How can I reduce the pressure of backpack straps on my collarbone, perhaps by fixing padding to the strap?

Question

As some of you who are also active on bicycles.se may know, I broke my collarbone in a bike crash last year, and it's now got a titanium plate in there. I'm not sure whether it's the plate or not, but some backpack straps now seem to press rather too much in the wrong place. My commuting backpack is worse than my good 40l daysack, for example, and I don't think it's just the weight-bearing hip belt on the latter. Adjusting the shoulder and chest straps makes little difference; the discomfort comes back soon.

A little testing with fingers or rolled up gloves suggests that pads above and below the collarbone would help a lot, but I'm not sure how to keep them in place. I don't want to simply glue bits of foam to the straps as they might need some adjusting, but simply wedging them in when I put the pack on doesn't work as they creep out. I'm also not certain that foam pads like this are the best idea, so am open to suggestions.

Here are two example packs: The blue one (right) is a hydration pack I use for running and mountain biking and the dark one (left) is the one I mention above for commuting etc. In the bottom left picture you can see that the strap that holds the chest strap stops too low; in the bottom right I'm pointing to where I believe the pressure point to be, but it would be hard enough to tell precisely even without minor nerve damage. As I'm tall and rather broad-shouldered, small one-size-fits-all packs like these are a less than perfect fit anyway.

Answer 1

I would consider two solutions:

1. Get a piece of foam or sponge. You can get in a vehicle repair/mod place, or in a place which makes/fixes sofa cushions. Attach it to the bag strap with velcro wrapped around the strap+foam combo. This goes over the collar bone region and spreads the load over a much larger area, so as to relieve pressure on the healed fracture. You might need to experiment with a couple of different types of foam/sponge of varying hardness/softness to find out what works best.

2. Get two pieces of hard foam and attach them (with velcro) to the bag strap above and below the healed fracture region. As a result, the strap does not touch/go over that region or pressure it in any way, because it is held up from both above and below, by the foam pieces. As opposed to the previous paragraph, harder foam/sponge is better than soft, in this case, because the strap needs to be held up and prevented from touching the collar bone. Once again, it will take a bit of experimentation to get it right.

Hope this helps.

Note on how to attach using velcro: get about 15cm of velcro, and lay out the opposing sides parallel to each other but shifted by about 5 cm, something like shown in the crude sketch below:

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Turn one of the strips around and attach it to the opposite strip. You now effectively have a single strip with opposing surfaces on either end. You can wrap this around the strap+foam and attach the opposite surfaces tightly enough.

I just quickly tried the first method, and it works well enough. I've attached a couple of pics to give a general idea. The velcro strip I have is longer than I'd like for this purpose, so I wrapped it an extra turn. You will probably need to try out a couple of times till you get it right..

Answer 2

To accomodate the shoulder straps sliding over the collar bone without displacing the padding, I'd build a sleeve of some kind. Especially biking, the straps will want to move around if you go in and out of the saddle.

Just to try it out, you could make it entirely of Duct Tape which would make for an easy and inexpensive way to test the concept.

Two small tape-width rolls at either ends of a two-layer tape tube that's inserted over the shoulder strap, like this:

The main advantage is that if this works, it would be possible to have one sleeve made that could be used on any pack. For example, the sleeve could be made to be undone by snap buttons or a zipper to remove it from the straps.

Answer 3

I think you need to find out why the plate hurts. If putting a load on the bone is putting tension/torque on the screws that attach the plate, then any form of loading on the bone may be a problem. You may want to talk to your doctor about ways to increase the bone density at the anchor points, or encourage more bone callus over the plate.

Meanwhile: I would do initial experiments with cut up ensolite (blue foam sleeping pads) and duct tape. This makes for a quick experimental process.

You mention that your commuter pack is different from your day pack. In addition to the difference in packs, you have a difference is posture. When biking, generally you are leaning more, so a component of the load is trying to bend your collarbone sideways. When hiking you are more upright. You can test this by going for a walk in the park with your commuter pack, and taking a bike ride with your day pack. Load them both to about the same weight.

Kind of an off the wall answer: Talk to a sports doctor and a plastic surgeon, and see if putting a pad of silicone over the plate would help.