RockyMounts BrassKnuckles Review

The Bottom Line

It’s hard to deny that the RockyMounts BrassKnuckles car roof bike rack is easy to use. It can fit virtually any crossbar, whether you have factory bars, square ones, aerodynamic, or any other option. The design is simple but elegant and provides a vertical support bar that can be a useful feature.

RockyMounts BrassKnuckles

At a Glance

45 lbs

18 lbs

Tire Width:
Up to 3″

40″x 13″x 4.5″

No matter how well you tie down your bike it will move slightly, creating a rubbing motion that will damage your bike, car, or both. The answer is to get a car roof bike carrier such as the RockyMounts BrassKnuckles bike rack. It fits most of the best car top carriers currently available. 

RockyMounts is a Colorado-based company that specializes in biking accessories. You can order products online, pop in store to collect, or even have them install the rack for you. They also have an extensive range of jerseys, if you want or need the authentic look of a cyclist.

Let’s take a look at the RockyMounts BrassKnuckles car roof bike rack:

The Good

There are plenty of good points with the BrassKnuckles that would seriously tempt me to make this my next car roof bike rack.


The RockyMounts BrassKnuckles is capable of carrying bikes with tires up to 3” wide and between 20” and 29” in diameter. But, you can also purchase a ‘fattie kit’, this will allow you to accommodate fat bike tires up to 5”.

In addition, you’ll notice that the tray is adjustable to allow virtually any bike to fit on your roof. It will accommodate bikes between 34” long and 48”.

However, it should be noted that if your bike has a front fender it won’t fit into the rack properly and won’t be able to be secured safely into position. 

Ease Of Use

It’s hard to deny that the RockyMounts BrassKnuckles car roof bike rack is easy to use. You don’t need to remove the wheels of your bike to mount and it can fit virtually any crossbar, whether you have factory bars, square ones, aerodynamic, or any other option. 

The crossbars must be no further than 43” apart, but this shouldn’t be an issue for most vehicles. 

To install your rack you’ll need to bolt the vertical arm, which folds, into position. You can then lift it into position and slide the clamps into position above your crossbars.  The clamps simply unclip and pull away from the rack, allowing you to secure them around the bar and back into the rack. You’ll then notice a screw on the top that needs to be tightened, securing the rack firmly in place. 

Repeat this with the rear clamp, and your rack is on, ready to load your bike. 

You can then release the vertical bar and lift it upward, locking it into position. There’s a small red button that allows you to fold this arm flat again.  Your bike can then be lifted onto the rack and the front wheel sits between the two clamps, one prevents it from moving backward, the other clamps over the tire, stopping it from moving. You tighten this into position by turning the brass knuckle style fastening. (Hence the name).

To finish securing the bike you wrap the straps around the wheels and click them tight.

You should note that the assembly is minimal and the rack can be ready to use in less than thirty minutes. The BrassKnuckles weight limit is an impressive 45 pounds – It’s worth noting that this weight limit applies to when the rack is fitted to Rocky Mountain, Thule, or Yakima crossbars. If you have standard factory crossbars then the weight limit is reduced to 35 pounds.

Lack Of Bike Contact

As you’ll notice from the video, the bike is clamped into position against the wheel and around the wheel. There is no frame contact, this ensures your bike will arrive in the same condition as when you left.


The RockyMount BrassKnuckles bike rack looks good. The design is simple but elegant and the brass knuckle feature in the vertical support bar is a really nice feature. You may be tempted to drive around with the arm up even when you’re not carrying your bike, just remember the height if you’re going under any bridges!

Rocky Mounts Brass Knuckles wheel base

The Bad

There really isn’t such a thing as the perfect bike rack, if it existed there would only be one on the market. However, there are very few things wrong with the RockyMounts BrassKnuckles:

Locks Separate

It’s always disappointing to note locks being sold separately. For me, and most bike owners, securing your bike is an integral part of carrying it. When you’re spending hundreds on a rack its nice to think the security comes with the rack.

The locks don’t come with the RockyMounts BrassKnuckles, they are sold separately.

Lifting Necessary

I always mention this when reviewing car roof bike racks but it is important to note. You will need to lift your bike onto the roof of your car, while this probably won’t be an issue you do need to consider the weight of your bike and whether you’re comfortable lifting it.

If you’re not, then this, or any roof bike rack, isn’t the best option for you.

Needs Looking After

The powder coating can be damaged very easily, resulting in water getting to the steel and rust appearing. For this reason, it’s essential that you take the very best care of your bike rack and repair any damage quickly.

Aluminum Arm

For most people, this may not be an issue but you should be aware that the rack does not work well when going far off-road. The aluminum support arm is likely to bend as a result of the car bouncing around. This means it won’t be able to hold the bike securely in place, rendering the rack useless. Proceed off-road with caution. 

In Conclusion 

I really like this rack. It looks good, whether supporting my bike or folded down and not in use and is well designed! If you’re looking to carry a bike on the roof of your car then it’s definitely worth considering the RockyMounts BrassKnuckles!

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