Complicated but of immense value if we manage to put this issue to rest once and for all.

My experience:

The Shimano 107 BB works fine with the Sugino 75. Not quite "on" but close enough.

I am now running the proper matching Sugino 75 BB with the cranks and it actually feels different. Smoother, quieter and a dead-on chainline.

While running the Shimano will do you just fine, if you can afford to, get the matching BB. Having the proper set-up just "feels" right on many levels.

I think the quieter and smoother might have also to do with the chainline and not just the BB.
I ran a 107 shimano with Sug 75 added a spacer to the bb and the chainline was dead on and it was quiet and smooth until the bb crapped out. Now running a phil and it is again smooth and quiet.

In your experience does the Sugino let the cranks sit deeper than the Shimano? My guess is it is the same, since it managed to change your chainline when switching from a 107 to a 109 bb. But who knows...

Definitely, the quiet and smooth changed with the chainline. It was 1mm off with the Shimano. You could barely tell but you could see the chain come onto the chainring at a very slight angle.

And yes, the Sugino BB lets the cranks sit in deeper. They're pretty close to the BB shell, with no odd gaps - whereas the Shimano showed quite a bit of gap. This of course has to do with the BB cup and cone sticking outwards but it also feels like it went on snugger. All of this is "feel" rather than actual science like you folks have been debating but sometimes, "feel" feels right.

Sugino may be managing their tolerances to a smaller variance. Shimano BB are made for gears and crossed over chainlines so will not care as much about how consistant their products are. Sugino prob cares a lot more and will reduce the variance in their products (i.e. impose a tighter manufacturing tolerance than the industry standard) which will result in repeatability between parts (i.e. better chain line as advertized). Remember there is industry tolerance and there is manufacturing variance. How you manage the variance depends on what your audience demand and how much they are willing to pay.

if you want to be cheaper about it, just buy the damn sugino bottom bracket spindle and use whatever japanese cups and bearings that you have. i run sugino 75s on my gitane, which is french threaded and just use sugino french threaded cups and quality loose bearings. my price ended up not being too much lower than the actual 75 bottom bracket cost, but that's because the french cups are rare and expensive. almost any garbage-ass bottom bracket on a bike from the 80s japanese bike boom will have suitable cups. buy the 30$ spindle from aebike or realize that the shimano (or whatever) JIS bottom bracket that you buy will work alright, but is not ideal, and shut the **** up.

The Shimano BB-7610 square taper 109mm track bottom bracket is still available from the UK. If you want to use a sealed BB this is a good option.

I use it. No chainline worries. No noisy drivetrain. It works.

I have three. All bought from Swinnerton in the UK.

smell that? *sniff sniff* has a hint of "faux-antagonism."

haha, that was me being annoyed by the ridiculousness of this thread.

Ridiculous in a sense we can't come up with a straight answer on what exactly Sugino taper is.

Its going to be a long winter

Sugino taping is killing the music industry.

Naz, I was waiting for you to weigh in. I'm kind of wincing at the thought of spending $90 on a part that I'm not even going to get to see on a daily basis, but I'm determined not to cut corners with this build (spare me the usual "bottom brackets are as important as hubs" speech, everybody). Always nice to see threads that are actually about bikes get this much attention. Maybe I'll be able to get a DA headset off of eBay for $5 and it'll all even out.

Schloe-no frame yet. This week, hopefully? I'm taking the mailroom guy at work out to lunch tomorrow in anticipatory thanks for signing for an endless barrage of boxes over the next couple of months.

I heard it was the reason metallica cut their hair.

You might actually see the BB daily - the cups are on the outside so if you look down, there they are. It's a beautiful BB, very nicely made. But that's aesthetics and quality I guess.

As for DA headsets - ebay has em cheap! There are a few for $6 right now. You can get them under $30 easily. Campy too...

Yeah, I keep going back and forth on that...I love the look of the Campy headset, but this damn forum's kind of got me hooked on uniform component groups by nationality...which is weird, because there's no way I'm going to shell out for a Jaguar seatpost, and likewise Record Pista cranks.

Fortunately, it's all interchangable...