If you are an avid athlete or charity runner who has previously entered a race, you will have had the experience of struggling with safety pins to attach your allocated number to your vest, shirt or jersey. Not to mention the annoyance of completing a race to find out that your number has disappeared along the way, or worse still, the pins you used have created a hole or tear in your favourite, lucky competition attire
However, there is an alternative – using magnets to attach your race number. Strong magnets, such as neodymium disc magnets as little as 10mm in diameter and just a few millimetres thick can provide sufficient hold to clamp a number in place through your shirt, vest and even neoprene jerseys.
Kathryn from Sheffield, an avid charity runner, has started using magnets to attach her race numbers and sent us these photos to show us just how well it worked. Kathryn purchased a pack of 10 20mm diameter x 2mm thick N42 neodymium disc magnets, each of which has a 2.6kg pull strength, more than enough to attract through the thickness of a running shirt.
As you can see by using two magnets in each corner, one on each side of the shirt, the number is securely held in place. On this occasion, Kathryn could have used smaller weaker magnets such as 10mm diameter x 1.5mm thick N42 neodymium disc magnets but the ideal magnet really does depend on the thickness of the garment and the type of competition you are entering. Here’s a few tips:
1) A magnet’s strength quickly reduces when it is trying to attract another magnet through an air gap such as a piece of material. The thicker the garment, the stronger the magnets will need to be to cope with the large gap. For example, a gap of 1mm will reduce the magnets pulling force by half.
2) Opposite poles of a magnet attract and like poles repel. Disc magnets have their north pole on one flat face and their south pole on the other. Therefore, you need to align the magnets in the below configuration. As like poles repel, this arrangement will stop the magnets on the inside of the garment snapping together when you try to put it on.
3) If you have a nickel allergy, we would advise that you use gold-plated magnets such as 12mm diameter x 2mm thick gold-plated neodymium disc magnets, rather than our standard nickel coated varieties.
4) Magnets are very brittle so you should always avoid letting magnets slam together as they could chip and break.