Sudden chain stretch

[PauliusD]

Hey everyone,

Has anyone ever experienced a sudden big stretch of their chain?
For context:
I had a trip of a 1000 miles the previous weekend (did check the chain slack before the trip, right in the middle of the spec) and 800 miles in I heard some loud clicking from the back wheel. I stopped dreading the wheel bearing let go but no, the chain was extremely loose. So lose that it chewed up the chain guide where it needs to be replaced (the one on the swingarm).
I have to mention that 60% of that trip was in the pouring rain and highway speeds. Wanting to get out of the rain did not really inspect the chain during fuel stops. Also cleaned a bucket of sand when dissasembling for the chain and sprocket replacement.
The chain was already ~20k miles old, but in my multiple 3k+ mile trips nothing like that ever happened. So seems a bit odd
Anyway, all parts ordered and waiting to put it back together

 

[Gary in NJ]

Also cleaned a bucket of sand when dissasembling for the chain and sprocket replacement.

I've ridden dirt bikes with o-ring chains in deep sand countless times, and I've never had a catastrophic failure of a chain. Are you sure that your adjustment didn't slip? It's more likely than having several hundred o-rings fail at once. Inspect the length of the old chain from the new one - what's the difference in length (same number of links)?

Modern o-ring chains rarely fail...heck they don't even need to be lubed (they are lubed internally) that often. Seriously, lubing an o-ring or x-ring chain just guards against potential surface rust and keeps the rollers...well...rolling. Maintaining proper slack is more important than lubing your chain every ride. Driving solvents into the o-rings (what most chain cleaners are) will destroy an o-ring chain faster than being dry on the surface.

According to Ryan from Fortnine - clean your chain with WD-40 or Simple Green with a rag, and lube with gear oil.

 

[PauliusD]

Are you sure that your adjustment didn't slip?

Hey Gary, thanks for the reply.
I've doubled checked this and the adjustment screws are tight. Also both of the adjusters are adjusted the same so would not make sense that both of them slip and the exact same amount.

The old chain is already disposed off and I completely forgot to measure the new chain with the old one.
I did however inspect the old chain when it was off the bike, the x-rings have seen better days and it was so full of sand and dirt it was way stiffer than usual. A few links were begining to seize up. The front sprocketwas pretty worn (was ok about 2,5k miles ago), but that was also probably chewed up by the really loose chain

It is really weird as I never heard anything like this happen to anyone. The chain looked perfect before the trip - clean, lubed up, no stiff links and the slack was in spec. And yes, the slack was measured on the center stand, not the side stand. Guess this will be another one of life misteries

 

[Gary in NJ]

The o-rings must have been failed or darn-near failed prior to the trip - and the constant rain may have driven out any remaining lube behind the rings. Honestly, I can't remember the last time I even had to adjust a chain that had less than 20k miles. Maybe sudden death is the failure mode of these chains.

 

[PauliusD]

Gary, with you mentioning F9 - It also could be my fault for the gnarly looking x-rings as the chain was being cleaned mostly with kerosine. Looking back at that video, it does show how easily kerosine seeps past the o-rings.
Will stick with simple green for the new chain.

 

[tuning-forks]

Were you riding in gravel? From your description, the chain was cleaned then you went on the trip. At some point you had to clean out a lot of sand and the chain was badly stretched. I would guess the grit either worked it's way into the rollers or ate at the sprockets. You said you also had rain, so that may have also removed any lube. When replacing the sprockets, compare the new to old for wear.
I have to ride through a few miles of gravel every day to get to the pavement. It shortens the life span compared to pavement only usage. You said the chain had 20 thousand miles on it. I feel lucky to get 10. When they are worn out they stretch fast.

 

[PauliusD]

Were you riding in gravel?

I rode paved roads only during this trip, but we tend to get quite of bit of sand on the roads during heavy rain.
But yeah, I'm more than happy with the 20k+ lifespan of the chain. Was weirded out that it stretched so suddenly