Sorry Taya, your new rollerless chain isn’t an innovation
Every two links of a typical bicycle chain consist of eight pieces – two outer plates, two inner plates, two rollers, and two pins to hold it and the adjoining link together. Chains of this nature, known as roller chains, are used every day throughout countless critical industries. Sketches of such things date back as far as the 16th Century.
Taya, a Taiwanese bicycle chain manufacturer, recently announced the production of its new Rollerless Series 11- and 12-speed chains. This new chain removes the roller entirely and instead puts enlarged inner links in contact with the teeth of the cassette and chainrings. Taya says its Rollerless chains save weight, run quieter, last longer, and are more efficient. And while some of that may be true, the reality is that Taya’s new product is likely a step back in the wrong direction of engineering history.
The purpose of the roller
Rollerless chains are nothing new. They were the industrial staple until the late 1800s when roller chains came in and took over due to significant benefits in system wear resistance. Today rollerless chains are still found in high tension applications such as elevators and hoists – elsewhere roller-based chains rule the roost and that’s certainly the case with our two-wheeled mechanical friends.
Before we dive into why the roller matters, here’s a very quick refresher on chain wear basics.
Traditionally chain wear is measured by the elongating distance from one pin to another (aka the pitch). This increased length is caused by wear on the pin and the wearing of the inner diameter of the inner plate hole. However, and as covered in our complete guide to chain wear, the roller also acts as a wear point as the outer diameter of the inner link wears on the inner diameter of the roller.
Whether you want it or not, most popular chain wear tools actually include the roller diameter and roller wear in the wear measurement. And roller wear can impact how the chain interfaces with the cog. This is exactly why Taya can claim that its new Rollerless series chains are more durable.
Ok, so why is the roller beneficial? That’s a question I posed to Jason Smith, formerly the brains behind FrictionFacts and now the head of R&D at CeramicSpeed. Smith is widely considered an expert in this field and has his name on many a white paper explaining the function of chains, friction in chains, and why so many chain lubes suck.
“The purpose of the roller is two-fold,” Smith said simply, before providing a not-so-simple answer. “Firstly, if the chain is severely worn/elongated, the pitch of the chain becomes greater than the pitch of the (cog) teeth. When a severely elongated chain articulates into or out of a sprocket, the teeth will try to pull the chain into the tooth trough, at least to some extent. The roller allows the elongated chain link to ‘roll’ into the tooth trough, rather than slide into the trough. Same with the exit – the roller allows the chain to roll out, rather than slide out.”
However, Smith notes that this first element isn’t such a big deal as most riders don’t take their chains to the point of severe elongation (wear). In reality, the chain will probably cause sloppy shifting before the roller is needed to actually roll.
“Now for the second purpose. This is super important and happens with a chain in any condition, new, or old, perfect pitch or elongated,” said Smith. “With a traditional roller chain – say, like a state-of-the-art Shimano Dura-Ace or SRAM, or any modern chain with a roller for that matter – the inside diameter of the roller shoulders (pun intended) the wear of normal articulation. Without the roller, the wear will occur at the tooth face.”
Yep, the inner surface of the roller acts as a sacrificial wear surface to save the tooth face.
Rollerless shifts the wear point
So what about the Taya rollerless series? Well, Smith has legitimate concerns. “This chain creates a wear interface directly between the inner plate shoulders and the tooth face, in which wear will take place every other link articulation (when the inner links enter/exit),” he said. “The tooth is now a wear interface point. Every second tooth will be subjected to rotational wear. And if it’s a 1x setup with an even number of teeth at the chainring, every other tooth on the ring will show wear. This will happen on the cassette cogs too, but not symmetrically like the ring.”
Ok, so this is bad. With proper care your current roller chain is the wear item in your drivetrain’s system. Keeping it clean and replacing it when it measures as worn will mean you cause minimal wear to the vastly more expensive chainrings and cassettes. And while Taya’s chain construction won’t suffer from roller wear, it sure seems that the actual wear will occur where you don’t want it to.
Speaking of wear, Taya’s new Rollerless Series has a hidden trick: a lubrication reservoir stamped into the inner plates that surround the pins. It sounds cool in theory, but in reality this isn’t a motorbike chain with sealing O-rings. “I’m not sure how the reservoir is going to reserve lube,” said a skeptical Smith. “Any modern chain requires clearances between the internal parts to allow for cross-chaining (lateral bend) in a derailleur gear system. If the clearances were tight enough to hold lube as a reservoir then the chain would not be permitted to laterally skew.”
We don’t yet have any data on the actual efficiency of the Rollerless chain and Taya’s press representative wasn’t able to provide such information. That said, Smith hypothesises that there are two reasons this rollerless design would almost certainly suffer from higher drivetrain friction compared to a roller chain.
Firstly, the rollerless chain exposing a key sliding interface to the elements, whereas a roller chain somewhat hides it within. Secondly, the enlarged diameter of the inner links increases friction with each articulation.
“The sliding interface is now at the tooth surface, which effectively is a larger radius than before. With a larger radius, the sliding surfaces have further to travel with each articulation,” said Smith, before providing the example of a locomotive turntable that places the train’s weight on a single pin in the centre. “This design allows the train to be moved by a couple of men. There would be too much friction to move it if the bearings were on the outer circumference of the turntable.”
Then there’s Taya’s claim of reduced drivetrain noise. It takes energy to produce noise, and therefore you’d assume that the more efficient it is, the quieter it is. However chains are an odd item with multiple points of friction, and it’s known that ultra-thin and efficient lubes don’t always do as good a job of masking noise as slower and more vicious lubes that manage to suppress the sound and your watts at the same time.
It is entirely possible that Taya’s rollerless chain will run quieter than a chain with squeaky rollers, but that noise is unlikely correlated to wear or efficiency.
Weight is one area where ditching the rollers should have benefit, but it’s not that great of a difference according to Taya’s provided weights. The brand claims the 11S (11-speed) Rollerless Series weighs 248 g for a 116-link oiled chain, a somewhat average figure up against slotted and drilled chains like Shimano’s Dura-Ace HG-901 (251 g) or a KMC’s X11SL DLC (242 g).
Perhaps the biggest benefit here is one that Taya doesn’t mention – manufacturing costs. Those inner links with the “lubricant reservoir” aren’t necessarily any more difficult to stamp into shape than other chain pieces. No rollers means you don’t have to make rollers. And then the automated assembly of chains can be simpler and made to run faster.
These cost savings no doubt go a long way to explaining why Taya first produced rollerless chains to suit kids bikes and those with 6-, 7- and 8-speed derailleurs. Here the cogs are thicker, made of steel, and the bikes are unlikely to see as much load or wear – a cheaper chain makes plenty of sense.
Efficiency, noise or even weight aside, I’ll use Smith’s words to sum up this new product. “This chain is a step backwards,” he said. “Chains without rollers were first invented, then the wear problems were seen. Then, the roller was invented to mitigate the tooth wear. The roller is actually a great invention to solve a big problem in a simple manner. Maybe they think the physics issues from 150 years ago magically disappeared.”
Ouch. Needless to say, Taya may be onto something for mass-produced entry-level bikes, but don’t expect rollerless chains to become the future for premium and performance-oriented machines.