[Bike related:] Tandem bottom brackets

On Mon, 23 Mar 2020 19:59:47 -0400, Frank Krygowski
wrote:

On 3/23/2020 3:07 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 19:58:17 -0500, AMuzi wrote:

On 3/22/2020 7:40 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 12:47:49 -0400, Frank Krygowski
wrote:

So I did the work with the tandem on the ground, meaning lots of
bending over, getting up and down, moving the bike from one side of the
workspace to the other, stretching for tools that were just out of
reach.

Was there room enough to invert the tandem? The bottom bracket would
end up a little over 2ft off the shop floor. Not quite ideal height,
but better than the 1ft elevation in the normal position.

True, but when Frank drops a ball bearing it wends its way
into the tandem tube maze instead of landing on the floor.

I've used some old hard disk drive magnets to catch the ball bearings.
I don't know if this works with every frame configuration but methinks
it's worth a try. I also have some magnetic parts dishes to keep the
ball bearings and small screws from rolling away after I accidentally
kick the cat food cans I normally use for holding parts.
https://www.harborfreight.com/search?q=magnetic%20parts%20holder
The dish is stainless steel and can be used as an improvised grease
removal tank to clean the bearings.

As I vaguely recall, Frank's tandem frame is aluminum.

Hah! When I bought this tandem, aluminum wasn't even invented! ;-)

Actually, it's made of Reynolds 531 steel alloy, with oversized tubes.
But for non-steel bikes, that's a good tip about the magnets. (And I
gotta buy me a bore scope.) I used a magnet to help keep the loose balls
from running away when I did that work the other day.

I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses. :-(

On the other hand magnetic bearings may be the wave of the future
providing nearly frictionless motion.
https://www.youtube.com/watch?v=aSoCYi19NJ0
Think of it, no more nasty oil or grease, no more creaks and groans,
no wear and can be used in CF bicycles.
What's not to like?
--
cheers,

John B.

On 24/03/2020 00:59, Frank Krygowski wrote:
On 3/23/2020 3:07 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 19:58:17 -0500, AMuzi wrote:

On 3/22/2020 7:40 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 12:47:49 -0400, Frank Krygowski
wrote:

So I did the work with the tandem on the ground, meaning lots of
bending over, getting up and down, moving the bike from one side of
the
workspace to the other, stretching for tools that were just out of
reach.

Was there room enough to invert the tandem?Â* The bottom bracket would
end up a little over 2ft off the shop floor.Â* Not quite ideal height,
but better than the 1ft elevation in the normal position.

True, but when Frank drops a ball bearing it wends its way
into the tandem tube maze instead of landing on the floor.

I've used some old hard disk drive magnets to catch the ball bearings.
I don't know if this works with every frame configuration but methinks
it's worth a try.Â* I also have some magnetic parts dishes to keep the
ball bearings and small screws from rolling away after I accidentally
kick the cat food cans I normally use for holding parts.
https://www.harborfreight.com/search?q=magnetic%20parts%20holder
The dish is stainless steel and can be used as an improvised grease
removal tank to clean the bearings.

As I vaguely recall, Frank's tandem frame is aluminum.

Hah! When I bought this tandem, aluminum wasn't even invented!Â* ;-)

Actually, it's made of Reynolds 531 steel alloy, with oversized tubes.
But for non-steel bikes, that's a good tip about the magnets. (And I
gotta buy me a bore scope.) I used a magnet to help keep the loose balls
from running away when I did that work the other day.

I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses.Â*Â*Â* :-(

Magnetised ball bearings will "attract" iron alloy detritus from the
road and will stick to them. Tbh, probably not an issue, but I have
seen it.

On Tue, 24 Mar 2020 08:14:11 +0100, Tosspot wrote:


I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses.Â*Â*Â* :-(

Magnetised ball bearings will "attract" iron alloy detritus from the
road and will stick to them. Tbh, probably not an issue, but I have
seen it.

Yep, just dro a magnet on the ground anywhere.
Hint, pit it in a strong plastic bag first.
Useful tool in its own right.

On 3/23/2020 4:59 PM, Frank Krygowski wrote:
On 3/23/2020 3:07 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 19:58:17 -0500, AMuzi wrote:

On 3/22/2020 7:40 PM, Jeff Liebermann wrote:
On Sun, 22 Mar 2020 12:47:49 -0400, Frank Krygowski
wrote:

So I did the work with the tandem on the ground, meaning lots of
bending over, getting up and down, moving the bike from one side of
the
workspace to the other, stretching for tools that were just out of
reach.

Was there room enough to invert the tandem?Â* The bottom bracket would
end up a little over 2ft off the shop floor.Â* Not quite ideal height,
but better than the 1ft elevation in the normal position.

True, but when Frank drops a ball bearing it wends its way
into the tandem tube maze instead of landing on the floor.

I've used some old hard disk drive magnets to catch the ball bearings.
I don't know if this works with every frame configuration but methinks
it's worth a try.Â* I also have some magnetic parts dishes to keep the
ball bearings and small screws from rolling away after I accidentally
kick the cat food cans I normally use for holding parts.
https://www.harborfreight.com/search?q=magnetic%20parts%20holder
The dish is stainless steel and can be used as an improvised grease
removal tank to clean the bearings.

As I vaguely recall, Frank's tandem frame is aluminum.

Hah! When I bought this tandem, aluminum wasn't even invented!Â* ;-)

Actually, it's made of Reynolds 531 steel alloy, with oversized tubes.
But for non-steel bikes, that's a good tip about the magnets. (And I
gotta buy me a bore scope.) I used a magnet to help keep the loose balls
from running away when I did that work the other day.

I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses.Â*Â*Â* :-(

I should think that over a short period of time, the magnetic axis would
tend to align with the spindle, minimizing the drag. For just
$4,329,999, I can sell you a device to optimize this effect! Used by pros!

Mark J.

On Mon, 23 Mar 2020 19:59:47 -0400, Frank Krygowski
wrote:

Actually, it's made of Reynolds 531 steel alloy, with oversized tubes.
But for non-steel bikes, that's a good tip about the magnets. (And I
gotta buy me a bore scope.) I used a magnet to help keep the loose balls
from running away when I did that work the other day.

I suggest the 8mm diameter borescope. The big problem with using a
borescope is the very limited depth of field (i.e. focus range). Also,
try to get one that has adjustable LED lighting. Too much light is as
bad a problem as not enough. All the one's I've bought have a
removable right angle mirror for looking at tubing walls and around
corners. Very handy, but also easy to have the mirror fall off inside
the tubing. So, I sacrificed one camera and glued the right angle
optics in place. Most common use is inspecting the cylinder walls on
chain saws for scoring damage.

I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses. :-(

Never mind the balls. Perhaps you should worry about the axle:
"Demagnetizing Motor Shafts to Prevent Ball Bearing Failures"
https://easa.com/DesktopModules/EasyDNNNews/DocumentDownload.ashx?portalid=0&moduleid=3015&art icleid=2196&documentid=797
For demagnetizing, I have a variety of tools. A generator "growler"
for the big stuff, a 1/4" audio tape bulk eraser for the medium size
stuff, and a tape recorder tape head eraser for small stuff. I also
have a tape wound steel toroid coil that I attach to an old Weller
soldering gun for demagnetizing. For ball bearings, methinks the tape
bulk eraser would be best.

When demagnetizing, do NOT turn off the bulk eraser with the axle or
bearings still on the bulk eraser. Slowly remove the bearings (in a
plastic bag) from the field, and then turn off the eraser. Otherwise,
you might magnetize the bearings instead.

I should probably check if any of my loose ball bearings that I have
in stock are magnetized. Maybe later.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 3/24/2020 2:20 PM, Jeff Liebermann wrote:
On Mon, 23 Mar 2020 19:59:47 -0400, Frank Krygowski
wrote:

Actually, it's made of Reynolds 531 steel alloy, with oversized tubes.
But for non-steel bikes, that's a good tip about the magnets. (And I
gotta buy me a bore scope.) I used a magnet to help keep the loose balls
from running away when I did that work the other day.

I suggest the 8mm diameter borescope. The big problem with using a
borescope is the very limited depth of field (i.e. focus range). Also,
try to get one that has adjustable LED lighting. Too much light is as
bad a problem as not enough. All the one's I've bought have a
removable right angle mirror for looking at tubing walls and around
corners. Very handy, but also easy to have the mirror fall off inside
the tubing. So, I sacrificed one camera and glued the right angle
optics in place. Most common use is inspecting the cylinder walls on
chain saws for scoring damage.

I do worry a bit about that, though. I'm afraid the balls themselves
will become a bit magnetized. Then I'll have to deal with eddy current
losses as they rotate. A truly discerning cyclist can feel those eddy
current losses. :-(

Never mind the balls. Perhaps you should worry about the axle:
"Demagnetizing Motor Shafts to Prevent Ball Bearing Failures"
https://easa.com/DesktopModules/EasyDNNNews/DocumentDownload.ashx?portalid=0&moduleid=3015&art icleid=2196&documentid=797
For demagnetizing, I have a variety of tools. A generator "growler"
for the big stuff, a 1/4" audio tape bulk eraser for the medium size
stuff, and a tape recorder tape head eraser for small stuff. I also
have a tape wound steel toroid coil that I attach to an old Weller
soldering gun for demagnetizing. For ball bearings, methinks the tape
bulk eraser would be best.

When demagnetizing, do NOT turn off the bulk eraser with the axle or
bearings still on the bulk eraser. Slowly remove the bearings (in a
plastic bag) from the field, and then turn off the eraser. Otherwise,
you might magnetize the bearings instead.

Actually, I remember my high school physics teacher demonstrating
exactly that in front of the class. He was alternately magnetizing and
demagnetizing something (I forget what) in front of the class, and
asking what made the difference. I was the only one that spotted that he
was turning off the coil at the end of the magnetizing cycle.

That was back when electricity had just been invented.


--
- Frank Krygowski