Physics Module • Magnet Retention in Motion
Magnet Pull Force vs Shear Force
Most magnet marketing obsesses over pull force because it’s easy to demo. Real golf carts don’t care. On-course failures are dominated by shear (sideways slip), vibration, and wet mass. This page shows the difference with clean visuals and a test standard you can actually use.
Test Verdict
Pull force measures “straight-off” removal. Golf cart reality is mostly lateral: shear + vibration repeatedly load the attachment sideways, and wet towels increase dynamic load. If you want reliable docking, you must evaluate shear stability and cycle loading, not just a pull rating.
Hook
A towel can feel “locked in” when you tug it straight off… then slide down the cart rail over three holes like it’s melting. That’s not because magnets are fake. It’s because you tested the wrong force direction.
Conflict
Pull-force demos look impressive. But cart motion loads the magnet sideways (shear) and repeatedly “shakes” the interface. Those conditions create micro-slips that accumulate until detachment feels random.
Journey
We’ll define pull vs shear, show why shear dominates during motion, then explain how vibration + wet mass create dynamic load. Finally, we’ll give you a clean way to test stability with standards instead of vibes.
Quick definitions
- Pull (normal): force needed to pull straight away from the surface
- Shear: force needed to slide along the surface under load
- Dynamic load: vibration + swinging towel mass over time
Why pull ratings can mislead
Pull-force tests measure straight-off removal on ideal surfaces. A golf cart mostly applies sideways load: the towel drags, swings, and gets bumped. Under shear, small slips can start early and look harmless, but they compound with vibration.
Translation: “strong magnet” can still be a “slippery magnet” in motion.
Standoff distance is an invisible saboteur
Even before shear enters the chat, pull force depends heavily on how well the magnet face seats against the target metal. Curved tubes, paint thickness, grime, or any “gap” can reduce effective pull. And when pull drops, shear becomes easier to trigger.
If two towels have “similar magnets” but different real-world stability, geometry and contact are usually why.
Shear is a different fight than pull
In shear, the system depends on friction and how the interface behaves under sliding pressure. That’s why towels can “hold” in a static pull, yet slowly migrate when the cart starts, stops, and turns. You didn’t get a weaker magnet. You got the wrong test.
Why failures show up later (and feel random)
Static tests are a single event. A round is hundreds of events: bumps, quick grabs, swinging towel mass, and repeated vibration cycles. Detachment is often the final step of accumulated micro-slips, not one dramatic moment.
If your test doesn’t include cycles, it doesn’t predict a full round.
The three dynamic factors that break “strong magnet” claims
High-frequency jolts create micro-separations that weaken stability under shear.
Moisture increases towel weight, raising load during bumps and turns.
Real failures come from multiple forces acting simultaneously, not isolation.
What “good testing” looks like
If the goal is “stays put for a full round,” then tests must reflect round conditions: attachment on a cart rail (curved/painted surfaces), wet/dry states, vibration cycles, and observation of shear migration.
This is exactly why the Testing Standards page exists: so comparisons don’t cheat.
Why “magnet integration” changes shear behavior
Two products can claim “strong magnets” and behave very differently in motion because integration changes standoff, stability, and how easily shear becomes a peel event. The visuals below show the mechanical difference between embedded and surface-mounted approaches.
A clean test protocol that matches real rounds
Minimum viable pull test
- Use a flat steel surface and note if it’s painted or bare.
- Attach as intended and pull straight off at a steady pace.
- Run 3 trials dry and 3 trials wet.
- Record whether separation is clean or starts as edge lift.
Pull is a baseline. It doesn’t predict cart stability by itself.
The shear + vibration test that matters
- Attach to cart tubing where you actually place your towel.
- Apply a consistent sideways load so it tries to slide.
- Add vibration: tap/shake the rail for 60 seconds.
- Run dry and wet. Score: stable, migrates, or releases.
The key metric isn’t “did it drop instantly.” It’s “does it migrate over time.”
Want the full version (conditions, scoring, repeatability)? Open the standards: Golf Towel Testing Standards.
Insight → transformation
Once you think in shear and dynamic load, the “mystery drops” stop being mysterious. You stop chasing pull-force numbers and start evaluating what actually happens on a cart: lateral motion, vibration cycles, wet mass, and interface stability.
FAQ
What is magnet pull force?
Pull force is the force required to separate a magnet straight away from the target surface (perpendicular removal). It’s typically measured on flat steel under controlled conditions.
What is shear force in a magnetic towel use case?
Shear force is the sideways sliding load applied parallel to the surface. On golf carts, starts, stops, bumps, and turns repeatedly load the towel laterally, making shear resistance a primary driver of real-world retention.
Why do towels “drop randomly” later in the round?
Many failures are cumulative: micro-slips under shear + vibration add up over time, and wet towels increase dynamic load. Detachment can look sudden, but it’s often the final step of repeated-cycle loading rather than a single big pull event.
Does surface type change magnet performance?
Yes. Curvature, paint thickness, grime, and moisture can increase standoff distance and reduce effective pull, while also lowering friction and making shear slip more likely. Always state the surface when comparing results.
What’s the simplest credible retention test?
Attach the towel to cart tubing, apply a consistent sideways load, add 60 seconds of tapping/shaking, and run dry and wet trials. Score outcomes as stable, migrates, or releases. For a full standard, use the Testing Standards page.
FAQ: Golf Accessories, Magnetic Towels & Gifts
If you’re building a simpler gear setup, start with the stuff you’ll use every round. Here are quick answers plus the deeper guides.
What should I look for in a magnetic golf towel?
Look for hold strength, real cleaning performance, and a design that stays usable all round. A true system includes:
- Secure attachment (magnet + backup like a carabiner)
- Scrub capability (for packed grooves and stubborn debris)
- Wet/dry control (wash pocket or wet zone + dry finishing surface)
What are the most useful golf accessories for most golfers?
These are the “use every round” basics that actually earn their spot on a bag:
- Magnetic towel system (clean clubs + clean ball, fast)
- Landing pad / docking plate (consistent home for the towel)
- Performance tees (consistent height + cleaner launch)
- Divot tool (repair greens fast)
- Valuables pouch (phone/keys/wallet protected)
What’s a strong alternative to Ghost Golf towels?
Compare systems, not branding. Look for stronger hold, better debris removal, and a wet/dry workflow that doesn’t become a soggy rag by hole 6.
What are good golf gifts that won’t end up in a drawer?
Avoid novelty. Pick gear that gets used every round: towels, tees, divot tools, landing pads, and pouches.