Field Tested: Porcelain Rocket Mr. Fusion seatbag


The $175 Porcelain Rocket Mr. Fusion seat bag system blends the stability of traditional rack and the low profile of a frameless bikepacking seat bag. The system has two parts: a bag, and a super simple rack. The rack—which is covered in a fabric harness and attaches to the seatpost by a custom machined aluminum collar—functions like the internal frame of a hiking pack. The bag has a roll-top closure and one piece of Velcro to hold it tight against the seat post. Two compression straps run from the rack harness to the saddle rails, and one hugs the rear of the bag.


This configuration makes it easy to loosen the straps and pull the bag out of the rack when packing it up, which is super handy. Other seat bag designs have to be loaded while they’re on the bike, which inevitably leads to a bad packing job, and a fight to keep the bike from falling over. Unlike a traditional rear rack, the Mr. Fusion keeps the great mud clearance of a seat bag, and doesn’t get in the way when hiking the bike. The 13-liter bag is big enough for a puffy coat, sweater, change of clothes, and about two days worth of food.


Since the rack is solidly bolted to the seat post, there’s absolutely no movement in the system. On the fast chunky trails in the Western Colorado desert, Mr. Fusion’s stability was seriously impressive, which allowed me to focus on riding instead of worrying about losing all my junk. On rough ground even with the best buckles, rack-less bags eventually work their way loose, and start banging the rear tire or swinging into the rider’s legs. Mr. Fusion stayed as still and quiet as a heavily medicated fourth-grader.


The only downside to this 448-gram configuration is that each time the Mr. Fusion is installed or removed, the seat post has to be pulled. So for riders who mostly throw their big seat bag on for a quick beer run, a rack-less design is probably still the best choice. But for bikepacking on singletrack or rough dirt road, the extra stability is worth a couple extra seconds on the install.

All the fabric parts of Mr. Fusion are stitched together by Scott Felter in Calgary, Alberta. The steel rack is fabricated by custom frame builder Rick Hunter in California. The system requires six inches of exposed seat post and seven and a half inches of clearance from seat rails to tire, so small riders on 29ers may not have enough room for Mr. Fusion. A smaller version for those riders is in the works, and should be available soon.

Editor’s note: This review originally appeared in Issue #34 of Bicycle Times. To make sure you never miss a bike review, order a subscription and you’ll be ready for the everyday cycling adventure.


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