This Baffling Harley-Davidson Breakout Is So Beastly, It Redefines Muscle Cruisers

Summary

• Thunderbike’s GP Monza custom Breakout defies the dragster mold with show bike aesthetics and improved real-world riding experience. (114 characters)
• The bike features the punchy Milwaukee-Eight 117 engine with an aggressive torque delivery for a powerful, fast, and loud ride. (121 characters)
• The GP Monza custom has an adjustable chassis, upgraded suspension, and massive Brembo brakes for improved handling and stability. (122 characters)

The Harley-Davidson Breakout is a raunchy cruiser by the American giant. Yet, it’s a great canvas for custom bikemakers to build stunning pieces of art. This is particularly true on the other side of the pond where the Breakout has continuously been on sale for half a decade. A German custom shop, Thunderbike, has been producing such customs forever, and since 2018, it has been using the Milwaukee-Eight chassis for its projects.

One of its latest creations is a custom Breakout that honestly defies the mold of dragster customs. This badass cruiser combines show bike aesthetics with performance without forgoing the real-world riding experience. It even promises a better riding experience than the stock Breakout. That’s saying a lot since the 2024 Breakout is already a pretty engaging motorcycle on the road. Why are we saying this you ask? Read on to know.

In order to give you the most up-to-date and accurate information possible, the data used to compile this article was sourced from Harley-Davidson and other authoritative sources, including Thunderbike.

Dragster Worthy Of The GP Series Moniker

Breakout Torque Output: >123 LB-FT

Thunderbike is known for many custom bikes, most notably its GP Series. These motorcycles meet high riding requirements, and the new GP Monza lives up to this principle. According to the custom shop, this bike is a modern, sporty take on the dragster template, offering the experience of a new sprint at every start.

At its heart sits the punchy Milwaukee-Eight 117 engine known for its explosive torque delivery. It’s fast, powerful, and loud. Sure, it may not produce too much power to outrun other power cruisers like the Ducati Diavel V4 or the Triumph Rocket 3, but it’s more than enough to test your grip strength.

Thunderbike hasn’t revealed any performance figures for the motorcycle, though. Still, the bike gets a new tune and an exhaust system that promises better power delivery. The custom shop claims this motorcycle offers a more aggressive torque delivery right from the get-go, which should make you blast out (or should we say Break-out) of stoplights. You’ll have to dyno the bike for an actual output figure, but it’ll certainly be more than the stock 101-HP.

Harley-Davidson Breakout Performance Specifications

(Specs sourced from Harley-Davidson)

Custom That Breaks Out Of The Show Bike Mold

Most custom bikes fall in either category of a show bike or a performance bike, but the GP Monza is different. This has the stance of a show bike when it’s stationary, and the chassis geometry for drag racing when it’s moving. No, it doesn’t use Airride, which is known to be wallowy under pressure. Instead, Thunderbike has completely rebuilt the front and rear end of the motorcycle, making it a much better bike to ride.

Raises Or Lowers At Your Whim

The biggest element of this cocktail is the adjustable chassis, made possible thanks to the hydraulic monoshock at the rear. It’s still a Softail chassis, but the monoshock has been swapped out. This unit allows you to lower or raise the rear end, effectively changing the bike’s steering geometry. Not only does this let the bike drop to the ground, but it also helps the chassis handle the aggressive torque delivery without losing its damping properties.

Add A Pinch Of Biturbo And Brembo

The front end tells a similar story. The only original parts you’ll find here are the headlights and the speedometer; everything else is aftermarket. Upgraded Biturbo damping elements, adjustable for compression and rebound damping sit inside the forks. You can tune the suspension from traffic light to traffic light, as Thunderbike describes it. As an add-on, the triple clamps are milled from solid aluminum and the handlebar is replaced with two-piece GP clip-ons. Finally, the dip tubes have been upgraded to hold Brembo Radial Monobloc M4 calipers.

Massive Brakes For A Massive Bike

If Brembo M4s surprise you, wait till you get the full picture of the braking system. The front gets two massive 340 mm floating petal discs, and the rear is a bonkers perimeter brake, like the ones used on Buell sports bikes. Safe to say the Breakout will stop on a dime when you cross the finish line! Combined, the suspension and braking systems (with ABS) should make this bike more stable and safer to ride on the roads.

Modest Wheels For Bonkers Handling

Next, there are the massive wheels: 23 inches at the front and 21 inches at the rear. Each wheel has been milled from a single block of aluminum and finished in dual tones. But the rear wheel shines brighter, thanks to the single-sided swingarm. At a width of 260 mm, Thunderbike calls it modest in size, but for normal folks like us, it’s a very chunky tire. The custom shop ensures it improves directional stability since the front and rear wheel widths are not too far apart.

Fun fact:

The rear wheel is not only gorgeous but incredibly expensive. A single unit will cost you over €16,000 (roughly $17,000).

Spring Symphony For The Senses

The GP Monza looks so different from the stock Breakout that you’d hardly believe it’s the same bike at first glance. Stare at it for a while, and you’ll see the Breakout silhouette peeking through; it’s still long, low, and mean. Unlike the convention, the GP Monza goes above and beyond when it comes to styling, including a completely custom-made aluminum fuel tank.

Walk up to the bike and you’ll notice the gorgeous glossy finish, which is uncommon for the GP Series. Thumb the Rebuffini switch cube and the bike wakes up, with the instrument cluster lighting up in bright colors. Swing your leg over to sink into the deep dragster-style leather seat, and start getting a closer look at the bike. You’ll be hard-pressed to find welds — they’ve been sanded off to get a cleaner look. Even the front and rear spoilers are integrated into the frame for the same reason.

We can go on and on about the design, but we’ll let pictures do the talking here. However, one thing we wish Thunderbike had included is a clip of the bike’s exhaust note. The Thunderbike GP Monza is a symphony for the senses, but our ears are missing out big time here. (Yes, we haven’t touched it either, but you get the gist).

Design Highlights

• Gorgeous, minimalist Rebuffini RR90 controls and switch set grace the handlebar
• Design includes custom parts that are not even listed on Thunderbike’s shop
• Large diameter wheels and the single-sided swingarm look badass
• Thunderbike exhaust system neatly packs into the design
• Addition of cosmetic items like an EFI cover, headlamp cap, mirrors, turn signal strips, and more add a premium custom touch
• Rear wheel doesn’t look too wide for the bike; it fits just right

A Breakout Custom That Costs More Than Luxury Bagger

Harley-Davidson Breakout MSRP: $22,499

The Harley-Davidson Breakout has always been a drag special, but according to Thunderbike, this is its final form. The custom shop claims this bike gets more than 30 custom parts that give it such a bonkers stance and design. However, expect to pay a bomb for this Breakout custom, as it just might one of the most expensive Breakouts you’ll witness.

Only the parts list takes the bike’s price upwards of €50,000, without not even including the labor cost, paint job, and the base motorcycle! Add it all up and your Harley-Davidson Breakout custom GP Monza will easily cost you over $60,000!