On our ride today we rode through the local park on the bike trail, going down a small hill at a nice clip we kicked up a piece of debris and it passed through the Gates CDX belt and the rear sprocket. We stopped and found that it had actually caused the belt to ride part way off of the sprocket. I carefully turned the crank and it did pop back into position. I would have preferred to have loosened the eccentric but I did not have a long Allen wrench with me. I will add that to the tool kit.

We proceeded out of the park and made a left turn into a subdivision where the road crew had repaired some cracks in the asphalt with that patching material that we refer to as tar snakes, I negotiated them very carefully but still felt a little slip. It seems like they are slicker after a rain when the sun hits them and warms them up.

Us too! Bizarre coincidence.

Last night my stoker let out a squeal as I heard a snapping and clatter noise from the rear section. Turned out we had a twig flip up into the rear belt/ring area, and it stuck in the ring teeth for a couple revolutions, whipping around and hitting my stoker's left leg twice. The twig shredded and was gone before I was informed of what just happened. No apparent damage to bike, belt or stoker. No real difference than an occurance we previously had with a regular chain and timing ring.

Look up Joseba Beloki on you tube and it will tell you all you need to know about tar snakes.

Y'all have spare belts on hand, right???

I only ask because that's the one thing that I've looked at as the limiting feature of belts for off-road tandems: the ability to deal with ingesting nature between the belt and sprocket without damaging the carbon fiber strands inside the belt.

Getting a stick or other debris picked-up and sucked into the sync drive on a road tandem is a fairly rare occurance. However, on Off road single track here in the heavily wooded places we ride it's not at all that uncommon to ingest a branch and see it quickly chewed up by the chain & rear ring teeth or to simply have the rear chain either get derailled or moved a few teeth and end up out of sync.

So, looking once again at the special handling instructions on the belt and how a bend, kink or the act of hyper-extending the belt such as by rolling one on or off a sprocket vs. loosening the eccentric I would be inclined to keep an eye on the section that ingested debris just to make sure there aren't any signs that the core may have been damaged.

"Tar snacks"? Yuck. Doesn't sound good to me, either.

I did remove and inspect the belt and sprockets after we got home, everything "looked" good. I do have a spare belt. I actually checked the belt tension with my iPhone after getting the belt back in the groove and it was the same as originally set.

They are really good with mashmallows.

Not so rare for us. Many rides start with a short trip through a local heavily shaded multi use trail often in low light conditions. Every storm brings fallen twigs of various sizes. We avoided a couple Sunday and stopped to clear the path of one larger one.

Well, as another cooincidence, I had ordered a spare CDX belt yesterday afternoon - before the "twig-suck" ride.

I did not search for that "twig-suck" term and think I just invented it. Should I add a footnote... "copyright pending"?

Sure if you have the money to protect it. Apple in CA spent a lot of money "protecting" that word as its property and it took decades to settle with the Apple record label, started by the Beatles many years earlier. Really "Apple" and "Windows" ? Hardly as original as "Coke" or "Xerox"

I just got off of the phone with the tech at Gates and he suggested that I replace the belt and keep the old one for a spare. Since the belt was stretched by partially coming off of the sprocket, it may have broken a carbon strand. There is no way to monitor the stretching as the method of failure is catastrophic!

I will replace the belt! As he said if it does fail and the captain is standing it can be very uncomfortable! Stoker would not be happy pedaling home while I got a free ride.

:/

I am seeing zero marks on either ring or belt. Since our twig-suck event seemed to be less severe than yours (no mis-ship, etc), I think we are ok to keep using it as is. Not all twigs are created equal. lol.

At a little over $100 a pop shipped, I'm not sure how feasible it would be to use on a mtn tandem trail riding. That's one expensive chain maybe needing a frequent refresh.

The issue with mine is that the belt came part way off of the rear sprocket which elongated it. It might be fine but it will become my backup belt.