Originally Posted by
asmac
Could someone tell me what defines a "compact" crankset?
"Compact" refers to the number of teeth, not anything having to do with chainline. In other words, the diameter is compact, not the width.
"Standard" cranksets have 53 and 39 tooth chainrings. Old-school standards are 52/42.
"Compact" cranksets have either 50/34 or 50/36 chainrings. These are generally paired with a wider-ratio cassette with an 11-tooth small cog so that the effective top ratio--50x11--is nearly the same as a 53x12.
Cyclocross cranksets are pairing 46/36 or 42/34 rings.
Your current touring triple and MTB cassette have much lower gearing than any of the above can ever hope to provide. There may be external bearing touring triples out there, I'm just not aware of any.