It's actually already in use in cars (well race cars anyway) in the form of a kinetic energy recovery system (or KERS). Some Formula 1 cars use them.

by Steven Yates on Feb 6, 2012 10:54 am  

I volunteer to test-pilot this. I worry about the stopping power of the transmission down-shift, but it would work well on route I ride to work, with lots of stop signs. I think at long enough waits (lights) the flywheel would lose momentum and give you a very small kick, but for stop signs that require a short wait this could be good.

This would be even better on a recumbent bike because you could keep pedaling in neutral at a light so when it turns green you shoot out of the gate.

Too bad this guy is fixated on making this work for cars and has to say he isn't trying to reinvent the bicycle. What's wrong with reinventing the bicycle? I suspect this technology will be more successful with bikes than with cars. Cars need to full stop and would need to store a lot more energy in a flywheel to make it worthwhile, where as the tradeoff for a cyclist looks more straightforward.

by Ward 1 Guy on Feb 6, 2012 10:58 am  

Unfortunately, to store any significant energy, a flywheel has to be heavy, which is pretty much the last thing you want to add to a bike.

by Aaron Cohen on Feb 6, 2012 11:12 am  

I'd have to imagine a flywheel would weight a lot, and the extra weight isn't worth it in a bicycle.

by charlie on Feb 6, 2012 11:13 am  

"The flywheel, which was originally in a Porsche..."

Similar systems are used in hybrid vehicles and as costs are lowering are beginning to be seen in more vehicles.

by selxic on Feb 6, 2012 11:13 am  

Seems like you could possibly improve on the design by somehow integrating the flywheel into the rear wheel of the bike.

Also, a rimmed flywheel would probably be a bit more efficient in terms of weight (I think).

by andrew on Feb 6, 2012 12:08 pm  

Very cool idea. The weight of the flywheel probably makes it impractical, but maybe there's another way to store some of that energy - something elastic like a bungee cord type system maybe? Someone with a lot more mechanical sense than me would have a better idea.

by CBGB on Feb 6, 2012 12:16 pm  

"Starting and stopping frequently is often one of the most challenging aspects of urban cycling.

I may have missed it, but I didn't see anything about this flywheel application actually being used to stop or to start ... Just to pick up speed after slowing down. Can it also be used to help the rider get back on their way after coming to the full legal stop?

by Lance on Feb 6, 2012 12:56 pm  

Back in the 80's Volvo had concept flywheel buses.

by spookiness on Feb 6, 2012 12:56 pm  

@Lance:
The physics are the same. Let's say I come to a complete stop at a red light. I would probably give the bike a few pedals on green before engaging the flywheel, which means it's giving me a boost from 3mph, not 0.

I would do the pedaling not because the physics wouldn't work from a dead stop, but more to establish my balance first.

by Matt Johnson on Feb 6, 2012 1:01 pm  

This would be even more useful in San Francisco and other hilly locations. Nothing worse than having to stop at the bottom of a hill and wasting all that momentum.

by Dan Miller on Feb 6, 2012 1:04 pm  

This would be even better on a recumbent bike because you could keep pedaling in neutral at a light so when it turns green you shoot out of the gate.

Good point. And since recumbent bikes are already heavier than sin, and you can't really climb on one, adding another five pounds of spinning metal won't matter.

by oboe on Feb 6, 2012 1:58 pm  

So it will slow you down very slightly, or speed you up very slightly? Hardly seems worth the trouble. Part of the reason I bike is for the exercise, if I wanted to be lazy about it I'd just get a segway and be done with it.

by Joe on Feb 6, 2012 2:19 pm  

I wonder if you could do an efficient cross of the flywheel and http://www.thegyrobike.com/ (which uses batteries, but shows a flywheel in a front tire) so that you could effectively keep pedling at lights so that you can work at a constant rate while the bike is able to handle the changes in energy required.

I think it would be a very strange riding sensation though. Part of what makes bicycling fun is the interaction one has with their own locomotion. Of course city commuting has different goals than what is fun.

by RyanD on Feb 6, 2012 3:48 pm  

A flywheel will act like a gyroscope when it is all spun up. It will fight against turning motions. No problem if you want to continue straight ahead. But if you need to make a turn or evasive manuever it could be a problem for control.

by Wayne Phyillaier on Feb 6, 2012 4:59 pm  

Precession effect of a flywheel and consequent loss of control is one obstacle. Safety is another one -- if it stores plenty of energy, it may become dangerous during a fall or a crash. Suitable protection will add to the weight.

by roomd on Feb 6, 2012 7:25 pm  

@Matt Johnson, Thanks for explaining.

by Lance on Feb 6, 2012 9:31 pm  

Isn't this the Copenhagen Wheel!? LOL

by weedsfan on Feb 7, 2012 6:20 am  

The Economist recently did a good article on the resurgence of flywheel development - made possible by lighter, stronger materials. No discussion of bike implementation, but the reduced costs and weight being developed in the auto world could potentially allow this idea to spill over to bikes.

http://www.economist.com/node/21540386

by NWxDC on Feb 7, 2012 8:38 am  

I'll pass on having a high-speed spinning disc wedged between my legs.

by MLD on Feb 7, 2012 8:48 am  

It seems very few commenters actually listened to the video, especially the [art where he says he's "not trying to reinvent the bicycle" - that it's just a platform for testing the concept which he hopes to employ in cars. Yes, a 15 lb. disc is not what a bicyclist wants to contend with on their ride.

by Fischy (Ed F.) on Feb 7, 2012 9:04 am  

Understanding that it's a prototype for automobile use later, but some who think it would be an option for a bicycle are misguided. As mentioned, weight is a killer on a bike, and from being one of a number who have also experimented with bicycle flywheels, it doesn't work. The extra weight of the flywheel and mechanism far outweigh any practical effect you can get out of it.

To use one from a dead stop, will break a bicycle chain just about every time. A stronger chain needs to be used, and that means more weight, more expense and it won't work with normal bicycle sized chains and components.

The flywheel does not act like a gyroscope when it is spun up, because all three axis of rotation are not even close to coinciding. Precession IS a bit of an issue though, but is easily dealt with in practise.

A smaller version of a flywheel is being used in kids' bikes that reportedly helps them balance easier, but they are electric and are not attached to the drive train at all. Bicycle flywheels are great in theory, but no real use. Been around for a long, long time.

by Billy Dee on Feb 7, 2012 9:47 am  

Inasmuch as advancements in battery technology are most likely limited, Flywheel technology is here now and power flow is as smooth as an electric motor; see below

PRESS RELEASE
January 3, 2012
Reference: US Patent 7,931,107 B2
VEHICLE KINETIC ENERGY UTILIZATION TRANSMISSION SYSTEM. (KERS)

This recent patent enables the reduction of fuel consumption in motor vehicles by the storage of kinetic energy for reuse. This technology incorporates an infinitely variable transmission (IVT) in the form of an eddy current induction device (called a Modulator) coupled to a gear system to conquer the torque flow management problem caused by infinitely varying bi-directional energy flow between a moving vehicle mass and an associated rotating flywheel mass created by the fact that the respective mass velocities move in an inverse acceleration relationship.

To illustrate this phenomenon, observe that as kinetic energy passes from the moving vehicle to, and is captured by, the flywheel it is caused to accelerate, however the vehicle is consequently caused to slow; but to function efficiently, the flywheel requires an ever increasing input-speed factor from a source which is ever slowing. This always changing speed dichotomy can only be effectively managed by an infinitely variable transmission, and, other than that offered by the above patent, none have been successful for the subject purpose.

The technology reflected in this patent involves very few parts, and is therefore economical to manufacture. It is in addition, long lived, requires little maintenance, and is very durable. Importantly, this system is suitable not only for passenger car use, but also for delivery vans, trucks, and buses.

The conservation of kinetic energy through the use of battery energy-storage technology is exceedingly inefficient while such a mechanical approach is well known to be very high in efficiency. As may be realized, existing battery hybrid technology was developed because it was a way around this, now solved, torque-management problem. As these complicated and costly battery-related electric energy arrangements only avoid, and do not solve this problem, the penalty for this has been the great loss of efficiency as compared to a mechanical storage system such as that proposed by the subject patent.

Thank you,
South Essex Engineering

by johnjones on Feb 7, 2012 4:47 pm  

This idea has been patented and uses an IVT which is superior to the CVT demonstrated in the video.

by joh.n jones on Feb 12, 2012 12:04 pm