You’ve spent hundreds of dollars on the perfect pair of climbing shoes. They fit like a glove and stick to holds like magic.
But after storing them in your car during a hot summer or leaving them in a cold garage over winter, they suddenly feel different.
The rubber seems harder, less grippy, and you’re slipping off moves that used to feel secure.
This isn’t your imagination – temperature changes during storage can permanently alter the molecular structure of used rock climbing shoes, destroying their performance forever.
The Science Behind Rubber Degradation
Climbing shoe rubber is specifically engineered to work in a narrow temperature range.
Climbing shoe manufacturers design their rubber to work best in a specific temperature range—approximately 68° to 77°F, with some sources indicating the optimal performance temperature for climbing shoe rubber is 0-5° centigrade.
But here’s what most climbers don’t realize: when you expose rubber to extreme temperatures during storage, you’re triggering irreversible chemical changes.
Oxidative and thermal ageing of rubber are accelerated by stress and reactive gases, like ozone, resulting in cracking, charring and colour fading.
The rubber in your climbing shoes is made up of long polymer chains that give it flexibility and grip.
When exposed to heat, these chains can break down or form new crosslinks. Oxidative rubber degradation can cause hardening or softening, depending on the structure of the elastomer.
Hardening is more common because free radicals produced due to heat, oxygen and light combine to form new crosslinks, which reduces the flexibility of the rubber.
What Extreme Heat Does to Your Shoes
Summer storage in cars is one of the biggest killers of climbing shoe performance.
On a hot day in Texas, the inside of a sealed auto parked in the sun can soar to 150° F and beyond. At these temperatures, multiple things happen to your shoes:
Rubber Molecular Changes: The heat causes the rubber compounds to break down at a molecular level. High temperatures can cause ageing and deterioration of the rubber. Initial exposure to high temperatures can cause the material to soften. This softening can be reversed once the temperature drops again. However, if the rubber is held at a high temperature for a long period of time, chemical changes begin to occur within the rubber polymer.
Adhesive Failure: The glue holding your shoe together is heat-sensitive. Rubber will survive the heat, but the glue that holds it to the shoe is heat sensitive—your sole could delaminate. You’ll start seeing the rubber pulling away from the upper, creating gaps that worsen over time.
Shape Deformation: The adhesives will lose their stickiness more quickly, which can cause the shoe to become deformed. Your carefully designed shoe shape, especially the precise camber of aggressive shoes, can warp permanently.
Cold Storage Damage You Can’t See
Cold temperatures might seem safer, but they create their own problems. When rubber gets too cold, it becomes brittle and can develop micro-cracks. At very low temperatures, rubbers can become stiff. This loss of flexibility can cause cracking in the rubber which will remain in the material forever, even after it has been reheated.
Even worse, repeated temperature cycling between hot and cold creates stress in the rubber structure. One climber reported that old shoes left in a cupboard for a long time seemed to go hard & shiny as described. My guess was that the rubber had degraded (possibly oxidised).
Temperature Cycling: The Silent Killer
| Temperature Range | Damage Type | Permanence | Recovery Time |
| Above 120°F | Molecular breakdown, adhesive failure | Permanent | Never |
| Below 32°F | Brittleness, micro-cracking | Permanent | Never |
| Cycling 40°F+ swings | Oxidation, hardening | Progressive | None |
The most destructive scenario is when your shoes experience repeated temperature swings.
Rubber oxidizes. The term (in time) that your rubber oxidizes at cannot be said because of certain conditions, but I can name a few tips to help prevent that happening. Avoid heat, UV exposure, oxygen, and pressure.
Each heating and cooling cycle causes the rubber to expand and contract, gradually breaking down the molecular structure.
Unlike other materials, rubber contracts in heat and expands in cold temperatures.
This is because when the long molecular chains get hotter and vibrate, they shorten, causing the material to contract.
Real-World Storage Mistakes That Ruin Shoes
Car Storage: Your vehicle is essentially an oven in summer and a freezer in winter. Whatever you do, don’t leave your shoes in the car for extended periods of time. Vehicles are little heat-trapping ovens, and shoes don’t like heat.
Garage Storage: Unheated garages expose shoes to extreme temperature swings and humidity changes that accelerate oxidation.
Direct Sunlight: UV rays combined with heat create a double assault on rubber. Constant exposure to the sun’s rays can make the rubber sole of your shoes extremely brittle.
Wet Storage: Moisture trapped in shoes during temperature changes creates the perfect environment for rubber degradation and bacterial growth.
How to Spot Temperature Damage?
You can often identify temperature-damaged rubber before it completely fails:
- Hardened Surface: The rubber feels harder and shinier than when new
- Reduced Grip: You slip off holds that used to feel secure
- Visual Changes: The rubber may appear glossy or have a different texture
- Separation: Rubber pulling away from the upper, especially around the toe
According to the slipboard, the dirty rubber had 10-percent less holding power, e.g., if clean rubber stuck to a 70-degree slab, then the dirty rubber maxed out at 63 degrees. Temperature damage can cause similar or worse performance losses.
Proper Storage Methods to Prevent Damage
| Storage Location | Temperature Range | Humidity | Light Exposure | Recommendation |
| Indoor closet | 60-75°F | 30-50% | Dark | Excellent |
| Basement | 55-65°F | Monitor humidity | Dark | Good |
| Heated garage | 50-80°F | Variable | Minimal | Acceptable |
| Unheated garage | Variable | High risk | Variable | Poor |
| Car/trunk | Extreme swings | High risk | Variable | Never |
Best Practices for Long-Term Storage:
- Control Temperature: Once you have taken delivery of your rubber products, they should generally be stored in cold, dark, dry and oxygen-free conditions to slow the effects of rubber degradation.
- Ensure Proper Ventilation: Never store shoes in sealed plastic bags where moisture can build up.
- Maintain Shape: Use shoe trees or stuff with newspaper to prevent deformation during storage.
- Regular Inspection: Check stored shoes every few months for signs of degradation.
For serious climbers with multiple pairs, consider dedicating a climate-controlled storage area.
Think about a climbing gear storage rack in a small area of your non-heated garage where your shoes, harness, ropes, and other equipment get to enjoy the cold winters free from bacteria.
When Damage Is Beyond Repair
Some temperature damage can’t be fixed. If your shoes show signs of delamination, severe hardening, or cracking, it’s time to consider replacement or resoling.
Generally, we recommend you get a resole when your shoe rubber is about 80% worn.
If you get your shoes resoled early and often, you can extend the life of the shoe and obtain the most number of resoles.
However, minor surface hardening might be improvable. Wire-brush or swipe polished soles with coarse-grit sandpaper to expose fresh meat.
Notice how the soles on new shoes aren’t smooth but instead have a brushed texture—aim for this.
Understanding how temperature affects your used rock climbing shoes isn’t just about performance – it’s about protecting your investment.
Modern climbing shoes can cost $200 or more, and proper storage can extend their life by years.
The difference between shoes stored properly and those left in a hot car can mean the difference between sending your project and slipping off the start holds.
Frequently Asked Questions
Why does heat damage climbing shoe rubber?
Answer: Heat accelerates chemical reactions inside rubber. At 120°F+ (like inside a hot car), polymer chains break down or crosslink, making rubber harder, less flexible, and permanently less sticky. Adhesives can also fail, causing delamination.
Is cold storage safer for climbing shoes?
Answer: Not really. Below 32°F, rubber becomes brittle and can form micro-cracks. These cracks don’t “heal” even when warmed back up. Repeated hot/cold cycles are the most damaging of all because they stress the rubber structure.
How can I tell if my shoes are temperature-damaged?
Answer: Warning signs include rubber that feels harder or shinier, reduced grip on holds, visible cracking, or rubber separating from the upper. A warped shoe shape (especially in aggressive shoes) is another clue.
Can temperature-damaged rubber be restored?
Answer: Severe damage (cracking, delamination, major hardening) is permanent. But mild surface hardening can sometimes be improved with light sanding or a wire brush to expose fresh rubber.
Where should I store my climbing shoes to prevent damage?
Answer: The best environment is indoors at 60–75°F, low humidity, and out of direct sunlight. Avoid cars, unheated garages, or damp basements. Use breathable storage (not sealed plastic) and consider shoe trees or newspaper stuffing to maintain shape.
What’s the lifespan of climbing shoe rubber if stored properly?
Answer: Properly stored shoes can last for years and multiple resoles. Neglected shoes exposed to heat/cold may lose grip within a single season.
Can resoling fix shoes damaged by heat or cold?
Answer: Only partially. Resoling can replace worn-out rubber, but it can’t fix hardened rubber throughout the shoe, warped shapes, or adhesive failures. For best results, resole before damage becomes extreme.
What’s the best way to extend the life of climbing shoes?
Answer: Keep them clean, cool, dry, and dark. Rotate pairs if possible, avoid leaving them in cars/garages, and inspect every few months. Early and regular resoles also maximize lifespan.
