Originally Posted by
AllWeatherJeff
Argh.
No idea why, but I hadn't even considered this.
And, yep, I just checked. In its current configuration, there is only about an 1/2 -3/4 inch between the chainstay and the lower end of the FD cage.
Your 48T ring is 3.82" radius, 42T is 3.34" which is less than 1/2 inch, so your derailleur should clear OK. Even if not, many derailleur/crankset combinations will shift just fine with the derailleur non-optimally high, especially with a non-worn chain with good lateral stiffness.. Try what you've got you may be pleasantly surprised.