The Leatt Dual-Axis knee guard is a great combination of hard protection and comfort. I’ve gone over the MTB bars into rock gardens multiple times without damage--knock on wood. Relatively light, the guards are EN1621-2 tested and certified:

Knee Guard Dual Axis (2016) - Body Armour | Leatt® | Protective Neck Braces, Body Armour & Sports Gear
BikeCo Product Profile: Leatt Dual Axis & Race Face Ambush Knee Guards Video - Pinkbike

So I wear Dual-Axis on every single MTB ride. The guard itself is very tough but at several hundred ride hours per year the elastic straps wear out.

Unfortunately the straps are sewn into the protector and are not replaceable. Except, they are. Very easily it turns out.

The key is to get quality elastic, with at least 125% stretch and braided construction. This is serious, expensive elastic but it is the only thing that will work. Don’t bother with the 30% stretch cotton stuff available locally and on Amazon.

After lots of hunting around I found a US source that will sell 10 yard sample rolls of US-made 25% rubber and 75% polyester elastic used in medical and military products:

Braided Elastic Sample Rolls | WBC Industries

I paired 2 inch elastic with 1.5 inch ladder-lock buckles.

The oversized elastic does not go through the undersized buckles with complete smoothness, but it works fine. And the 1.5 ladder-locks are a lot cheaper than 2 inch. But I now believe 1.5 inch elastic would be strong enough too.

If you use the Leatts on bare skin, the perforated neoprene part of the straps may be important to you. This or similar material can be sourced and sewn in without difficulty using a Speedy Stitcher or finding someone with a machine. I always wear Lycra for MTB and enduro pants for moto, so plain elastic is fine and I cut away the neoprene when it wears out.

Now, simply make a loop using elastic and a ladder-lock. No velcro, no sewing, completely adjustable. Once you get the length adjusted you can use the quick-release buckles and pretty much ignore the ladder-lock.

Ten yards is enough to do about two complete sets of straps. It is great to be able to fix these $90 guards so easily.

A couple of other notes. These guards tend to collect sticks, leaves, and rocks inside over time. Easiest way to get this debris out is to insert a vacuum cleaner nozzle from the back side. If you break a “post” quick-release buckle, a “buckle and bolt pack” is available from some dealers.

Dual Axis Knee guard - Buckle & Bolt pack - Spare Parts | Leatt® | Protective Neck Braces, Body Armour & Sports Gear