What's the difference?
Well… I usually ride a size 54. My maximum tolerance is probably 545mm top tube C-C with a 100mm stem and non-set back seat post.
This current Merlin has a 550mm C-C top tube with a 110/120mm stem. Feels pretty stretched out for me right now, but still bearable. To add on a set back seat post means I'll be pushed back a further 10mm minimal, I'm not exactly sure if I'll be able to take the gamble.
_________________89 Merlin Ti Rd
, 89 Merlin Ti MTB, 93 MOOTS Ti YBB
, 94 Klein Adroit Night Storm
, 97 Klein Mantra Pro Night Storm
97 Morati Ti Pro Lite HC1.1, 03 Litespeed Ghisallo, 06 MOOTS Cinco, Litespeed Trike