PULLEY RATIOS & CAMS
Machine Exercise 1RM Calculator
Calculate your True One Rep Max for Cable Machines, Lat Pulldowns, Leg Extensions, and Pin-Loaded Stacks.
PULLEY & APPARATUS
Machine Specs
ESTIMATED PIN-STACK 1RM
101.3 kg
True Felt Resistance 1RM: 101.3 kg (223.3 lb)
RECOMMENDED HYPERTROPHY TARGETS
6 Reps (86%) 87 kg
10 Reps (75%) 76 kg
15 Reps (65%) 66 kg
MECHANICAL ADVANTAGE
How Cable Pulleys Change Felt Resistance
Gym cable machines utilize pulley mechanics that directly alter the force required to accelerate the weight stack.
Pulley Ratio Classifications
- 1:1 Ratio (Single Pulley): 50 kg selected = 50 kg felt load. Standard on Lat Pulldowns and Seated Rows.
- 2:1 Ratio (Double Pulley): 50 kg selected = 25 kg felt load. Standard on Functional Trainers and Dual Adjustable Pulleys. Allows double the cable travel distance for explosive speed work.
- 4:1 Ratio (Quad Pulley): 50 kg selected = 12.5 kg felt load. Used on high-velocity rehab systems.
FAQ
Frequently Asked Questions
Key questions on machine and cable 1RM calculations.
Look at the pulley wheel directly above the weight stack. If the cable connects to the frame and loops around a traveling pulley wheel attached to the stack, it is a 2:1 ratio.
Nautilus-style eccentric cams change their radius throughout the range of motion, matching the human muscle length-tension curve so resistance is highest where muscles are strongest.