Mr. Fusion vs Spinelock: Which One is the Most Stable Seatpack?

Susan Fernandez November 11 2021

In recent years, we have seen a lot of development in bike packing gear, and this particular statement is true when we talk about seatpacks. Whether small or large, the bag maker companies kept innovating, tinkering and creating different solutions to craft the right bag for avid bikers.

Stable Seatpack is not only the carrier for small gears, food, and water; it is also great as additional support to prevent unfortunate tumbles during biking. The market opened itself to different designs that fit everyone’s expectations of stability and durability, but there are some companies that stand out on their own with unique features that made them special aside from all the other bags on the market.

Patrick Sherrard, the founder of Porcelain Rocket, is an avid cyclist who was looking for a seatpack that can be easily mounted and durable enough to withstand the challenges of biking. A lot of time has passed by before he finally decided on his own unique solution which is both practical and beautiful.

The dual mounting system has two separate Velcro straps for easy installation over your standard seat rails. These straps are long enough to ensure there will be no gaps between the bag and your seat post when you tighten them up while riding. They also have TPU non-slip shoulder pads to further lower the risk of shifting position while in motion.

Two of the most advanced and perfect options that are currently available in the market are Porcelain Rocket Mr. Fusion and Revelate Designs Spinelock. Each bike-packing seat bag is a perfect choice for your biking needs, and it is never easy to tell which one is more stable than the other.

Porcelain Rocket Mr. Fusion

Mr. Fusion is a Canadian-made bike-packing seat bag and is considered to be among the favorite seatpacks for many. This bag is waterproof and has a holster system that prevents any movement and sway. It is highly durable, and you can also remove it in an effortless manner. It comes with a pocket that keeps your gears secure, and it even has an optional zippered wall divider to keep the bag’s contents in place.

Porcelain Rocket reworked the strap system of Mr. Fusion, whereas it is also available in the Mini and XL versions. Its latest version comes with a curved rack that can carry any load much better and has the ability to run 12 or 15-liter dry bags.

Porcelain Rocket Mr.Fusion has such advantages as:

  • Padded and adjustable harness system;
  • Sturdy construction;
  • It is easy to remove the bag from the platform when you want to take it off your bike.

Disadvantages of this seatpack are:

  • A limited load capacity;
  • That it is quite expensive.

Revelate Designs Spinelock

When we look at the Revelate Spinelock System from the outside, it resembles any other bike-packing seat bag, but the patented mounting system of this bag is something that differentiates it from any other products that are available on the market.

With the help of the Spinelock System, the biker can have a quick-release mechanism to get the bag on and off for packing and unpacking purposes, while it is also completely waterproof and highly stable. This bag features a one-way air purge valve, light mounting slots at the back, a shock cord deck to stash the extra gear as well as a skid plate on the bottom to offer extra durability. 

Spinelock is another bike-packing seatpack that is built for toughness. It keeps its shape while maintaining its stability regardless of changes in terrain or speed. It also has an internal compression system that allows you to easily access the smaller gears inside the bag while protecting them from being damaged by other items.

A few words from Revelate Designs: " In order to create the best possible experience when using my bags, each one goes through many iterations in design and prototyping. Once my designs are complete I use them on my own adventures for an entire season in order to find any remaining issues or things that could be improved."  - Eric Parsons, Owner of Revelate Designs

The advantages of this seatpack are:

  • It is a truly waterproof system;
  • Completely adjustable and removable from the bike in a quick-release mechanism;
  • Harnesses that allow you to easily tighten the bag on top of your seat without having to worry about additional straps.

Disadvantages of Revelate Designs Spinelock are:

  •  The price tag is pretty high compared to other similar products, but it is still worth it for what you get in return.

Comparing Mr. Fusion`s and Spinelock`s Stable Seatpack

It took a few years for Revelate Design to develop the Spinelock and then bring it to the market, and in order to reach perfection, Revelate went through a lot of testing and added a number of rounds of refinements. The Spinelock comes with a forged aluminum clamp securing the saddle rails and offers two U-shaped channels in order to fit the mounting plate.

Many riders choose Spinelock for a reason as it is almost weightless, and they can mount their stable seatpack to the rack without any inconvenience. The bag does not have its own frame or stiffeners, but what makes this product extremely secure and easy to use is the 3D-printed rubber mounting plate that attaches to your saddle rails.

What Revelate Designs Spinelock has over Mr. Fusion is:

  1. It only takes one click to take the bag off of your bike.
  2. The mounting plate goes inside the saddle rails which offers an increased level of security.
  3. There are many color options available because there are 2 size options – 18L and 22L.

Mr. Fusion tends to be a more versatile bag as it can be mounted on both full-suspension and hardtail bikes. Another thing that makes this product stand out is the fact that they added a removable aluminum stiffener bar which you can use to carry heavier items with ease.

On top of all of these differences, Mr. Fusion comes with a smaller pocket for your phone or other small items, but there is also an option for purchasing a zippered divider wall in order to keep everything organized and stable at the same time. However, what people usually don’t like about this seat bag is a lack of color options which is completely understandable due to its design characteristics.

Stable Seatpack Feature Differences

Despite similar design characteristics and common key features, we all know that there is no such thing as a perfect product. Everything has its pros and cons which you have to be aware of before purchasing it.

Mr. Fusion is a good choice if you want a quick-release system that offers stability regardless of terrain change or speed. The price tag is a bit lower than Revelate Designs Spinelock, and it offers a variety of options to choose from.

However, this stable seatpack might not fit your bike frame if it does not have traditional saddle rails because the mounting plate will require additional spacers. If you want to be confident that your bag won't move an inch during your ride then Spinelock is definitely worth considering. Even though there are no color options available you will pay more for extra accessories (strap management system) which can make it easier to access things inside your pack without taking off the entire bag.

Mr. Fusion was released by Porcelain Rocket around the same time Spinelock was out in the market, and it is considered a great solution that never sways back and forth when you paddle. Although both bag makers made minor innovations with time, both come with different ideas to make a tremendous bike-packing seatpack.


It can be pretty frustrating for the small riders to have a tire rub and a small seat bag clearance. Therefore, it is better to look for a bike-packing seat bag that cannot slip or sag and have well-engineered mounting systems. 

Porcelain Rocket Mr. Fusion and Revelate Designs Spinelock are both great seatpacks that are completely waterproof and come with unique attachment systems so that you can easily remove and install them, and they act as stabilizers to eliminate the side to side sway.