TreeUnit

I recently installed a Shimano 105 5600 9spd Groupset on my BikesDirect carbon frame.

Shortly after installation, the chain broke off. It did this several times, in fact.
I got the chain on securely (or so I thought). The next day while riding at low speed, the chain, rear derailleur, and cassette were tangled somehow. The derailleur hanger ended up being ripped off of the frame. I removed one damaged chain link, attached a new hanger (it was a screw-on, luckily) and reassembled the drivetrain.

About a week later, when beginning a steep ascent in low gear, a similar tangling happened, and the derailleur hanger was ripped off a second time. I again removed a broken link, and attached a new hanger.

My bike rode fine for several weeks, until today, another link ripped out while riding.

Can anyone provide me some insight on this issue? I have installed many, many chains and never had one do this to me.

Attached are photos of the second derailleur entanglement, and a typical chain break.

gyozadude

Is it happening while cross-chaining? (Big-big combination?) You might have insufficient chain for that and it rips the RD off and destroys the chain link. How are you connecting the chain?

TreeUnit

I do not have a master link, so I am connecting the chain links directly with a chain tool. The derailleur ripping might have been from having too much chain slack, but I cannot figure out the cause of the repeated chain breaking. I do not believe there is any gear in which the chain has been breaking. I have tried the chain long and short and many lengths in between, and it continues to break.

dsbrantjr

Are you using the special Shimano joining pin to rejoin the chain? It is required for successful rejoining of the chain and there is a different model for 7 and 8 speed, 9 speed and two diffferent ones for 10 speed chains. Trying to reuse the original pin after pressing it out will cause chain failure since the factory peened-over head will be sheared off. Another alternative is the proper model of master link. Here is the Park Tool procedure with an explanation. https://www.parktool.com/blog/repair-...railleur-bikes

If your chain is properly-sized and you remove a link after it breaks the chain will then be too short and can result in the kind of damage you are experiencing if you shift into the big-big combination. Only in a dire emergency should you run a too-short chain.

TreeUnit

I was wondering if the chain might have been special like this. I have never heard of this chain variety. I think that is the problem. Thank you.

gyozadude

First of all, new narrow chains -require- new pins or master links for re-connection. Failure to follow manufacturer suggestions will result in chain failure. Using just the tool is likely to lead to failure.

But that said, you need to describe the reason why you've had several RD hanger breaks and you aren't in the hospital from crashes. Typically, when a chain breaks under load, you're pedaling with some power on the pedals. The chain fails catastrophically on the upper section and you lose all tension and spin really fast, lose balance, possibly slip out of the clips on the forward prone foot, and fall badly, possibly twisting or tearing the other foot/ankle or tearing a knee or breaking a collar bone.

But you haven't described any of that. So you must not have been hurt significantly.

So that suggests that the RD hanger failure was catastrophic but occurred first and the destruction of your chain was the result of you continuing to pedal and pull the whole RD up and around through the cogs (as witnessed by the picture where the cable housing is underneath the chain - meaning the chain was still under tension when the hanger broke). So the chain didn't break first. It was what pulled the RD up and around, so it was still connected. The break came later. The only other phenomenon that might cause the RD to wrap is loss of freewheeling function (a siezed freehub). If somehow you broke the chain at exactly the same time the freehub siezed and went into "fixie" mode, then it could snap off the RD hanger like that. But the probability of simultaneous failure like that is near zero.

So something broke off the hanger. Most likely, it's a chain that is too SHORT. Without threading the chain through the RD pulleys, does the chain wrap around big cog and big front chain ring with some slack? Like about 2 - 4 half-links? If it doesn't you've got potential to break off the hanger and destroy your drivetrain.

AlphaDogg

So now get a new chain, make sure it is the correct size for your big/big combo, and connect it with a master/power/whatever they call it link.