Stupid Musings (It involves magnets)

[Halloweenie]

Bit of a back story, I've been planning my hardtailed bike build and I'm about set on the TC Bros. air bag suspension for the solo seat. I also have a strong fondness for powerful neodymium magnets and trains.

Now here's my thought. Would it be practicable to create a maglev solo seat? I'd imagine you'd be able to make it out of either permanent magnets in a Halbach array or active electromagnets, electromagnets having the added ability to vary the strength of the field for the perfect "cushion". I started pondering about this while playing with some neodymium magnets and I noticed how the repulsive force isn't linear, but curved like a progressive spring. I'm just putting this out there, it's probably a dumb idea because it would needlessly complicate the "simple" bike I plan on building, but it sure would be a nice trick if it could be pulled off.

Any thoughts? Has anyone tried this at all?

 

[LuckyLeprechaun]

This is a very interesting idea, and in theory seems like it could be great.

I personally would like to go with solid state magnets just because of simplicity. The main problem I could forsee with solid state is I think that when magnets are kept together, they slowly loose their magnetism. If this is true it could be overcome by changing out the magnets every so often, but that could be a problem depending on mounting and cost.

Apart from complexity, electro magnets seem like they might be a better option since you would have some control over strength of field without having to change solid states out until you found the correct combination. Something to think about is power required and wiring required. If you're planning on going with a more minimalistic look for the bike, both of these things could potentially disrupt that look because of the power source you would have to carry and the amount of wiring you would have to hide. Water might also potentially be an issue here, but there are ways to seal things and it's not really a problem if you're not going to be riding on a wet road.

With solid states, the way I envision it is a set of magnets on legs that come down from the bottom of the seat and go into tubes, lets say aluminum pipes, where another set of magnets are mounted so similar poles end up facing. The size and strength of magnets I don't know, but you seem like you have a decent idea about that sort of thing.

Another way to do it depending on your front seat mount would just to have many solid state magnets mounted to the bottom of the seat however you choose, and a replica set of magnets below the seat. Or the same set-up, but with electro magents. Your front mount would have to be made in such a way that it allows up and down movement(arc), but not side-to-side movement so the magnets can't push your seat in to an awkward position.

*edit* I suppose if your front seat mount was made as mentioned above you could really go for any magnet set-up/mounting, solid or electro, that you wanted as long as your seat movement was within check so it didn't end up being cocked at a funny angle or "sliding" around all the time

Another thing to think about is the magnetic field as a whole. What can it effect? Cell phones, electronic controlers? I know someone who believes they fried their laptop due to wearing a hematite braclet. Whether this is true or not, I don't know, but it's what they believe, so i'm just throwing the thought out there.

All that being said, I don't have any real experience with electro magnets, just a loose understanding of the concept. I also think that this is potentially a great idea, very unique, could make for a nice ride, and puts physics to good use.

 

[Tron]

This is a fucking awesome idea.

 

[Halloweenie]

With solid states, the way I envision it is a set of magnets on legs that come down from the bottom of the seat and go into tubes, lets say aluminum pipes, where another set of magnets are mounted so similar poles end up facing. The size and strength of magnets I don't know, but you seem like you have a decent idea about that sort of thing.

I had the exact same idea, but I think you kind of hit the nail on the head. I hadn't considered the damage a massive electromagnetic field could reap on nearby electronics such as the Pamco and I hadn't thought about weather concerns. I'd have to either coat the electromagnet coils or the permanent magnets to protect them. I also had forgotten that all magnets lose their magnetic properties when heated, so the repeated heat cycles of the machine would slowly kill any permanent magnets, so they're out unless they can be shielded from the heat.

I actually started diagramming the forces involved and attempted the calculations. Unless I wanted a completely vertical suspension, as you've described, then it would almost impossible. If I went with a standard hinge for the saddle, I'd need no less than six teams of magnets to adapt to the different levels needed to maintain levitation and I'd need a sensor on the hinge to activate and vary the strength of the field of each magnet bank. The weight and power consumption alone would be immense to keep someone of my weight in the air.

God knows how even a manhole cover would react to such a large electromagnetic field, most likely any ferrous debris on the road would be attracted to the magnets, even in an isolated vertical suspension. Think of the number of nails that would be pulled toward the bike. Plus, any credit cards and such in my wallet and my smart phone would probably fry very quickly. There are too many factors that would only present themselves during on road testing. So for now, the idea is scrapped, although I could see it working for automotive seats, possibly even semi tractor seats when there is a large amount of electricity available and shielding from the engine. Now I just need to convince myself that a magnetic suspension fork would be impractical.

It looks like I got caught up in the Jurassic Park syndrome, "...so preoccupied with whether or not they could that they didn't stop to think if they should." Thanks for grounding me, sometimes I get so engrossed in a concept that I become somewhat narrow minded that I only think of getting something to work, and fail to notice outside factors.

 

[1974jh5]

Actually a pretty cool idea, particularly if it could be done with no mechanical attachment at all. The thing about frying cell phones and credit cards is not necessarily all bad: just let your wife sit on it.

 

[Dakota_Lew]

In theory it should work and you would want it to be dynamic so you could alter the electromagnets. Only un forseen issues would be the field it creates. You would probably need to shield the alternator somehow, and possible other electrics (don't really know). If it was strong enough would it have increased wear on the ferrous internal components of the engine? You can't kid your self, to hold up an average 200 pound man she got to have some serious kick in those magnets, that's going to produce a pretty big field.

Super cool idea, I guess you need to try it out and see!

 

[LuckyLeprechaun]

I am by no means saying "don't do it", because it's an awesome idea and sometimes things just have to be done for the sake of doing them and experimentation. I was just pointing out the thoughts that came to my mind while thinking about the idea.

You'd think there would have to be some way to shield the electronic ignition components from the magnetism, even if that meant just putting them in a different position than originally antisipated. As for cell phones and credit cards, they're both big conveniences, but guys rode without both of those things for a long time, so who really needs them, lol. Or maybe carry your phone and wallet in your jacket(if you're wearing one that is) instead of in your pants.

As for heat, i'm not sure how much the engine heat would really effect something mounted under the seat. I'll admit that it's something i've never thought about, but it would seem to me that if the whole engine is air cooled, and you're opening the frame up even more to space(air), that it, and the magents, would have a decent chance of being cooled. Now if magents produce heat from being cycled(closer, further, closer, etc), then that could be a whole different scenario since they would be doing this quite often.

As for road debris, if you're speaking for an electo magnet, I can't really say anything since I have no experience with such things, but as for solid state, I don't think it would be that big of a deal. I've played with some small, but fairly powerful solid state magents, and i've never really had problems with them picking up random particles. They are quite powerful when repelling each other, but it's not like they're going to pick up a nail a foot away(not in the strengths I was playing with anyway). Obviously the less the mass of the object the further away it can be and still be attracted, but I would think at seat heigth, let's say you're going real low at 16", that's still a hell of a long way for them to attract random things. Plus if you were to go with a more "sealed" system like with the guide pipes, then you could just wipe any debris off.

As for size/mounting I just remembered an episode of Mythbusters where Jamie used large solid state magnets to pull himself up a metal wall. He used 2 magnets to do such a thing(but he would hang from one as he moved the other), so I would think that that would be the maximum size of magnets needed. Even if Jamie isn't that heavy, my thought process is this: 1 magnet has an attraction force of 150lbs(I would think Jamie weighs more, but the point is the same), then it should also have a repelling force of 150lbs. You need 2 magnets to make a floating seat, so if both are the same size, you now have a repelling force of 300lbs. This is my thought anyway, but I am not really into magnets or exactly how they work.

Hopefully that gives you some food for thought. If I were you, I might still try this. Like I said, I am by no means trying to discourage you, i'm just trying to present you with enough information/ideas to make an educated design/decision. I would think that the next step might be looking in a magnet supply catalog(do those exist?) to see what options are available because to me personally even with some of the disadvantages it looks like solid states are coming out ahead in this scenario.

 

[Halloweenie]

I definitely hear ya about just trying it. It's a prickly idea, it just sticks in your head because you'd think someone would have tried it by now.

As for protecting the ignition, phones, and cards, etc., if using solid state magnets, a Halbach array would be useful. It is a way of arranging magnets to increase the strength of one pole, while almost completely canceling out the other pole. A Grade N52 neodymium magnet measuring 1 1/2" x 1 1/2" x 1 1/2" thick has a repelling force of almost 240 lbs when under .10 in, that's just two magnets. Imagine a Halbach array of 13 of these things (I'd need that many just to keep me lifted), one mounted to the bottom of the seat pan, the other on the frame rail. That would be very large installation as well as a MASSIVE magnetic field (hence my concern about road debris). The only problem is that the repulsive force decreases so much that at a distance of only 1.5 inch, the repulsive strength is only about 20 lbs. The only way I see this working is with a lot of magnets, with very little travel; somewhere from 1.5 to 2 inches.

Another issue is that it won't even be easy to even experiment with these things, because they are extremely dangerous and cannot even be separated by hand once stuck together. They're usually shipped in wooden boxes because they are so dangerous. Not only that, they are extremely costly. So if was going to work, it would have to be electromagnets. I have to make some new sketches and figure out if it feasible, it might require too much power to use on an XS.

I was just curious if anyone else had thought about using maglev technology before. Thanks for all the input. Maybe someday I'll figure out the secret.

 

[LuckyLeprechaun]

I'm starting to see how problematic this set-up really is , but it seemed so simple!

I think i'm going to have to agree with you that with a motorcycle as a platform it may just be unfeasible to do such a thing. But I will also agree with you that it is a prickly idea and just has a way of sticking in your mind.

Just a random thought, but what if you used a tube-type set-up as discussed before, but with multiple magnets repelling each other in a column? Would this allow for more cushion? IE: N/S S/N N/S S/N all inside of an aluminum pipe vertically

 

[Halloweenie]

It is actually better to join them as they naturally would through their strongest poles because it would increase the strength of the magnetic field for each set. I had thought of a stack in an aluminium tube mounted as S/N - N/S - S/N with the center unit as the only movable structure, mounted on a rod passed though fixed ring magnets at the top and levitating off of solid cylinders at the bottom. That way, the top magnets would be a dampening force for the repulsion from the lower, more powerful magnets so you are not thrown from the saddle.

 

[LuckyLeprechaun]

It seems like a good idea, but I would assume that it would still be cost prohibitive, and that fine tuning would be a royal PITA.