Paul Kopit wrote:
On 2 Jun 2005 05:24:26 -0700, wrote:
I'm not sure what exact point regarding compact doubles the OP was
addressing, either. But I do wonder why anyone would pay to have the
potential utility of a crank *reduced*, as in your Sugino triple to
double conversion.

There are little bumps where the threads for the inner ring are. When
the chain is derailled, it will lodge between the bottom bracket and
those bumps and become very difficult to get back up. Remember, when
using as a double, the crankarm is closer to the frame. Those pumps
are particularly pronounced on something like an RX 100 crank.

In addition, converting a triple to a double can result in a lower
Q-factor (tread) than many purpose-built doubles, which is something
that a lot of people, including me, like a lot.

Once upon a time, Sugino and others built triple cranks that used
separate spacers for the inner ring (and had no "bumps"), and bottom
brackets had interchangeable axles, so you could go back and forth from
a triple to a double as you saw fit without any grinding or filing. But
then, a lot of double cranks back then also used the 110mm BCD, too.

I wonder why the move to integrated granny spacers happened. I can't
see any benefit in it, for the consumer at least.