from velo-retro.com:
1978 - C.P.S.C. (Consumer Product Safety Commission) mandates changes to NR/SR. Included are a front derailleur lip, 2.5 mm increase in spacing between crank spider and arm to clear the front derailleur lip with corresponding increase in bottom bracket axle length, a curved quick release lever and ball-end added to quick release conical adjuster, dome-shape added to quick release cam lever on brake calipers, plastic covering added to the wheel guides on the brake shoes, and plastic safety-shields added to rear derailleur screws. The word "Patent" is changed to "Brev." on the chainring, chainring bolts and crank dust cap.