Harley-Davidson Softail Gear Ratios and Highway rpm (2026), Worked Out
All eight 2026 Harley-Davidson Softail cruisers share one drivetrain: a six-speed gearbox, a chain primary drive and a toothed belt to the rear wheel. Harley-Davidson publishes the overall ratio for each gear, and from those, the primary and belt ratios and the tyre size, you can work out road speed in any gear and engine rpm at any speed. This guide does that, shows the working, and explains what a pulley or tyre change does.
Quick answer
- Overall ratios, 1st to 6th: 9.311, 6.454, 4.793, 3.882, 3.307, 2.79.
- Primary 34/46 (1.353:1), belt 32/66 (2.063:1), 6th gear direct (1:1).
- At 70 mph in 6th: about 2,580 rpm on a 150/80B16 rear, 2,570 on a 240/40R18 and 2,530 on a 180/70B16, before tyre squash.
- A front pulley two teeth bigger (34 instead of 32) cuts rpm by about 6 percent: roughly 2,430 rpm at 70 mph on a 150/80B16.
From overall ratio to gearbox ratio
The overall ratio is how many times the crankshaft turns for each turn of the rear wheel. It is the product of three reductions: primary (engine sprocket to clutch), gearbox, and final drive (front belt pulley to rear pulley):
overall = (46 / 34) × gear × (66 / 32) = 1.353 × gear × 2.063 = 2.790 × gear
Divide each published overall ratio by 2.790 and you get the gearbox ratios. 6th comes out at exactly 1.000, a direct drive:
| Gear | Overall (published) | Gearbox (worked out) | Speed at 2,500 rpm, 150/80B16 |
|---|---|---|---|
| 1st | 9.311 | 3.337 | 20 mph (33 km/h) |
| 2nd | 6.454 | 2.313 | 29 mph (47 km/h) |
| 3rd | 4.793 | 1.718 | 40 mph (64 km/h) |
| 4th | 3.882 | 1.391 | 49 mph (79 km/h) |
| 5th | 3.307 | 1.185 | 57 mph (92 km/h) |
| 6th | 2.79 | 1.000 | 68 mph (109 km/h) |
2,500 rpm is where the 117 Classic makes its claimed peak torque. Road speed = rpm ÷ overall ratio × tyre circumference. The gear chart calculator opens with these numbers and shows every step.
The tyre sets the rest
Every model has the same ratios, so the only thing that changes road speed between them is the rear tyre. Unloaded diameter is rim diameter plus twice the sidewall height (width × aspect ratio); circumference is π times that:
| Rear tyre | Models | Circumference | 60 mph | 70 mph | 80 mph |
|---|---|---|---|---|---|
| 150/80B16 | Street Bob, Super Glide, Heritage Classic, Deadwood | 2,031 mm | 2,210 rpm | 2,580 rpm | 2,950 rpm |
| 240/40R18 | Fat Boy, Breakout | 2,040 mm | 2,200 rpm | 2,570 rpm | 2,940 rpm |
| 180/70B16 | Low Rider S, Low Rider ST | 2,068 mm | 2,170 rpm | 2,530 rpm | 2,900 rpm |
Under load a tyre squashes and rolls a little shorter than its unloaded size, typically by a few percent, so the tachometer will read slightly higher than these figures. For the most accurate number, measure your own rolling circumference: mark the tyre, roll the bike one full turn in a straight line with you aboard, and measure the distance. Then use the cruising rpm calculator.
What a pulley change does
The final drive ratio is rear pulley teeth divided by front pulley teeth. Two examples, worked through for a 150/80B16 rear:
- Front 32 → 34 teeth: final drive 66/34 = 1.941, 5.9 percent taller. 70 mph in 6th drops from about 2,580 to about 2,430 rpm, and every gear pulls 5.9 percent less hard.
- Rear 66 → 70 teeth: final drive 70/32 = 2.188, 6.1 percent shorter. 70 mph rises to about 2,740 rpm, with quicker acceleration in every gear.
Any pulley change also moves the rear axle on the same belt, and may need a different belt. The belt drive guide covers that. Check pulley availability, clearance and your speedometer’s pickup before you buy; a different final drive or tyre makes the speedometer read differently on bikes that measure speed from the gearbox or wheel, and the speedometer error calculator gives the size of the error for a tyre change.
FAQ
Is 6th gear an overdrive on a 2026 Softail?
Worked out from the published overall ratios, 6th is a direct 1:1 gear inside the gearbox. The overall top-gear ratio of 2.79 comes from the primary (1.353) and belt (2.063) reductions.
What rpm does a Street Bob turn at 70 mph?
About 2,580 rpm in 6th on its 150/80B16 rear tyre, before tyre squash.
What is the primary drive ratio on a Milwaukee-Eight Softail?
34/46 by chain, 1.353:1, as listed in the 2026 spec sheets.
How do I lower rpm on the highway?
A bigger front pulley or a smaller rear pulley gives taller gearing. Two extra teeth at the front cut rpm by about 6 percent, and also cut acceleration in every gear by the same amount.
Sources
- Double Eagle Harley-Davidson, 2026 Deadwood (overall ratios 1st to 6th): doubleeagleharley.com
- AE Harley-Davidson, 2026 Low Rider ST (overall ratios, 34/46 primary, 32/66 belt): aeharley.com
- Cycle News, 2026 Super Glide (34/46 primary chain, 32/66 belt): cyclenews.com
- Total Motorcycle, 2026 Fat Boy (6th gear 2.79): totalmotorcycle.com
- Model tyre sizes: see each model page’s sources on the Harley-Davidson section.
- ETRTO Standards Manual (tyre size designations); Gillespie, T. D., Fundamentals of Vehicle Dynamics (rolling radius).
