Why the holes in old BB shells?

From Carl Fogel:

http://www.nostalgic.net/pictures/1720.htm

Whats that inside the BBshell? It almost looks lie a spider gear.

Playboy bunnies have hairy nostrils?

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Compliments of:
"Your Friendly Neighborhood Wheelman"

If you want to E-mail me use:
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From:

The person you replied to indicated he
has a vent hole in the end of his LeMond
CARBON chainstays. Does a carbon
tube also need vent holes? I think he
is correct in that the vent holes in his
carbon chainstays are manufacturing
artifacts.

And why would you ned a vent hole in the CHAINSTAY? The end that is
attached to the BB shell is open anyway. The only competely closed tubes
on a diamond frame are the seat stays and front fork blades.

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Compliments of:
"Your Friendly Neighborhood Wheelman"

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On 1 Dec, 20:34, Martin Borsje wrote:
explained :





Matt O'Toole writes:

I never understood why older racing frames have big holes in their
BB shells. Is this to drain water, to allow flushing and
re-greasing without disassembly, or just to look cute, with heart
shaped holes and such?

This always seemed stupid to me, because of road spray, etc.

I recall that the keyhole slot in the seat tube was deeper than the
clamping depth for the seat post and that spray from the rear wheel
could enter to fill the bottom of the frame with water. To avoid
this, we made sure there was liberal grease in that slot.

Then someone started drilling a hole in the center of the BB to let
the water out, after which the idea was widely imitated. Various
logos were cut to make even larger openings, so much so that the shell
had no lateral strength and developed nonparallel faces in use.

Yes, I found that to be stupid because it did not address the problem
of allowing water to enter, aside from being an inexcusable structural
weak spot.

Jobst Brandt

I think you can never fulle avoid water entering the frame.

Is it through the seatpost or other likely routes as the steerer tube
or the bracket itself.

What comes in must go out!

Wherefore else holes in the fork tube ends (4x)?

Martin- Dölj citerad text -

- Visa citerad text -

Absolutely, i have changed at least 20 Scott mtb BB this year, and
they have all been wet and rusted, so the BB should have a hole
underneath, and it has, but its blocked by the screw holding the cable
guide. Of course the best thing isnt to get the water out, but keeping
it from getting in...

On Dec 3, 2:17 pm, (It's Chris) wrote:
From Carl Fogel:

http://www.nostalgic.net/pictures/1720.htm

Whats that inside the BBshell? It almost looks lie a spider gear.

Playboy bunnies have hairy nostrils?


I've never heard it called a nostril before! ;-)

"Ozark Bicycle" wrote in message
...
On Dec 3, 2:17 pm, (It's Chris) wrote:
From Carl Fogel:

http://www.nostalgic.net/pictures/1720.htm

Whats that inside the BBshell? It almost looks lie a spider gear.

Playboy bunnies have hairy nostrils?


I've never heard it called a nostril before! ;-)

Thought most of them have razors?
-tom

http://farm3.static.flickr.com/2203/...531a76f621.jpg

More bottom bracket holes, cables thread through and come out a slot
towards the rear (the lip that is visible is presumably to direct
water flow away from the hole).

On Mon, 3 Dec 2007 15:17:24 -0500, (It's
Chris) wrote:

From Carl Fogel:

http://www.nostalgic.net/pictures/1720.htm

Whats that inside the BBshell? It almost looks like a spider gear.

Playboy bunnies have hairy nostrils?

- -
Compliments of:
"Your Friendly Neighborhood Wheelman"

If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net

My website:
http://geocities.com/czcorner

Dear Chris,

It's the front end of a shaft-drive bicycle.

Don't go into otorhinolaryngology if you want to preserve your
illusions that beauty is more than skin deep:

http://simple.wikipedia.org/wiki/Nasal_hair

Typical Playboy model before nose job:

http://tinyurl.com/2f6rq9

After cosmetic surgery and manicure, but before thorough depiliation:

http://tinyurl.com/2f4v26

Final version, where Jessica Rabbit usually has only a single nostril:

http://tinyurl.com/2o3trx

Cheers,

Carl Fogel

On Dec 3, 12:05 pm, wrote:
How about holes on the dropout end of the chain stay? My Lemond
carbon frame has an open hole at the end of the drive side stay
where the dropout attaches, and I've noticed holes in other
chainstays. The water will of course drain right down to the BB,
and the hole is big enough to let crud accumulate on the interior of
the stay.
Near as I can figure it's a manufacturing artifact. I'm thinking
about plugging it up with something.
You haven't been following this thread well enough to have read
what the purpose of these holes is. The 1mm holes are for venting
expanding air when the part is brazed.

It isn't a 1mm hole. The entire rear of the chain stay is
open. The dropout is formed such that there is a hole
that matches the end of the chainstay on both sides,
leaving a completely open "tunnel" down the end of the
chain stay. The dropout, which I think is Al, slips inside
the chain stay and is bonded to it in some way.

I'm guessing that it was used for a bladder when forming
the carbon stay and dropout. Once the stay was cured the
bladder was deflated and removed from the hole.
The seat stays do not have a similar open hole at the
dropout, so I may be wrong. But this also cuts against
the gas venting theory, since one would expect at
least a small hole on the seat stay. There's no hole
of any sort present on the seat stay near the dropout.

My Cannodale Al rear triangle has ~1mm holes near the
dropout on both the chain and seat stays.

Perhaps someone else can look at their carbon frame
and see if there are "vent holes" present near the
rear dropouts.

I think the adhesives have the same problem of out-gassing and would
compromise the joint if the temperature during curing changed or even
stayed the same. I wouldn't rely on a closed volume not changing gas
pressure.

Tom Nakashima wrote:
"Ozark Bicycle" wrote in message
...
On Dec 3, 2:17 pm, (It's Chris) wrote:
From Carl Fogel:

http://www.nostalgic.net/pictures/1720.htm
Whats that inside the BBshell? It almost looks lie a spider gear.

Playboy bunnies have hairy nostrils?

I've never heard it called a nostril before! ;-)

Thought most of them have razors?

Like this? http://www.razor-help.com/razor-kick-scooters.html

For shorter distances, push scooters are an excellent choice of
transportation.

--
Tom Sherman - Holstein-Friesland Bovinia
"Localized intense suction such as tornadoes is created when temperature
differences are high enough between meeting air masses, and can impart
excessive energy onto a cyclist." - Randy Schlitter