I have presta valves on two of my bikes. I have a presta floor pump. I have an air compressor. I have a schrader adapter. I have a blowgun and a tire inflator for my compressor. I can attach the blowgun and the tire inflator to the presta valve using the schrader adapter.

What I want to know is what kind of attachment do I need to screw my air compressor on to the presta valve after the core is removed? The schrader adapter screws onto the valve core, so without the valve core, none of my attachments fit. What do I need?

This post indicates that people remove the valve core to get a high volume of air into the tire (which I want to do to seat my tubeless bead), but nowhere can I find exactly how to attach my air to the valve without the core installed.

The only things I can find in videos that actually claim to do this are the Park Tool INF-2 Inflator and the Silca Hiro Locking Chuck, which exceed $150 CAD ($115 USD) and $90 CAD ($65 USD), respectively.

Please help, I've wasted hours trying to get a solid answer to this question.

  • Does the blowgun nozzle fit inside the emptied presta stem ? – Criggie Oct 11 at 6:57
  • 2
    @Criggie - that is what I use. I have a rubber tip I can screw into my blow gun and I can get the air in fast. Doesn't fit exact, but seals well enough. The only problem with that is being careful not to exceed the max tire pressure, since I have the air hose maxed and no gauge between the gun and valve. – Gary Bak Oct 11 at 12:01
up vote 14 down vote accepted

Park inflator

Inflator heads with Presta fittings let you do this because they tend to (always?) seal down around the stem, not the core. I don't know any other way. I suppose you could also take a spare Presta core from a dead tube, break the plunger out of it to get more airflow, then temporarily install it in your tubeless valves and put your adapter on that. This is conjecture.

If you haven't already, one thing you might try if seating the beads with your inflator head plus an adapter just isn't working is first install the tire with a tube, seat the bead that way, then break just one of the beads free and try to do the tubeless seating. This can make obstinate ones go pretty smooth.

  • Okay, after additional research, this is the correct answer. However, you didn't mention what @Criggie does in his comment above. A rubber tip for a blowgun will create a seal. I ended up purchasing the Silca Hiro Locking Chuck because, between the price and the compatibility with existing inflator heads (i.e. I can switch it between any schrader head), it seemed to be the best quality deal on the market. Edit your post Nathan to mention the blowgun rubber tip, and I'll mark it as the correct answer. – Aubrey Robertson Oct 16 at 18:41

Use the same kind schrader-to-presta adapter you would use with the valve core, but tightly press it against the valve stem when inflating the tire.

People indeed often remove the valve core when converting to tubeless, but inflating the tire without it doesn't necessarily require an airtight between the inflator hose and the valve stem. A minor leak most likely does not matter in the process of rapidly deploying large quantities of air in there, and the air doesn't need to stay in for long. You're only seating the tire beads to the rim and will later need to properly inflate the tire with the valve core in place anyways.

For the same job, I use an old fire extinguisher that I've simply just cleaned thoroughly. The hose has a solid round exit hole without even a rubber seal, and it still does the job perfectly well. Admittedly, operating the air release lever while also holding the hose end at one hand can be a bit tricky, but manageable:

  1. Sit down on something and place the tip of your foot between the spokes, on the rim, on the opposite side of the valve.
  2. Press whatever is at the end of your hose against the valve stem and pull it towards you with one hand
  3. Gently push the rim downwards with your foot, but try not to squish it against the ground as it could create bigger leaks.
  4. With your other hand, operate the inflator.
  • Good advice, but the first line misses OP's point - there is nowhere for the little adaptor to thread onto when the core is removed. On a Presta valve, the core's external threads are what that adaptor screws to. Good thinking with the extinguisher as a pressure vessel. – Criggie Oct 12 at 6:58

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