A while back, our shop needed a floor pump that was as cheap as possible and compatible with all three valve types—French, American, and English—so
I bought a Zyo floor pump without even an air gauge.
Since we already have floor pumps from Sapo and SKS at the shop,
this makes the third one.
...Three! With this, my long-held dream has finally come true.
I can now connect floor pumps to all three
tubeless-type Presta valves simultaneously—
a triple combination is now possible.
It looks like something out of a cult temple.
Here's to more of this in the future...
↑Zyo chuck with French valve selected
↑Sapo / Hirame horizontal cam French valve seal
↑SKS / Hirame vertical cam French valve seal
This rim is 28H, so from the one original valve hole,
I've drilled two new holes spaced 9 and 1/3 rim holes away—that's 1/3 of 28H.
The distance between the two newly drilled holes is also
9 and 1/3 rim holes,
creating valve holes at 120° phase intervals.
When you pump air while connecting multiple pumps with gauges,
the gauge needles move in sync.
So you can check for individual differences
in pressure readings between pumps.
Between our Sapo and SKS, the pressure readings are nearly identical.
In the image above, both show exactly 4 bar,
and when they're reading 4 bar, that means
the pressure inside the gauge is 4 bar, the hose is 4 bar,
and the tire is also 4 bar.
At this point, I think the seal on the valve core is lifted outward by tire pressure,
but during the instant air flows in from pumping,
the seal gets pressed toward the tire side and air enters.
Instead of the chuck that normally grabs the valve,
I tightened the Hirame dial to grab
the threaded portion of the valve core.
From this position,
during pumping,
the seal gets pressed and lifted.
I couldn't get a clean shot with just two arms, so
in the image above, I've positioned the valve core pointing down
with the seal dropped
and rotated it 180°.
The valve core only gets pressed toward the tire and air enters
during the pumping stroke itself,
but when pumping stops,
the tire and hose/gauge pressures equalize
and the seal floats. Then the tire's internal pressure
pushes the seal outward on the valve, causing
the "tire" and "hose and gauge" to become separated
even though they're at the same pressure.
So when you remove the chuck from there, only the hose and gauge side
goes "psssht" as pressure drops,
while the tire retains its high pressure.
Now, this French valve seal—whether it would disconnect
under the unusual circumstance of pumping from the tire side... it does disconnect.
Why? Because when I pump on the Sapo side,
the SKS gauge needle rises (and vice versa).
I connected a pump to the valve at the 8 o'clock position
and pumped air in.
From here, I loosened the valve core at the 12 o'clock position, pressed the head,
and released air. The gauge needle dropped rapidly.
After pressurizing to 4 bar with Sapo, I connected SKS.
From then on, the Sapo pump did no more pumping whatsoever.
The gauge shows Sapo at 4 bar, and the SKS needle hasn't risen.
With one full telescopic stroke on the SKS,
SKS rose to just under 3 bar, and Sapo dropped slightly.
At the moment the separation was released,
it seems SKS sucked in the pressure from the Sapo hose and gauge.
By the second full stroke, they're nearly synchronized.
After another 15 full strokes,
both gauges read exactly 6 bar.
But here's the thing—even if separation occurs at both valves
during each pumping stroke, timing-wise
the gauge on the pumping side should read slightly higher pressure...
or so it seems to me. If I repeated
Sapo's pump raising the SKS needle →
SKS's pump raising the Sapo needle
a few times, I could verify this. But I've been wanting for a while
to do "the third floor pump raises both the Sapo and SKS needles."
Though that wasn't the reason I bought the Zyo pump.
The gauges have upper limits of 12 bar on Sapo and
16 bar on SKS—both high-pressure designs,
and the pump specs match accordingly, so
the telescopic outer diameter is small
and each stroke delivers less volume, but
the design allows easy pressing even at high pressure
(the image above shows the shaft outer diameter coming from the handle,
not the telescopic outer diameter),
this Zyo floor pump
inflates quickly up to around 4 bar,
but after that pumping becomes extremely heavy,
so it seems designed with 7 bar as an unexpected upper limit
(which makes sense given there's no air gauge).
As for results, after pressurizing up to 7 bar several times,
the Sapo and SKS gauge needles remained nearly synchronized—
the conclusion didn't change.
I bought a Zyo floor pump without even an air gauge.
Since we already have floor pumps from Sapo and SKS at the shop,
this makes the third one.
...Three! With this, my long-held dream has finally come true.
I can now connect floor pumps to all three
tubeless-type Presta valves simultaneously—
a triple combination is now possible.
It looks like something out of a cult temple.
Here's to more of this in the future...
↑Zyo chuck with French valve selected
↑Sapo / Hirame horizontal cam French valve seal
↑SKS / Hirame vertical cam French valve seal
This rim is 28H, so from the one original valve hole,
I've drilled two new holes spaced 9 and 1/3 rim holes away—that's 1/3 of 28H.
The distance between the two newly drilled holes is also
9 and 1/3 rim holes,
creating valve holes at 120° phase intervals.
When you pump air while connecting multiple pumps with gauges,
the gauge needles move in sync.
So you can check for individual differences
in pressure readings between pumps.
Between our Sapo and SKS, the pressure readings are nearly identical.
In the image above, both show exactly 4 bar,
and when they're reading 4 bar, that means
the pressure inside the gauge is 4 bar, the hose is 4 bar,
and the tire is also 4 bar.
At this point, I think the seal on the valve core is lifted outward by tire pressure,
but during the instant air flows in from pumping,
the seal gets pressed toward the tire side and air enters.
Instead of the chuck that normally grabs the valve,
I tightened the Hirame dial to grab
the threaded portion of the valve core.
From this position,
during pumping,
the seal gets pressed and lifted.
I couldn't get a clean shot with just two arms, so
in the image above, I've positioned the valve core pointing down
with the seal dropped
and rotated it 180°.
The valve core only gets pressed toward the tire and air enters
during the pumping stroke itself,
but when pumping stops,
the tire and hose/gauge pressures equalize
and the seal floats. Then the tire's internal pressure
pushes the seal outward on the valve, causing
the "tire" and "hose and gauge" to become separated
even though they're at the same pressure.
So when you remove the chuck from there, only the hose and gauge side
goes "psssht" as pressure drops,
while the tire retains its high pressure.
Now, this French valve seal—whether it would disconnect
under the unusual circumstance of pumping from the tire side... it does disconnect.
Why? Because when I pump on the Sapo side,
the SKS gauge needle rises (and vice versa).
I connected a pump to the valve at the 8 o'clock position
and pumped air in.
From here, I loosened the valve core at the 12 o'clock position, pressed the head,
and released air. The gauge needle dropped rapidly.
After pressurizing to 4 bar with Sapo, I connected SKS.
From then on, the Sapo pump did no more pumping whatsoever.
The gauge shows Sapo at 4 bar, and the SKS needle hasn't risen.
With one full telescopic stroke on the SKS,
SKS rose to just under 3 bar, and Sapo dropped slightly.
At the moment the separation was released,
it seems SKS sucked in the pressure from the Sapo hose and gauge.
By the second full stroke, they're nearly synchronized.
After another 15 full strokes,
both gauges read exactly 6 bar.
But here's the thing—even if separation occurs at both valves
during each pumping stroke, timing-wise
the gauge on the pumping side should read slightly higher pressure...
or so it seems to me. If I repeated
Sapo's pump raising the SKS needle →
SKS's pump raising the Sapo needle
a few times, I could verify this. But I've been wanting for a while
to do "the third floor pump raises both the Sapo and SKS needles."
Though that wasn't the reason I bought the Zyo pump.
The gauges have upper limits of 12 bar on Sapo and
16 bar on SKS—both high-pressure designs,
and the pump specs match accordingly, so
the telescopic outer diameter is small
and each stroke delivers less volume, but
the design allows easy pressing even at high pressure
(the image above shows the shaft outer diameter coming from the handle,
not the telescopic outer diameter),
this Zyo floor pump
inflates quickly up to around 4 bar,
but after that pumping becomes extremely heavy,
so it seems designed with 7 bar as an unexpected upper limit
(which makes sense given there's no air gauge).
As for results, after pressurizing up to 7 bar several times,
the Sapo and SKS gauge needles remained nearly synchronized—
the conclusion didn't change.