Luna is selling a bike with specs that don’t seem to be possible. A 58-pound carbon-fiber full-suspension mountain bike with a Bafang M600 motor and a 48V 18.5Ah battery that somehow achieves 2.5kW of power. That makes it a recently marked down $4,000 mountain bike with light moto-like speed that can propel the bike past 30mph on flat dirt.

I’ve been riding the Luna X2 with the $350 Ludicrous option for almost a year now, and I’ve grown to love this thing, but with some important caveats…

Luna X2 Ludi

Luna sells some special bikes and motos, and the Ludi X2, which bridges the two, might be the best example of that. They took the Class 3 500W-rated Bafang M600 Motor that advertises 120Nm of torque and are pumping more than quadruple rated power through there, sometimes up to 2500W.

While there are some amazing advantages to this – notably, the incredible acceleration, even uphill – it also presents some problems. Obviously, that motor should be overheating, considering both the way more volt and amps than it is specced for. Luna is famous for hot-rodding Bafang motors, however, especially the M600, and they’ve done some really smart stuff here with heat dissipation with their bespoke controller. After a year of riding this thing, I can say it somehow works! Mostly.

Another problem is when you add pedaling to 2.5kW of power – all of a sudden, a mountain bike sprocket and chain rated for under 1kW of power are going to be pushed to their limits. I’ve already melted some sprockets by mistakenly changing gears up a steep hill on the Frey CC. I’ve been careful to avoid doing that on the X2 Ludi, but I still experience some slippage in high-torque situations. Unlike the Frey CC, where I’ve lost use of my second lowest sprocket, however, I’ve not done any damage in a year of riding the Luna X2, even up significant hills.

Speaking of going up hills, that unbelievable power will often pull the front wheel off the ground when climbing steep hills, presenting issues with steering and unintended wheelies.

Overheating

My first ride up our local 800-foot hill was going great at about 20-plus mph until about two-thirds the way up – I lost power and got an “Error 10.” I was able to power cycle the bike, and after a few minutes, I regained power. After rooting around in the forums, I found that the motor was overheating and shutting down.

Obviously, I can slow down to around 15mph and a lot less power and get a lot farther. But I wanted to understand exactly what was going on. Turns out, in steep hill climb situations, you want to keep your cadence very high to cool the motor and lessen the amps requirement. Most people that push this thing to the limit use the VESC tool running on an Android app to fine-tune this thing and keep it running optimally.

Luna uses the VESC app to tweak the Ludicrous controller, which is a paid download for $4 for Android or iOS, but I got an older version from Luna’s site. It allows you to pair to Luna’s controller and get almost real-time readouts of most of the vitals of the bike. The app isn’t terribly user-friendly to set up but is incredibly informative and great for keeping an eye on speed. You can then create different rider profiles to allow you to change your speed and power characteristics. I did find the readout to be a little small on rides, as someone that requires glasses for reading. I guess I need a bigger Android tablet!

In my case, the important readout is the bottom right motor heat sensor. When you start going up a hill at high power output, it will start rocketing upward. Once you are at 100 degrees C, you’ll hit the orange indicator, which is your signal to lay off the throttle and lower the pedal assist. Because the heat indicator is lagging by a few seconds, the motor is probably already closing in on its 120-degree cutoff, so you need to cut power immediately.

You can scale back to lowering heat by limiting the motor to its original 500W 120nm output. That is still plenty for hill climbing, just not at 20-plus mph. I find the bike operates quite well in the 80-100°C range.

On the other side of the spectrum, I wasn’t able to coax out even half the power on freezing cold days. That’s a shame because the bike’s Maxxis Minion tires are great for snow. After a few minutes of riding, the battery and controller do heat up, and the characteristics again go back to normal.

Once I learned my way around the heat factors, I could push this thing to its maximum.

For instance, I was able to easily climb Bromley Mountain’s 1,334 feet (407 m) in Vermont, which doesn’t have a bike lift or official bike riding path. I made it up the mountain with level 2 pedal assist without even coming close to overheating (myself or the bike!). At the same time, with the light frame and still powerful motor, I was still flying up the mountain to the point that it was actually fun to climb.

Because there is no lift and most mountain bikes don’t have this kind of power, I had the mountain to myself and was even able to find some off-the-beaten-path trails, which were tons of fun.

I was able to do four separate rides up the mountain before I needed to recharge, which I thought was pretty impressive. Luna knows their batteries, and even with driving Ludi with these chonky tires, I was seeing ranges over 20 miles. If I put smoother tires on here and ran on a road, I could see hitting 40 miles at 20mph.

Luna X2 specs

The Luna X2 is loaded up with some premium, if not top-shelf, components that would almost justify the $4000 price tag without a battery and motor:

• Rockshox Debonair Yari 160mm front fork
• Rockshox Deluxe Select+ 210mm x 55mm in rear 
• Sram Eagle SX 12-speed cassette (standard HG driver, not the XD from SRAM)
• Sram GUIDE 4 piston hydraulic brakes 200mm front 180mm back (6 bolts rotors)
• Maxxis Minion 27.5×2.8-inch tires 
• 44 56 non-integrated headset
• Double wall alloy 40mm 27.5-inch rims
• Dropper seat-post with internal routing
• All cables throughout the bike are internally ran
• Thru-axle hubs in both front and rear 15×110 Boost front, 12×148 Boost rear (length 180mm, 1.75 pitch)
• 160mm front travel and 140mm rear travel

One little extra bonus on the Luna X2 is the Carbon Fiber frame paint job. You’ll notice we’ve got the metal flake galaxy paint job, or as my wife likes to call it, “your glitter bike.” No shame here – I love the look of this thing.

In fact, to the untrained eye, the X2 looks a lot like an acoustic mountain bike. The 820Wh (48v 17.5Ah LG) battery is well hidden in the downtube, and the Bafang M600 motor or its heat sink only peeks out a bit from behind the pedals.

However, for those who know, the big “Luna” logo is what is going to be the big tell. Luna has long been outfitting electric bikes that pay more attention to what is possible than what is technically legal. Nowhere is that more apparent than the X2, which is described on Luna’s site:

This bike features our brand new Luna Controller the Ludi v2 which is a game changer. This controller will put out up to 60 battery Amps (2500 watts) As most Luna fans know, Luna has been hot-rodding Bafang motors for years with great success and this controller is sporting the heritage from our mighty BBSHD v2 controller. The Ludi v2 is 72V-rated controller which makes it extremely reliable at 48V and balances the user-adjustable buttery smooth pedal assist with the raw torque of 100 phase Amps readily available at the throttle. It even spins faster than any other M600 thanks to the Field Weakening and smoothly protects the motor from thermal overloads.

The X-2 comes in three sizes:

Electrek’s Take

The Luna X2 is truly a ludicrous mountain bike. It is a relatively light carbon fiber mountain bike that can hang with the more expensive bike shop brands, like Specialized Turbo Levo and Trek E-Caliber and, in many cases, has better components.

Where the Ludi X-2 really shines is the drivetrain. Having 2.5 kW of power at your disposal, even if just for short bursts, is like temporarily turning your mountain bike into a Talaria/Sur Ron and screaming across dirt roads at 30+mph. Having that power on a light mountain bike frame just doesn’t seem real.

Because of its high speed, I even found myself taking the X2 on my daily coffee shop commute if I was in a rush or wanted to blast up our big local hill.

The noted downsides of high power stress on the chain and sprockets as well as the overheating can be mitigated with some care and learning the bike. Luna has recently dropped the price of the X2, which can now be had for under $4K with an additional add-on for the Ludi controller.

Overall, this feels like the hot rod of mountain bikes, and I’m here for it.

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