Apidura make waterproof bike packing bags with welded seams and waterproof zips. However the zips are excluded from their warranty. I understand why as they are easy to stress either by over packing or by pulling the zip without holding the line of the zip straight. I consider myself a considerate user of equipment but one of the zips on my frame bag failed after 9 months. Because of Covid 19 lock down I haven’t even used it for real bike packing yet just day trips around my local area.
It turns out zip replacement is straight forward and not expensive. The original zip is welded in and I don’t have a welder for plastic and anyway I’m not sure it would be possible to remove the old zip in a way that a new one could be welded in it’s place.
You will need:
From Point North profabrics.co.uk
YKK Aquaguard No5 single sliders – Black £0.49p
YKK Aquaguard Nov Water Resistant Continuous Zipping 1 metre £5.95p
From Ultralightoutdoors.co.uk
McNett Gear Aid Seam Grip WP Sealant and Adhesive (2 x 7g tubes)
Code: OC2456 £10.99
Tools: Craft Knife, Small wood block, Small sharp scissors, Anpro clips for sewing quilts. Note these clips have a flat arm and a curved arm. The curved arm is needed so that the clip presses on the fabric behind the zip not on the zip spiral.
Optional – Sewing machine or you can hand stitch.
So I took a craft knife and small block of wood. Place the wood block inside the bag under the place where the zip joins the bag material. Make an incision so that you can insert a small pair of sharp scissors and cut out the zip around the join with the bag material. Be careful at either end to go inside the material and cut out the end of the zip.
Cut a length of replacement zip the same length as the one you have cut out. Fit one of the sliders on one end. To do this tease open one end and feed the spirals into the open end of the slider in parallel so that so that the zip closes as you pull the slider onto the zip. Make sure you do not go right to the end of the zip. You want the last 1 cm to remain closed. You can just put a stitch in around the two spirals before you start if you want to be sure. Now open the zip making sure you leave 1 cm closed at both ends.
Lay the zip in the bag and check you can get it to clip along the fabric and lay smooth. When you are happy remove the zip and apply the Seam Grip along the top outside edge of the zip about half the width. Carefully insert the zip and clip in place. Take special care to make sure the flat arm of the clips is on the inside and the curved arm on the outside so that it presses on the fabric behind the spiral. Put on lots of clips!!! Leave to cure for 24 hours.
Remove the clips and apply the Seam Grip along the bottom outside edge of the zip about half the width. Carefully insert the zip and clip in place. Take special care to make sure the flat arm of the clips is on the inside and the curved arm on the outside so that it presses on the fabric behind the spiral. Be especially careful to make sure both ends are stuck in. Put on lots of clips!!! Leave to cure for 24 hours.
Remove the clips and sew the centre section of the zip where there is the most stress. I used a triangle stretch stitch as this is effectively a double stich for extra strength. Because of the limited space with my sewing machine I managed about 80% of length of the zip. Apply Seam Grip over the stitching to make it waterproof. Be careful not to let the flap fall onto the wet Seam Grip! Leave for at least 24 hours for the Seam Grip to cure and stop being tacky.
You are Done – Happy cycling