On Jul 16, 1:30*pm, 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)

I always like to think that the smallest sprocket must only be used
with the outer ring and the biggest sprocket must only be used with
the smallest ring. This help reduce the strains imposed on the
derailleur pulley spring(s) and sometimes is the only way to shift
cleanly over the entire range without having a drooping chain.
Depending upon your derailleur it might be as well to limit the mid
ring off the bottom two sprockets (if its a racing type der).