Put equal weight on both sides: weigh both panniers before loading and allow a maximum difference of 2 kg, put heavy items at the bottom and close to the animal’s sides, and put light, bulky items on top. An unbalanced load shifts, the saddle rotates, and within minutes you are repacking on the trail while the load hangs under the animal’s belly.
Part of Pack Animal Management
Where weight goes on a pack animal: side to side, high and low, near and far, and the lever arithmetic that explains why the rules work.
Balance Is A Torque Problem
A load on one side of the animal’s spine tries to turn the saddle around it. The turning effect (torque) is the weight times its distance from the spine, so both a heavier side and a farther side tip the saddle. The rules in the source article are each a way of keeping the two torques equal and small:
- Equal weights — same force on each side.
- Heavy low and close — a short lever arm, and a low centre of gravity.
- Light and bulky on top — little torque for its size.
The source article gives no front-to-back figure. The sawbuck fit points show where the weight should sit: between the front X behind the shoulder blade and the rear X ahead of the hip. Keep the load centred over the saddle between them.
What You Need
- A scale or balance — see Logistics & Load Planning for ways to weigh.
- A list of cargo with weights.
- The animal’s allowance — see Weight Limits by Animal.
- Panniers and a top pack — a light bundle lashed on top between the panniers, such as sleeping bags, tents or clothing.
Method: Pack By Rule
Step 1: List and weigh the cargo. Know each item’s weight.
Step 2: Assign to two sides. Distribute so that the two panniers differ by no more than 2 kg.
Step 3: Put heavy items at the bottom and close to the animal’s sides.
Step 4: Put light, bulky items on top. A top pack should be light.
Step 5: Recheck by weighing, not by hefting. Hand-lifting misleads; weigh.
Step 6: Recheck after the first 15 minutes on the trail. Loads settle; see Soft Panniers.
Worked Example
Torque from an imbalance. The lever arm is an assumed 0.3 m from the spine to the centre of the pannier (the source gives no figure), and g = 9.81 m/s^2.
- A 2 kg difference: weight 2 x 9.81 = 19.6 N; torque 19.6 x 0.3 = 5.9 N m.
- A 10 kg difference: weight 98.1 N; torque 98.1 x 0.3 = 29.4 N m, which is 10 / 2 = 5 times as large.
Moving a 5 kg item from 0.40 m out to 0.25 m out reduces its torque from 5 x 9.81 x 0.40 = 19.6 N m to 5 x 9.81 x 0.25 = 12.3 N m, a 37% reduction (12.3 / 19.6 = 0.63).
The source’s “2 kg (about 3% of a typical load)” holds for a 70 kg load: 2 / 70 = 2.9%. For a 40 kg load the same 2 kg is 2 / 40 = 5%, and for a 30 kg load 6.7%. The 2 kg is the rule; the percentage depends on the load.
Common Mistakes
- Judging by hefting — a few kilograms cannot be felt; use a scale.
- Heavy items on top — raising the centre of gravity makes the load sway.
- Equal weight, unequal reach — a lighter but bulkier side can still tip the saddle.
- A heavy top pack — it adds weight and height at once.
Safety
A rotated saddle is a bolt risk
When a load slips, the saddle swings under the belly and the animal may panic and kick. Stop the animal before repacking, keep clear of the hind legs, and never pull on a hanging load from below the animal’s belly.
What’s Next
- Learn next: Weight Limits by Animal — how much each animal may carry
- Combine with: Hitches & Lashing — holding it in place