— Urban Transport
Velogical shrinks the rim drive to "world's lightest" e-bike drive
The Velogical Velospeeder rear rim motor system
Friction drives like the Rubbee provide a lighter, simpler option for transforming a regular bicycle into an e-bike. Velogical's all-new Velospeeder makes the friction drive even lighter. The compact e-drive solution weighs under 4 lb and allows for seamless switching between e-assist and manual riding. The company claims it's the lightest and smallest bicycle e-drive (soon-to-be) available.
Cologne-based Velogical builds rim dynamos for powering bike lights, and at first glance, that's what the Velospeeder looks like. However, it's actually a sized-down e-drive that offers up to 600 watts of power and 29.5 lb.ft (40 Nm) of torque. At 3.5 lb (1.6 kg) for the entire package, it comes in much lighter than other e-drive kits. The current iteration uses a 92-Wh lithium-polymer battery that provides up to around 12.4 miles (20 km) of e-assist. Velogical says that the battery is light enough to carry a spare and easy to swap.
The dual Velospeeder motors mount to the seat stays of a traditional bicycle frame, where they transfer power to the rear rim by way of their polyurethane rings. A toothless drive system on a smooth metal rim sounds ripe for slippage, but Velogical says that the dual swing-axle design of the drive keeps the motors in optimal contact with the rim at all times. In this way, the Velospeeder is able to efficiently apply pressure and power the wheel at start and slow speeds, but also decrease pressure during faster speeds, preventing unwanted braking and wear effects.
One advantage of a lightweight e-drive is that it doesn't add a brick-ton of weight to the bike, freeing up easier manual pedaling. The most recent Velospeeder design makes it easy to switch between manual and electric-assist riding. When the rider powers the motors on, they automatically adjust to contact the rim at the same time. When the rider shuts the motors off, they adjust off the rim, freeing up natural wheel spin.
The Velospeeder is in the prototype stages and was revealed at the Spezialradmesse last month. Velogical has put 4,000 km (2,485 miles) on its Velospeeder-equipped test bike, in a variety of weather conditions, and reports that the there is no noticeable wear on the rim. The company plans to continue testing and optimizing the system before moving to start distribution next year. It will be selling the drive to bicycle manufacturers for installation on new models and bike shops for retrofitting, but it does not plan to sell directly to consumers as it does with its dynamo.
Velogical doesn't have a polished video yet, but the short clip below shows how the Velospeeder applies torque to the rim and shuts off to allow natural spin. Velogical told us that one of its next steps will be working on the noise level.
About the Author
Upon graduating college with a poli sci degree, Chris toiled in the political world for several years. Realizing he was better off making cynical comments from afar than actually getting involved in all that mess, he turned away from matters of government and news to cover the things that really matter: outdoor recreation, cool cars, technology, wild gadgets and all forms of other toys. He's happily following the wisdom of his father who told him that if you find something you love to do, it won't really be work.
All articles by C.C. Weiss
Weight matters a lot for bikes but this is sort of a solution to the wrong problem. A lot of the energy would likely get lost as this thing spins at high RPM loosely transferring some of its energy into forward momentum.
Because it relies on friction against the rim it seems like if you applies force on the wheel (like going up hill) it would just spin freely against the rim. Because the biggest contributor of weight in e-bikes is by far the battery I can't think of many scenarios where the weight this saves would be worth the efficiency loss that you would have to compensate with a much heavier/more expensive battery.
Maybe its just me and I don't follow e-bike design really but this doesn't seem that difficult to solve. Instead of applying force to the outer edge of the rim why not look at something like the front disk brakes as an example?
A disk/cog with teeth could be added to the right side of the front tire meant to pair with the electric drive system so you wouldn't see high system losses from slipping. You could engage/disengage it allowing the bike to freewheel similarly.
Because of the offset/angle of the mount the traction from the drive motor on the rim requires a counteracting moment. The motor looks like it is free to rotate so it is up to the normal force of the traction drive wheel against the rim to prevent the motor from spinning. As torque increases so does the normal force and therefore friction between the drive wheel and rim. With two motors the forces cancel out and there is no excessive side load on the axle bearings.
I'd imagine if you were to pedal faster than the motor could spin (theoretical) there would be a torque reversal (motor braking) that would reduce the normal force/traction until it slips.
so friction drive wasn't dead enough that someone had to try and reinvent it (rubbee) but now someone went and jumped the shark.
impressive technology. ridiculously stupid application.
rims are for transmitting compression of tension spoked wheels to the ground through the tire ( though you can ride 'the rim' without a tire)
secondarily ----rims can be used as an imperfect breaking surface for applying torque.
NOW rims have ALWAYS BEEN A BAD WAY TO BREAK.
hence the invention of the
-----fixed cog. (technically you could break using fixed cog before freewheel was ever invented)
-------foot drag break ( early 'bone shaker' design you push and break with your feet dragging hte ground. people and kids still use this method
---COASTER BREAK inside the bottom bracket pedal axle.
------DISC BREAK MOUNTED IN THE FREEWHEEL.
the problem with applying breaking torque to the rim is that the rims primary purpose is to bear the compression load transmitted through the tension of the spokes.
that is the PURPOSE of a bike rim.
when you use that rim for a frictional surface for breaking. you get a whole slew of problems with BREAKING and with THE RIM.
ordinarily the problems are solved through continuous maintaince of the breaks and of the rim (truing the spokes and hammering out the rim)
now-----------these problems aren't bad enough so this inventor now wants to put MORE torque on the rim. not to mention on the seat stays.
maybe genius, but not wise.
I love the smell of burning rubber in the morning!
Wow, zevulon. Not only is your ramble incomprehensible and completely wrong (you really should talk to somebody who actually knows about bicycling engineering and science, like David Gordon Wilson, author and emeritus professor of engineering at MIT), the word is "brake." A word to the wise, even if a word is spelled right, mixing in all caps HERE and THERE usually makes someone look like a raving lunatic.
Actually, electric motors are more efficient at high RPMs. Normally, you would need loss-inducing reduction gearing to get motor speed down to a good speed at the wheel, but friction drive sidesteps that. Although personally, I prefer mid-drive designs that take advantage of multi-speed bicycle transmissions.
I wonder how much lighter - and thereby efficient - would you get by using a set of 4 of these on one of those Rhodes cars (4 wheel 1-4 passenger bikes)?
Its brilliant and because its a system that assists the rider rather than being used for primary power, I see no issues with wear or efficiency. I's love to see the looks on the faces of those cocky 14lb carbon-fiber riders on the way up Lion's Gate Bridge or even on the downhill run through Stanley Park as they shoulder check only to see my fat-tired mountain bike drafting close behind...
Thank You Gadgeteer,
While this approach still needs work it is not necessarily all that bad. A far more elegant design still needs to have an attainable price tag to be a success.
This might be fine on the flats, but I can't imagine it has much torque to assist going up hills.....
600 watts in (2) of those small packages? they are way off the mark in a specialty market with that breakthrough, or is this the norm with low volt d.c. motors now, excuse me, but even with rare earths?!?
I agrtee the use in mid mounts, preferably on the foot side, the steady cadence side, but then regen does not operate with a derailer..."pushing a chain" just doesn't occur.
we got a price point yet?
Price point will be the key........$350 or less installed would be tolerable.......if its $500+ I would forget it.........and they certainly need to get it where owners can install as well.......
Can it be adapted or modified to work on a Wheelchair???
The 1 TaiN
@ The 1 TaiN
I think you would need to fit two, one for each wheel, otherwise you would go round in circles. As it is, even with two, there would be direction problems unless they were perfectly matched.
I suppose it would make a nice project for an electronics guy to split that power supply so that it steered (and acted as a speed control while it was at it). In short, couple of power triacs, pulsewidth modulated all linked to an Arduino is where I would start, though where I would finish is another matter entirely! (Have a go, you might find it fun, especially if you're new to electronics.)
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