unfortunately i can't do a search now, but i started a thread a while back asking why nagasawas come with 109mm square taper bb's installed, since the only current production cranks that fit that are the suginos. here's what tomity said:

Hi!! This is Tomity
90% of Japan nearby professinal Keirin rider uses the crank of old square-taper type.
Therefore, Mr. nagasawa equips it with bb of hatta R9400.

The crank of most square-taper type of NJS suits bb of hatta R9400.
Professional Keirin rider doesn't frequently remove the crank usually.

The reason is that square-taper of the crank extends.
The possibility of it that the chain line shifts is high.

There are a lot of fans because Sugino grand mightys is more flexible than Sugino 75s.
Because Shimano octalink splined system should exchange bb, popularity is low.

However, Shimano octalink splined system is a repetition of the installation of the crank and
doesn't have the change in the chain line.

Were you able to understand?
Tomity


onetwentyeight asked for confirmation:

Tomity - Are you saying that the Grand Mighty's are not as stiff as 75s??

PS. I got my tomity cog, it is lovely, thanks!

Tomity confirmed:

Yes!! Almost rider says its opinion
The reason is related to the sectional area of the crank.

In it, I am very honored. Thank you!!

here's the thread