A freewheel does not have an easy job. If you are not pedalling, it must rotate with as little resistance as possible. If the rider then suddenly starts pedalling, high forces must suddenly be introduced into the rotation of the wheel. In conventional freewheel systems, pawls are pressed into the teeth of a ratchet ring via small springs. Stan's NoTubes takes a completely different approach with the new M-Pulse hubs and relies on "pulling instead of pushing". In the freewheel of the new rear hub, powerful permanent magnets pull from Neodymium the pawls into a hardened steel ratchet ring.
The tensile force of the rare earth magnets should guarantee the perfect alignment of the six pawls in the M-Pulse hubs. This means that the new freewheels are not only more reliable than conventional spring-based pawl designs, but also contribute to faster progress.
This is because the magnetic attraction force decreases with the distance between the magnet and the pawl. This is why it is minimal when disengaged, i.e. when idling, and supposedly lower than the compressive force of mechanical springs. According to the manufacturer's promise, this should reduce friction and rotational resistance when pedalling is not in progress.
The magnets should offer a further advantage in terms of durability. Mechanical springs can fatigue and break. The magnets of the M-Pulse hubs, on the other hand, are designed to outlast the ravages of time. The magnetic pawls are joined by a new freehub body and main seal design for improved protection against environmental influences. Each bearing of the M-Pulse hub is shielded so that no bearing seal is directly exposed. This should ensure smooth turning under all conditions and a longer bearing life.
The 17 mm axles are made of 7075 aluminium and roll on double-row main freewheel bearings from Enduro Bearings. Stan's had established their durability advantages over two single bearings in tests. In order to withstand high torques, the angle of the pawls has been adapted so that the load is distributed away from the rotating bearings. With 216 points of engagement, M-Pulse hubs require 1.66° of rotation to transfer the force to the rear wheel.
The M-Pulse hubs have an adjustable preload, which is designed to reduce resistance and thus ensure less effort and more speed. The adjustable preload promises to extend the service life of the bearings, as the bearing tension can be adjusted with greater precision. Both the front and rear hubs are finely adjustable. A specially matched grease filling in the bearings should further reduce the resistance of the hubs.
The M-Pulse engagement system is based on Project321's innovative magnetic pawl design. All freehub bodies, magnetic pawls, pawl rings, spacers and axles are manufactured in Project321's low-volume CNC shop in Bend, Oregon. Each M-Pulse hub is then fully assembled at No-Tubes headquarters in Big Flats, New York. By manufacturing key M-Pulse components in the USA and assembling the hubs in-house, Stan's aims to ensure the highest level of precision, attention to detail and quality control.
The M-Pulse hub options include Shimano Micro Spline, HG or SRAM XDR freewheel hubs with 6-bolt or Centrelock disc mounts. They are also available in all standard thru-axle widths. The new hubs are equipped with optimised flanges to better balance the spoke tension on both sides of the rim. This means that a single spoke length can be used for a complete MK4 wheelset.
Further information on the innovative M-Pulse hubs can be found at www.NoTubes.com
Jan Timmermann
Editor
