My Bianchi Veloce has a 111 mm BB spindle, and the seat tube is 28.6 mm dia. It came with a Veloce triple, and I've fitted both a 53/39 double and a 50/34 Compact double without having to change the spindle. I think the only time you might need the 115 mm spindle is if your frame has the wider (32 or 35mm dia.) seat tube.
- Wil