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This is part of the chest strap of an Altura Morph backpack/pannier that I use for commuting. I've lost half the strap and one of my bikes can't take a pannier rack so I use backpack mode on that bike. That tends to be the bike I use in the rain; with a wet waterproof jacket the shoulder straps slide around in the absence of a functioning chest strap.

It's not a cheap bag, so I'd like to repair it

The part is question is plastic, a slotted tube with the dimensions shown in the first picture:

Strap part

This part slides up and down a stiff track on the shoulder strap, like a wire wrapped in fabric, so the chest strap height can be adjusted: enter image description here

It should be prevented from easily coming off the end of the track, but some damage to that region of the left shoulder strap means the left half of the chest strap went missing.

If I can buy a replacement I can easily make a new chest strap from spares I have, but I've no idea what to search for. My guess is that it's generic but most of my other kit is quite old and I haven't seen one on anything else. I could make something or buy a generic replacement strap but this was quite a nice design that stayed in place unless it snagged on something.

  • While this is bike-related, I felt the backpack aspect made it more relevant here. – Chris H Aug 16 '18 at 14:07
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It looks like this piece goes by 3 different names,

You could also try contacting the manufacture, since these parts don't seem to be extremely common.

  • I've obtained a list of readily available spares already (not official), and it's not listed. Piping is the word I was looking for when writing the question, but unfortunately as a synonym for "pipe" as in water pipe gets me lots of irrelevant hits. I think with your help I shoudl be able to track something down – Chris H Aug 16 '18 at 15:00
  • I'm clearly not the only person to have faced this, as a model is available for 3d printing. So if I can't find one to buy I can try to find a UK-based 3d-printing service (shapeways shipping more than doubles the price) – Chris H Aug 16 '18 at 15:16
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    @ChrisH not all plastic is created equal—if you 3D print, I’d make it much bulkier than the original and ideally make a few so you can break some. Another option is to machine it—and by “machine” I also mean make those shapes by whatever means ie a hand drill and the saw from a multitool. The critical shapes are the part that fits over the piping (a long hole of the proper diameter, and a slot cut in the side of the hole) and the place the strap goes. Use a plastic cutting board for raw material and make everything other than those critical shapes 2 or 3 times as thick as the original. – mmcc Aug 18 '18 at 17:13
  • @mmcc I have some experience of both SLS and FDM, including designing for the latter. Either would be strong enough for this, especially as the likely failure would be for it to come unclipped if tightened too much. But I can't currently get the price reasonable – Chris H Aug 18 '18 at 18:14
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    @ChrisH yeah 3D printing (as used by people who take the time to learn the strengths and weaknesses of the process) is great but I always worry people forget all the other ways of “rapid prototyping”—if you’ve got welding or silver solder available another way to deal with piping is to cut a slit in a piece of (relatively thick walled) stainless tube and attach a bit of bent wire for the buckle. The pain in the butt there is deburring the cut...wonder if copper and plumbing solder would be strong enough... – mmcc Aug 19 '18 at 15:44

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