Roll Race Tool

Bike Setup

Enter your bike's specs — this is the foundation for every prediction.

Bike Setup

Year

Make

Model

Horsepower (hp)

Torque (lb-ft)

Redline RPM

Shift RPM

Wet Weight (lbs)

Rider Weight (lbs)

Rider Height (in)

Fuel Type

Tune Type

Exhaust Mods

Intake Mods

Wheelbase

Stock Wheelbase (in)

Length Over Stock (in)

56.8″

Stock WB

—″

LOS

56.8″

Current WB

48.0 / 52.0

F / R Weight %

Total run weight: 633 lbs · Power-to-weight: 304.9 hp/klb

Gearing

Primary drive, sprockets, gear ratios, and tire size — drives the speed-per-gear chart.

Gearing

Primary Drive Ratio

Front Sprocket (T)

Rear Sprocket (T)

Chain Pitch

Chain Links

Sprocket Ratio

2.706

Individual Gear Ratios

1st

2nd

3rd

4th

5th

6th

Rear Tire Size

Circumference (in)

79.30

Diameter (in)

25.24

Speed Per Gear (mph)

Gear	Ratio	6k	8k	10k	12k	Shift
1st	2.750	32.9	43.9	54.8	65.8	75.7
2nd	2.062	43.9	58.5	73.1	87.8	100.9
3rd	1.647	54.9	73.3	91.6	109.9	126.4
4th	1.400	64.6	86.2	107.7	129.3	148.7
5th	1.240	73.0	97.3	121.6	146.0	167.9
6th	1.111	81.5	108.6	135.8	162.9	187.3

Tire Setup

Tire type, PSI, and temperature affect traction score and wheelspin risk.

Tire Setup

Tire Size

Tire Type

Cold PSI

Hot PSI

Tire Temp (°F)

8.8

Contact Patch (in²)

4.4/10

Traction Score

1.120

Friction Coeff (μ)

HIGH

Wheelspin Risk @60

PSI tip: Drag radials perform best at 16–20 PSI hot. Street tires at 30–34 PSI. Slicks at 20–24 PSI depending on compound and temp.

Temp tip: Optimal grip window is 160–200°F for most sport compounds. Cold tires (<120°F) reduce grip significantly.

Race Conditions

ZIP code auto-fills weather. Density altitude and surface condition affect predictions.

Race Conditions

ZIP Code

Temperature (°F)

Humidity (%)

Baro Pressure (inHg)

Elevation (ft)

Wind Speed (mph)

Wind Direction (°)

Road Surface Temp (°F)

Road Condition

Density Alt (ft)

↗ Tail

Wind Effect

Clean

Surface

DA impact: Every 1,000 ft of density altitude costs roughly 3–4% engine power on a naturally aspirated engine. High humidity and heat add up fast — 3,000 ft DA is a real penalty.

Dragy / Real-World Data

Log your actual times. The app compares them to predictions and builds a calibration factor.

Dragy / Real-World Data

Run Date

Location

ZIP Code

Air Temp (°F)

Density Alt (ft)

Tire Size

Tire PSI

Rider Weight (lbs)

Front Sprocket

Rear Sprocket

Dragy Results

0 – 60 (s)

0 – 100 (s)

60 – 130 (s)

100 – 150 (s)

1/8 Mile ET (s)

1/8 Mile Trap (mph)

1/4 Mile ET (s)

1/4 Mile Trap (mph)

1/2 Mile ET (s)

1/2 Mile Trap (mph)

Notes

Race Predictions

Physics-based estimates for roll races and standing runs. Toggle Calibrated once you have Dragy data.

Predictions

Roll Races

40 – 100 mph5.065s

60 – 130 mph6.840s

100 – 150 mph5.230s

Standing Runs · ET / Trap Speed

1/8 Mile (660 ft)7.495s115.0 mph

1/4 Mile (1,320 ft)10.825s153.1 mph

1/2 Mile (2,640 ft)16.015s190.2 mph

Standing Mile25.355s192.8 mph

Ideal Shift Points

1st

101

2nd

126

3rd

149

4th

168

5th

187

6th

1st

Best Start Gear @40

153 mph

¼ Mile Trap

193 mph

Mile Trap

⚠ These are estimates based on physics modeling. Actual times depend on rider technique, traction conditions, gearing, and mechanical state. Add Dragy runs in the calibration section to generate corrected predictions for your specific bike.