ferrous road debris pickup for bike using neodymium magnets?

[neptronix]

Wondering if this exists already.
I'm trying to prevent the giant screw/nail problem that destroys tires, without getting something like a tannus armor that increases tire drag dramatically.

I have some magnets from desktop size hard disks that can pick up iron/steel nails from 1/3 of an inch away.
I'm thinking that if you mount some kind of plate with magnets just behind the front tire, you could theoretically catch a very high percentage of tire destroyers.

Anyone done it / seen it?

I searched and i can only find very bulky units which sit behind the rear wheel and are built to clean the streets for others but not yourself.

 

[Nix Liou]

Wondering if this exists already.
I'm trying to prevent the giant screw/nail problem that destroys tires, without getting something like a tannus armor that increases tire drag dramatically.

I have some magnets from desktop size hard disks that can pick up iron/steel nails from 1/3 of an inch away.
I'm thinking that if you mount some kind of plate with magnets just behind the front tire, you could theoretically catch a very high percentage of tire destroyers.

Anyone done it / seen it?

I searched and i can only find very bulky units which sit behind the rear wheel and are built to clean the streets for others but not yourself.

My main thought here is that unless it can pick up nail thrown by it at 20 mph, or however fast you ride, it probably wont get most of the debris. I think those sweeper units are meant to move pretty slowly as well.

 

[scianiac]

Behind the front so it doesn't run into stuff if you go over a bump? Also means it only protects the rear.

I see no reason why this wouldn't work though given a sufficiently powerful magnet, may want to soft mount it though so if you go off a sharp edge like a curb at low speed it just gets bumped out of the way. Like it pivots around the axle and is suspended by adjustable cords, like to make the magnet strength less critical you want it as close as possible, almost touching and probably touching sometimes with a slider or little wheels depending on the surface.

The question is how does it compare to other options, because it's going to be a little clunky no matter what. While I don't have a problem with punctures so I've never tried it I still think my idea of drilling a second valve stem hole and putting in two lightweight TPU tubes, one inflated and one uninflated pushed against the rim would work nice. You get a puncture and you pull the offender out and just inflate the backup tube, you still have to take the wheel off to replace it but you can do that at home. It's a middle ground which is cheaper, easier and lighter than armor, inserts, etc with the downside you only have one puncture per ride and still have to change the tubes when you get home.

 

[wturber]

Wondering if this exists already.
I'm trying to prevent the giant screw/nail problem that destroys tires, without getting something like a tannus armor that increases tire drag dramatically.

I have some magnets from desktop size hard disks that can pick up iron/steel nails from 1/3 of an inch away.
I'm thinking that if you mount some kind of plate with magnets just behind the front tire, you could theoretically catch a very high percentage of tire destroyers.

Anyone done it / seen it?

I searched and i can only find very bulky units which sit behind the rear wheel and are built to clean the streets for others but not yourself.

I have not seen or done it. The big question I would have is what would be the best location? Right behind the front wheel? Bottom Bracket? I harvest these magnets and may start experimenting myself.

 

[neptronix]

Have you ever played with hard drive magnets? they're nutty powerful.

I think if you could be 1/3 inch off the ground you could probably catch some stuff at very fast speed.

Behind the front so it doesn't run into stuff if you go over a bump? Also means it only protects the rear.

Exactly. The magnetic plate would also need to be able pivot backwards an up in situations like, you're going over a pothole or very large curb.

I see no reason why this wouldn't work though given a sufficiently powerful magnet, may want to soft mount it though so if you go off a sharp edge like a curb at low speed it just gets bumped out of the way. Like it pivots around the axle and is suspended by adjustable cords, like to make the magnet strength less critical you want it as close as possible, almost touching and probably touching sometimes with a slider or little wheels depending on the surface.

Soft mounting is a really good idea because this thing will have to conform to all kinds of road irregularities. I was thinking there's be a curved pivot it could travel backwards and upwards on.

I like this idea of strings actually instead of a pivot, so the motion can be as chaotic as necessary.

The question is how does it compare to other options, because it's going to be a little clunky no matter what. While I don't have a problem with punctures so I've never tried it I still think my idea of drilling a second valve stem hole and putting in two lightweight TPU tubes, one inflated and one uninflated pushed against the rim would work nice. You get a puncture and you pull the offender out and just inflate the backup tube, you still have to take the wheel off to replace it but you can do that at home. It's a middle ground which is cheaper, easier and lighter than armor, inserts, etc with the downside you only have one puncture per ride and still have to change the tubes when you get home.

I tend to get a flat every ride. Tubes are an expensive habit that may make my ebike less environmentally friendly than a car because i throw out tubes so often. It's a major problem out here.

 

[wturber]

My main thought here is that unless it can pick up nail thrown by it at 20 mph, or however fast you ride, it probably wont get most of the debris. I think those sweeper units are meant to move pretty slowly as well.

I would expect most objects to be travelling much slower than the bicycle's speed. Keep in mind that the very bottom of the tire is travelling at very close to 0 MPH. I'd assume it is the pressure applied to the object and/or the tendency of the debris to stick to a soft rubber tire combined with the upward motion of the tire. And the upward motion is also very much less than the bicycle speed when the tire is close to the ground. Yes, the mere pressure of the tire pressing on things like rocks can cause them to be popped/kicked to the side at pretty high speeds. But this is uncommon and not the kind of thing we are trying to catch with the magnet anyway.

 

[wturber]

I tend to get a flat every ride. Tubes are an expensive habit that may make my ebike less environmentally friendly than a car because i throw out tubes so often. It's a major problem out here.

You don't patch? Is your main problem steel objects. My main problem was goatheads and the like. Running a tire within a tire was my best solution.

I'd be concerned about having anything super low. It would be interesting to run an experiment using a magnet that could be suspended at different heights. Ride it around and collect data on the heights vs. amount (type?) of debris accumulated.

 

[neptronix]

You don't patch? Is your main problem steel objects. My main problem was goatheads and the like. Running a tire within a tire was my best solution.

I do sometimes. I was running stans no flats and.. it didn't work against this and left a super nasty wet mess - tube was unpatchable in the field and tire way too wet, so i did the usual walk of shame home.

I'd be concerned about having anything super low. It would be interesting to run an experiment using a magnet that could be suspended at different heights. Ride it around and collect data on the heights vs. amount (type?) of debris accumulated.

Just doing a test with a neodymium magnet in hand, 1/3 inch is about where the effective distance of picking up a nail stops.
If the front tire were to kick the item upwards, we're in luck. But i can't count on that

 

[maiz]

I searched and i can only find very bulky units which sit behind the rear wheel and are built to clean the streets for others but not yourself.

Tire Wipers

Maybe mount the magnet on something like this?

 

[amberwolf]

Dogman had a thread about this very subject around here somewhere, but since he has about as many posts as I do, I'm not sure how to find it. :/

 

[amberwolf]

Just doing a test with a neodymium magnet in hand, 1/3 inch is about where the effective distance of picking up a nail stops.

You need to be even closer at speed, otherwise the item will have passed the magnet before there is time for the force to pick it up.

So...I think what you would want is a magnet between rollers (skate wheels, hoverboard wheels, whatever) that is on a "fishing rod" suspension over the front wheel, as if you were leading the bike on with a carrot on a stick but not hanging on a line, rather the rod goes around the front wheel far enough from it and offset to one side just enough that it can't ever get caught in the wheel, while the rollers/magnet would be in the tire path but again far enough from it that regardless of the road conditions it can't be sucked into the tire. (cuz that would really really suck for the rider).

To prevent lateral sway you probably need two "fishing rods", one on either side of the wheel, parallel with the fork legs.

It might be more proof against tire suck if the rods curve down from the crown then meet the axle nut then out front and down to the road.

 

[BicycleJoe]

I have seen this magnetic pickup of sharps. It works, under certain conditions.

Airport service Tugs can be seen with a long magnet-bar hanging across the full 5'-6' front of the vehicle.

These are olde-time magnets, weighing about 10 pounds per foot length. They do pick up the steel, the main offender in pneumatic tire flats.

These magnets work at airports because the terrain is almost dead-flat so they can hang low. Also, these airport tugs don't go faster than 6-7mph.

I'm always in favor of flat prevention but I don't think any bike-friendly magnet is strong enough to pickup sharps at ebike speeds.

I use tubeless-ready tires and rims, plus Stan's Tire Sealant.

 

[offGridDownUnder]

think if you could be 1/3 inch off the ground you could probably catch some stuff at very fast speed.

I'm thinking of you not being 1/3 inch off the ground while riding your bicycle at a very fast speed and trying to catch stuff.

However, on the magnet side of things, I suspect your gizmo would pick up a great pile of iron filings in short order. Pictures or it didn't happen!

 

[offGridDownUnder]

I still think my idea of drilling a second valve stem hole and putting in two lightweight TPU tubes, one inflated and one uninflated pushed against the rim would work nice

You have attempted this? If so, did it work as hoped?

If not, go for it, we're right behind you!

 

[amberwolf]

I don't know if this is the thread I was thiking of, but it is one of dogman's posts on it Is there more I could be doing to avoid flats?

 

[wturber]

Just doing a test with a neodymium magnet in hand, 1/3 inch is about where the effective distance of picking up a nail stops.
If the front tire were to kick the item upwards, we're in luck. But i can't count on that

Mine picks up at about 3/4". If I stack a few magnets on top of each other, I can get a pickup distance of over an inch.
My main concern is items being kicked up by the tire. My hypothesis is that the front tire kicks the debris up causing it to tumble and increasing the chance that it can contact the rear pointy side up. Most nails and such will sit on the road pointy side down or sideways most of the time. They become more dangerous once the front tire kicks them around. My experience is about 3 or 4 to 1 more punctures from staples, nails and tacks in the rear tire. Maybe 2 to 1 for organic punctures like stickers and thorns. To be sure, this is not data I've measured and collected. It is only my impressions from memory.

 

[neptronix]

Tire Wipers

Maybe mount the magnet on something like this?

What a find! it says smooth tires only but.. we can give it a gap!

You need to be even closer at speed, otherwise the item will have passed the magnet before there is time for the force to pick it up.

So...I think what you would want is a magnet between rollers (skate wheels, hoverboard wheels, whatever) that is on a "fishing rod" suspension over the front wheel, as if you were leading the bike on with a carrot on a stick but not hanging on a line, rather the rod goes around the front wheel far enough from it and offset to one side just enough that it can't ever get caught in the wheel, while the rollers/magnet would be in the tire path but again far enough from it that regardless of the road conditions it can't be sucked into the tire. (cuz that would really really suck for the rider).

To prevent lateral sway you probably need two "fishing rods", one on either side of the wheel, parallel with the fork legs.

It might be more proof against tire suck if the rods curve down from the crown then meet the axle nut then out front and down to the road.

Interesting but i think hitting a number of things could bash carrot on stick in front, but.. it's not so much of a problem to go behind.

I like the idea of strings.. too bad we cannot make a fuzzy dice out of neodymium cubes ( they'd stick together! )

I don't know if this is the thread I was thiking of, but it is one of dogman's posts on it Is there more I could be doing to avoid flats?

Interesting but seems nonconclusive

Mine picks up at about 3/4". If I stack a few magnets on top of each other, I can get a pickup distance of over an inch.

Woah, really

I measured 1/3 inch with a single laptop hard drive magnet and so i'm imagining the full size hard drive ones are way stronger then.
Interesting to know that they parallelize, 1 inch distance is amazing and it makes me think this project is feasible.

My main concern is items being kicked up by the tire. My hypothesis is that the front tire kicks the debris up causing it to tumble and increasing the chance that it can contact the rear pointy side up. Most nails and such will sit on the road pointy side down or sideways most of the time. They become more dangerous once the front tire kicks them around.

I think that's also the case. These objects may get a little lift.. so the back of the front tire would be a fantastic place to catch things.

My experience is about 3 or 4 to 1 more punctures from staples, nails and tacks in the rear tire. Maybe 2 to 1 for organic punctures like stickers and thorns. To be sure, this is not data I've measured and collected. It is only my impressions from memory.

On the recumbent bike where i have the problem, i have 2.5 - 2.8" tires and thus far it's more like a 8:1 rear to front flat ratio.

Yeah maybe on a standard upright you could use something ahead of the front wheel.. if that's even possible ( i'm imagining that a 1 inch thick curb might put an end to that idea )

 

[wturber]

Woah, really

I measured 1/3 inch with a single laptop hard drive magnet and so i'm imagining the full size hard drive ones are way stronger then.
Interesting to know that they parallelize, 1 inch distance is amazing and it makes me think this project is feasible.


I think that's also the case. These objects may get a little lift.. so the back of the front tire would be a fantastic place to catch things.

Definitely. I went out to the garage to check. I tried it with a roofing nail with a large head and a finish nail with a smaller head.

I routinely harvest these magnets and have them around for various jobs. And yes, these were from 3.5" hard drives. The laptop drives have teeny tiny thing magnets. And stacking definitely increases the field strength/reach. intuitively it seems like the increase is reduces logarithmically. Two magnets don't double the strength and adding a third doesn't seem to help as much as adding the second. So a stack of three or maybe four seems to be a likely sweet spot. But again, this is something that could be tested.

 

[PaulD]

Perhaps every city needs a hero like this guy: Login • Instagram

 

[amberwolf]

Interesting but i think hitting a number of things could bash carrot on stick in front, but.. it's not so much of a problem to go behind.

But if it's behind the wheel, it can't do anyting to protect it?

 

[neptronix]

I checked my desktop hard drives from 2018-2021. The magnets are laptop sized... so sad!

Here's a thought. Many times my bike needs to hop off a 5 inch curb. I think this has a high chance of destroying a tire wiper or anything solid behind the front wheel.

String is a good idea but it could get snagged on things at high speed.

But if i had these magnets on some kind of strings, then they'd simply drag across the curb as the front wheel goes downwards and not be destroyed. That would work, but they'd need periodic replacement.


Here's a thought. How about a tiny sacrificial wheel?
Line the tire with neodymium magnets between the tube and the tire and you've got a great metal picker-upper.
Locate it on a pivot so that as you are going over a curb etc, the baby wheel doesn't get smashed, it just moves upwards.



The only problem is if we're going over a big curb, we could lose the baby wheel.
A reasonable minimum diameter would be 12 inches.

The problem is that from an aesthetics point of view, this is on the uglier side.

 

[neptronix]

But if it's behind the wheel, it can't do anyting to protect it?

Nope, we're just trying to protect the back wheel since this is where most of the metal things get stuck.

 

[amberwolf]

FWIW, a less strong magnet can have a more distant field effect.

I don't recall the specifics, but there was a discussion aobut ceramic vs neos that showed something like twice the distance to start affecting something for a ceramic than a neo even though the neo held the item harder once it caught hold of it. I'm sure it depends on the specific magnets, and probably the materials being picked up. Unfortunatley I can't find the discussion, and am presently being detained by the schmoo for attentionals, so I can't get up to go do a test with the various things stuck on the tool cabinet door.

 

[neptronix]

Since we are going high speeds we want:
Strong enough to pick up a screw moving at 30mph
Not so strong that our bike gets stuck on a train track

Here's the same idea except we don't have a roller. It's instead levitating by ~3/4 of an inch and we are making the bet that the front tire kicks some things up for us. We still have a pivot for this situation where we're rolling down a curb.

 

[jkrienert]

What about... elephant tusks? Some Ridgid cold rolled steel stock (green in my annotation of the above diagram) maybe 1/4" diam rod with a bracket on the end to mount stop the brake caliber, and arc down in front of the tire contact patch by about 3 to 5 cm leading on the road. The last 5 cm or so could have the magnets mounted on the stock. Would require periodic cleaning , but avoids adding any additional rolling resistance by surface friction? The challenge would be, keeping the arc ridged enough to prevent bouncing and contacting the road surface...
As a possible added benefit, either setup with magnets in vicinity of the front wheel contact patch, could setoff any inductive stoplight switches, more than without(?), though I'm not even sure how many Tesla you'd need to effect those inductive sensors, as well as, I'm supposing many intersections also use combined or substitute detectors for weight or visual by cameras. I digress...
Having ran solid tires for several years and acceptance of the added rolling resistance, this potential solution the OP has mentioned is pretty intriguing...