Good luck exeeded bad luck, when my chain broke today: No damage to my
brand new (too expensive) winter jacket, when I fell. And I could make use
of my road aid insurance and was picked up within 20 minutes after I phone
for help, just as I started to freeze. So all in all I felt like winning
But broken chains are not on my list of likely cycling incidents. I could
cary a chain tool and a connecting link, but never bothered, because in my
long cycling life with 9000 km a year, I have experienced a broken chain
only once before. Which was the result of my ignorance six years ago of
the fact, that pins in a Shimano chain cannot be reused (any more). I
wount make that mistake again.
I have four bikes: three of them with 9 speed and one with 10 speed - and
the chain that broke today was the 10 speed, with (only) 1755 km on it -
and it was still shifting perfectly. When I bought the bike two years
ago, the shop keeper told me, that 10 speed chains should be renewed every
1000 km. But I keep a clean chain and check it with a chain wear
indicator, and the last chain lasted 2665 km. Anyway a chain should not
break from normal wear, should it?
Being an old cyclist I tend to prefer the way things were done before, and
instinctly I assume that nine speed is better than ten speed.
However the ten speed system has been working perfectly for me for two
years, and I was beginning to consider, that maybe 10 speed wasn't that
bad after all and maybe my next bike should also be a ten speed.
The chain broke today while I was accelerating after a stop, and on top of
my natural 90 standing kg I was pulling hard, so there was max load on the
chain. But again, a chain should not break through normal use, should it?
Both sideplates in the same link were broken through the pin hole but in
opposite ends: One side broke first causing the other to break,
evidently. But that doesn't look like it was the pin slipping out of the
hole. "The sideplates could not withstand the load" is the conclusion of
As I am writing I am looking at two new Shimano chains from my stock. A
CN-6600 like the one that broke and a CN-HG93 which I use on my 9 speed
bikes. And clearly the side plates are thinner on the CN-6600. Are they
too thin? Are they so thin, that you must renew the chain after 1000 km to
prevent chain breaking?
I have bought an extra Ultegra 9 speed crankset and a buttom bracket to be
sure to have spares, when you can only get 10's. That is because of my
conservative instinct, I'll admit. But is my lucky fall today an
indication that 10 speed chains are not as strong as they should be? On a
scale from 1 to 10, how good was my conservative instinct to stick with
the 9 speed as long as possible?. ;-)
Ivar of Denmark