Breezer Posted November 2, 2015 Posted November 2, 2015 Hi all.On the weekend during a race my chain snapped, derailleur broke and three teeth on my chain ring broke. I was accelerating in a standing position and only heard a hard bang. My question is this, did the chain break and caused the damage to the other parts, or did the the chain ring teeth break and caused the chain to slip between the derailleur and chain ring? The chain snapped in three parts. The chain did about 1200km and the cluster did 3000km. The chain ring did about 15000km. The chain is a SRAM 1071 with hollow pins and the crank is a FSA. Thanks
kosmonooit Posted November 2, 2015 Posted November 2, 2015 Chain ring looks very worn, the teeth breaking off could have had a domino effect on the chain.
EmptyB Posted November 2, 2015 Posted November 2, 2015 Don't know what went first but that's some serious mileage on the chain ring...
Breezer Posted November 2, 2015 Author Posted November 2, 2015 Chain ring looks very worn, the teeth breaking off could have had a domino effect on the chain.Remember, you only see the broken teeth, the rest looks much better. Some only chipped.
Bomberman Posted November 2, 2015 Posted November 2, 2015 Lay off the juice dude. Joking I think the chain snapped and got lodged between the derailleur and the chain ring, causing the teeth to snap off. With the amount of kms on the teeth, the material should have some sort of metal fatigue.
JXV Posted November 2, 2015 Posted November 2, 2015 No quicklink visible on the remains of that chain.....how was it joined?
GaryvdM Posted November 2, 2015 Posted November 2, 2015 Where is the master links (aka powerlink)? Is the front derailleur bent? Here is my theory: a link (either the master link, or the other link that broke) opens up enough to create to create a gap for it to hook on the front derailleur. Other damage is a result of this.
BDF Posted November 2, 2015 Posted November 2, 2015 Highly unlikely that the 3 teeth on the chainring would just break. I agree with Bomberman that the chain probably broke. Why do you have such a smartiebox of components if I may ask? It is possible that the varying ages of your components added to increased stress and wear among them and the weakest link gave way. (pun intended!). I have friends who swear by Sram but I have notices that their chains don't last anywhere near as long as Shimano.
Spinnekop Posted November 2, 2015 Posted November 2, 2015 My guess would be your front derailleur moved down.
Breezer Posted November 2, 2015 Author Posted November 2, 2015 Highly unlikely that the 3 teeth on the chainring would just break. I agree with Bomberman that the chain probably broke. Why do you have such a smartiebox of components if I may ask? It is possible that the varying ages of your components added to increased stress and wear among them and the weakest link gave way. (pun intended!). I have friends who swear by Sram but I have notices that their chains don't last anywhere near as long as Shimano.I have a sram chain and cluster only for the ratio of the cluster (26,11). This is my racing combination, I train with Shimano parts. I like having that 1 tooth more when I might need it. The power link was still intact with 1 link on both sides of it. I lost that part if the chain when the recovery vehicle picked me up.
Breezer Posted November 2, 2015 Author Posted November 2, 2015 My guess would be your front derailleur moved down.That make alot of sense, I built the bike about a month ago, so that might be it. Then it was only a coincidence that it happened when I applied full power.
Simonpurdon Posted November 2, 2015 Posted November 2, 2015 Recently did a case study in a Material Science module for mechanical engineering on metal failure. The investigation was on a car accident and they were trying to establish whether one of the drive-train components caused the crash or failed during the crash. From what I can see in the photo of the broken teeth, the failure 'surface' of the teeth looks pretty rough, which would indicate a brittle fracture, as opposed to a smoother surface that would be evident if it the fracture was caused by gradual yielding and plastic deformation of the material. So, as a (sort of) educated guess I'd say the broken teeth were as a result of sudden impact and therefore a symptom of the first thing that went wrong, not the cause of it. Maybe a more clear photo of the top of the fracture surface could help. Thats my two cents. I could also be completely wrong, in which case my exam won't go so well in a few days.
DirtyDan Posted November 2, 2015 Posted November 2, 2015 Everything is just old and tired. Clearly you're not.
'Dale Posted November 2, 2015 Posted November 2, 2015 Could've really hurt yourself there (like losing a few front teeth on your stem) Glad you're okay
Breezer Posted November 2, 2015 Author Posted November 2, 2015 Could've really hurt yourself there (like losing a few front teeth on your stem) Glad you're okayHow I stayed upright is a miracle, my knee hit the handelbar so hard that it turned blue. I was really lucky.
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