Following up on the problem three speed hub:

First, I see I mislabeled the hub. It's a Shimano 3CC coaster brake
model, not a 333.

I took the bike home and spent several evenings gazing at and
pondering the hub's internals. The Shimano mechanism is much
different than Sturmey-Archer's.

Everything inside is pristine and now clean of grease and lubed with
oil, except the ball bearings, which are greased. 2nd gear drive is
via axial meshing of two members with 56 tiny crown teeth. I looked
hard at that, since 2nd gear is where the irritating slipping occurs. But I see absolutely nothing wrong.

With the guts assembled and the axle held in a vise, but with the
shell (or wheel) removed, everything seemed fine, with one
largely irrelevant detail mentioned below. Installing the shell
plus wheel also seemed fine. For that work, I was holding the
bellcrank in the various gear positions by means of a tapered
wedge. But installed on the bike in a workstand, the hub first
seemed fine, but then started the 2nd gear skip.

Seems the cable tension adjustment had somehow shifted again; and
it seems to me this hub is much less tolerant of misadjustment
than the S-A hubs I'm more used to. Late last night, I re-adjusted
yet again, and at 11 PM it seemed OK, but I remain worried.

At this point, weather will prevent test rides for maybe a week.
We'll see how things go after that.

BTW, I thought the hub felt draggy. Applying a spring scale to
a chain on the sprocket, it took about 1000 grams (2 pounds) to
turn the sprocket even with no load, or even with the wheel
overrunning. That seems to be built in to the design of this
coaster brake version. There is a sort of steel band spring in the
brake mech, wrapped about 330 degrees around a "spring guide", and
normal pedaling rotates the guide inside that spring, with sliding
contact. I thought "That can't be right," but on further thought
and computation, it wastes only about 4 Watts. It's a little
offensive to this guy used to perfectly free-running bearings, but
it's mostly an aesthetic problem.

And digging around the internet and printed sources, it seems
Shimano tried and tried again with these hubs. There are several
generations, some with bellcranks on the left, some on the right.
The internals vary as well. I don't know where my hub is in the
trial-and-error cycle. Overall, I like Sturmey-Archer better.

- Frank Krygowski