On Wednesday, June 14, 2017 at 7:08:21 PM UTC-7, 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.


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.

James - stay on track. This thread started with Joerg asking it the newer Shimano square taper BB with sealed bearings had the same taper as his original Shimano 600.

Most of what he supposedly said is entirely made up.

_I_ am the one that said that the newest hollow cranks are far better.

Don't you people think it's about time to follow the subject and not some subjective ideas you have?