Lovely weather here in Rabat Morocco this morning. Was enjoying my daily commute when about 1.5 kilometers into the ride my chain snapped.

Upon inspection my wipperman connex masterlink was gone. Right before the chain parted I had experienced chain suck. I think it caused the master link to compress longitudinaly and the two halves separated. I was eventually able to find one half but the other was no where to be found.

I used my Mt bike as a push scooter to get back to the house where I had a piece of dura-ace chain that I was able to use to splice a link back into the chain on my mt bike.

My mt bike drivetrain is 9 speed and I am almost positive the dura-ace chain was for a 10spd set up but I measured everything with my digital calipers and everything was within a hundreth of a milimeter or so between the two chains.

The spliced link held for the re-run of my commute, though I am a littel pensive about standing while pedaling as I did not have any of the special shimano replacement pins and had to make the splice old school style by partially pressing out the old pins and re-pressing them. Not ideal but it got me rolling again.

So...lesson learned so far from this is that while I like wipperman masterlinks I do not think they are the component to use in situations where chain suck could be a problem.
Other lesson learned is that I am going to order a couple of extra masterlinks and stick one in my seat pouch with my spare tube and tire levers.

I hope the splice I made holds until the new masterlinks arrive...mail here can take a few weeks to arrive. Also glad I was sitting when it happened as some other parts could have been severely damaged.

-j

Wippermann Conex links are supposed to be installed in a specific direction and it's emphasized and detailed in their instruction sheet. I don't know if that has anything to do with your problem but you might want to be sure it's installed correctly if you get another one.

The Wippermann Conex links are held in the locked position primarily by tension on the chain. They were indeed installed correctly, in fact every time I pull the chain to clean it I reference the instructions on the wippermann website because I can never keep straight which way the slot is supposed to arch.

My running partner and I passed through the intersection where things went kablooie this morning and we were able to find the half of the link that I could not find this morning. Both halves are undamaged. What I suspect happened was that this was a total fluke...chain suck caused chain to pivot at that link as well as caused chain to no longer be under tension; conex link pins were able to budge along their channels which then allowed them to come apart from each other.

This was not a catastrophic failure of the chain. It was just a weird fluke. But based on this experience my recommendation to folks with compact cranks and mt bike cranksets is to use a different master link such as one of the SRAM ones...the one that has a more positive lock when connected.

-j