Hi folks,

Well... I hit my usual trail the other day and, about 3 miles into it, my bike started shifting gears on its own... then, the cause became obvious when my chain dropped off my bike. Had to walk my bike back to the car in my clipless shoes... I know some of you are very familiar with doing that.

Now, I know people snap older chains from time to time. However, mine was not old... it had less than 700 miles on it. IMO, that doesn't seem like very many miles for a chain, but I could be wrong.

I had washed my chain a few times using one of those plastic snap-on chain degreaser gizmos... but, that couldn't have possibly caused it, could it? Also, when I got my bike, I had them remove the 11/28 cassette and install the 11/32 version, planning to go back when I'm in better shape. I don't know if they replaced the chain with a different one or not, but I do know they swapped out the rear derailer. All of it was supposed to be Ultegra (full gruppo). It served me well until just the other day...

Although I sometimes crank it pretty hard, I'm certainly not a sprinter, or even a racer. Also, living in Texas, the highest hills I might climb would still only be measured in 100's of feet, not thousands.

So, nothing about the chain seemed to indicate why it snapped. Unfortunately, I couldn't find the rivet through the links in question, though one link was obviously bent outwards (that probably happened after the rivet came loose). I played it safe anyway, and had them install a brand new chain... so, why the original chain broke is kind of moot now.

Nevertheless, I'm still curious...

Has anyone had a chain break that was this new? Did you figure out why it happened? I can't believe it's a brand problem... Ultegra is supposedly great. Any experiences and/or speculations are welcome.

Maybe when you had them install the 11/32 cassette, they had to add in a couple of links. Instead of using the Shimano pins, they may have used a chain breaker to partially push out a pin, then push it back in.

Or maybe they didn't lengthen the chain, therefore making it too short and you shifted into large/large.

Or sometimes things just happen.

Forced shifts too hard? repeatedly...

That goes double for MTB's Off Road..

Moved here from general

did it possibly snap at the joining link? My only chain failure ever happened at the quick link

This was my first thought. Hopefully they joined (and sized) the chain correctly this time, and, if they used Shimano pins, they used the correct pin for the chain. This kind of uncertainty is why I do my own work (and use quick links on my chains instead of "special joining pins").

The way I see this post is that since you don't have the broken parts to inspect there is no way to know what happened. There are plenty of ways a chain can break. There are thousands and thousands (millions?) of trouble free Ultegra chains that have been produced. Chalk it up as another bike experience and move on.

Same here. I once damaged a rim and had the shop where I bought the bike build up a new wheel. When I got the wheel home I noticed that, while the rim was true enough, the spoke tension was all over the place by large amounts. Since that experience I have learned to true my own wheels and as much of my own maintenance as possible.

The 'broken' chains that I have seen were the result of not being assembled correctly. The pin is not plaece in the outer hole correctly, whitch will bend the outer plate, and fail quickly. The invention of quick links makes putting the chain back together with a chian tool, and not doing it right, a non-issue. It's quite possible the bent plate you found was bent when the chain was put back together, and the point of failure.
BTW, before I started using quick links, I did many road side chain repairs.

I've done three roadside repairs but all on other people's bikes, never on my own, and have used Shimano chains and their joining pins for the vast majority of my 30 years of riding. Assembled with any reasonable care, the Shimano pins are very reliable. Master links are convenient but they can be assembled incorrectly too.

I know it's not possible to really know what happened without examining the chain in question... I'll know to keep it next time.
Regardless, I was just hunting around for opinions from Those That Know here at the forum...
My chief suspicion was that the chain was installed badly, but it's really too late to point fingers. Thanks for the replies!