On 16 jul, 14:30, John B. Slocomb wrote:
"Cross shifting", i.e., Large chain Ring/large cassette cog or small
chain ring/small cog is generally taken as a mortal sin. But with a
triple chain ring what limits are made to the shift pattern when on
the center ring? Assuming that the chain line through the center line
of the 5th cog, on a 9 speed cassette, and the center line of the
center chain ring?

It appears to me that considering the actual distance between the
three chain rings versus the actual distances on the cassette that the
center chain ring should be able to shift to any cog without problems.

John B. Slocomb
(johnbslocombatgmaildotcom)

Middle ring should shift any cogs. Large chainring avoid two largest
cogs; small chainring avoid two smallest cogs. It is that simple.

Lou