mburchard

Data point on Gates belt life, perhaps.

We started having groaning noise when under load, pretty clearly the belt, mainly under me (captain), when going uphill. Noise was annoying, and vibration bad enough that seemed like a fair bit of energy going to make noise! Not alignment, and nothing loose. Sent a note to Gates, they said I should check BB/eccentric/cranks. I think probably 3000 miles on the belt, did not look worn, no visible wear on rings. We are just under 300 pounds and reasonably fit.

I replaced the belt, without touching anything else, and groaning noise is gone. Asked the guy from Gates if he wanted to see the belt, no response.

CaptainHaddock

3k and it's wearing out? that's not awesome.

Bent In El Paso

We have more than 6K miles on our belt with only a little wear showing. We get groaning under load under two circumstances...

1) If I get the belt too tight, it will groan (creak) under load. Since I started using the Gates Iphone app to "tune" the belt, I have not had to deal with it being too tight or too loose.

2) When the belt gets dirty, it will groan under load. When it starts doing this, I can spray some water from a water bottle on the front pulley and the noise will go away for a while. I can solve it by using a wet rag and running it through each individual tooth on the belt (like flossing the belt). This gets the dirt out of the low spots and the belt is silent for another couple hundred miles or so.

waynesulak

In summary you have to floss the teeth on the belt every 200 miles?
Does the tension stay set permanently once dialed in or how often does that need adjustment?

Bent In El Paso

200 +/- miles. It just depends on the conditions we are riding in. Since we live in the desert, we don't ride in wet conditions very often which could serve to clean the belt while riding. (Or get it dirtier?) It seems like the dust and sand needs cleaned out of the valleys in the belt where it gets "packed" in by the pulleys. It doesn't take but a few minutes to clean it. It is much faster and easier than dealing with a dirty chain.

Once I get the tension set, it seems stay dialed in. We prefer to take the coupled bike apart whenever we are travelling more than an hour or more to a ride so that we can get it inside the vehicle. Because of that, the belt gets removed probably every couple of months. I haven't had to mess with the tension in between removals.

I'll add that I went through a difficult learning curve to get the belt tension correct. I first used the 10-lbs and 1/2 inch of deflection method. Then I went to the krikit (sp??) tension tool. I could not always get the belt tensioned properly using those methods. If it was too loose, it would not stay centered on the pulleys. If it was too tight, it creaked and groaned while riding. Only after I started using the Iphone app was I able to repeatedly get the tension set where the belt tracks perfectly in the center of the pulleys.

I know others use the belt without these issues. A friend keeps his belt much looser than I do and he doesn't have the same issues. I thought maybe my pulleys were not aligned properly, but I have checked and they are in perfect alignment. Since I have figured out what works on our bike, I just set it up and ride.

Chris_W

Our belt only makes noises when installed in one orientation, in the other orientation it is totally quiet. When I've mentioned this before other people have said that their belt is unaffected by orientation, but I would give your old belt another try in both orientations.

mburchard

Didn't try that, and not a bad idea. But I ordered two spares and the one on there is good for now, so might wait a bit.

On one of the other responses, I do use the iPhone app to check tension, and was/am running at just over 60 Hz. Looser did seem to reduce noise, but loose also seemed a little scary to me.

TandemGeek

I'd definitely go with cleaning the original belt and rechecking to see if that solves the issue. Gates also allows that the use of some CRC 05074 Heavy Duty Silicone Multi-Use Lubricant can be used for anyone who seems to have a chronically noisy belt where soap and water alone don't seem to address belt stiction (vibration) or friction (noise).

I can't imagine the belt has "worn out" with only 3k miles. Short of damaging a belt, they should have a service life of 10k+. In fact, I think we've seen enough reports from high mileage teams at this point to realize the sprockets will likely be what belt-users will need to keep an eye on for cues as when it will be time to order replacement sprockets and a new belt.

Riding in wet conditions seems to accelerate wear more so than purely high mileage.

Ritterview

Gee, in three years and several thousand miles the only trouble we've had with our Gates is the tiresome amazement and inquiries from onlookers that our tandem has a belt!?

Yes...it has a belt.

Deflecting such conversation is the only attention I've paid to the belt. No maintenance, or cleaning, tightening, or flossing or anything.

Our drive chain, on the other hand, I've replaced, and changed, and lubed, and cleaned again. I've got a bin full of drivetrain cleaning products, brushes, wipes, sprays, etc. After cleaning the drive chain, I'd not particularly relish having to turn the bike around and do the same with the sync chain.

So, now that I think about it, the lack of maintenance required is a big benefit of the Gates.

Carbonfiberboy 

As TG intimated, here in a PNW winter I got 1300 miles out of a set of sprockets, completely worn out. The belt was worn but still fine. We never had any noise from our belt. Just used the "feels right" method of tensioning. Our belt never needed retensioning even though we had worn out the sprockets. We abandoned the belt, BTW. With the new lower pricing we might have stuck with a CDX belt, that is, if it had the lower pricing. I liked the "no black marks" quality of the belt and the bling factor was fun, but I thought we were a tiny tad slower with it. I think the frictional losses in a chain are less than the hysteresis losses in a belt.

akexpress 

We have about 6K on this belt and have had one experience with it getting noisy during Cycle Oregon last year. We had some wet roads then some dusty conditions in the same day and it got noisy. I squirted it with a water bottle and no problems since. We are on our second belt only because we replaced one sprocket that had been damaged in the case from packing (it still worked but I did not like the bent lip) and I replaced the belt at the same time. I have used all the tensioning methods and now just use the it feels right method without any incidents. We travel with our bike about 5-6 times a year so it is on and off each time and I do not worry about which way it goes on. I also am not particularly careful with it on packing and just twist it to coil it. I like the belt for the ease of maintenance and have no desire to go back to a chain. I would even consider going to one on our mountain tandems if the spacing was right.

Ritterview

Ay, there's the rub. Literally. Such are chains' efficiency that belts are hard pressed to match. How many watts are lost from that belt? It isn't known. When the Vector power meter is released the question can be answered by having a tandem with two Vector pedal meters and a Powertap rear-wheel power meter. *Ride a circuit with a belt, and then a chain, and subtract the Powertap reading from the sum of the two Vectors. The difference represents drivetrain losses. The difference between the drivetrain losses of the belt and chain is their relative efficiency.

waynesulak

A tandem with one power meter that measures the captain's power at the crank or pedals would be enough to measure the efficiency difference between chain and belt. Captain with no stoker climbs a course at constant speed with belt installed. Replace belt with chain and repeat. Compare power required.

Bent In El Paso

From personal acquaintances and feedback here on the forum, it seems we are the exception versus the norm when it comes to belt tension and cleanliness leading to proper tracking and silent running. I suspect that many of our troubles are the result of the stoker's sprocket being improperly installed by the shop that built our tandem. The rear sprocket was installed backwards by the shop. We rode it that way for probably 2K miles and had constant issues with the belt making noise.

Once I discovered through research that the rear sprocket was installed backwards, I went to Co-Motion for assistance. They agreed to replace the belt, but did not want to replace the sprocket(s). I replaced the belt and corrected the sprocket. Since then, the system has been very sensitive to proper belt tension. Once I get it set up correctly, we basically forget about it except for cleaning with a wet rag periodically when we notice it beginning to make a bit of noise under heavy load.

After reading previous posts about sprocket wear, I am suspicious that the rear sprocket may have worn improperly during the time it was installed backwards. Could that be the reason our belt tracking is so sensitive to tension? Now that the cost of the sprockets and belt have come down to reasonable levels, I am tempted to replace both sprockets and the belt to see if that results in the more robust performance most other users are experiencing.

DubT

The updated CDX system is supposed to be available soon, I have been told after interview. You might want to wait until it is available.

Ritterview

Captain sans stoker introduces variability and thus doubt. Maybe stoker power and weight affects efficiency. No point to going to the trouble of the experiment without a definitive result.

Besides, a crank-based captain's powermeter would need be reversed if on left sync spider, and the stoker crank couldn't be a triple and might be affected by power from the captain. So, for practical purposes, tandem powermeters await the pedal-based solution. Polar/Looks are available now, but these are way expensive and not ANT+.

Finding a 135 mm OLD road wheel with a PowerTap hub would not be easy. Would I be able to use a 130 mm hub road wheel with a spacer?