Underground Manufacturing 1-Hole SS Simple Replacement Spool

Stainless steel replacement spools/pulleys for the venerable Petzl Simple descender. Made of 316 stainless steel, these replacement spools last approximately 6-10x as long as the stock 6061 Aluminum spools. They offer reduced friction and a much smoother ride. We recommend replacing only the bottom spool (which sees the most wear) with the stainless steel version—replacing both is unnecessary. Each spool weighs approximately 147g (5.2oz). We also make 7075 Aluminum (light weight, but more durable than stock) as well as 2-hole upper spools for the older simple (in stainless or aluminum).

316 stainless steel is a costly raw material and is somewhat difficult to machine requiring extra time and more robust and expensive tooling than aluminum. The stock 6061 spools are cheap at around $15-25 depending on your source but our stainless spools last so much longer that they end up being significantly cheaper than the number of aluminum spools you would use in the same time-frame. It depends on your use case of course, but most people should expect get many years of regular use from just one! For some, it will be the last replacement spool they ever need to purchase. These spools are in use all over the world and hand made in the USA.

The reduced friction of these spools is really what makes them worth the extra cost—they are quite smooth and easy to control with less of the ‘grabbiness’ of the aluminum versions. This is especially helpful for lighter weight cavers who struggle with the Simple on long pitches or fat/muddy ropes. The reduction in friction is nothing crazy—I weigh around 200lbs (91kg) and still much prefer them even on ropes down to 8mm. They make the Simple ‘smooth’ rather than ‘fast’.

It is, of course, your responsibility to familiarize yourself with your new spool(s) (and any other changes to your vertical setup) in a controlled setting prior to real world use. Replicate all conceivable scenarios you might encounter. Make sure your setup works to your satisfaction, your life depends on it! If you aren’t happy with the performance of your spool(s) after this step, you may return them.

All spools are tested for fit and function prior to shipping, please excuse any resulting minor cosmetic imperfections that may result. Serial numbers may be laser engraved or stamped.