Non-contact generators

It's probably down to sheer, unforgiving physics.
The magnetic field decays rather quickly, which lessens the available power significantly as soon as you have a bit of clearance - like what you need in a flexible set-up like a bicycle wheel.
So, barring some amazing break through this leaves us with either fairly small lights(to be seen with rather than to see with) powered by magnets in the spokes, or one of the traditional solutions.
Of course you can attempt to counter for the poor power transfer characteristics by adding more and bigger magnets, but not many riders would appreciate heavier wheels.
Another option would be to use a storage system, much like some of the reelights do today but taken further. It might not do a commuter much good, as it would need a bigger portion of daylight riding in order to support a smaller portion of night time riding.

Any other solution I can think of are just other means of integrating the generator into other rotational parts of the bike, which functionally isn't much different from the hub generator and would require quite a lot of custom work.

bazmond said:

[FONT=Calibri]there seems to be very few products on the market of that type and its made me think why?[/FONT]

I would guess it's because bicycle generators are a very niche product and that niche is already filled quite well with the hub and bottle dynamos you mentioned as prevalent. There just aren't a lot of customers in that market to be putting a lot of effort ($$) into designing new generator technologies.

bazmond said:

[FONT=Calibri]Hello,[/FONT]
[FONT=Calibri]I’m on the final year of my degree and i’m currently researching into generators and dynamos for bicycles. I already have an awareness of sidewall dynamos and hub generators but I’d like to find more data regarding non-contact systems such as the reelight product. As you may already be aware the reelight system uses magnets that are connected to the wheel spokes to induct electricity. So far the reelight system is the only non-contact generator i could find. I’v done a patent search and there are at least half a dozen patents for this technology, some of which are quite old. Having said that, there seems to be very few products on the market of that type and its made me think why?[/FONT]
[FONT=Calibri]I was wondering if you guys could give me some info regarding this type of generator? [/FONT]
[FONT=Calibri]Has there ever been any high output, non-contact generators that you know of, or have you ever experimented with this type of technology before? Any links, product names etc are most appreciated.[/FONT]
[FONT=Calibri]Thanks for your time.[/FONT]

I can answer probably why there aren't more of these systems out there.

With the magnet on the spokes, and the coil on the frame, the system actually makes a thump every time the magnet passes the coil (something that you can hear and feel in your hiney), at least with the one system on the market that produced enough light to be worth carrying around. I suppose anything without a powerful enough magnet to go 'thump' wouldn't produce the requisite power.

Having more magnet poles smoothes it out some. The Shimano hub uses 8 poles, which can be felt while turning the axle by hand, but not while riding.

But yeah... strong magnets are required because of the clearances involved, as mentioned above.

Thanks to everyone who responded to my original message, your input is most appreciated! I'll have to come back on here later in the year and report on how things went on my degree and possibly get some feedback reguarding any designs.

One thing that I'm curious about is if the seat post possibly could be put to some use. As long as you're in the saddle the seat post will see some bumps and varying degrees of compression. It'd be neat if the seat post could be equipped with some piezo crystals, or an extremely short stroke suspension coupled to a linear generator. Have that piezo/genny powering a rear light high up under the saddle and you'd be set for rear light for the lifetime of the system. Then maybe a similar thing could be integrated into the stem as well.

bazmond said:

[FONT=Calibri]Hello,[/FONT]
[FONT=Calibri]I’m on the final year of my degree and i’m currently researching into generators and dynamos for bicycles. I already have an awareness of sidewall dynamos and hub generators but I’d like to find more data regarding non-contact systems such as the reelight product. As you may already be aware the reelight system uses magnets that are connected to the wheel spokes to induct electricity. So far the reelight system is the only non-contact generator i could find. I’v done a patent search and there are at least half a dozen patents for this technology, some of which are quite old. Having said that, there seems to be very few products on the market of that type and its made me think why?[/FONT]
[FONT=Calibri]I was wondering if you guys could give me some info regarding this type of generator? [/FONT]
[FONT=Calibri]Has there ever been any high output, non-contact generators that you know of, or have you ever experimented with this type of technology before? Any links, product names etc are most appreciated.[/FONT]
[FONT=Calibri]Thanks for your time.[/FONT]

Mr. Fusion - Futurepedia - The Back to the Future Wiki

in order for this type of generator to function the wheel set would have to be perfectly straight otherwise there will be contact between the spoke mounted magnet & stationary coil. since most wheels go out of wack often & require trueing up this would be a problem...

bazmond said:

[FONT=Calibri]Hello,[/FONT]
[FONT=Calibri]I’m on the final year of my degree and i’m currently researching into generators and dynamos for bicycles. I already have an awareness of sidewall dynamos and hub generators but I’d like to find more data regarding non-contact systems such as the reelight product. As you may already be aware the reelight system uses magnets that are connected to the wheel spokes to induct electricity. So far the reelight system is the only non-contact generator i could find. I’v done a patent search and there are at least half a dozen patents for this technology, some of which are quite old. Having said that, there seems to be very few products on the market of that type and its made me think why?[/FONT]
[FONT=Calibri]I was wondering if you guys could give me some info regarding this type of generator? [/FONT]
[FONT=Calibri]Has there ever been any high output, non-contact generators that you know of, or have you ever experimented with this type of technology before? Any links, product names etc are most appreciated.[/FONT]
[FONT=Calibri]Thanks for your time.[/FONT]

this idea isn't new at all. i once had a light that worked on magnets mounted on the spokes. it was a rear l.e.d. light & it would flash when the spoke mounted magnet passed by it's coil. nothing really rocket science about this. installing more magnets on the spokes to use it to power a front & rear light would be possible, but as i already posted any wobble in the wheel sets would cause problems with magnet to coil contact. there would also be a problem with blinking until the bike reaches a high speed. on my road bike i use a "non contact" hub dynamo which powers a high power led light set with a photo cell switch which keeps the set off until dark. very efficient & bright with no noticable drag at all. to improve on this combination would be hard to beat....

a hub dynamo is really non contact as well & i say stick with this as they are the best out there...

saturnsc2 said:

in order for this type of generator to function the wheel set would have to be perfectly straight otherwise there will be contact between the spoke mounted magnet & stationary coil. since most wheels go out of wack often & require trueing up this would be a problem...

FYI, the vast majority of riders have wheels that rarely, if ever, need truing.

alienator said:

FYI, the vast majority of riders have wheels that rarely, if ever, need truing.

must be nice. try riding your bicycle on our city streets right after winter. if car wheels get damaged, & their front ends need re-aligning due to monster potholes, imagine what they would do to a bicycle wheel set...

saturnsc2 said:

must be nice. try riding your bicycle on our city streets right after winter. if car wheels get damaged, & their front ends need re-aligning due to monster potholes, imagine what they would do to a bicycle wheel set...

Wow. FYI, you apparently don't ride the streets around here. When you've ridden where other people ride, feel free to comment on how good or bad people have it compared to Cleveland. Having lived and ridden in that part of Ohio, I can safely say, I've seen worse, as have loads of people. "Bad roads" aside, well built wheels don't need to be trued much at all, if ever. Are you going to allege that after Parix-Roubaix-easily a lot harder on wheels than Cleveland-- all of the wheels from that race are out of true?

alienator said:

Wow. FYI, you apparently don't ride the streets around here. When you've ridden where other people ride, feel free to comment on how good or bad people have it compared to Cleveland. Having lived and ridden in that part of Ohio, I can safely say, I've seen worse, as have loads of people. "Bad roads" aside, well built wheels don't need to be trued much at all, if ever. Are you going to allege that after Parix-Roubaix-easily a lot harder on wheels than Cleveland-- all of the wheels from that race are out of true?

send me a link to a company who sells those well built wheels that rarely need to be trued. i would love to see them. i had more trouble with snapped spokes/wheels going out of true from the pounding of the roads around here then you will ever know....

if you do a search on this you will see me asking many questions throughout these forums about wheels going out of true & snapped spokes often from me here throught the years...

we're starting to get a little off topic as this thread is supposed to be about non contact generators. i maintain the hub type are the best out there to date...

saturnsc2 said:

send me a link to a company who sells those well built wheels that rarely need to be trued. i would love to see them. i had more trouble with snapped spokes/wheels going out of true from the pounding of the roads around here then you will ever know....

if you do a search on this you will see me asking many questions throughout these forums about wheels going out of true & snapped spokes often from me here throught the years...

we're starting to get a little off topic as this thread is supposed to be about non contact generators. i maintain the hub type are the best out there to date...

Where do you buy your wheels? Are they hand built or factory built? What spec are they? If you do a search of this forum, you'll find that links to loads of wheel builders have been provided in the last few months as well as over the years.

alienator said:

Where do you buy your wheels? Are they hand built or factory built? What spec are they? If you do a search of this forum, you'll find that links to loads of wheel builders have been provided in the last few months as well as over the years.

i have a local bicycle shop that does it. my rims are sun rins & double wall construction. i use d/t stainless steel spokes. the latest set of wheels are so far ok. i'm a heavy rider 250# + & that's another thing that causes my rims to snap spokes & go out of true sooner than most.

saturnsc2 said:

i have a local bicycle shop that does it. my rims are sun rins & double wall construction. i use d/t stainless steel spokes. the latest set of wheels are so far ok. i'm a heavy rider 250# + & that's another thing that causes my rims to snap spokes & go out of true sooner than most.

How many spokes per wheel? Which DT spokes?

alienator said:

How many spokes per wheel? Which DT spokes?

36 spokes. their just regular round stainless steel d/t spokes on 27 x 1 1/4" rims.

saturnsc2 said:

36 spokes. their just regular round stainless steel d/t spokes on 27 x 1 1/4" rims.

What matters is the gauge of the spokes and whether they're straight gauge or butted. Butted spokes are less likely to break. Also, what sort of profile does the rim have? I'm not too familiar with Sun rims, so I don't know how they stack up against Velocity, Mavic (meh), DT, Ambrosio, and etc.

alienator said:

What matters is the gauge of the spokes and whether they're straight gauge or butted. Butted spokes are less likely to break. Also, what sort of profile does the rim have? I'm not too familiar with Sun rims, so I don't know how they stack up against Velocity, Mavic (meh), DT, Ambrosio, and etc.

ah hell i really don't remember the gauge, but they are straight guage. butted spokes are flat in the center right? how about titanium spokes are they stronger than stainless?