Would I get away with a shorter BB spindle if I was running a SS. At the moment I am using a 122mm
(from what I can see) on a triple ring set.

But is it worthwhile using a 113mm?

Discuss please..?

Depends on the profile of the crankset. Older and cheaper cranks use 122 or 127.5 Newer ones run 113 or sometimes 118. You could possibly put on a shorter bb and run the middle ring on the outside. Measure the chainline (center of seattube to centre of ring) for the outer ring, subtract half the difference in the old and new bb lengths and see if it equals about 50mm. Usually 47-50mm is about right.

Thanks bike whisper. Don't quite understand it yet but have saved it for later. Ordered the shorter one now 😕