On a Spectra breast pump, “cycle” refers to the number of suction pulls the pump makes per minute, often written as CPM (cycles per minute). Think of each cycle as one “suck,” mimicking how a baby nurses. A higher cycle number means faster, lighter pulls. A lower number means slower, deeper pulls. This single setting, combined with vacuum strength, controls your entire pumping experience.
How Cycles Mimic a Nursing Baby
The cycle setting exists because babies don’t nurse at one constant speed. When a baby first latches, they suckle quickly to trigger a let-down (the moment milk starts flowing). Once milk releases, they slow down into longer, deeper pulls to actually draw milk out. Spectra pumps are designed around this two-phase pattern, and the cycle number is what controls which phase you’re in.
Cycle Speeds by Mode
Spectra’s S1 and S2 pumps have two modes, each with different cycle behavior.
Massage mode (also called stimulation or let-down mode) runs at a fixed 70 cycles per minute. That’s 70 quick, light pulls every minute, designed to signal your body to release milk. You typically stay in this mode for about a minute and a half to two minutes, until you see milk starting to spray steadily.
Expression mode is where you do the actual pumping. Here, cycles are adjustable from 38 to 54 per minute. These slower, stronger pulls draw milk out once let-down has happened. You can pair any cycle speed in this range with vacuum levels from 1 to 12, giving you a wide range of combinations to find what works for your body.
Cycle vs. Vacuum: What Each Controls
These two settings work together but do different things. The cycle number controls speed: how many times per minute the pump pulls. The vacuum number controls strength: how hard each individual pull is. You can have fast and gentle (high cycle, low vacuum) or slow and strong (low cycle, high vacuum), or any combination in between.
A common mistake is cranking vacuum to the highest level and ignoring cycles entirely. But cycle speed often matters just as much for output. Some people get significantly more milk at cycle 54 than at cycle 38, or vice versa, even at the same vacuum level.
Finding Your Best Cycle Setting
There’s no single “correct” cycle speed in expression mode. Bodies respond differently, and the ideal setting can even change over the course of a pumping session. A practical starting approach that many pumpers use: begin in massage mode (cycle 70) at a low vacuum like 3, stay there for two to three minutes until let-down starts, then switch to expression mode at cycle 54 and a moderate vacuum of 4 or 5.
If milk flow slows down during a session, switching back to massage mode for a minute or two can trigger a second let-down. Then you return to expression mode and continue. Some people cycle through this pattern multiple times in a single session, gradually lowering the cycle speed and increasing vacuum with each round. One approach that works for people with stubborn let-downs: start at cycle 70, drop to 54, back to 70, then down to 46, back to 70, then to 38, increasing vacuum slightly each time.
If you have a slow let-down and struggle to get milk flowing at all, try staying in massage mode longer rather than immediately jumping to expression. Some people need three to four minutes in massage mode before switching.
Cycle Settings on the Synergy Gold
The Spectra Synergy Gold works on the same principle but offers more granularity. It provides 5 cycle options in expression mode and 5 in massage mode, compared to the continuous range on the S1 and S2. The Gold also lets you adjust vacuum levels independently for each breast, with 15 vacuum settings in expression mode and 5 in massage mode. The cycle concept is identical; the Gold just packages the controls differently.
For the S1 and S2 specifically, the two models are functionally identical. The S1 is blue with a built-in rechargeable battery. The S2 is pink and needs to stay plugged in. Cycle ranges, vacuum levels, and modes are exactly the same on both.
What the Numbers on Your Screen Mean
When you turn on your Spectra and see “70” on the display, that’s telling you the pump is pulling 70 times per minute in massage mode. When you switch to expression mode and see a number between 38 and 54, that’s your current cycle speed. Use the cycle buttons (the ones with the wave icon) to move that number up or down. The separate vacuum buttons (with the droplet icon) control suction strength independently.
If you’re not sure which number you’re looking at, the cycle number is always the one that starts at 70 when you first power on. Vacuum always starts at the lowest level.