then. The "U-brake" was merely a later (and not-very-good)
variation of the same thing.

Quoted message said:

The foible of the Universal centerpull was its center bolt and pivot
arch. That made it almost as floppy as the single-pivots of the day.
The foible of the Mafac brake was the whole stinking brake. Boy, did
those brakes suck.

Stud-mounted U-brakes were (and are) good brakes, which is why they
never went away on freestyle bikes. The only problem with them on
MTBs was sticking them down in the muck under the chainstays. Add
full fenders, and even that isn't a problem.

http://www.danscomp.com/products.php?cat=PARTS&show=Brakes

After seeing this-
http://www.cyclingnews.com/tech.php?id=/photos/2007/tech/features/specialized_tarmac_launch07/Specialized_S-Works_Transition_rear_brake

I recognize that the "new" Specialized brake does, in fact, have
strong similarities to a "U" brake not found in older road
centerpulls . Most notable are the under-chainstay mounting and fixed
mounting studs.

DR

Quoted message said:

Quoted message said:

Michael Warner said:

I ride with someone who hasn't fixed a creaking bottom bracket because
(so he claims) if it's not creaking he knows he's not working hard enough.
It's a training aid!

Quoted message said:

Michael Press said:

Does he positively, absolutely know,
exactly why it creaks?
Some creaks signal imminent fracture.

Chalo said:

That's true; some things creak while they are in the process of
growing a crack. In my long experience of breaking stuff, my
observation is that most things that break don't make noticeable noise
before they snap off. But some do.

However, I have found a myriad of things that can and do creak at any
time whatsoever. For me, the most likely culprit is a sprung saddle.
Drops of oil banish these creaks for only a frustratingly short time.
Mostly I just live with them.

Second most likely is a steel-to-aluminum interface at the bottom
bracket shell. When I hear this sort of ticking or creaking, I know
it's time to disassemble, inspect, grease, tighten all fasteners, and
reinstall. It's during such service that I often find a worn
cartridge bearing before it gets noisy or sloppy.

After those two sources of creaks are eliminated, I find that any
remaining creaking or ticking could be _anything on the bike_, with no
clear order of probability. Pedal spindles, pedal cages, stem quill
or clamp, luggage rack, crack in the frame, cracked headset crown
race, rim joint, saddle clamp, dry seatpost... just about anything.
Worst of all, the sound can seem to come from an area of the bike
that's nowhere near the problem part. I hate that.

So true. And yet customers expect noises diagnosed and rectified right
now. 'and do you mind if I watch/help/kibitz/interfere?'
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On Fri, 06 Jul 2007 23:51:10 -0600, [email hidden] wrote:

[snip]

And speaking of wives and tricycles, I just stumbled over this 1907
photo while looking for elephants on bicycles:

http://www.loc.gov/exhibits/bobhope/images/vcvg43.jpg

Cheers,

Carl Fogel

Marcus Coles said:

Quoted message said:

Thanks, did you dig back or forward six decades?
It seems almost anything one can think of has been attached to a bicycle.

Quoted message said:

I leafed backward, but the book ends in 1959, so it was only a dozen
years back to 1947. This 1952 brake on p. 160 struck me as even
stranger:
http://i12.tinypic.com/6evvs51.jpg

A BeboLuxe! They also had a bolt-on model.
The parallels to Deltas are creepy, eh?
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

BOONEN LAST SEEN RIDING OFF CLIFF

a reminder to never look back

A Muzi said:

Quoted message said:

Quoted message said:

Michael Warner wrote:
> I ride with someone who hasn't fixed a creaking bottom bracket because
> (so he claims) if it's not creaking he knows he's not working hard enough.
> It's a training aid!

Michael Press said:

Does he positively, absolutely know,
exactly why it creaks?
Some creaks signal imminent fracture.

Chalo said:

That's true; some things creak while they are in the process of
growing a crack. In my long experience of breaking stuff, my
observation is that most things that break don't make noticeable noise
before they snap off. But some do.

Quoted message said:

However, I have found a myriad of things that can and do creak at any
time whatsoever. For me, the most likely culprit is a sprung saddle.
Drops of oil banish these creaks for only a frustratingly short time.
Mostly I just live with them.

Quoted message said:

Second most likely is a steel-to-aluminum interface at the bottom
bracket shell. When I hear this sort of ticking or creaking, I know
it's time to disassemble, inspect, grease, tighten all fasteners, and
reinstall. It's during such service that I often find a worn
cartridge bearing before it gets noisy or sloppy.

Quoted message said:

After those two sources of creaks are eliminated, I find that any
remaining creaking or ticking could be _anything on the bike_, with no
clear order of probability. Pedal spindles, pedal cages, stem quill
or clamp, luggage rack, crack in the frame, cracked headset crown
race, rim joint, saddle clamp, dry seatpost... just about anything.
Worst of all, the sound can seem to come from an area of the bike
that's nowhere near the problem part. I hate that.

So true. And yet customers expect noises diagnosed and rectified right
now. 'and do you mind if I watch/help/kibitz/interfere?'
--
Andrew Muziwww.yellowjersey.org
Open every day since 1 April, 1971- Hide quoted text -

- Show quoted text -

Hmmm the LBS types are getting cranky!
you guise try the earplugs, forehead on tube or water pipescope on
forehead with plugs approach?
rumblerumblerumblesquweekrumblerumble...
relax! the cold fall rains will soon fall.