By 'undergeared' they mean you'll have to spin the pedals like a madman if you want to crack 30 MPH.
EDIT:
To elaborate, these are the gear ratios for the i4:
GEAR INCHES
1st: 39.3
2nd: 48.7
3rd: 58.9
4th: 72.3
Assuming you can turn the pedals at 100 RPM, here are your top speeds for each gear:
1st: 11.7 MPH
2nd: 14.5 MPH
3rd: 17.5 MPH
4th: 21.5 MPH
Last edited by stocksy; 06-09-09 at 09:31 AM.
Reason: clarity