Modern Roadracing


SOUND OF SINGLES/BATTLE OF TWINS/SOUND OF THUNDER MISSION STATEMENT: AHRMA’s mission is to showcase single-, twin- and three-cylinder motorcycles which historically have been under-represented in modern roadracing. The Battle of Twins concept was born in the late 1980s as modern Superbike racing became increasingly dominated by inline four-cylinder machines. BoT racing kept alive the thunderous roar of twin-cylinder machines from British, European and American manufacturers. Sound of Singles racing features modern interpretations of the classic single-cylinder racebike, encompassing everything from production bikes to one-off custom-built machines.

Deadlines: Pre-entry deadlines typically are the Friday two weeks before an event. For certain events, pre-entries may close sooner. Consult the Schedule page of this website for exact closing dates.

Race fees for all events:* Pre-entry: First class each day, $95; each additional class $85. Post-entry: First class each day, $110; each additional class $100. AHRMA-run practice days: $135 (pre- or post-entry for all events except Barber Vintage Festival). Barber Motorsports Park practice: Thursday, $90; Friday, $155; Sidecar (Friday only) $55. Note: Each day of racing is a separate event with a separate fee schedule.

You can save at least 10-percent by registering online with our partner SeriesTracker, click here.

Practice days will be available at most venues on the Friday preceding race weekend (see schedule).

Confirmation and event details: Receipt of your entry will be confirmed by mail. Details such as directions, starting times and lodging are published in Vintage Views and by following the “Preview” links on the Schedule page.

Membership: Current AHRMA membership is required to compete in AHRMA National events. For AHRMA membership information, please contact us.  Memberships and renewals are available at the track.

Required racing license: New AHRMA roadracers are required to provide evidence that in the past two years they have either successfully completed an accreditied roadrace school or competed with another roadrace organization acceptable to AHRMA, including but not limited to AMA, CCS, WERA or AFM. New, novice AHRMA roadracers may not be permitted to ride at certain venues. AHRMA offers a roadracing school at most venues; for more information click here. The minimum age for riders is 18.

Required Transponder: AHRMA uses MYLAPS transponders for timing and scoring (for more-specific information, click here). This unit is required and is available for purchase from, or for rent from AHRMA. To rent a transponder, please use this form.

Medical insurance: Proof of personal health coverage is required. Jones-Birdsong Insurance offers a Rider Accident Medical Plan; to apply, use this form: Medical Insurance Application (pdf)

Refunds: Refunds will be issued only to pre-entered riders who have filed a Refund/Credit Request Form with the AHRMA National office. A refund form is in the Handbook, may be obtained from the office, or can be downloaded here. The form may be filed by mail, email, fax, or the office may be telephoned with the relevant information. Please see AHRMA Handbook rule 4.7a for more details.


The following classes are offered. Check the AHRMA Handbook for complete details of class requirements.

Sound of Singles® (SoS)

Sound of Singles®3: (SoS3) Two-stroke singles to 550cc and four-strokes up to 250cc. (See Handbook for a list of the eligible bikes.)
Sound of Singles®2: (SoS2) Water-cooled four-strokes to 450cc and air-cooled four-strokes to 610cc.
Sound of Singles®1: (SoS1) Unlimited-displacement four-strokes.
Motard Motocross, off-road, dual-sport and Motard-specific four-stroke single-cylinder machines of unlimited displacement.

Battle of Twins® (BoT)

Formula 3: Pushrod OHV twins to 1000cc, OHC two- or three-valve to 805cc and OHC liquid-cooled four-valve to 650cc.
Formula 2: Pushrod OHV machines to 1250cc, liquid-cooled OHC to 850cc, air-cooled two-valve OHC to 1000cc and air-cooled four-valve to 1000cc.
Formula 1: No displacement limits. Engine modifications are unlimited, with the exception that liquid-cooled four-valve twins over 1150cc must be US road-legal production bikes in Supersport spec.
Thruxton TransAtlantic Challenge: Supersport rules apply with some exceptions to the Triumph Thruxton, modified Triumph Bonnevilles and Harley-Davidson XL883 and XL1200 Sportster.

Sound of Thunder®

Sound of Thunder is open to unlimited-displacement four-stroke singles or twins; three-cylinder machines to 1000cc; twin-rotor rotary engines and any eligible Open Two-Stroke machine. Turbocharging or supercharging is permitted only on single-cylinder machines; engines and frames may be of any origin.

Open Two-Stroke

Any two-stroke motorcycle is eligible, regardless of displacement, number of cylinders, frame type, cooling type, or date of manufacture.