As you readers of Twenty Nine Inches know, we have done several posts on Gates Carbon Belt Drive bikes and have tested their “traditional” set up in the past. (See some of theses posts here, here, and here.) We also have reported on the positives that the new “Center Track” technology was to bring to the system. Here we can finally say that Center Track bikes are currently available, (first from Spot Brand Bikes, others later in 2011), and after market belts and cogs to convert belt drive bikes out there already to Center Track will become available in July.
What Is “Center Track”?: The previous versions of Gates Carbon Belt Drive were very similar in appearance to automobile applications of belt and pulley set ups. There was the rounded tooth profile of the belt’s inner run that mated with matching profiles molded into the Gates pulleys. These “cogs” also had a flange on one side to help keep the belt from “walking off” the cogs due to flexure in the bicycle frame, or from slightly misaligned cogs.
Obviously, as you can see from the image above, there are no more flanges on the front or rear cogs, and rear cogs are now machined stainless steel in their entirety now. Front rings for Center Track are all aluminum. The cog features a center ridge which mates into a slot molded into the center of the belt. The belt itself is now 12mm wide to accommodate the “center track” and to avoid the carbon strands which are placed every two millimeters from belt edge to edge and which run laterally along the length of the belt in an unbroken circle. These carbon strands prevent the belt from stretching. Gates claims a “20% increase in tensile strength” over the older version of their belts, but this may simply be an outcome of having an extra carbon strand in the 12mm belt versus the 10mm ones before it.
Because the belt now runs in a track, it is more tolerant of mis-alignment and flex incurred by frames which can slightly mis align cogs while under hard pedaling forces. Another benefit of Center Track is that it can be used at slightly lower tensions than the older Gates Carbon Belt Drive Systems could be run at.
The new Center Track belt and cogs can be retro-fitted to current belt drive bikes as long as there is clearance for the wider belt. (Gates claims a “slimmer profile” for the cogs, but the belt is 2mm wider than what the older system had.) As of post time, we were told that Center Track cogs and belts would become available in July. No word on pricing, but be prepared to spend more than currently available Gates Carbon Belt Drive parts sell for.
Gates says the initial product launch for after market parts will be focused on the most popular sizes and will be expanded through the second half of 2011. For more information about Carbon Drive go to the Gates blog.
Twenty Nine Inches should be taking delivery of a Spot Brand Center Track equipped single speed soon for test/review. We’d also like to thank Spot Brand for providing information and images for this post.
They keep trying and I applaud them for that, but it’s yet not winner:
1) Narrow selection of cogs and rings 2) Requires long chain stays, stiffer rear end and clearance accommodation 3) An expensive and propriety system 4) Their BDC works with certain cranks but not others. For example my XX, which I like most due to a low Q-Factor, cannot work with their system.
I wonder, though, how much weight had their system gained with the beefing up and a large stainless steel cog at the rear?
@RubberBoy: Weight is still claimed to be far lower than a chain drive single speed set up. With the Center Track design, they still could minimize the weight, even though the materials were changed from the original set up. Had the old stuff been done in stainless steel and aluminum, the weight gain would have become an issue.
Sounds like a lot of work and ducats just to keep your right leg and pants clean. Good to see Spot is still alive and well, they’re an OG SS company. I would love to get another Spot SS chainring!
Will Gates now offer smaller chainrings? This would address many of the frame issues the large chainrings have caused.
This is definitely looking better than the first-generation cogs and belts. I’m still not crazy about the idea of breakig a seatstay to install the belt, and upping the stiffness is a dealbreaker for me–I like flexy steel hardtails.
Well, horses for courses and all that: I certainly hope the new belt and cog designs work as intended and make their owners happy.
I think this is the make or break for belt drive.
After converting several bikes and a couple of years use, I am keen to see this succeed because belt drive works and is better than an exposed chain IMO
The big downer isn’t the technical side, but that it is an expensive and proprietary system with limited availability of crucial sizes needed.
However even better would be a fully enclosed oil bath chain (eg Katz). The chain and rings could be smaller pitch if enclosed and so could save considerable weight.
@ BMac.
I read so many horror stories about the belt skipping and putting stress on the bearing that my appetite to test one is quite dull. You are right, it is a make or break moment. If this revamp system finally solve these issues, I will consider a purchase.
@sluggish — the Spot pictured above is steel-framed. i guess we’ll both be tuned in to see how she goes….
This looks like a definite improvement on the first generation belt system — which wasn’t half bad in any case.
The only caveat (according to my LBS guys): You have to get the belt alignment exactly right, or the center tracks on the pulleys rub on the belt. Or think of this another way: This system has an automatic pulley-alignment gauge; if your pulleys aren’t right, the belt will tell you about it.
Still, once it’s dialed in, this looks to be an amazing system. I’d surely move to it, but I’m told I’ve got 5 or 10 thousand miles to go on my current belt.
Sorry, but I cannot understand benefits of Center Track over flanges…
The flange system only uses a single flange, on just one side of each pulley (on opposite sides, in fact, front and back). So, in some cases, generally when belt tension is off or the wheel alignment isn’t quite right, the belt slides off the side of the pulley. Of course, you can just slip it back on — IF the belt wasn’t damaged in the process. The carbon fibers in the belt are immensely strong, but easily broken by some kinds of twisting or cutting.
The center track system eliminates this slipping off. The groove in the belt fits directly into the track on the pulley. It also guarantees good chainline alignment of the rear wheel, since the track will rub on the groove unpleasantly if alignment is too far off.
And, at least in theory, by eliminating the side flange, a bit of weight is removed from the pulley — though I gather the pulley metal has changed with the new version. If that’s true, then the change in metal weight may overshadow the weight loss achieved by removing the flange.
Thanks for your reply. I have another question. Why not make flanges on both sides of pulleys?
@Dima: Center Track eliminates the need for any flanges at all on the outside edges. Flanges cause issues with noise, (as pointed out above), and also with slight, out of alignment issues, such as those that occur in a frame under hard pedaling. Flanges actually cause more problems than the cure for belts on bicycles.
Center Track also eliminates the former cogs “windows” that were there to help clear mud and debris. On Center Track, the mud and debris is cleared by the simple interfacing of the center flange and grove on the belt, and then the tooth interface can also push out any debris and mud to the sides without interference from the “window frames” in the older system.
Finally, the wider belt could be used on Center Track, which gives maximum interface with cogs and teeth, and also helps to lower the necessary tension needed to keep the belt from ratcheting.
All in all, it is head and shoulders above the older ways Gates employed to make belts work on bikes, and I have tried them all. Grannygear and c_g also report similar things to my findings, which leads me to believe that Gates has it right with Center Track, and anything else that they have done with flanged cogs is far sub-standard to Center Track. No need for further discussion in that direction. It simply isn’t good enough. 😉