Michael Turner
Place the hip belt centered on the iliac crest and measure straight up to the C7 vertebra (the most prominent bone at the base of the neck). Select a pack whose back-panel height equals that vertical measurement; that alignment transfers load to the hips and prevents shoulder digging.
Size guide (typical manufacturer spans): XS 33–38 cm (13–15 in); S 38–43 cm (15–17 in); M 43–48 cm (17–19 in); L 48–53 cm (19–21 in); XL 53–58 cm (21–23 in). If your measurement falls between sizes, pick the smaller frame for heavier loads and the larger for light loads or thick clothing layers.
Measure while wearing the clothing and hipbelt you will use in the field: stand relaxed, breathe normally, have an assistant mark C7, then run a tape to the top of the hipbelt where it sits on the iliac crest. For packs with sliding harnesses, loosen shoulder straps, slide the harness until its top aligns with the C7-to-hip mark, then lock the slide and re-tension straps.
Load the pack to your typical weight and walk for 10–15 minutes: the hipbelt should carry roughly 70–80% of the load. Fine-tune shoulder strap tension so straps follow the curve of your shoulders without lifting the belt; set the sternum strap for comfort and breathing clearance. If persistent pressure points appear, re-check the vertical measurement and try the next size or a different chassis style (floating harness vs. fixed back panel).
Measure C7–iliac crest distance and record cm
Use a flexible cloth tape; locate the C7 vertebra and the top of the iliac crest, measure the vertical distance along the midline and record the value in centimeters to the nearest 0.5 cm.
Step-by-step procedure
Stand upright with feet shoulder-width, shoes off, pelvis in a neutral position and arms relaxed at the sides. Have a partner palpate the most prominent cervical vertebra when the head is bent forward – that is C7. Mark it with a small washable dot.
Palpate the iliac crest by placing hands on hips and finding the highest point of the hip bone on each side; draw an imaginary horizontal line between the two peaks and mark the midpoint on the spine. That point is the iliac crest landmark.
Apply the tape at C7 and run it straight down the spinal midline to the iliac crest mark. Keep the tape snug against the skin without compressing tissue and follow the natural curve of the back. Read and record the measurement in centimeters.
Repeat the measurement twice more and use the average. If two values differ by more than 1 cm, take a fourth measurement and discard the most divergent reading.
Recording standards and quick reference
Record values to the nearest 0.5 cm and note posture (standing, neutral pelvis). Typical adult ranges for the C7→iliac crest distance: small ~38–43 cm (15–17 in), medium ~44–48 cm (17.5–19 in), large ~49–54 cm (19–21.5 in). Use these ranges only as a guide; rely on the averaged measured value for sizing decisions.
Identify the suspension system: ladder webbing, sliding track, or bolt-on panel
Inspect the harness-to-frame junction and act based on visible hardware: horizontal stitched webbing rows indicate a ladder system; a vertical channel with a movable plate or rails indicates a sliding-track system; fixed bolts, rivets or a removable back panel indicate a bolt-on panel system.
Visual and tactile checklist
- Ladder webbing: Rows of sewn webbing under the shoulder straps; ladder rungs spaced ~1–2 cm apart. Pull the harness down – the anchor point is woven through webbing rungs and moves in discrete steps. Typical effective range: 8–18 cm depending on model.
- Sliding track: Vertical metal or polymer rail behind the harness with a sliding plate and a cam or Velcro lock. Plate moves smoothly for continuous micro-positioning; common usable range: 10–20 cm. Look for adjustment buckle or quick-release pin at the base of the track.
- Bolt-on panel: Shoulder harness secured to a removable panel by bolts, screws or studs; panel often offered in size-coded options (S/M/L). Changes require unbolting and swapping panels or moving bolts between set holes – typical size steps of 2–4 cm per panel increment.
Quick practical checks
- Open the top lid or access the back panel to see the anchor points; photograph them and compare with manufacturer diagrams.
- Test movement: hand-slide the anchor along the rail for a sliding system; lift the harness and see which ladder rung engages for ladder webbing; inspect bolt pattern for removable panels.
- If hardware is hidden, locate a manufacturer tag or model number and search the brand site or manual for “suspension” or “fit” specification, or contact support with that model ID.
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Set ladder-style harness: unclip, move shoulder straps one rung, and resecure
Immediate action: Unclip the ladder-style yoke at the rear, slide each shoulder strap exactly one rung toward the head or hips (one rung ≈ 10–20 mm change in rise), reclip until you hear the click, then perform a short loaded walk with 10–15 kg to verify comfort and load transfer.
Procedure: 1) Release the rear yoke clip and hold the pack upright. 2) With light tension on the shoulder straps, lift the webbing out of the ladder slot. 3) Move both straps one rung the same direction and seat the webbing fully into the new rung. 4) Re-engage the clip and pull the webbing through until the anchor is snug; test by pulling the strap with 15–20 N (approx. two fingers) to confirm no slippage.
Tolerance and pacing: Change only one rung per trial; a single rung equals ~10–20 mm of vertical change in anchor position. If fit still feels off after three single-rung trials, change panel type or consult manufacturer specifications rather than making multi-rung jumps.
Common faults and fixes: If straps sit twisted, fully unthread and retread flat; if webbing creeps, inspect ladder teeth for wear–replace ladder or webbing if teeth are rounded or fabric shows >3 mm fray. For asymmetric feel, ensure both straps moved the same direction and check hipbelt tension differs by no more than 5 mm between sides.
Verification checklist: With load on, shoulder straps should not carry the majority of weight; perform two 5–10 minute walks and note pressure points. Recheck clip engagement by lifting the pack handle sharply–no slippage allowed. Record the rung position (e.g., +1 up from factory) for repeatability.
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Sliding-track harness – loosen, align to measurement marks, secure
Loosen the Velcro cover and release the top cam-buckle(s) or backing bolt(s) until the sliding plate moves freely along the rail; do not remove fasteners completely unless required by the manufacturer.
Slide the plate so the shoulder-strap anchor centers on the centimeter mark that matches your recorded C7→iliac-crest measurement; if the indicator is an arrow or notch, line its tip precisely with that mark. Match left and right anchors to identical marks; a mismatch of more than 5 mm will create asymmetric load transfer.
Re-seat the cover and re-engage cam-buckles or torque bolts. If no torque spec is provided, tighten bolts with an Allen key until snug, then add 1/8–1/4 turn; fasten Velcro until fabric compresses fully and cams click. Avoid over-tightening hardware to prevent stripping or frame distortion.
Verify by lifting the pack by the shoulder straps and giving a firm 20–30 N lateral and vertical pull; the plate must not slip more than 5 mm. Walk for 10 minutes, re-check symmetry and fastener tightness, and re-torque if any movement appears. If repeated loosening occurs, inspect threads, apply a removable threadlocker, or consult the maker’s spec sheet.
Load-test: walk with weight, verify hipbelt transfer and shoulder pressure
Wear the fully loaded pack at your expected trail weight (include water, food, clothing). Walk continuous for 20–30 minutes on mixed terrain; include one sustained climb of 100–300 m elevation or 10–15 flights of stairs. Stop and check each item below immediately after the walk and again after 1 hour.
Quick tests to run
Hip transfer check: Place palms flat on the iliac crests. Lean forward ~20–30° from vertical and relax shoulders. If most downward pressure is felt through your hands on bone, hips are carrying the load. Aim for perceived transfer of ~80–90% of pack mass to hips.
Shoulder-pressure check: After 15 minutes of walking, remove pack briefly and inspect shoulder strap marks. Red, deep creases or numbness/tingling in hands/arms indicate excessive shoulder load. Normal light pressure leaves faint, even impressions and no pins-and-needles.
Stability and sway: Walk on uneven ground and accelerate/decelerate quickly. If the bag rocks side-to-side or pulls you backward/forward, the load is too high or sits away from your back; the center of mass should track within ~5 cm of your spine during normal gait.
Troubleshooting steps with concrete changes
If shoulders are overloaded: Loosen shoulder straps incrementally by 1–2 cm of webbing and retest; raise the hip-pad so the belt rides on the iliac crest (move it up ~2–4 cm if currently below the crest). Shorten load-lifter straps until they form a 30–45° angle to the ground to bring the upper bag closer to you.
If hips aren’t taking weight: Slide the hip-pad higher until its center contacts the iliac crest; tighten the belt until padding is compressed and you can slide only one finger under the top edge. Repack heavy items lower and centered over the hip frame; shift 0.5–1 kg forward/backward to eliminate backward pull.
If pack sways or shifts on climbs: Tighten side compression straps in 3–4 cm increments to pull load inward; move heavy gear lower by 5–10 cm inside the main compartment; consider removing or redistributing nonessential items until stable.
Re-test after each change with another 10–20 minute walk and the same climb or stairs. Make only one change at a time and record the effect so you can return to the previous setting if the modification worsens comfort.
