Thunderbike Built

The Harley-Davidson Sportster S attempts to blend cruiser and sport bike attributes but achieves neither with its conflicting design. While the powerful 1250cc engine shows promise, the wide front tire and forward ergonomics compromise aggressive handling.

We review how aftermarket company Thunderbike transforms it into a corner-carving sport naked by replacing the front suspension, brakes, tires, and peg position to unlock the chassis’ true potential. Despite leaving owners wanting in stock form, the Sportster S serves as an intriguing platform for performance customizations.

Harley-Davidson is ushering in a new era of sport performance capabilities with their refreshing take on the Sportster S model. The motorcycle giant equipped it with their brand new Revolution Max 1250 engine, creating unmatched power and torque for the legacy line.


Revolution Max Engine Boosts Sportster Performance

Harley Vividly transforms the Sportster S identity by powering it with their new 60-degree 1,252cc Revolution Max engine. It boasts 121 horsepower and 94 ft-lbs of torque, putting it in the major leagues with heavyweight streetfighters. The engine’s lightweight design drops the curb weight to just 500 pounds, giving it power-to-weight parity with many middleweight performance bikes.

Chassis and Suspension Primed for Upgrades

The capable trellis frame and responsive suspension beg to be unleashed at full performance. While held back by the stock 160mm front tire and cruiser peg position, the foundation provides huge potential. Aftermarket companies like Thunderbike quickly recognized the platform as the perfect base for building a true sport naked machine.

Thunderbike Showcases Aftermarket Potential

Noting the restricted performance of the stock setup, German shop Thunderbike set out to convert the Sportster S into the hardcore street machine at its core. They equipped it with a 21-inch front wheel able to accommodate stickier sportbike rubber. Paired with radially mounted dual discs, it stops with ferocity.

Thunderbike also revised the ergonomics with rearsets and a flat bar, allowing riders to fully exploit the responsive powerband when carving corners. With these simple modifications, the Sportster S is transformed into a razor-sharp naked bike.

Owners Embrace Versatile Performance Platform

While stock it appeals more to cruiser riders, owners praise the Sportster S as a blank canvas for performance customs. Its lightweight powertrain begs to be unleashed on twisty backroads. Harley has created their most upgradeable platform yet, made even more versatile with aftermarket modifications.

The Sportster S signals a new chapter for Harley, appealing to wider demographics with its customization potential. It forms the basis for both radical cruiser modifications and all-out sport bike conversions. Harley is empowering a new generation to make the Sportster S their own.

Pros and Cons for the Harley-Davidson Sportster S:

Powerful 1,252cc Revolution Max engine producing 121hpConfused styling – not a full sportbike or cruiser
Lightweight design at just 500 lbs curb weightWide 160mm front tire limits cornering ability
Upgraded suspension and brakes over other SportstersForward-set footpegs not ideal for aggressive riding
Excellent platform for customizationStock configuration compromises sporty handling
Striking neo-retro design stands outExpensive for unrealized performance potential
Increased performance brings new ridersDoesn’t fully deliver on “Sportster” name
Hundreds of aftermarket mods availableLean angle limited by mid-controls
Excellent torque well-suited for modsLacks premium suspension components
Custom shops unlock true sportbike potentialPurpose-built sportbikes handle better for the price

FAQ About the Harley-Davidson Sportster S

What engine does the Sportster S use?

The Sportster S uses Harley-Davidson’s new liquid-cooled 1,252cc Revolution Max engine making 121 horsepower, the most powerful Sportster offered from the factory.

Is the Sportster S good for sport riding?

In stock form, the Sportster S is compromised for aggressive riding due to its cruiser ergonomics and limited suspension and tire setup. Aftermarket customization can unlock more performance.

Why does the Sportster S have such a wide front tire?

Its exaggerated 160mm wide front tire gives it styling similar to a chopper, but negatively impacts handling potential by limiting front end grip.

How did Thunderbike improve the Sportster S’s handling?

Thunderbike replaced the 19-inch front wheel and 160 tire with a 21-inch sportbike wheel and sticky 120 tire. Paired with radially mounted brakes and improved ergonomics, it handles like a sport naked.

What is the difference between a cruiser and a sport bike?

Cruisers emphasize relaxed ergonomics and style over performance, while sport bikes are focused on aggressive riding positions, advanced suspension, sticky tires, and horsepower. The Sportster S awkwardly sits in the middle.

The Harley-Davidson Sportster S provides an excellent base for customization thanks to its powerful Revolution Max engine. But conflicting design decisions in stock form prevent it from claiming either cruiser or sport bike prowess. For riders seeking aggressive performance, aftermarket work is required to match its potential.


Harley-Davidson actively enters the modern era with the new Sportster S. They equip it with an impressively powerful Revolution Max engine that outmuscles anything else in the Sportster line. While conflicting design choices hold back the stock model, Harley crucially creates an ideal platform for customization.

Aftermarket shops like Thunderbike expertly transform the Sportster S into a corner-carving machine by upgrading the critical performance components. In the end, Harley empowers a new generation of riders to customize this blank canvas into their perfect streetfighter. The Sportster S represents an exciting new chapter where Harley embraces individual performance expressions over one-size-fits-all cruisers.

Intrigued by the Sportster S but unsure if it fits your riding needs? Take one for a test ride and pay attention to front end feel at speed, ability to attack corners, confidence under hard braking, and a seated position facilitating active maneuvering rather than just relaxed cruising. Envision the bike’s potential with aftermarket upgrades as you evaluate its performance.


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