In a message dated 9/2/03 6:56:40 AM Pacific Daylight Time, firstname.lastname@example.org writes:
> I know most of the literature says don't use the small-small or big-big
> combinations. Doesn't this generally refer to triples and/or modern bikes
> with wider spacing? I would think that on bikes in the CR timeframe, with
> double chainrings, cross-chaining would not be as big of an issue, unless
> the chainstays were really short.
> I only have 12 speeds, I'd like to use them all.
The first thing you should do, is take a look at your chainline. I used to
have a preference for having the cranks a little farther "in" than perfect, as I
was more likely to use the big ring, 2nd biggest cog a lot. With the
chainline in a little I could also use the big/big combo for short stretches if
necessary (but never very often). With the chainline favoring that direction, if you
use the small/small combo, the chain will drag on the big ring starting with
the 2nd smallest gear.
If your riding style favors the small ring and smaller cogs, you might think
about setting the cranks "out" a bit more than perfect, but you'll lose some
performance in the big/2nd biggest position.
If you have a 10 speed, you really only get to use 8 gears, if you have a 12
speed, you only get 10 useable (otherwise, you wear it all out, a LOT faster).
For that reason, you want to map your gears on a gear chart and make sure you
don't have any silly duplications in useable spots.
That said, if you have a size gear that really works for you in the area that
you ride a lot, it can make perfect sense to have that gear available on both
the large and small ring.