It took seven years to grow the tree and eight years to train the person who built your tire.
Freehub magazine went to Thailand and filmed how our tires get made, from a rubber tree to a boxed tire.
The film is from 2019, and the craft in it hasn't dated. It's also the part of a tire you never see: almost none of this shows up on a product page.
The compound came from moped drag racing
Our rubber is made by V Rubber, and the compound we build on wasn't designed for bicycles at all. It came out of Thailand's underground moped drag racing scene.
It's a slow rebound rubber, and that's what a mountain bike tire wants: a knob that springs back instantly is a knob that has stopped gripping. Getting it onto trails took only a small chemistry tweak.
Seven years before the first cut
Fifty miles outside Bangkok, a rubber tree takes about seven years to reach maturity before anyone can tap it. After that it gives roughly 19 pounds of rubber a year, for up to thirty years.
Latex is harvested by hand, with hand tools and buckets, in the cooler parts of the day when it flows more easily and dries more slowly.
Worth knowing what latex is: unlike most tree sap it doesn't carry nutrients. It's a defense mechanism, and its job is to seal a wound in the bark. The material that holds your tire together evolved to hold a tree together.
Once it hardens, it's called cup lump. It's inspected, cleaned of debris, and left to sun-dry and cure for weeks, sometimes months. The blocks then travel to V Rubber's factory, where the chemical agents for each compound get mixed in.
Stills from Freehub Magazine's film Made With Love (2019), in the order the tire is made.
Turning a drawing into a mold
While the rubber is curing, the tread pattern becomes metal.
Copper blocks are machined into dies, section by section. Those dies go to the spark department for electric discharge machining, where a rapidly recurring current between copper and steel erodes the steel in a controlled way. What's left is the inverse of the die, imprinted into the mold.
Building the tire by hand
Compounded rubber is heated, extruded into belts, and then calendered, which takes as many as seven people. The rubber is rolled down to between 0.2 and 0.4 millimeters and fused with nylon threads for structure. That sheet is a ply, and plies become casings.
The tread itself arrives as a cap of two different rubber compounds, chosen for softness and tack. It's run through water to cool, then rolled onto spools until it's needed.
Then the tire is built on a drum, by hand, in order: casing, Kevlar bead, tread cap, sidewall reinforcements, adhesive between each layer, all under continual tension.
A builder needs a minimum of eight years of experience before they're allowed to operate a building drum. The job needs a sharp eye, and that kind of attention takes years to develop.
At that point it's a green tire, uncured and shapeless. Experienced builders turn out as many as sixty green tires a day.
Each green tire gets a hot patch carrying its markings and our branding, then goes into a mold with an air bladder inside it. Pressurized and heated for seven minutes, and the tire takes its shape and its tread at the same moment. Those seven minutes are the vulcanization, the step that turns soft rubber into a tire. Two dozen cure at once.
Then we try to fail it
Every single tire is tested, not a sample.
Leak test. Mounted on a rim, inflated to 36 psi, dunked in water. Any bubble and the defect is marked and the tire is pulled.
Wobble test. Remounted, spun on a truing stand, examined for warping or inconsistency.
Batch destruction. Random tires from every batch are cut up and tested for glue strength, cured rubber quality, and abrasion longevity.
The results are recorded and fed back into the next batch.
Tires that pass are folded, tagged, boxed, and shipped.
The current range is the Gen3 Grappler lineup.
Why the film is called Made With Love
There's a version of manufacturing content that's all robots and sparks. Freehub's film is mostly people. A person tapping a tree before dawn, a person watching a tire spin for a wobble nobody else would catch, a person who waited eight years to be allowed near the building drum.
