Prestacycle Pro Presta Head

Tech Tech Help
1

I have a Silca Super Pista Digital pump. I just bought a Prestacycle Pro Presta Head to replace the Hiyo head on the Silca pump. I like the Hiyo head, but it’s a bit hefty. I don’t like that way it hangs off of my Fillmore valves. The Pro Presta Head is lighter and it goes on and comes off a bit easier since it doesn’t have the large locking lever that the Hiyo does. I have a couple of questions:

  1. Does anyone have any idea what the thread spec is on the stem of the Prestacycle head or the Silca head? They seem to have the same diameter, and the thread pitch is identical.

  2. Does anyone make a small extension to screw on to that stem on the head?

Someone gifted me an STL file for an attachment that would include a magnet so that the Presta head could be stowed where the Hiyo head is magnetically stowed. An extension for the stem on the Presta head would solve my problem. With the Prestacycle head attached it’s 30-40mm short of where it ideally should be to use the 3D printed solution.

Two Heads
Two Heads1320×1236 133 KB

Connection on Hose
Connection on Hose1320×1198 903 KB

FWIW, both heads plug into a push to connect fitting on the end of the Silca pump’s hose.

2

@Dave_Rome I know you’ve done some creative stuff with pump or pressure related testing. Do you have any suggestions?

3

Both of those pump heads feature a thread identical to a Schrader valve. I believe it’s 0.305 inches x 32 TPI.

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4

Do you know if that’s a common size of pneumatic fittings?

5

Not common in pneumatics but common in refrigeration / HVAC and scuba.

Further to Dave’s comment above: although the thread is technically .305” this is a very uncommon size for tooling. Far easier to obtain .302” x 32 UNF which will work perfectly well (.003” is about 0.07mm). If the thread is tight in the tapped hole, just run the tap though a couple more times.

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6

Deleted because I answered my own question.

7

I’ve used both of them with the Schrader coupling on my electric pump. I kept having problems with the Presta head on narrow, high-pressure tires (over 75 psi) and on several tubes that had short stem length above the rim. No such problems with the Silca head, although occasionally it will not release cleanly, leading to pressure loss and another round of pumping. Presta and the seller each replaced the defective head, but every copy has the same problem.

8

You can buy a Schrader valve stem extender like in this link: Amazon.com: HuGuWdy Valve Stem Extension 4Pcs 39mm, Tire Valve Extension Valve Stem Extenders Tire Valve Extenders Brass Tire Stem Extension Wheel Tire Cap Extender Adapter for Car Motorcycle Truck, Silver : Automotive

You might need to search for something similar to get the correct length.

@Robin do you know where I can get/buy the 3D print (STL) file that you mentioned?

9

Thanks! I found a suitable length extender. I’m sending a virtual keg of this deliciousness your way.

Beer
Beer716×1064 61.7 KB

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10

@Robin Can you post an update on the 3d print and final result? I have the same pump and presta head and would like a nicer solution than my current velcro one.

Thanks

11

Car tyres, Truck Tyres, Tractor tyres all use Schrader valves. So reasonably common.

12

Actually, I just received the 3D printed part to make it all work. I just have to find in what box my wife put the magnets (we recently moved.. I did slide the 3D printed part onto the Presta head and mounted it on the press to fit, uhm, fitting on the Silca pump’s hose. Everything lines up and the 3D printed thingee sits in the “pocket” on the Silca pump. Just gotta either find my magnets or find a way to magnetize ABS plastic. The former will be easier, but the latter could get me a Nobel prize.