Answered by the USAC Technical Director in Today's Technical Director Update
Disc Brakes for Road
So...are disc brakes allowed for road events?
Rule 1I1(e) indicates that bicycles must meet current UCI technical regulations at events that select 17-18, U23 and Elite riders for international competition or national teams. All bicycles used in National Championships (for age 17 and older riders) and NRC races must comply with the current UCI regulations. At the discretion of USA Cycling, UCI rules may be adopted or modified for Masters National Championships.
With this rule in mind, disc brakes would NOT be allowed in National Championship road events (unless an exemption is given), NOT be allowed in NRC races, NOT be allowed in UCI races (i.e. Tour of Utah, Tour of California, etc.), etc.
Rule 1I3(b) indicates that for road (and cyclo-cross and MTB) only a bicycle with a freewheel and one working brake on each wheel shall be used, except as allowed elsewhere in these rules.
With this rule in mind, do I care what kind of brake your bike uses? Not really - it could be cantilevers, calipers, and yes even disc brakes. As long as the brake is functional, that's what we want to see. So in this case - yes, disc brakes are allowed.
So the end result: YES, disc brakes are allowed in road events as long as the event is not a UCI race or a race where UCI regulations are being enforced (such as National Championships, NRC rac