I announced the arrival of some Gates Carbon Drive Center Track components earlier this month, and here follows my technical and First Impressions report from the few rides I’ve put in on it so far. Let’s take a look at the advancements made over the previous Carbon Drive belt set ups.
First, if you have not seen our post on Center Track from June, you should check that out here and read up on some of the particulars. I’ll be focusing on some of Gates’ claims made there in the following paragraphs. Back at 2010′s Interbike show, we actually sat down with Spot Brand’s Wayne Lumpkin, (formerly of Avid), and Gates Carbon Drive engineers to discuss the original Carbon Belt Drive and the Center Track that is now available, but was just announced back then. Here’s what we had to say in one of our Interbike 2010 posts:
The Center Track was an outgrowth of Gates involvement with Spot Brand owner, and former owner and founder of Avid, Wayne Lumpkin. Mr. Lumpkin was brought in as a consultant on how Gates could improve upon the performance of their Carbon Belt Drive.
The outcome was Center Track. As you can see, it dispenses with the flanged cogs and replaces that with a central “fin” that runs in a “track” molded into the center of the belt. The belt itself was also increased in width slightly to improve upon engagement. The tooth profile remains the same as before, but Mr. Lumpkin described the new arrangement as being far more tolerant of lateral misalignment between the cogs and as an added bonus, it actually repels dirt and mud better than the older “windowed” cog system.
An Evolving Design: I think it is also important to note that during our sit down meeting at Bootleg Canyon, the Gates engineers were very forthcoming in their responses concerning our criticisms of the then current Carbon Drive in single speed mountain bike usage. They also were refreshingly honest about telling us their goals. First, the criticisms we put forth were met with reasoned responses. Basically, we were concerned with our own experiences, and that of others, where belts “ratcheted”, and sometimes broke. Gates’ engineers told us that coming into the bicycle designs they were suddenly made aware that the single speed mountain bike had a reverse demand on design than anything else they had developed. Normally, they were used to “High RPM-Low Torque” applications, whereas single speed mountain bikes were “High Peak Torque- Low RPM” machines. The resulting issues encountered led to the development of the wider belts, and ultimately, to Center Track. (Amongst other things like frame specifications and tests for manufacturers interested in equipping their models with Carbon Drive belts)
As for Gates’ intents, they voiced to us that they want to succeed in giving mountain bikers, and all cyclists, an alternative to a chain drive that is reliable, efficient, and reasonably priced. They also said they were not out to replace chain driven bicycles, but they obviously believe their product has the potential to be a better alternative. Are they arriving there with Center Track? This is the question we will seek to answer here.
Our Experiences: My concerns with using the older Carbon Drive belt concerned belt tension and wear on the rear cog. The tensions required to keep the older 10mm wide belt from ratcheting was quite high. High enough that premature wear on the rear free hub bearing was happening and could be evidenced by the crunching and snapping sounds emanating from the hub due to the high belt tension. No doubt the bottom bracket suffered as well, since the crank had little free spin. When this same crank was unloaded from the belt tension, it spun quite freely. I wasn’t impressed with the extra effort required to turn the crank and the prospects of wearing out bearings faster than I would have with a chain.
I also was concerned with the original Gates design for the rear cog. Both Grannygear and I experienced a chewing up of the interface on the cog with the steel free hub body. This was after only a few months of riding. So, while the interfacing teeth of a Gates rear cog and belt would likely outlast a chain, it was obvious that the cassette interface would fail far before a chain/cog would, thus negating the advantage claimed by Gates.
The Promise Of Center Track: Now with the new Center Track design, a few things have changed that may make some headway in overcoming our concerns. First, the obvious change to the belt and cog design will, as stated above, allow for more lateral intolerance. (But make no mistake, you’ll still need to be dead on with your “belt line” from front to back.) The new design should be more tolerant of frame flex, so this is good to see. Obviously, the mud shedding abilities are much appreciated here as well. Secondly, the wider belt, along with the tolerance for a slight amount of flex means slightly lower belt tensions will be necessary, which should make all free hub bodies and bottom brackets last longer and spin freer with the Center Track. Note: Gates says it isn’t that the Carbon Drive Center Track takes “less tension”, but that it doesn’t need to be over tensioned. Okay…..you say tomato, I say “toe-mah-toe”.
Finally, the cog has been rendered in CNC’ed stainless steel, which should eliminate any of the chewing up of the cog’s splined interface that we had experienced before. Overall, the entire system is more refined looking and feeling, in my opinion.
What Is Missing?: So far, so good, eh? Well, Gates is still trying to crank out different choices in the Center Track cogs and belts. This, by their own admission, will take some time. So, if you rush out as of the writing of this post to find a Center Track set up, the choices available now might not suit your desired gear ratios. Also, Gates has ballyhooed the iPhone ap for tensioning the Center Track, (and other Carbon Drive set ups), but not everyone carries an iPhone, (Yes- believe it or not!), and beyond the “gee-whiz” factor, this fails to address a practical means that every rider could use to tension the belt. This is critical to success, so I would like to see Gates come up with some mechanical means to determine a consistent and proper belt tension. Finally, beyond the scarcity of choices at this point, Center Track isn’t cheap. (At post time, I couldn’t find any MSRP’s on parts, but as we were told, Center Track is considered Gates “premium” product, and will be more expensive than Carbon Drive is now.) Assuming that prices for Center Track will top current belt drive component prices, you can figure that one could buy a couple complete chain driven single speed drive trains for the same amount of money it takes to set up one Center Track bike.
Ride Impressions: With all that discussion now behind us, the real question is, “Does it work?” Well, the old system “worked”, but with caveats. The Center Track does seem to be better from a couple of standpoints. First: The belt set up does spin better with Center Track’s lower tensions. In fact, within the belt’s necessary “tuning range” of 70-85Hz, I could get my crankset to spin backwards as easily as it would with a chain driven set up.
The other thing was that there was no weird noises, no feared ratcheting, no popping, nothing but sweet silence. The belt felt smooth, and after a bit, I began to feel more confidence in the system, and was doing everything I would have done with a chain set up. Again, this sounds really promising, but the niggling issues with set up and tensioning still remain. For instance…
When I first got the Center Track components, and tried fitting them to the Sawyer, the first belt I received was juuussst too short. It would have been nice to be able to run the shortest possible chain stay length dimension. The next belt came, a size up, and it put the sliders nearly all the way back in the throw. Hope I like 18″ chain stays! If I don’t, well, at least for now, Center Track wouldn’t be for me.
As for tensioning, I do not own an iPhone, so I actually tuned my belt to 70Hz with the aid of a bass guitar and a tuner. (That would be a scene in the pits at your local XC race! ) Obviously, if I had a bike that required re-setting the tension after removing the rear wheel, or if/when Gates gets more cog options, and you want to change a belt/gear, etc, then tensioning the belt becomes a matter of some guess work on the part of someone. Especially in the field. It may not be a big deal in some situations, but it could be. What I am saying is, it should never be, for a premium system like Gates Carbon Drive. This needs to be addressed to make the system more practical for users.
Performance-wise, this seems very dialed. I will keep up riding it for awhile until I come back with a Final Review. We will see how it holds up in the longer term.
Note: Gates sent the Carbon Drive Center Track for test/review at no charge. We are not being paid, nor bribed for this review and we will strive to give our honest opinions and thoughts throughout.