What Do Cable Ratios Mean

Have you ever wondered how the weight stack / weight plates on a cable machine compares to the weight you lift with a barbell or dumbbells? You’re not alone. Pulley system can be confusing, especially when it comes to the concepts of mechanical advantage(MA) and disadvantage(MD). In this article, we’ll break it down and help you understand the details of pulley ratios and why is that important.

Mechanical Advantage (MA) and Mechanical Disadvantage (MD)

Cable system is based on the concepts of mechanical advantage (MA) and mechanical disadvantage (MD). Mechanical advantage occurs when the pulley system allows you to lift more weight with less effort by rearranging the pulleys to multiply your force while mechanical disadvantage occurs when the system requires you to use more effort to lift the same weight, but often at the expense of speed or a longer range of motion. Using a pulley system to gain MA or MD is a trade-off – you can’t have it all, and you’ll often sacrifice total weight capacity or speed for range of motion, or vice versa.

What is the 2:1 Ratio

One of the most common pulley ratios is designed to create “fast cables” – cables that move quickly with minimal slack, which is typically achieved with a 2:1 mechanical advantage ratio. With a 2:1 ratio, the cable travels 2 feet while the weight stack moves 1 foot. This reduces the inertia of the weight stack, making the cable much snappier and easier to control. The trade-off is that the resistance is significantly reduced. A 10lb weight stack only feels like 5lbs, for example. This is helpful for rehab patients or someone like a baseball coach who needs to work on their rotator cuff and only wants to use light weights. The 2:1 ratio also works well for functional training exercises that require quick movement and changes of direction.

What is the 1:1 Ratio

The other type of pulley ratio is a true 1:1 ratio, often used on lat pulldown machines. With a true 1:1 ratio, the cable travels the same distance as the weight stack – 1 foot per 1 foot. This is why a full lat pulldown rack with multiple pins is so nice – the weight stack doesn’t move until you pull the bar down a significant distance. A 10lb weight plate on the stack is very close to 10lbs of resistance. Having said that, we’re not perfect and the pulleys do introduce some friction into the system. A single or double pulley system negates this friction, but multiple pulley systems can actually increase the resistance due to friction. A 3 - 4 fold increase in resistance is not uncommon with multiple pulley systems. The 1:1 ratio works well for exercises that require a lot of weight, such as lat pulldowns or leg presses, where the cable and weight stack move in sync. It does not work well for movements that require quick cable movement, such as shoulder rotations or bicep curls.

What Ratio Should I Use?

Now that you understand these pulley ratios, you can choose the right cable machine setup for your training. If you’re a strength training enthusiast, a true 1:1 ratio is likely your best bet. You need heavy resistance and don’t care how fast the cable moves. If you’re into functional training or rehabilitation training, the 2:1 ratio is a great choice. You’ll get much faster cable movement and more range of motion with only a slight sacrifice in total weight capacity. Ratios higher than 2:1, such as a 4:1, are typically used for very specific applications, like machine-based leg curls and extensions, where you need extremely fast cable movement. The trade-off is a significant reduction in total weight capacity.

Think of a 2:1 ratio like a vest or rotary cable machine. You can strap weight to a vest or rotate the cable around your head and the 2:1 ratio keeps the cable moving quickly. This is great for stability and agility training. A high speed cable attached to a vest is much more fun than a heavy weight. A 1:1 ratio is better for traditional strength exercises like lat pulldowns or leg presses because you want the weight stack to move in sync with your resistance. If you’re doing a lat pulldown, you want the weight stack to descend when your lats pull the bar down – a 1:1 ratio makes this happen. A 2:1 ratio would make the weight stack move up while your lats pull the bar down. Rehab patients love the 2:1 ratio because it allows them to use very light weights and focus on rebuilding strength without putting too much stress on their joints.

Conclusion

Cable ratios greatly impact how resistance is delivered to your body. You can have maximum strength, functional training or rehab capabilities – it’s up to you to understand these ratios and make intelligent equipment choices. Pulley systems are all about mechanical advantage and disadvantage, and it’s a trade-off. You can’t have it all, so choose wisely based on your training goals. Now that you understand these ratios, you’re ready to optimize your training and achieve your goals.