jkuper

Went for a ride this morning to test a new bike I built for my wife. Mix of SRAM with KMC X10SL chain. Everything except levers is new. Bike shifted fine for the most part, I was going to fine tune after the ride. Anyway, came to a stop light and when I clipped in to get going again the chain got "stuck". It happened almost immediately after I tried to get going again, I don't think I turned the crank even 1/2 revolution. I looked down an the chain was bunched up/twisted right behind the FD cage.

IthaDan 

Chainsuck

fauxto nick

Did you suck or drop your chain lately? Typically this happens from the chain getting sucked between the frame and the back of the chain-rings or it happens from it getting caught between the front derailleur and chain-rings on a bad shift. Lastly it could be from it coming off on the outside of the chain-ring too. To put it simply, it got caught somewhere and you most likely kept pedaling and the force of your legs twisted it. It's toast.

JerrySTL

I hate to ask the obvious, but is the cassette and chain rings also 10-speed? I did try to count the gears on the cassette.

jkuper

Never dropped the chain. Like I said, aside from few hours on a trainer, this is the first ride on it. It happened at about 26 miles into the ride. I didn't shift, I was in 50/11 before the light and remained in the same gear when I started again.

Yes, SRAM Force crank/1070 cassette, SRAM Rival RD and SRAM Red Yaw FD

OldTryGuy

Chain GREMLINS, nasty buggers they are.

Did you happen to torque on the cranks with the chain crossed, inner ring/outer cog?

jkuper

No I was in 50/11

OldTryGuy

WOW!!!, that is strange.

To me, looking at the bend in the chain could indicate a deflection in the bottom bracket with left pedal power application as the chain came off the cog. Pretty sure the frame wouldn't be that flexible though.

fauxto nick

Pretty odd, I've had a lot of people come in the shop over the years who have said they heard a weird clicking sound and found a chain kinked like this. Upon further questioning I've found that they had sucked a chain weeks before and just noticed it now.

My only other guess is that pushing a big gear like 50/11 from a stop the chain skipped as it came up and onto the 11t cog and tweaked. That being said you would have heard or felt a pop or shudder. Very odd. Pushing 50/11 from a stop would produce enough force to bend a chain though, that makes sense, but only if it misaligned up with the cog and got caught.


I would just put a new chain on it, and when you do have someone check the limiters, check that everything is in good running order and ESPECIALLY that your derailleur hanger isn't tweaked.

jkuper

Could it have happened if I turned the pedal backwards trying to get a better position to start? I am not saying I did but it's possible I did. I will definitely recheck the limits when I get a new chain. I am thinking of just going with a SRAM 1091r this time. I did have the hanger aligned when I had the frame prepped by a LBS. I have no reason to suspect it's moved since. Like I said, light trainer use only prior to today's ride and bike's never been dropped.

hhnngg1

I had the same exact thing happen to me.

Mine was more obvious though - in my case, my chain had come off the front cog (happens sometimes if I shift too fast, even on my Dura-Ace), and I did my normal trick of getting it back on, which was to shift up to the big gear in front and slowly pedal.


Unfortunately, I think the chain caught briefly, and during that time it must have gotten a twist while it was bunched up while I pedaled. It undid itself very quickly, but I immediately noticed a regular clunk with each pass of the chain. When I stopped, I had the same deal you did, twisted link.

My chain was easy to fix when I got home (called a ride for a pickup that day) - used a chain tool to remove the damaged link and replaced it with a KMC missing link. I now have 2 missing links on my chain, but it rides fine.

fauxto nick

Very possible. When you pedal backwards sometimes a chain will miss a tooth and pop up before it finds itself and goes back in. Like I said, assuming your derailleur hanger is aligned, your limiters are good and your cassette doesn't have any marred teeth, this was probably a fluke. 98% of the time though when I see this happen on a bike, it's from chain suck up front.

nhluhr

From a stop? Are you sure your shifters are working?

jkuper

Yes and yes and if you head read the first post you would have seen I didn't get very far

nhluhr

Just wondering how/why a person doesn't shift out of the tallest gear he has when coming to a stoplight.

jkuper

Because I just missed the light

nhluhr

Although it wouldn't really make it acceptable, i wonder if the extreme torque of a 50x11 start-from-stop had anything to do with it.

IthaDan 

No way

popeye

You have the least amount of torque in big small.

merlinextraligh

Really? There are at least 3 ways to ride home in that event: 1) carry a chain tool; 2) "rachet pedal" i.e. pedal short of the point where the twisted link comes to a cog, backpedal, repeat; 3) "hobby horse" i.e., push off with your foot,coast, repeat.

Calling for a ride is admitting failure.

canam73

Or just being a man who lives in reality with work, kids/family and other time obligations that take precedent over some self-centered cycling pride.

cyclezen

my guess...

you were stopped
you, somehow, hit the rear shift lever so that the RD pulleys moved the chain under a larger cog - prolly 2 or more positions over.
chain is still engaged on the small cog as you get out of the saddle and push down.
however chain now also engages the larger cog from underneath, while still remaining engaged on the small one
these chain plates, by their design are less twist resistant than solid plates.
chain is now twisted and as it progresses forward, the first twisted link rides onto the top of the ring tooth it meets and bucks upwards causing the chain to catch/bunch on the FD roof...

there is a chance that a similar scenario could potentially happen if you had hit the front shifter and the FD had moved the chain over so that the chain became engaged on both the outer and inner rings at the same time, again causing the chain to twist. Given the twist, the inner ring because of pressure of the twisted plate onto the tooth, might not have allowed the chain to release under pressure - hence causing the chain to bunch up...

in either case, I would expect that there's a real possibility that the FD cage alignment might be mucked up... I'd check for that, for sure.
don't think there would be any issues with the rear jockey assembly...

merlinextraligh

The chain tool option at least would get you home quicker than waiting for a ride. Next two options would depend on how far you were from home and how fast the ride would get there.

canam73

That part I agree with. I don't ride anywhere without a chain tool and spare quick link in my flat kit.

But if I have a mechanical that is going to both add a chunk of time and negate getting any kind of quality ride in I fail to see the point of wasting the time & effort and I know my wife and kids would rather I made the call and regrouped for whatever else is going on.

hhnngg1

Sometimes, calling for the ride is the best option. It was in my case, I think.

- I don't carry a chain tool anymore. Sure, I could have probably fixed it with a chain tool, but this is like a once in a lifetime event. Not worth jiggering with a portable chain tool, imo. If I were doing a multiday event, I'd definitely carry such hardware, but not on a weekend training ride where I know I can get a ride. My last experience with a portable chain tool was so horrible that I'm sure it would have ended badly and frustratingly so even if I did have a portable chain tool on hand. I'm ok messing with chains at home, but not on the road.

- You want to rachet pedal or hobby horse for 22 miles home with 1200ft of climbing en route?