OK I am sitting here looking for luxeon flashlights that use NiMH batteries to see if the parts could be adapated to a bike lighting system, when I see these shake to charge flashlights. You just shake the thing back and forth 90 times to get 20 minutes of light.

OK, so now I start to think, when a suspension fork operates it employes oil dampening. The oil heats up as energy is transferred from the moving sliders, into the oil, when it is forced through a tight orifice. So, why not use that robbed energy to make electricity?

You could use electromagnetic dampening to create electricity, just like the shake to charge flashlight. The technology could be built into a suspension fork, perhaps on one side of an oil dampened fork. The energy generated would not rob any more energy from the rider, since it is energy that is already being wasted through dampening.

Your fork could charge the batteries for your lighting system, while you ride and so could extend battery life, perhaps indefinitely, depending on how much energy you could get out of it. Perhaps with a luxeon start lighting setup, you might never have to charge again.

Mind you, it would not do commuters much good, since they don't get the fork going too much, but it would be terrific for off road use.

Another idea I considered is magnetic repulsion used for suspension, in your fork. There would be no springs, like air forks, but there would be no air seal issues either. You would not worry about air leaking.

So, you could have a fork that uses magnetic repulsion for spring, that generates electricity while dampening.

old_dude

a magnet cannot be made progressive without a varying current, not to mention that it would take immense power to suspend a riders weight with a magnet.

but nice idea with the light...i think that could work, kind of like a primitive electric motor...!

a magnet cannot be made progressive without a varying current, not to mention that it would take immense power to suspend a riders weight with a magnet.

but nice idea with the light...i think that could work, kind of like a primitive electric motor...!

OK, you could do this a couple ways.

1) You have a standard coil or air spring on one side of the fork, with an adjustable oil damper.

On the other side, you would use powerful but light weight permanent magnets for the spring, possibly with air spring assist.

Mount one magnet inside the slider at the bottom, and the other magnet on the bottom of the stanction. Heck, if you have steel stanctions, you could magnetize the stanction.

The magnets would be oriented to repel each other. No electro-magnets required. Now you build a wire coil into the inside surface of the slider tube. The permanent magnet on the stanction moving back and forth inside the coil will generate current in the coil. Voila, you are charging your battery.

2) You put magnets and coils into both sliders, but make the fork an air fork, with air pressure assisting the magnets for spring. Of course you use adjustable oil dampening too. This way both forks generate electricity, and the air pressure in the fork is lower, due to the magnetic repulsion assist.

3) You leave out the magnets at the bottom of the sliders and run the thing as a regular oil dampened air fork, but with built in generator coils and magnets on the bottom of the stanctions, or magnetized steel stanctions..

Check out these links:

http://www.machinedesign.com/ASP/strArticleID/48797/strSite/MDSite/viewSelectedArticle.asp

http://www.physics.lsa.umich.edu/demolab/demo.asp?id=811

old_dude

OK, you could do this a couple ways.

1) You have a standard coil or air spring on one side of the fork, with an adjustable oil damper.

On the other side, you would use powerful but light weight permanent magnets for the spring, possibly with air spring assist.

Mount one magnet inside the slider at the bottom, and the other magnet on the bottom of the stanction. Heck, if you have steel stanctions, you could magnetize the stanction.

The magnets would be oriented to repel each other. No electro-magnets required. Now you build a wire coil into the inside surface of the slider tube. The permanent magnet on the stanction moving back and forth inside the coil will generate current in the coil. Voila, you are charging your battery.

2) You put magnets and coils into both sliders, but make the fork an air fork, with air pressure assisting the magnets for spring. Of course you use adjustable oil dampening too. This way both forks generate electricity, and the air pressure in the fork is lower, due to the magnetic repulsion assist.

3) You leave out the magnets at the bottom of the sliders and run the thing as a regular oil dampened air fork, but with built in generator coils and magnets on the bottom of the stanctions, or magnetized steel stanctions..

Check out these links:

http://www.machinedesign.com/ASP/strArticleID/48797/strSite/MDSite/viewSelectedArticle.asp

http://www.physics.lsa.umich.edu/demolab/demo.asp?id=811

old_dude
...that which occurs with electrolysis?

When permanent magnets are forced to repel each other they demagnetize themselves over time. Currently the strongest permanent magnets for thier size and wieght are neodymium (or neo) magnets. Check out kjmagnetics.com, purchase what you need to build a scale model or a full size prototype. Let us know.

I am waiting for this technology to make it to MTB. :D

Magnetic Ride Control: Fact Sheet

What is Magnetic Ride Control?

Magnetic Ride Control is a complete, stand-alone vehicle suspension control system that uses magneto-rheological fluid-based actuators, four wheel-to-body displacement sensors, and an on-board computer to provide real-time, continuous control of vehicle suspension damping.

How does it work?

Magnetic Ride Control is made possible by the development of magneto-rheological (MR) fluid located inside the monotube shock dampers. The fluid is a suspension of magnetically soft, tiny iron particles in a synthetic hydrocarbon-based solution. The fluid's consistency can be manipulated through the precise application of electronic current, resulting in continuously variable, real-time damping. In fact, the development of MR fluid is so significant that medical researchers have adapted it for use in high-tech prosthetic devices, such artificial knees.

What are its benefits?

The system provides a greatly expanded range of soft to firm damping capability, a truly continuous range of damping settings providing increased control over vehicle motions for a flat ride and more precise handing. The enhanced road-holding capabilities improve wheel control for a safer, more secure ride.

Magnetic Ride Control offers greater roll control and handling during transient maneuvers, and helps reduce noise, vibration and harshness for a smoother ride. This new technology helps reduce the traditional tradeoff between ride and handling, and responds 5 times faster than previous real-time damping systems. In addition, greater reliability is possible with its simpler design.

The 2002 Cadillac Seville STS is the world's first production car with this leading-edge active suspension.

Magnetic Selective Ride Control will debut in 2003 as standard equipment in the 50th anniversary Chevrolet Corvette. The system also will be optional on other 2003 Corvette coupe and convertible models, except the Z06.

as a mechanical engineering student here in chicago i must say i am impressed. i thought i would be the first to bring this big public. i am hoping to do a senior design project on this exact idea of magnetic shocks. i figured if they can hover an entire monorail system on it i am sure that you can make a simple shock system out of it. my plans were to eventually do it for downhill forks just beacuse you do not have to keep the weight down as much as a X country. i look forward to doing this project much more now. i will post all of my results and hopefully how you can get these forks in about 2 yrs. yeah i hate reality of design and building. not to mention that i have to learn a bit more about dynamics of mechanisms first. untill then it is to just reconfiguring the current parts that are out there now.

Sorry I haven't posted months earlier!!

We had a big thread on rheomagnetic fluid in bike forks on Pinkbike.com. We pretty much came to the conclusion that permenant magnets were out - electromagnets were in - the electronics involved were relatively simple - apart from the sensors required to gauge fork travel - rate of travel etc. There isn't much about that can withstand the pressures involved in a lot of forks while still being accurate enough. We actually had a bloke posting that worked with suspenion day in day out, and he pretty much said that he could do it, it would definiately work, but unfortunately the amount of funding needed to get a prototype together was just way out of reach for him.

A shame though, because I wouldn't mind a DH fork that could go from bump eating plushness through the rough stuff, to XC firm for the climbs with a touch of a button. Even with a simple microcontroller, it would be possible to have a fork that changed it's compression and rebound characteristics during the forks stroke - fancy a fork that never botoms, and never bucks!! It would be easy to create a map which could be uploaded to your PC and modified to suit the race course you're going to be racing on next weekend..... (a bit like advanced EFI systems for cars). :)

A bit of food for thought!

Cheers, Dave.

Sorry I haven't posted months earlier!!

We had a big thread on rheomagnetic fluid in bike forks on Pinkbike.com. We pretty much came to the conclusion that permenant magnets were out - electromagnets were in - the electronics involved were relatively simple - apart from the sensors required to gauge fork travel - rate of travel etc. There isn't much about that can withstand the pressures involved in a lot of forks while still being accurate enough. We actually had a bloke posting that worked with suspenion day in day out, and he pretty much said that he could do it, it would definiately work, but unfortunately the amount of funding needed to get a prototype together was just way out of reach for him.

A shame though, because I wouldn't mind a DH fork that could go from bump eating plushness through the rough stuff, to XC firm for the climbs with a touch of a button. Even with a simple microcontroller, it would be possible to have a fork that changed it's compression and rebound characteristics during the forks stroke - fancy a fork that never botoms, and never bucks!! It would be easy to create a map which could be uploaded to your PC and modified to suit the race course you're going to be racing on next weekend..... (a bit like advanced EFI systems for cars). :)

A bit of food for thought!

Cheers, Dave.

what is so wonderful is that in a year i have a senior design project. i have access to anything i woud ever need from my uniiversity. i really really want to do this. time is my issue. i will have it though. i mean i have to do a senior project. i will have 3 people working with me on this also. i just have to convence my partners that we can do it. if nothing else we will get a design made up. i am also trying to get hired by Rock Shox. they only hve 13 engineers here so it is tough to get in. untill then it will reamain on many pages of physics and chemistry notes for me. not to mention a few subway napkins. thanx for the info. as soon as i have some news on it i will post it. depending. i mean if i spend a year on it i could very possably make alot of money on it. a patent is definatly a life goal. we also have a great micro mechanics lab here on campus. this stuff is so cool. i just was calculating where the center of mass should be so that if you apply a certain acceleration at a certain grade that you will not lift the front wheel. may be a nerd but it is something to think about instead of the burn from the climb. well have a good day.

I remember 7 or 8 years ago Cannondale designed a prototype Moto (predecessor to the Lefty) that had electronically controlled damping. It used an infrared camera to read the trail just ahead of the wheel so the computer could optimize the damping for the next individual bump.

Wow - 7-8 years ago!! They would of just about needed a susper computer to control it back then!!! The fork we were designing/hypothesising about at pinkbike was just going to be any old standard oil dampened fork with the guts pulled out, a custom orriface made (probably two rigged up for compression and rebound) with an electromagnet controlled by a controller that changed the viscosity of the oil. We worked out it could be run from a battery for short periods of time (enough for a DH run or two) and then hopefully we could make it more efficent for the future. We came to a bit of a dead end later on though, mainly becuase of the cost of the rheomagnetic fluid, and the buggerising around needed to build a controller for it.

Rheomagnetic fluid has been around for a fair while - mainly used for dampners in mines, washing machine prototypes, car suspension etc. Try a search in google, theres heaps and heaps of information about it.

Cheers, Dave

I've also seen where the military is testing combat suits containing rheomagnetic fluid. The suit detects the shockwave of an incoming round and the suit hardens at the point of impact .

This is some hot info! I think delphi is the company that makes the magnetic susp on the corvettes- you guys should check it out. That rheomagnetic fluid is pure genius. The only downfall is the reliance on electricity on a manually powered application.
hey Chirider990 - why rockshox? I personally dislike most of their products, no offense, but I've had only bad luck with them. anyways- good luck. Once you get some basic designs and prototypes head to Interbike, I'm sure many respectable companies will be all over you. ;)

This is some hot info! I think delphi is the company that makes the magnetic susp on the corvettes- you guys should check it out. That rheomagnetic fluid is pure genius. The only downfall is the reliance on electricity on a manually powered application.
hey Chirider990 - why rockshox? I personally dislike most of their products, no offense, but I've had only bad luck with them. anyways- good luck. Once you get some basic designs and prototypes head to Interbike, I'm sure many respectable companies will be all over you. ;)

thanx for your support. i can not wait to do this. it is going to be great. i look very forward to building this.

Unfortunately I've seen a LOT of projects get to this stage and never get any further - best of luck!!

For some great information check out:

http://www.lordcorp.com/DesktopDefault.aspx?tabid=522

Cheers, Dave.

It wasn't rehomagnatic, but a few years ago K2 and Noleen offered an automatic electronically controlled "smart shock" that would adjust damping based on compression speed. All you need to have is a tiny stepper motor- or better yet a piezioelectricically controlled valve, to change the orifice size. This seems like it would be a lot more electrically efficient than rehomagnetic fluid (let alone magnetic springs).

Ohhhh...I just had an ephinany. I need to think something over before I let the cat out of the bag though.

Oh- I had a completly different idea too. This one would be fun, but not very practical so I feel OK to share it. What do you guys think about regenerative braking for a DH bike? I was thinking, DH bikes can have a little extra weight on them, and their frames often have a large volume of air inside. It would be fun to seal off the main part of the frame and have a little air compressor attached to one of the wheels through a crank. When you first touch the brakes, you would engage a little CVT that would begin to turn the air compressor. This would provide some braking force, and begin to fill the frame with compressed air. The further you pull back the brake lever, the faster the CVT would make the compressor turn. After the compressor is going as fast as it can, a real brake would take over, just like in a hybrid car. Now, the next time you need to put some power down...maybe like in the sprint to the finish, you could push a button that would reverse the valves on the compressor, turning it into an air motor, like on those "Air Hogs" toys, giving you an extra power boost.

You know...something like this might actually work better on a commuter bike. I know when I commute on a bike, I HATE coming to stops, and I really hate using my brakes while going downhill. It wastes sooo much energy, and it is hard to get going again. Regenerative braking would help this problem. You could even use your compressed air to fill your tires when you get a flat!

Like I said- not very practical, but it sure would be a fun project.

i missed your thread on pinkbike, interesting idea. the electronics required would be prohibitive, did you guys consider the effect of the spring inside the fluid, or go with a linkage design fork? (sorry to ask, maybe alink to the PB thread)

i think it is great technology, but wonder about the practicality to adapt to MTB use. perhaps only one leg with MR, and one with an airspring. the non-linear damping would sure be nice, i wouldn't want to write the software though!

Incredibly, the software and electronics is the easiest bit. The hard part about it is coming up with the funds and time to build one. The easiest way would just to be to replace the dampening side only of a fork with the new internals, the air or coil spring would just stay the same.

This seems like it would be a lot more electrically efficient than rehomagnetic fluid (let alone magnetic springs).

Yeah to a degree. The pinkbike design would of run off a couple of light batteries from a lighting system, but this fork was only going to be intended as a DH/FR 'toy' wih the hope of making it more efficent for normal use. @dam mentioned a stepper motor, but the respone time would be waaay to slow, by the time the stepper motor had done it's thing the fork would of bottomed out, it's unreal how quick a fork can go through it's travel..... Thats why rehomagnetic fluid would be so great, because it's pretty much instant, and there would be no mechanical stuff to get damaged or wear out.

Unfortunately the PB fork thread has disapeared, I'll try and dig it up, but it wasn't real pretty... wev'e pretty much covered everything that was in it in this thread now anyway.

Cheers, Dave.