How to use a Schrader pump on a Presta valve

If you find yourself in a situation of needing to use a Schrader pump (what is typically seen at service centers and gas station tire pumps in the USA) on a Presta valve (common on bicycles), you can modify the Presta cap to make an adapter.

WARNING: This will obviously make the cap's ability to be a cap, no longer possible. But hey, now it's an adapter!

The Presta valve

Step 1

3/16 drill bit will get you EXACT measurements for the threading (this is critical to get proper threading for an air seal). I was lucky that we had this on hand — if you don't have this drill bit, you will struggle to get the hole to the proper size, BUT IT'S POSSIBLE with patience. (Did it on a second valve cover just to test with only a phillips screwdriver.)

3/16 drill bit

Step 2

Drill the hole in the closed tip of the Presta valve cover as seen in pic:

Drilled hole

Step 3

You will now need to FORCE thread the adapter by applying firm downward pressure while twisting in the tightening motion. You should feel it start to grip and thread itself — this is a good sign you have an air seal.

This pic is the final product: DIY adapter perfectly screwed on the Presta valve. The threading is KEY to achieve the seal. You might could try thread tape or liquid sealant if you have that on hand (I didn't test that).

That's it! Now you can use the Schrader pump as you would normally.