DIY custom-molded Kydex frame protection

Review: REEB Ti Donkadonk Fat B
January 4, 2021
Review: Niner JET 9 RDO
August 22, 2022

Maximum durability with minimum weight and cost.

F or the most part, the standard frame protection that comes stock on mountain bike frames is decent, but it has limits. There's a lot of variability though, from thick screw-on plates to thin adhesive clear films. Unfortunately, those protectors are generally pretty minimal, both in thickness and coverage, which isn't surprising when manufacturer is trying to balance cost, aesthetics, advertised weight, and assembly ease. The rubber frame protection pads on my last Guerrilla Gravity Trail Pistol frame starting falling off after the first ride. The frame protection on my new Niner RIP 9 RDO has been solid, but after I took a rock strike to the paint on the down tube—just barely missing the stock rubber protector—I decided to take things a bit further.


How much protection?

In searching for replacement frame protection that could be customized to fit any bike shape, I didn't come across much. Of course, there's a plethora of various adhesive films (here's a Pinkbike review of 7 different films) but those films do very little against kicked up rocks that can hit your frame in excess of 20mph on fast descents. Those films are great for non-impact areas where you want some discrete protection against scratches and rubbing, like on chainstays for heel rub, or on the side of the head tube to protect against cable rub. But on the down tube… not so much.

For the most part, any flexible frame protection isn't going to do much for impacts. This includes those thin shuttle pads that are supposed to protect the frame when it's resting on the tailgate of a truck. I recently listened to a interesting podcast featuring Ruckus Composite Repair. He noted that it's pretty common for to see cracked carbon down tubes from being shuttled and the bikes bouncing around on the tailgate with your homie flooring it up the fire road.

Before we move on to the actual build process, I would just caution against thinking that this issue only affects carbon fiber frames. Aluminum frames in particular can sometimes be even more fragile than carbon because of how thin modern alloy tubing has become in effort to save weight. I can't speak for titanium and steel, but my guess is that denting and tearing of those materials is much harder to do, outside of a crash.

This is where Kydex comes in...

So how do you get a durable, hard, customizable frame protection? Kydex. Traditionally, Kydex is a very popular material for making knife and handgun holsters, but I've seen it creatively used for all kinds of things. It's basically a rigid thermoplastic that comes in flat sheets of varying size, thickness, color, and surface texture. Once it's heated (either with an oven or heat gun) it becomes very pliable and can be molded around nearly any shape, and it cools quickly where it hardens again. It can be re-heated and re-molded as needed. I decided to give it a go for a down tube protector on my Niner RIP 9 RDO. Here's my process, hope it helps you!


  1. DK says:

    Great guide and pictures, thank you for this it helped me massively!

  2. OldDude74 says:

    Well done, sir! I’m going to attempt the same thing. Hopefully my results will be as good as yours.

  3. Todd says:

    How’s the tape holding up? I’m building up a light XC frame (Fezarri Solitude) and haven’t found any downtube protector to my liking. This both looks good and seems like it would protect very well.

  4. BobV says:

    What about removing the protector from the frame when it needs replacing? Does that tape adhesive damage the finish at all to the frame when removed? Thanks, Bob

    • Spoke Twist says:

      To be honest, it shouldn’t need replacing. Kydex is extremely hard and durable stuff. If you ruin it, your frame is likely also in bad shape or the bike will be too old to matter much. That said, the VHB tape has a foam center, so you can use dental floss or a thin wire and use it to “cut” the foam in half. Then you just need to remove the leftover adhesive from the bike frame. Look up automotive de-badging if you’re concerned, same thing. The adhesive won’t ruin the paint, as long as you don’t do anything silly trying to get it off. Use a hair dryer, Goo Gone, etc.

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