How to make bike lights magnetic with sugru + magnets

Picture of How to make bike lights magnetic with sugru + magnets

Bike lights can be frustrating and slow to attach & remove, especially in bad weather with gloves on! By adding magnets to your lights, and your bike, you’ll be able to snap your lights on and off with your gloves on, and in a matter of one very satisfying move.

Once you make your lights magnetic, you might wonder why all lights aren’t like this.

For this project you will need:
- x4 strong neodymium magnets (x2 per bike light) - we used the magnets in our sugru + magnets kit - buy one here.

- x2 minipacks of sugru (half a pack needed per magnet) - buy some sugru

- your bicycle, helmet or whatever else you want to attach your lights to!

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Step 1: Find some neodymium magnets

Picture of Find some neodymium magnets

For this project we are using the strong neodymium disc magnets from our sugru + magnets kit. They’ve been life-tested on our bikes all over the streets of London for a year... and they survived the English weather! (Check out the video below for the shake test)

You can try this project using your own neodymium magnets + sugru - but make sure the magnets you choose are strong enough to hold your bike lights while riding.

Step 2: Open your sugru

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Cut open a minipack and divide it into two equal parts.

Top Tip: One minipack of sugru is enough to attach two magnets.

Step 3: Build a pyramid

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Squidge a sausage shape onto the back of the magnet and press it into a pyramid shape.

Step 4: Squidge the sugru

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Carefully but firmly press the magnet onto your bike’s handlebars, so that sugru squeezes out around the edge of the magnet.

Top Tip: Make sure the surface you are applying the sugru to is clean.

Step 5: Press in the sugru

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Press the sugru in around the magnet, ensuring there is a good bond.

Step 6: Smoothen the sugru

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Gently rub the sugru with your finger to smoothen it and leave for 24 hours to fully cure.

Top Tip: use a little soapy water on your finger to get a really smooth sugru finish. More tips here.

Video Tip: How to make your sugru projects look awesome

horcc2 months ago

Hi, I'm from Malaysia, and i wonder how long will sugru hold up to the hot sun at my place... mostly 80% sunny all the time, and 20% rainy days...

davmaldo1 year ago

How do the connections hold up against bumps? do the lights jostle significantly? Since the magnets are round, do they have a tendency to rotate (might be a problem for the headlight). This could be a great solution for me as i have multiple bikes and just one headlight/taillight combo.

projectsugru (author)  davmaldo1 year ago

Yup, a friend has a city commuter and a long distance racer and uses magnets for his lights so they transfer easily between them. You are correct, as the magnets are round, there is a little bit of movement but that seems to happen only when you knock the bike about a lot, like hitting a pothole for example.

Here's an idea. Before encasing the magnets in sugru, start a small pilot hole on both magnets(be sure to put them off center). On one of the magnets epoxy a tiny ball bearing into the pilot hole. Leave the other hole open. With a little bit of care in the installation process this could eliminate the movement between magnets and make a more solid connection. It's basically a mechanical detent reference. A lot of rifle parts use this same concept!

I've noticed that the red sugru doesn't hold as well as the black

qx871 year ago

Do you think this could also work with a Phone? I am looking for an easy/ cheap way to attach my phone (Defy+ /118 g 4.16 oz) to my bike for touring/ routing, but not sure if this would stay attatched in rough terrain. Anyone tried this?

projectsugru (author)  qx871 year ago
great question but I haven't tried it. But if I was to suggest an experiment it would go like this: 1: get a cheap phone case for your phone. 2: sugru 2 magnets to the back of it and let the sugru cure fully. (one single use pack is enough for 2 magnets) 3: attach a magnet to each of the magnets on the back of your phone case. 4: apply sugru to the back of these magnets (in a pyramid shape) and press onto your bike in the desired position (your phone should not be in the case during this process) 5: Use masking tape to hold the case in position while the sugru cures fully. Finally, do some progressive tests to ensure that this works to your satisfaction for the desired application. 5: let us know how you get on.... I hope this helps? James

on second thought, amateurish me should probably not mix big magnet with electronic memory device.

I already have a multi-pack of sugru mini packs. Is there a comparable magnet that I could buy on it's own?

I know there's plenty out there, but I'm looking to specifically replicate the strength and size of those tested here.

projectsugru (author)  toekneebullard1 year ago
great. We use N42 Neodymium magnets that are 20mm diameter and 3mm thick with a pull force of 4.5Kg. We are pretty proud of the very simple additional feature of a dimple on the north face which makes building this project much easier. Happy hunting.
I couldn't imagine a better reply. Unless you figured out a way to include ice cream or something...

(or some free sugru :) ...)

Question, why would you NOT enclose the entire magnet in a thin layer too? At the very least use Plasti-dip on the magnet for weatherproofing, then do the sugru magic. I might try this if it weren't for the insanely high price of sugru.

projectsugru (author)  gravityisweak1 year ago
great question. OK, so we have tested coating a magnet in sugru but doe to the high abrasion of the application, it will wear down after some time. Additionally, you will reduce the strength of the magnets.
Your plastidip idea is interesting but I don't actually know if sugru will bond to it. A final note, we have tested these magnets for over a year on our bikes in London and they are still going strong with negligible signs of wear. Hope this helps.
-chase-1 year ago

Nice instructable, I'll have to keep it in mind for future reference.

19 bikes stolen so far and a ton of stuff stolen off them including lights I'm not getting another soon. Not till I move to another state - or perhaps country.

clazman1 year ago

I m still a newbie considering this material. I am a fan of epoxies and would use a paste epoxy in this case.

I cannot believe that this material has the strength to withstand the stresses created when separating the magnets for it does remain quite elastic. But reading, and seeing, is believing

I guess I am going to have to experiment with this material.

Thanks for the presentation. Maybe this puppy will try another "new" product.

projectsugru (author)  clazman1 year ago

sugru has excellent damping properties so that helps absorb a lot of the shock from impact when the magnets strike each other thus helping to prolong their life.

sugru sets to a relatively firm rubber.

Happy experimenting.

davmaldo1 year ago

What are the dimensions of the magnets? they look like 3/4"D x 1/8"t ?

projectsugru (author)  davmaldo1 year ago

they are .787" x .11" :)

haasebert1 year ago
Is this sturdy enough to use for mountain biking?
projectsugru (author)  haasebert1 year ago

yes, we've tested it quite a lot. The key factor will be the size of the light used. The Cat Eye lights in this example would survive some pretty intense downhill:)

sschoemann1 year ago

I'm still a fan of stainless hose clamps and hard drive magnets

Very very good I like this I dear a lot nice one
tjk19391 year ago

Awesome, haven't used any yet, but now I'm gonna. Hello Amazon.

rzeeshan11 year ago

Nice :-)

Magic Sugru! :-)

hunter9991 year ago

Wow! This looks awesome! :-)