Transmissions par courroie

On a well-maintained bike with clean wheel alignment, 60,000 to 100,000 miles is realistic. The things that end belts early are grit ingestion on UK lanes in winter, rear sprocket wear that creates uneven loading, and running too slack — a loose belt whips against the sprocket teeth and frays from the inside out. Inspect for cracks, missing cogs, and correct tension at every service.

Yes — on a Softail the swingarm pivot comes out to get the belt off the rear pulley, and the primary opens to release the inner belt guard. It's a solid half-day job the first time. Since you're already in there, inspect the rear wheel bearing, rear sprocket for wear, and the primary chain — treat it as a drivetrain service rather than just a belt change.

Check the mid-span deflection — Harley spec is typically 5 to 6 mm with light finger pressure. If the rear axle adjuster is already near maximum rearward travel and the belt still sags, it's past it. A belt forced to run on a maxed-out adjuster also wears the pulley teeth unevenly; don't try to nurse it further.

Gates supply the belt Harley-Davidson fit as OEM, so at that level the comparison is academic. The risk is with cheaper 'premium aftermarket' alternatives that don't use the same cord specification — they stretch faster. Stick to Gates or genuine Harley OEM and the lifespan difference comes down to maintenance, not brand.