We’ve seen lightweight e-bikes before, however none have ever approached the 15.15-lb (6.872 kg) Freicycle electrical bike constructed by mechanical engineer Dennis Freiburg.
His featherweight e-bike not too long ago set a brand new Guinness World File for the Lightest Electric Bicycle – Prototype.
The Freicycle took Freiburg the higher a part of a yr to design and construct, serving as a part of a venture for his doctoral diploma.
Constructed on a carbon Merida Scultura street bike, the Freicycle benefited from the beginning with an ultralightweight body weighing lower than 2.2 lb (1 kg).
Freiburg stored the remainder of the load down with as a lot carbon fiber as attainable for crucial load-bearing elements such because the wheels, fork, and cranks.
Different elements that couldn’t be sourced mild sufficient have been 3D-printed, similar to particular ultralight pedals.
However in fact, the beating coronary heart and soul of any electrical bicycle are the motor and battery.
For the motor, Dennis relied on a decidedly low-tech however light-weight answer: a friction drive.
Lightweight hub motors and mid-drive motor exist, however they will’t examine to the minimalism of a properly-designed friction drive.
All these e-bike drives have been round for many years on account of their simplicity. A powered curler is pressed in opposition to the bicycle tire, requiring minimal mounting and nil gearing. Freiburg used a brushless RC helicopter motor able to placing out 600 watts of energy, wrapped in an abrasive sleeve to offer grip to the rear tire.
The torque of the motor causes its easy mount to swing down and interact the rear tire. When the motor’s energy is lower, the spring-loaded mechanism pulls it again out of the way in which of the tire. Easy. Efficient. Gentle.
For the reason that Freicycle was inbuilt Europe, the motor is proscribed to a street-legal 250 W and a high velocity of 15.5 mph (25 km/h). However when limitless, the Freicycle can apparently attain speeds of as much as 30 mph (48 km/h) with its full 600 W of energy.
A simple technique to save on weight could be to put in a tiny battery. A watch battery would possibly make the wheel spin a revolution or two with a step-up converter, but it surely wouldn’t take you very far.
To chop down on shenanigans like that, Guinness requires a battery of a minimum of 137 Wh for a legitimate report try.
Freiburg constructed a regulation battery and managed to stuff it inside a light-weight drink bottle held in place by a 3D-printed bottle cage. The bottle cap even serves double obligation because the on/off change, which you’ll see within the video beneath.
The battery isn’t big, however with sufficient pedaling it would apparently take the rider between 12-22 miles (19-35 km).
I’ve ridden lightweight e-bikes before that passed the one-finger lift test, however I’ve by no means seen a 15 lb e-bike.
And whereas this clearly isn’t one thing that you may purchase right now, the DIY nature of the venture remains to be spectacular. We’ve featured a number of DIY e-bike builds and even undertaken our own. However we’ve by no means seen something fairly like this!
As e-bike building continues to evolve and more carbon fiber e-bikes reach production in the coming months, it is going to be attention-grabbing to see if a retail e-bike can ever problem Dennis for the report.
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