Cable machine weight stacks are lying to you

So, I very much like to know exactly what I’m doing in the gym. Free weights are the gold standard for being reproducible, but there’s something to be said for the convenience of cable-based weight machines and their weight stacks and pins. I’m not going to lie; I use them myself quite a bit.

But if you use a variety of these cable machines, you’ll find that they aren’t even close to consistent. The same exercise on one machine feels significantly lighter than it does on another, and heavier still on another. This is not just the feeling; this is actually the layout of the cables resulting in the pulleys being positioned differently from one machine to the next.

The network of pulleys used in any given machine provides mechanical advantage, and the weight you’re pulling will not require the same force you’d need to use in order to move that much in free weight.

This means you don’t really know how much weight you’re lifting, do you? So how do you measure it?

Simple – the cable machines use eyelet hooks to connect to the handles, yes? So, bring a crane scale to the gym (setup instructions below) and hook the eyelet hook from the cable machine to one end of the scale, and hook the handle you want to use to the other end. I recommend setting your weight stack to a number that’s simple to compute with and is below your 1RM in case you encounter a machine with a 1:1 gearing ratio. I for instance am using 100lbs as a weight, because then whatever the scale shows me will be the percentage used in this machine’s gearing. If you can handle 100lbs (which is easy for most folks if they leverage their body weight to move the weight stack), the math gets quite simple.

As you can see in the image to the left, I just hooked up the scale and pulled. This rowing machine, as you can see from the scale, is actually around a 4:1 ratio! Despite the weight stack being 100lbs, the scale shows that it only took 23lbs of force to pull the stack.

At any rate, you might ask why this matters. The answer is that it matters when and if you compare your numbers with others, with something like But if you’re using the same machine every time, and only comparing against yourself, it technically doesn’t matter what the numbers are as long as you’re trending upwards over time. What matters is whether or not you’re getting into the right weight range for your muscles, and doing enough reps to effectively exercise. On the other hand, there’s very little that’s more disappointing than working hard and then finding out your actual strength is only half of what the numbers say on the weight plates.

At the gym I attend, I went ahead and measured how much force it took to pull 100lbs of weight on all of the cable machines. I also intend to come back and try to measure some of the Scorpion / Hammer Strength style non-cable leverage machines, to see how much actual resistance they provide.

Setting up the Scale

I bought my crane scale from Amazon, and added this snap hook to one end and this carabiner to the other (see picture below for setup).

The carabiner I chose for the bottom of the scale has two sets of retention springs – one which you can hook onto the scale, and then a second one which you can attach to your cable attachments. The scale did come with an S hook, which I am sure would’ve been strong enough but it had a tendency to slip off. I wanted a scale I could throw in my gym bag easily, and not have to worry about the S hook getting separated. You can click the images to enlarge (though it seems you have to click twice if you really want them large).

Above are the pics of what I did. In the left image, I identified the part of the carabiner which wouldn’t allow the scale to go through into the bottom part of the carabiner. The middle picture is me using my Ryobi rotary tool to trim away some extra metal, which I prefer over any of the name-brand Dremel tools I’ve used in the past. It’s never going to replace my beloved Proxxon for workbench use, but the Ryobi is the best cordless rotary experience I’ve had. At any rate, I didn’t need to remove much material in order for the scale to slip by.

You can see the final outcome to the left – it really only took a tiny bit of metal removal to slide the hook onto the scale. After that was done, I attached a small regular carabiner to the top, given that I don’t have a second one of those dual spring carabiners.

The resultant scale is set up to hooked onto the various machines. I tested all of the cable machines at the gym I go to, and on most of the machines, it read in the mid-40s, which is around a 2:1 ratio. On one notable machine though, which had a couple of extra pulleys, it was 23lbs. On another notable machine by the front, it showed 103lbs! Machines with a 1:1 gearing ratio do make tracking your workout quite convenient, but unfortunately gyms tend to have a combination of different ratios on their machines.

Ratios of Machines at Ozark Fitness Center

Given that I work out here, I felt a need to list out the machines I use, for my own reference. Unfortunately, not all of the machines are labeled as to what they are, so I must refer you to the images above in some cases.

  • Long dual cable machines at the front of the gym: These machines both translated a 100lb weight stack to 43lbs of effort.
  • Seated row directly in front of the bench by the lockers: 45lbs of effort to move 100lbs.
  • Tricep pushdown machine near the leg sled press: 104lbs of effort to move 100lbs.

Ratios on my Ritfit M1

I was pleasantly surprised to see that my Ritfit M1 home gym almost perfectly matched their specifications, which is to say that it read almost precisely 2:1.

Disclosure: The links here are affiliate links in most cases. If you purchase things via them, I may receive a small commission from Amazon; it does not change the price of your product one way or the other.


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