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Why does chain guide suck at guiding the chain?

canadmos

Cake Tease
May 29, 2011
20,421
19,431
Canaderp
Two times in the last month, my chain has somehow fallen off of chain ring. This is after two seasons of the guide and ring working in perfect harmony.

The first time it happened, admittedly I did crash. The bike didn't bounce around or anything though, the bike just slid with me along the ground. When I got up, I found that the chain fell off the ring (which is what the picture if of). No worries, I assumed it was just the perfect combination of events that led to that happening. Popped the chain back on and off I went...

Fast forward to yesterday and while just riding a long, all of a sudden my bike made the most awful of noises. At first I thought my shock got stuck down and my seat was dragging on the tire or something. But nope, when I finally came to a stop I found that the chain had somehow wedged itself in between the chain ring and the upper guide piece. It was incredibly hard to pull the chain out, I can't figure out how it got in there?

Both times this has happened, I was going fairly fast and in 2nd smallest gear on the cassette.

Am I doing something wrong? Has this ever happened to anyone else?

The chain guide on the bike is an E-Thirteen SRS+ (32t-35t version) and I am also using a 34 tooth E-Thirteen chain ring. I have it set up as tight to the chain ring as possible with minimal rubbing when in the lowest and highest gears on the cassette. All of the bolts are tight, as well as the chain ring bolts. I haven't changed anything on the bike since I put it together last year.

What worries me is having what happened yesterday, repeat itself. I wasn't pedaling when it happened, if I was I most likely would have bent the crap out of the chain guide, my chain ring and god knows what else. IMG205_edited.jpgIMG206_edited.jpg
 

juanbeegas

Monkey
May 6, 2008
355
2
Singapore
Guide not spaced out proper? There shouldn't be enough space for the whole width of the chain to fit between the guide upper and the back of the chain ring. I ran a 32-36T guide on my Spitfire with a 34T ring too, I remember running the guide with the thin washers, supplied with the guide, installed.
 

canadmos

Cake Tease
May 29, 2011
20,421
19,431
Canaderp
That is the thing that I can't figure out, there isn't enough space for the chain to fall between the upper guide and the chain ring. Yesterday when it happened, I was almost unable to get the chain out from between the ring and guide, it was in there that tight.
 

Dogboy

Turbo Monkey
Apr 12, 2004
3,209
584
Durham, NC
Also check for side to side play in the BB. If everything is straight and tight with proper spacing then the chain shouldn't drop.
 

Kanye West

220# bag of hacktastic
Aug 31, 2006
3,741
473
Looks flexy...

No seriously though, the combination of the backplate flexing, the hub dragging and causing upper chainline droop, and the teeth hooking the drooped chain inwards will jam the biotch in there, make the backplate flex inwards, and trap the chain. Seen this a bunch of times. Caused me to have a real hard get-off once myself a few years ago.
 

buildyourown

Turbo Monkey
Feb 9, 2004
4,832
0
South Seattle
Worn chain.
After even a couple months of use I've found that 9sp chains get enough side to side slop to jump out of some guides. They work and shift just fine, but won't stay in a guide.
I've switched back to 8sp because of this and my chains last much longer.
 

JustMtnB44

Monkey
Sep 13, 2006
840
114
Pittsburgh, PA
I have a very similar issue with my Spitfire as well. I am using the E13 XCX guide with a 1x9 drivetrain so it only covers the upper section of the chainring. On rough descents where I am not pedaling, the chain likes to fall off the inside of the chainring and get jammed in between the ISCG tabs and chainring. I was wondering if it has something to do with the chain growth causing excess slack that is not taken up properly when I am not pedaling. I will also check the chain although it is not all that old.
 

CoyoteRun

Chimp
May 29, 2008
56
0
SF, CA
any chance you have a picture of drive side of the bike? Can't really see how you set up with the seat-tube in the way

That is the thing that I can't figure out, there isn't enough space for the chain to fall between the upper guide and the chain ring. Yesterday when it happened, I was almost unable to get the chain out from between the ring and guide, it was in there that tight.