The BMC Speedfox 03 is the all-aluminum brother that streamlines the impressive trail platform. BMC knows that there are plenty of people who want their APS suspension kinematics that come with all BMCs, and the durability and value that come from aluminum.
The aluminum employed is Al-13 triple-butted and hydroformed aluminum. the shapes mimic the shapes they engineered for carbon. The only difference here is that the tubing wall thicknesses are dictated by the butts, not by the layup. The shapes are designed to provide maximal torsional stiffness for efficiency, and a bit of vertical compliance as a little extra bit of comfort can only help leave you fresher for riding faster.
BMC built this bike to take you to the extremes of trail riding without sacrificing either end. Its a good climber, with little pedal-induced bob, and a sure-footed descender that feels stable when the speed gets high and the trail gets rough. The people who design BMCs ride out their door into the mountains of Switzerland. They need a bike thats a good climber, because theyll be doing lots of that. They need a bike thats a good descender because that payoff always comes eventually. BMC gets to this place with medium-length chainstays and moderate head angle. They expect riders to install relatively short stems, as they spec their S frame with a 45mm stem, and the rest with 55mm.
The frame also features Boost technology. Thats a 148x12mm rear thru-axle. The extra width means greater lateral stiffness as well as room for wider tires. You can fit 58mm wide tires between the rear stays with 6mm of clearance. The fork on complete bikes comes as a Boost fork as well. The steerer tube is designed to take a tapered 1 1/8 to 1 steerer. The frame was designed to work with 51mm offset and 120mm travel forks for the 29ers and 46mm offset and 130mm travel for the 650b wheels.
Even though theyre working in aluminum, all the cables are routed internally. Youll also find a rubber bumper underneath the bottom of the downtube, a mudguard covering the lower linkage, and another bumper on the right chainstay. The bottom bracket is a 73mm wide English-threaded design.. You can set this bike up either with a 1x system, or with a sideswing front derailleur and multiple chainrings. The rear derailleur can mount to either a standard or direct mount hanger.
The frame has postmounts for the brake mounting. It can fit 140mm rotors without adapters, and can go up to 180mm with adapters. When bought as a complete bike, 180mm rotors, front and rear, are standard.
One of the concessions BMC made for the 03 was doing without their Trailsync integrated seatpost and rear suspension tuning system. This is a benefit to those who prefer traditional dropper posts, as the seat tube accepts posts, standard or dropper, of 31.6mm in diameter. Some of the 03 offerings also come with a dropper post as standard equipment.
The BMC Speedfox 03 is an expert-level bike made for those dipping their toes in the trail waters.