Chain Line

On Thu, 15 Jun 2017 07:20:57 -0700 (PDT), wrote:

On Wednesday, June 14, 2017 at 11:54:46 PM UTC-7, John B. wrote:
On Wed, 14 Jun 2017 20:38:04 -0500, AMuzi wrote:

On 6/14/2017 5:28 PM, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old
square
tapered BB to a modern Shimano outboard bearing bracket.
The argument
was that this would destroy the perfect chain line of the
original
three piece BB.

Now, I have changed back and forth between the original
square tapered
axle to the outboard bearing BB and to my recollection
the chain line
didn't seem to change noticeably.

Over the weekend we took a trip "up country" to visit
some of my
wife's relatives and as we used my wife's car she drove.
It is about
250 Km, one way, so I had a lot of time to think abut
things and one
of the things I thought about was how could I change
bottom brackets
with no appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did
some measuring
and it turns out that with the old fashioned three piece
BB there is
slightly over 10mm clearance between the inner edge of
the crank arm
and the outer edge of the BB. The outboard bearing
"flanges" measured
12mm in thickness and the old sty;e BB flange is `1mm..

Thus the changing from the old style to the more modern
BB results in
very little, if any, difference in chain line. Certainly
less then the
difference between two cogs on the cassette.

Granted that bicycles are all different but the above
does explain why
I, after switching from one type to the other, and back
again, have
seen no noticeable difference in chain line.


The discussion you were referring to was about Shimano 600
gear which is
what I have on my road bike. The clearance from the inner
edge of the
drive side crank to the outer surface of the BB is 3mm.
Now assume your
12mm measurement minus the 1mm that the regular cartridge
BB has. That's
already 11mm of chain line offset. A lot. You could reduce
the clearance
to 2mm but that much wiggle room you really need for
square taper and
that would still leave you with a chain line 10mm off from
where it was.


On my previous frame, I migrated from Campagnolo square
tapered BB & cranks to Campagnolo outboard bearing BB assy,
and the chain line didn't shift 10mm.

Why do you think you are special?


Chainline errors are entirely from not using the
manufacturer's specified parts.

Only a complete idiot would pull a functional spark plug
from a V8 and drop it into a 4-cyl Asian econobox. Yet
people mix arms and spindles which are ridiculously
incompatible every day and then ride over here to complain
that the crank's no good. Oy!

p.s. Almost all derailleur systems will work well with
+1mm/-1mm chainline error. Few can accept 10mm either way,
that is a very large distance.

I think I would have to be a bit picky here. A Big chain ring to a
small cassette cog is going to be about 21 mm out of line, assuming
that the chain line was initially aligned, big ring to 5th cog of a 9
speed cassette, and it still shifts.

But, of course, if the chain line was initially 10 mm out of alignment
then certainly shifting would be a bit "iffy" at least in one
direction :-)

On a triple the middle ring is aligned with the 5th cog.

Yes it is. And as soon as you shift either end it is no longer
aligned.
--
Cheers,

John B.

On Thu, 15 Jun 2017 07:38:18 -0700, Joerg
wrote:

On 2017-06-15 07:23, wrote:
On Thursday, June 15, 2017 at 6:28:34 AM UTC-7, Joerg wrote:
On 2017-06-14 19:08, James wrote:
On 15/06/17 08:33, Joerg wrote:
On 2017-06-14 15:28, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old
square tapered BB to a modern Shimano outboard bearing
bracket. The argument was that this would destroy the
perfect chain line of the original three piece BB.

Now, I have changed back and forth between the original
square tapered axle to the outboard bearing BB and to my
recollection the chain line didn't seem to change
noticeably.

Over the weekend we took a trip "up country" to visit
some of my wife's relatives and as we used my wife's car
she drove. It is about 250 Km, one way, so I had a lot of
time to think abut things and one of the things I thought
about was how could I change bottom brackets with no
appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did
some measuring and it turns out that with the old
fashioned three piece BB there is slightly over 10mm
clearance between the inner edge of the crank arm and the
outer edge of the BB. The outboard bearing "flanges"
measured 12mm in thickness and the old sty;e BB flange is
`1mm..

Thus the changing from the old style to the more modern
BB results in very little, if any, difference in chain
line. Certainly less then the difference between two cogs
on the cassette.

Granted that bicycles are all different but the above
does explain why I, after switching from one type to the
other, and back again, have seen no noticeable difference
in chain line.


The discussion you were referring to was about Shimano 600
gear which is what I have on my road bike. The clearance
from the inner edge of the drive side crank to the outer
surface of the BB is 3mm. Now assume your 12mm measurement
minus the 1mm that the regular cartridge BB has. That's
already 11mm of chain line offset. A lot. You could reduce
the clearance to 2mm but that much wiggle room you really
need for square taper and that would still leave you with a
chain line 10mm off from where it was.


On my previous frame, I migrated from Campagnolo square
tapered BB & cranks to Campagnolo outboard bearing BB assy,
and the chain line didn't shift 10mm.


Did you buy new cranks? If not, was there sufficient clearance
to make up for the added millimeter of the outboard bearing? On
my bike there isn't.


Is there an outboard BB bearing assembly that uses a square
tapered axle?

I don't know. I bought a Campag Ultra Torque crank & BB assy
back in 2007-8. I've replaced the bearings once, about 5 years
ago. No bearing slop noticeable yet.


Sure, if you buy matching cranks it's all fine. However, in the
referenced thread it was not the objective to throw away a
perfectly good set of cranks just because of a new BB.

Five years is good but that depends on how many miles you put on,
the amount of uphill sections and whether you usually spin or
mash.


Why do you think you are special?


See above. There simply is no room for another 11mm without the
crank moving at least 10mm outward. Naturally, the goal was to
keep the Shimano 600 cranks. Installing a UN55 internal
cartridge bearing allowed me to do that and so that is what I
did.


So you think you're special because you want to keep cranks that
aren't compatible.


I am not special but among the people who wish not to belong to a
throw-away society.


Good luck.


Not needed. I received the new BB a while ago, installed it and all
is well. Cost me all of $20.

I'm still trying to figure out how the conversation got from your
worrying about a 1 mm realignment to a 10 mm realignment.


The BB I bought was 115mm instead of the 116mm of the previous installed
one. That didn't really concern me and, as Andrew hinted, it could be
remedied via spacer and would in the end only be 0.5mm per side.
Peanuts. I started the original thread because there are conflicting
statements about the Shimano UN55 BBs in the various ads. Many in the UK
said it's ISO-taper while in the US it was listed as JIS-taper (which
luckily turned out to be the case). Mostly, however, there was no
statement at all. There is a 4.5mm offset between JIS and ISO which
would not be good.

The 10mm offset came up because someone suggested a BB with outboard
bearings and that clearly does not work for Shimano 600 gear.

I think you must have misunderstood as the outboard bearings are not
used with a tapered square crank. As I remember it the suggestion was
made in response to your bemoaning the one piece UNxx bottom bearing
and whether it was strong enough. Something about the plastic insert
on the right end, or something.

Anyhow, it's all done, the new BB-UN55 works and has survived three
rides now. I still have the steerer hose clamp though :-)
--
Cheers,

John B.

On Thursday, June 15, 2017 at 6:54:43 PM UTC-4, Joerg wrote:
Snipped
Same here, one year used to be it for BBs. This one I rode longer but I
pushed it well past the point where others would call it shot. Where you
had to trim the front derailer when shifting more than one cog in back
because of the chain ring sway. Without friction shifters I couldn't
have kept using it.
Snipped

In other words you abused the bottom bracket and the crankset by riding it when there was a lot of play in it.

Yet another contradiction to your claiming to maintain your bikes.

No wonder your stuff breaks or wears out prematurely.

Cheers

On Thu, 15 Jun 2017 18:45:23 -0700 (PDT), Sir Ridesalot
wrote:

On Thursday, June 15, 2017 at 6:54:43 PM UTC-4, Joerg wrote:
Snipped
Same here, one year used to be it for BBs. This one I rode longer but I
pushed it well past the point where others would call it shot. Where you
had to trim the front derailer when shifting more than one cog in back
because of the chain ring sway. Without friction shifters I couldn't
have kept using it.
Snipped

In other words you abused the bottom bracket and the crankset by riding it when there was a lot of play in it.

Yet another contradiction to your claiming to maintain your bikes.

No wonder your stuff breaks or wears out prematurely.

Cheers

But according to his posts he needs the time to brew beer :-)

I'm retired and so have plenty of time and my bike maintenance is
usually washing the bike weekly, in the rainy season, and every two or
three or four weeks in the dry season, and I usually check for loose
nuts and bolts when I wash the bike. I re wax the chain perhaps once a
month and that is about it. Counting on my fingers, that is maybe one
hour to an hour and a half each month spent in bike maintenance. Given
that there is about 730 hours in the average month that doesn't seem
excessive.

Oh! I forgot. After each ride I remove the tail light and the battery
from the front light and charge them, so add another 5 minutes, per
ride, to the count.
--
Cheers,

John B.

On 2017-06-15 18:18, John B. wrote:
On Thu, 15 Jun 2017 07:38:18 -0700, Joerg
wrote:

On 2017-06-15 07:23, wrote:
On Thursday, June 15, 2017 at 6:28:34 AM UTC-7, Joerg wrote:
On 2017-06-14 19:08, James wrote:
On 15/06/17 08:33, Joerg wrote:
On 2017-06-14 15:28, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old
square tapered BB to a modern Shimano outboard bearing
bracket. The argument was that this would destroy the
perfect chain line of the original three piece BB.

Now, I have changed back and forth between the original
square tapered axle to the outboard bearing BB and to my
recollection the chain line didn't seem to change
noticeably.

Over the weekend we took a trip "up country" to visit
some of my wife's relatives and as we used my wife's car
she drove. It is about 250 Km, one way, so I had a lot of
time to think abut things and one of the things I thought
about was how could I change bottom brackets with no
appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did
some measuring and it turns out that with the old
fashioned three piece BB there is slightly over 10mm
clearance between the inner edge of the crank arm and the
outer edge of the BB. The outboard bearing "flanges"
measured 12mm in thickness and the old sty;e BB flange is
`1mm..

Thus the changing from the old style to the more modern
BB results in very little, if any, difference in chain
line. Certainly less then the difference between two cogs
on the cassette.

Granted that bicycles are all different but the above
does explain why I, after switching from one type to the
other, and back again, have seen no noticeable difference
in chain line.


The discussion you were referring to was about Shimano 600
gear which is what I have on my road bike. The clearance
from the inner edge of the drive side crank to the outer
surface of the BB is 3mm. Now assume your 12mm measurement
minus the 1mm that the regular cartridge BB has. That's
already 11mm of chain line offset. A lot. You could reduce
the clearance to 2mm but that much wiggle room you really
need for square taper and that would still leave you with a
chain line 10mm off from where it was.


On my previous frame, I migrated from Campagnolo square
tapered BB & cranks to Campagnolo outboard bearing BB assy,
and the chain line didn't shift 10mm.


Did you buy new cranks? If not, was there sufficient clearance
to make up for the added millimeter of the outboard bearing? On
my bike there isn't.


Is there an outboard BB bearing assembly that uses a square
tapered axle?

I don't know. I bought a Campag Ultra Torque crank & BB assy
back in 2007-8. I've replaced the bearings once, about 5 years
ago. No bearing slop noticeable yet.


Sure, if you buy matching cranks it's all fine. However, in the
referenced thread it was not the objective to throw away a
perfectly good set of cranks just because of a new BB.

Five years is good but that depends on how many miles you put on,
the amount of uphill sections and whether you usually spin or
mash.


Why do you think you are special?


See above. There simply is no room for another 11mm without the
crank moving at least 10mm outward. Naturally, the goal was to
keep the Shimano 600 cranks. Installing a UN55 internal
cartridge bearing allowed me to do that and so that is what I
did.


So you think you're special because you want to keep cranks that
aren't compatible.


I am not special but among the people who wish not to belong to a
throw-away society.


Good luck.


Not needed. I received the new BB a while ago, installed it and all
is well. Cost me all of $20.

I'm still trying to figure out how the conversation got from your
worrying about a 1 mm realignment to a 10 mm realignment.


The BB I bought was 115mm instead of the 116mm of the previous installed
one. That didn't really concern me and, as Andrew hinted, it could be
remedied via spacer and would in the end only be 0.5mm per side.
Peanuts. I started the original thread because there are conflicting
statements about the Shimano UN55 BBs in the various ads. Many in the UK
said it's ISO-taper while in the US it was listed as JIS-taper (which
luckily turned out to be the case). Mostly, however, there was no
statement at all. There is a 4.5mm offset between JIS and ISO which
would not be good.

The 10mm offset came up because someone suggested a BB with outboard
bearings and that clearly does not work for Shimano 600 gear.

I think you must have misunderstood as the outboard bearings are not
used with a tapered square crank.


That would be moot because I had specifically asked about a replacement
for the Shimano 600 BB, not a partially new road bike.


... As I remember it the suggestion was
made in response to your bemoaning the one piece UNxx bottom bearing
and whether it was strong enough. Something about the plastic insert
on the right end, or something.


I was simply asking about whether it is JIS-taper. The UN55 has a metal
cup on the left side and both the UN55 and UN26 have metal cups on the
right. I wasn't too enthused about the fact that the left cup isn't
steel but aluminum. We'll see whether that lasts.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-06-15 19:44, John B. wrote:
On Thu, 15 Jun 2017 18:45:23 -0700 (PDT), Sir Ridesalot
wrote:

On Thursday, June 15, 2017 at 6:54:43 PM UTC-4, Joerg wrote:
Snipped
Same here, one year used to be it for BBs. This one I rode longer
but I pushed it well past the point where others would call it
shot. Where you had to trim the front derailer when shifting more
than one cog in back because of the chain ring sway. Without
friction shifters I couldn't have kept using it.
Snipped

In other words you abused the bottom bracket and the crankset by
riding it when there was a lot of play in it.

Yet another contradiction to your claiming to maintain your bikes.


I maintain as needed. With friction shifters I could easily tolerate a
BB with slop in there. Gave me a lot more miles out of the last one.


No wonder your stuff breaks or wears out prematurely.


Nothing down there wore out prematurely.


Cheers

But according to his posts he needs the time to brew beer :-)


Oh yeah :-)


I'm retired and so have plenty of time and my bike maintenance is
usually washing the bike weekly, in the rainy season, and every two
or three or four weeks in the dry season, and I usually check for
loose nuts and bolts when I wash the bike. I re wax the chain perhaps
once a month and that is about it. Counting on my fingers, that is
maybe one hour to an hour and a half each month spent in bike
maintenance. Given that there is about 730 hours in the average month
that doesn't seem excessive.

Oh! I forgot. After each ride I remove the tail light and the
battery from the front light and charge them, so add another 5
minutes, per ride, to the count.


Get an on-board Li-Ion battery. I have them on both bikes. Park the
bike, plug in, done. For the MTB that took some time in the shop because
the commercial bicycle battery holders are too flimsy.

--
Regards, Joerg

http://www.analogconsultants.com/

On Thursday, June 15, 2017 at 3:42:43 PM UTC-7, James wrote:
On 15/06/17 23:28, Joerg wrote:
On 2017-06-14 19:08, James wrote:
On 15/06/17 08:33, Joerg wrote:
On 2017-06-14 15:28, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old square
tapered BB to a modern Shimano outboard bearing bracket. The argument
was that this would destroy the perfect chain line of the original
three piece BB.

Now, I have changed back and forth between the original square
tapered
axle to the outboard bearing BB and to my recollection the chain line
didn't seem to change noticeably.

Over the weekend we took a trip "up country" to visit some of my
wife's relatives and as we used my wife's car she drove. It is about
250 Km, one way, so I had a lot of time to think abut things and one
of the things I thought about was how could I change bottom brackets
with no appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did some
measuring
and it turns out that with the old fashioned three piece BB there is
slightly over 10mm clearance between the inner edge of the crank arm
and the outer edge of the BB. The outboard bearing "flanges" measured
12mm in thickness and the old sty;e BB flange is `1mm..

Thus the changing from the old style to the more modern BB results in
very little, if any, difference in chain line. Certainly less then
the
difference between two cogs on the cassette.

Granted that bicycles are all different but the above does explain
why
I, after switching from one type to the other, and back again, have
seen no noticeable difference in chain line.


The discussion you were referring to was about Shimano 600 gear
which is
what I have on my road bike. The clearance from the inner edge of the
drive side crank to the outer surface of the BB is 3mm. Now assume
your
12mm measurement minus the 1mm that the regular cartridge BB has.
That's
already 11mm of chain line offset. A lot. You could reduce the
clearance
to 2mm but that much wiggle room you really need for square taper and
that would still leave you with a chain line 10mm off from where it
was.


On my previous frame, I migrated from Campagnolo square tapered BB &
cranks to Campagnolo outboard bearing BB assy, and the chain line
didn't
shift 10mm.


Did you buy new cranks? If not, was there sufficient clearance to make
up for the added millimeter of the outboard bearing? On my bike there
isn't.


Is there an outboard BB bearing assembly that uses a square tapered axle?

I don't know. I bought a Campag Ultra Torque crank & BB assy back in
2007-8. I've replaced the bearings once, about 5 years ago. No bearing
slop noticeable yet.


Sure, if you buy matching cranks it's all fine. However, in the
referenced thread it was not the objective to throw away a perfectly
good set of cranks just because of a new BB.

Five years is good but that depends on how many miles you put on, the
amount of uphill sections and whether you usually spin or mash.

In recent years I raced A grade veterans (over 35) and generally ride
over 10,000km per year. I often head for the hills. I use 175mm cranks
and my cadence is usually around 90 on the flat and less while climbing.
Where I live now, a gentle hill is 5%, and most are up around 10%.

I don't think you could claim I give the BB an easy time. I used to
kill square taper cartridge BBs within a season - Shimano and Campagnolo.



Why do you think you are special?


See above. There simply is no room for another 11mm without the crank
moving at least 10mm outward. Naturally, the goal was to keep the
Shimano 600 cranks. Installing a UN55 internal cartridge bearing allowed
me to do that and so that is what I did.


So you think you're special because you want to keep cranks that aren't
compatible.


I am not special but among the people who wish not to belong to a
throw-away society.


Good luck.


Not needed. I received the new BB a while ago, installed it and all is
well. Cost me all of $20.


As I said, good luck. It will last a long time if you don't use it.

I am 190 lbs, 6'4" and use 175 mm cranks. The hills around the bay area have many 10% and steeper paved climbs. 19% in one case. I have NEVER worn out a square taper BB. Even the cheap ones. I can only assume that you ride out of the saddle on climbs and put huge loads on the BB that end up having nothing to do with a forwards drive.

On 2017-06-15 18:11, John B. wrote:
On Thu, 15 Jun 2017 06:28:39 -0700, Joerg
wrote:

On 2017-06-14 19:08, James wrote:
On 15/06/17 08:33, Joerg wrote:
On 2017-06-14 15:28, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old square
tapered BB to a modern Shimano outboard bearing bracket. The argument
was that this would destroy the perfect chain line of the original
three piece BB.

Now, I have changed back and forth between the original square tapered
axle to the outboard bearing BB and to my recollection the chain line
didn't seem to change noticeably.

Over the weekend we took a trip "up country" to visit some of my
wife's relatives and as we used my wife's car she drove. It is about
250 Km, one way, so I had a lot of time to think abut things and one
of the things I thought about was how could I change bottom brackets
with no appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did some measuring
and it turns out that with the old fashioned three piece BB there is
slightly over 10mm clearance between the inner edge of the crank arm
and the outer edge of the BB. The outboard bearing "flanges" measured
12mm in thickness and the old sty;e BB flange is `1mm..

Thus the changing from the old style to the more modern BB results in
very little, if any, difference in chain line. Certainly less then the
difference between two cogs on the cassette.

Granted that bicycles are all different but the above does explain why
I, after switching from one type to the other, and back again, have
seen no noticeable difference in chain line.


The discussion you were referring to was about Shimano 600 gear
which is
what I have on my road bike. The clearance from the inner edge of the
drive side crank to the outer surface of the BB is 3mm. Now assume your
12mm measurement minus the 1mm that the regular cartridge BB has.
That's
already 11mm of chain line offset. A lot. You could reduce the
clearance
to 2mm but that much wiggle room you really need for square taper and
that would still leave you with a chain line 10mm off from where it
was.


On my previous frame, I migrated from Campagnolo square tapered BB &
cranks to Campagnolo outboard bearing BB assy, and the chain line didn't
shift 10mm.


Did you buy new cranks? If not, was there sufficient clearance to make
up for the added millimeter of the outboard bearing? On my bike there
isn't.


Is there an outboard BB bearing assembly that uses a square tapered axle?

I don't know. I bought a Campag Ultra Torque crank & BB assy back in
2007-8. I've replaced the bearings once, about 5 years ago. No bearing
slop noticeable yet.


Sure, if you buy matching cranks it's all fine. However, in the
referenced thread it was not the objective to throw away a perfectly
good set of cranks just because of a new BB.

Five years is good but that depends on how many miles you put on, the
amount of uphill sections and whether you usually spin or mash.


Why do you think you are special?


See above. There simply is no room for another 11mm without the crank
moving at least 10mm outward. Naturally, the goal was to keep the
Shimano 600 cranks. Installing a UN55 internal cartridge bearing allowed
me to do that and so that is what I did.


So you think you're special because you want to keep cranks that aren't
compatible.


I am not special but among the people who wish not to belong to a
throw-away society.


Good luck.


Not needed. I received the new BB a while ago, installed it and all is
well. Cost me all of $20.

I don't understand this continual complaining about prices. Here you
brag that you only spent $20 and in another post you said, "If I can
find decently priced cassette", and yet when I suggest that you go
into the bike carrier business as you claimed that everyone wanted a
rack like you made you said about you already had plenty of money.


No. Repeating it for the umpteenth time, my business is in _electronics_
and in particular the design of those. Yes, I am gradually retiring but
never 100% because then the sky falls for me, I need some tech-sizzle.

I have no problem spending $50 on a cassette. I do have a problem
spending $150 on a cassette because I consider that wasteful and
unnecessary. Just like I would not spend $150 on a tire for my car
(which lasts me north of 70k miles).

--
Regards, Joerg

http://www.analogconsultants.com/

On 2017-06-16 07:09, wrote:
On Thursday, June 15, 2017 at 3:42:43 PM UTC-7, James wrote:
On 15/06/17 23:28, Joerg wrote:
On 2017-06-14 19:08, James wrote:

[...]



Good luck.


Not needed. I received the new BB a while ago, installed it and
all is well. Cost me all of $20.


As I said, good luck. It will last a long time if you don't use
it.

I am 190 lbs, 6'4" and use 175 mm cranks. The hills around the bay
area have many 10% and steeper paved climbs. 19% in one case. I have
NEVER worn out a square taper BB. Even the cheap ones. I can only
assume that you ride out of the saddle on climbs and put huge loads
on the BB that end up having nothing to do with a forwards drive.


I am around 220lbs. Steel frame bike, often lots of load to be carried.
Fedex packages, plumbing parts, brewing supplies. The only BB that
lasted "forever" (until that bike was stolen) was one I built myself out
of Timken bearings. Others show signs of wear after about a year. The
recent (and last) Shimano 600 BB lasted about three years but that was
because I spent half of my miles on the MTB and also let it go well past
the point where I'd normally replace it. No big deal on a
friction-shifter bike.

Supposedly the UN55 cartridge is good for 10-15k miles and if it holds
that long I'd be happy. Takes only 1/2h or so to replace and $20 isn't
very expensive. Also, I can keep riding for some time even if it
develops some slop. So I don't need to keep a spare in the garage.

--
Regards, Joerg

http://www.analogconsultants.com/

On 6/16/2017 10:53 AM, Joerg wrote:
On 2017-06-15 18:11, John B. wrote:
On Thu, 15 Jun 2017 06:28:39 -0700, Joerg
wrote:

On 2017-06-14 19:08, James wrote:
On 15/06/17 08:33, Joerg wrote:
On 2017-06-14 15:28, James wrote:
On 15/06/17 06:31, Joerg wrote:
On 2017-06-13 19:09, John B. wrote:

In a recent discussion I suggested changing from the old square
tapered BB to a modern Shimano outboard bearing bracket. The
argument
was that this would destroy the perfect chain line of the original
three piece BB.

Now, I have changed back and forth between the original square
tapered
axle to the outboard bearing BB and to my recollection the chain
line
didn't seem to change noticeably.

Over the weekend we took a trip "up country" to visit some of my
wife's relatives and as we used my wife's car she drove. It is
about
250 Km, one way, so I had a lot of time to think abut things and
one
of the things I thought about was how could I change bottom
brackets
with no appreciable difference in chain line.

This morning I turned one of my bikes bottom up and did some
measuring
and it turns out that with the old fashioned three piece BB
there is
slightly over 10mm clearance between the inner edge of the crank
arm
and the outer edge of the BB. The outboard bearing "flanges"
measured
12mm in thickness and the old sty;e BB flange is `1mm..

Thus the changing from the old style to the more modern BB
results in
very little, if any, difference in chain line. Certainly less
then the
difference between two cogs on the cassette.

Granted that bicycles are all different but the above does
explain why
I, after switching from one type to the other, and back again, have
seen no noticeable difference in chain line.


The discussion you were referring to was about Shimano 600 gear
which is
what I have on my road bike. The clearance from the inner edge of
the
drive side crank to the outer surface of the BB is 3mm. Now
assume your
12mm measurement minus the 1mm that the regular cartridge BB has.
That's
already 11mm of chain line offset. A lot. You could reduce the
clearance
to 2mm but that much wiggle room you really need for square taper
and
that would still leave you with a chain line 10mm off from where it
was.


On my previous frame, I migrated from Campagnolo square tapered BB &
cranks to Campagnolo outboard bearing BB assy, and the chain line
didn't
shift 10mm.


Did you buy new cranks? If not, was there sufficient clearance to make
up for the added millimeter of the outboard bearing? On my bike there
isn't.


Is there an outboard BB bearing assembly that uses a square tapered
axle?

I don't know. I bought a Campag Ultra Torque crank & BB assy back in
2007-8. I've replaced the bearings once, about 5 years ago. No
bearing
slop noticeable yet.


Sure, if you buy matching cranks it's all fine. However, in the
referenced thread it was not the objective to throw away a perfectly
good set of cranks just because of a new BB.

Five years is good but that depends on how many miles you put on, the
amount of uphill sections and whether you usually spin or mash.


Why do you think you are special?


See above. There simply is no room for another 11mm without the crank
moving at least 10mm outward. Naturally, the goal was to keep the
Shimano 600 cranks. Installing a UN55 internal cartridge bearing
allowed
me to do that and so that is what I did.


So you think you're special because you want to keep cranks that aren't
compatible.


I am not special but among the people who wish not to belong to a
throw-away society.


Good luck.


Not needed. I received the new BB a while ago, installed it and all is
well. Cost me all of $20.

I don't understand this continual complaining about prices. Here you
brag that you only spent $20 and in another post you said, "If I can
find decently priced cassette", and yet when I suggest that you go
into the bike carrier business as you claimed that everyone wanted a
rack like you made you said about you already had plenty of money.


No. Repeating it for the umpteenth time, my business is in _electronics_
and in particular the design of those. Yes, I am gradually retiring but
never 100% because then the sky falls for me, I need some tech-sizzle.

I have no problem spending $50 on a cassette. I do have a problem
spending $150 on a cassette because I consider that wasteful and
unnecessary. Just like I would not spend $150 on a tire for my car
(which lasts me north of 70k miles).

You'll never guess which chain lube makes your cassettes last longest. :-)


--
- Frank Krygowski