We've installed the new Co-Motion Gates Carbon Drive on our 1.5 year old Macchiato tandem. We have the non-adjustable chainline carbon cranks and our chainstay does not have the dimple that the newest Macchiato frames may have. As a result the belt drive rear ring was contacting the frame and had prevented me from installing the one that I'd bought for my personal bike.

The solution proved to be simple enough. We ordered some 2mm chainring bolt spacers for the front and rear timing rings along with longer chainring bolts. Cost for the parts is about $30. This gives the needed clearance (it's still close, but doesn't touch) between the rear ring and the chainstay. In my case the eccentric moved a hair out of the shell towards the timing rings in order to get the belt alignment spot on. Visually, the chainring spacers are hardly visible (see pics below). The belt is a snug fit, lengthwise. The eccentric is in the rearmost position now and sliding it onto the rings takes care as there's very little slack to be had.

We've gotten in two good rides on it now and it seems to work perfectly. The alignment that was easily achieved in the stand (once the spacers were installed) hasn't needed any further adjustments on the road. Since the clearance is so tight in the rear it's easy to tell that the belt is tracking straight. It can only move inwards and would leave a mark on the frame if it were to try and come off the inside. It's easy to glance down during hard pedaling, cornering, or climbing and see that it's riding right up against the timing ring like it's supposed to. Gates tells me that the rings are designed to direct the belt towards the keeper while pedaling. It seems to work.

It's light, yes. Our tandem lost half a pound and is now 25.8 pounds (with SRAM Force and weighed without pedals). But I'm not sure that is the main selling point. It is much quieter up front with less chain noise. Amy noticed it too - but not as much as she's still sitting right over the drive chain. I also noticed less vibration in my pedals as the belt feels much smoother than a timing chain. Drag doesn't seem like an issue. It's not scientific, but I'm able to spin the pedals backwards and get 1 to 1.5 revolutions before they come to a stop. With the chain on it was the same or less. It certainly wasn't more.

I've been entertained by only having to lube the drive chain before our ride. I like that. But the thing I like most about it so far is that, maybe because it is so taut when compared to a traditional timing chain, there is zero delay from captains to stokers cranks. On a chained tandem there's just enough slack in the chain that you can get a tiny bit of play between front and rear cranks under load. With the belt drive it's almost digital from front to rear. It has tight spots in it just like a traditional chain - due to rings and crank spiders not being perfect - but it's always taut, or more taut. Maybe this is the reason that is also seems to have a nice, snappy feeling when jumping out of the saddle to accelerate or climb.

It's different for sure, and my first impressions are that I really like it. So far I think it's a winner.

Henry Abel

ADDITIONAL - CO-MOTION GATES CARBON DRIVE IMPRESSIONS (Feb. 4, 2009)

Winter had kept us from putting too many miles on our road tandem, but we've definitely been getting in some long rides on occasion when the streets are clear and dry. We might have 500 miles on the belt at this point and as a whole are really happy with it.

The one negative that we've run into so far on New Years Day we got in a long ride that had some wet pavement and a lot of water and road grit got on the tandem and belt. During the ride the belt started to squeak. Not loudly - but enough that our silent bike all of a sudden got kind of annoying. After the ride I cleaned the bike and belt - and at the same time noticed that the belt could be a touch tighter so snugged it up as well. The belt was quiet afterwards - but I'm not sure if it was the moisture and grit - or the belt being a bit loose that caused it to squeak. Co-Motion tells me that when the belt gets wet it makes some noise. We haven't ridden in enough wet to know how much of an issue that is.

I may squirt it with the hose prior to a ride just to see if this is an issue - but would love to hear from a team in a wet area that might have some more insight for us. Until then I've got the belt snugged (my first adjustment I've made since we installed it - but a sign that the belt does break in some) and it's rolling quiet for now.

Henry Abel

ADDITIONAL - CO-MOTION GATES CARBON DRIVE IMPRESSIONS (Feb. 19, 2009)

I contacted Gates to find out what I can use to safely clean the belt. My usual Simple Green and Ivory soap was given the OK for use on the belt - so I got to giving my bike and belt a good cleaning. I used a toothbrush to gently wipe any grit out of the teeth of the belt. Just didn't want there to be any doubt that the belt was clean so I could make sure the squeaking was not caused by that.

And I snugged up the belt again. Zero squeaking. I'm thinking that belt tension has more to do with it than any dirt that may have been on it. Too loose, and it squeaks some. We did our first race with the belt last weekend. It worked great - but it still didn't keep me from missing the break. *sigh*

Henry Abel

ADDITIONAL - CO-MOTION GATES CARBON DRIVE IMPRESSIONS (Jan. 30, 2010)

With over a year of regular riding and racing on our belt we're totally impressed. We haven't had to adjust tension on it but maybe once in the last year. I used a belt tensioning tool that you can buy at an auto parts store for $9. It tells you how tight the belt is, and is the same tool that a mechanic would use to confirm that a fan belt in your car is at the right tension. This took all the guess work out of getting the belt just right, and in my experience correct belt tension is the key to keeping the belt quiet and will probably make your bottom brackets last longer!

One of our customers was the first, and to my knowledge only, team to break a belt. They violated the number on rule of never rolling the belt onto the rings under tension and the sharp edges of the rings scored the belt. A month later it broke. The belt is very strong with no weight limit, but like a carbon handlebar - once you put a deep score/scratch into it then it becomes very prone to failure. Install it carefully and I can testify that it'll last a very long time.

We've recently swapped out original belt and rings for a new 69T belt and rings only so that Gates could look at our original belt and see how it's wearing (or not wearing). The 69T rings make it much easier to take the belt off and on and was made to allow more people (who don't own Co-Motions) to install the belt on their tandems. Trek and Cannondale tandems were in need of that tiny bit of extra length provided by the slightly smaller rings. The belt is unchanged and remains in only one length.

Henry Abel