On Fri, 1 Feb 2008 13:35:02 +1100, Dan Burkhart
wrote:


Andre Jute Wrote:
On Feb 1, 12:19*am, That'll be the viewpoint which completely ignores
what the manufacturer
says, would it?

That's not right, Clive. I ignored what Rohloff *didn't* say:

Rohloff don't specify maximum gearing.


Andre Jute
Heretic

Actually, Rohloff does state there is no maximum.
http://www.rohloff.de/fileadmin/rohl...fo_2.13.en.pdf
Page 13, left column near the bottom.
"Larger chainrings can be used without exceptions"
I've seen it elsewhere on their web site, but I can't find it right
now.
Dan[/color]

Dear Dan,

Probably this:

"Of course, the use of larger chainrings is completely allowed, this
increases the primary force and the entry force at the same time for
the hub to reduce."

http://www.rohloff.de/en/info/faq/fa...289/index.html

It's worth belaboring the point, since otherwise someone might
mistakenly swap in a _smaller_ chainring and destroy an expensive hub.

Rohloff sets a _minimum_ front:rear sprocket ratio.

A 40:17 (2.35:1) is the minimum ratio for normal riders.

A 40:16 (2.50:1) is the minimum ratio for heavier riders and tandems.

The 40-tooth front in the example can be increased to any size--the
front:rear ratio just gets bigger. Switching to 42-tooth or 72-tooth
is fine.

But he 40-tooth front in the example should not be reduced--the
front:rear ratio would fall below the minimum, and Rohloff expects
that the increased force inside the hub would damage its gears.

For example, replacing the 40-tooth front with a smaller 32-tooth
would be begging for trouble, since 32:16 is only 2.00:1, well below
the 2.35:1 minimum front/rear sprocket ratio.

Again, the rear wheel doesn't matter because the problem occurs in the
tiny gears inside the hub.

Cheers,

Carl Fogel