Kenda is one of the largest bicycle tire manufacturers in the world, and they make car, ATV, scooter and various other tires, too. We took a tour of their bicycle tire factory in the Yuanlin Township, Changhua County, in Taiwan. Turns out they also make inner tubes here, which is in Part 2, and cooler than you think.
They’ve been at it since 1962 in this original location. Now, they have more than 1000 employees and 11 locations, two of them in Taiwan. The complex is sprawling, hidden by the normal office building facade. Inside the delivery portal lies a vast tunnel running past building after building. The bike tires use much of it, with rubber moving from section to section, floor to floor, as it goes from raw material to a finished, rideable product. Here’s how it happens…
Get through the gate and walk to the center and you’ll be staring down what seems like a mile of factory. They make more than just bike tires at this location, but each type of tire seems to mostly stick to its own sections.
Rubber arrives in its natural state…
…then is mixed with silica to create the proper durometer and carbon to turn it black. Other materials can be blended in to create different color tires.
They sometimes use multiple blending steps, adding more silica on a second mixing, to end up with the right durometer.
Everything is heated, melted and turned in monstrous machines with huge drums that twist and fold it into itself repeatedly.
UPDATE: Kenda has asked that we remove the videos for now, hoping we can get them back online in the future.
The end result are giant sheets of rubber, which are then sliced into appropriate widths and moved to the next stage.
Meanwhile, giant spools of wire are turned into wire beads for DH and less expensive bicycle tires. The wire is pulled and manipulated to get it to the correct diameter and roundness.
Then it runs thru a machine that melts rubber onto it. Note the bare wire coming in on the right, and exiting on left coated in rubber.
A wire is then bent into a circle, cut and taped to hold its shape. A worker pulls them from the machine, then they’re moved over to this testing station to check circumference. Once they pass inspection, they’re sent up to the tire layup station.
By this time, the rubber has moved on to the extrusion process to create the tread layer. It’s folded, layered as necessary to create a single or dual density rubber compound, then extruded into the basic profile needed for the intended tire. Above, you’re probably looking at the rubber for a tire like the Happy Medium, which has lower profile center knobs with taller side knobs – so, the rubber will be a little thicker at the outside edge of the tread.
After running through a cooling batch, the tread layer is rolled up with a coarse cloth between layers to prevent sticking.
Elsewhere in the building, they’re coating the base casing fabric with rubber. Depending on the ply (30tpi, 60tpi, 120tpi, etc.), different rubber compounds are used to ensure they saturate the fabric.
The roll is then cut into strips based on the tire size and model it’s going on. The angle of the cut is also customized to create the correct bias. The strips are then fed by a worker into a machine that connects them and rolls them up for transport to the next step.
Once the beads, casings and tread blocks are all created, they are fed into this machine for construction into a raw tire. Here’s how it works…
UPDATE: Video removed, per Kenda’s request.
The finished result is a layered, flat tire that’s ready to be molded.
These blanks are rolled to another building with rows of heat presses.
The layers are very visible prior to molding.
First it’s stretched and put onto a rubber tube…
…then placed in the oven and pressurized into a mold to create the tread pattern. The heat also cures it, altering the rubber’s characteristics to turn it into the final desired durometer and fuse all of the layers together.
Each and every tire is set up and placed into the molds by hand, removed by hand and checked over for any obvious flaws. Then they’re bundled up and sent to another section for quality control.
After curing, every tire is checked for size and weight balance. There are rooms and rooms of finished tires waiting to be QC’d, then stacks upon stacks of approved tires ready to go to packaging. All packaging and boxing happens onsite, too, then they’re shipped off around the world.
Kenda’s U.S. facility houses their North American sales and support, but also doubles as their advanced research lab. The new tires we’ve seen recently (and some cool ones coming this fall) were developed there. They will be made at this Taiwanese factory, adding to the roughly 15,000 bicycle tires they make per day!
Stay tuned for Part Two to see how their tubes are made.