Not Another Link in the Chain: Gates Carbon Drive System

By Eddie Clark

(June 20, 2012) DENVER, Colo.—Just over 100 years ago Charles Gates Sr. purchased the Colorado Tire and Leather Company in Denver, Colorado, and over time the Gates Rubber Company grew to become a leader for producing tires, belts and hoses that have powered cars and industries across the world.  Now known as the Gates Corporation, the company employs 14,000 people in 30 different countries, and is in the public spotlight again with their new CenterTrack Carbon Drive System.

While belts have been widely used in numerous automotive and industry applications for the past century, it wasn't until 1987 when the low-end commuter Strida bicycle was produced that belts were deemed as a feasible drive system.  Although, the old rubber belts stretched under heavy loads causing them to skip and jump teeth, and so the bicycle belt drive application stagnated. 

The real game changer came about when Harley Davidson Motorcycles, who had been using belt drives for 20 years, asked their long time belt provider, Gates, to design a belt that would last for 60,000 miles on their motorcycles.  Soon after, Gates engineers began tinkering with using the same new belt technology on bicycles.  In 2006, Gates' Todd Sellden approached Frank Scurlock who at the time was working with Spot Brand Bicycles to further develop the Carbon Drive System into a reliable drive train that provided superior performance to the chain.

"From Gates' standpoint it was the perfect opportunity to actually improve and change a system that has been working for hundreds of years.  Gates loves replacing anything that uses a chain with a belt whenever possible", explained Frank Scurlock who now works as the Global Business Development Manager for Gates Carbon Drive.

Sellden, the Gates Carbon Drive Global Technical Director added, "What's unique about the Gates belt is it's the first time that a company has applied a poly-belt that has the carbon tensile cord that keeps the belt from stretching at all.  You previously couldn't get that with rubber based belts."

The first versions of belts used were from industrial applications that weren't designed with bicycles in mind, and were prone to skipping so the team held off on releasing it to further refine the system.  Specifically, the belt was too wide and the teeth were too small which still allowed for unacceptable cog/teeth skipping.

For the second version, they developed a belt that was specific to the bicycle drive train application.  The new design featured larger teeth which resulted in a larger pitch (the distance between teeth on the belt).  The larger pitch and narrower belt provided a more robust platform that wasn't as sensitive to belt tension, and ultimately gave a much higher level of performance.  The system also featured cogs and sprockets that had ports under the teeth to help clear out mud, snow and debris to create a virtually maintenance free system.

In 2007, Trek started using the Gates Carbon Drive System on their commuter bikes which proved to be the real market impetus behind the belt drive revolution.  Much of it can be attributed to the cycle commuters of Europe who were quick to adopt the new system which is not only maintenance free, but also more importantly in the context of cycle commuting it is grime and mess free. 

In fact, the commuter bike market in Europe has grown so much that it now accounts for the majority of belt drive systems sold.  In fact, Shimano is now producing approximately 5 million internally geared hubs worldwide, which is partially attributable to the belt drive revolution.  Between Shimano and SRAM four new models of internally geared hubs are being released, and are also being sold with accompanying Carbon Drive Systems on higher end commuter bikes.  For 2012, the Gates Carbon Drive System is being spec'd by 68 brands on 158 different models of bikes.  Additionally, companies such as Rohloff and NuVinci are also pushing the movement forward with new offerings that represent the next evolutionary steps in internally geared systems.

"We have a perfect storm of things coming together with the commuting movement here in the US.  Shimano and SRAM see the current belt drive movement as an opportunity to sell more internally geared hubs, which is reflected in their development being put into improving the internally geared hubs", notes Scurlock.

But what about mountain bikes?  Well, that is where the revolution started, and it's also where Gates' belt drive innovation continues.  Specifically, Wayne Lumpkin of Spot Brand Bicycles continued to work with Gates to develop their newest offering in the CenterTrack Carbon Drive System.  The big benefits are that its slimmer belt and pulley profile offers greater chainstay and frame clearance for running the newest internally geared hubs.  Another big performance attribute to the CenterTrack system is the actual center track in the middle of the belt, which has an even higher tensile strength, and is also more forgiving of frame flex and chain line deficiencies.

So, just how good is the new CenterTrack system?  Besides the obvious increases to performance and reliability, the Gates belt driven cyclocross team racked up a string of impressive results in the 2011 racing season, and for 2012 they are fielding their own mountain bike team which has already taken several top podium finishes.  As of this posting, Ollie Whaley of New Zealand is not only leading the Tour Divide southbound grand depart, but he's also in contention to set a new course record on his Gates CenterTrack Carbon Drive and Rolhoff equipped Ventana 29'er.