Chain Keeps Dropping While Not Moving

[bentbike33]

@JanaeBixby 146109 wrote:

Every morning, I take my bike off my front porch, get on it, and maybe back peddle about 1/4 turn to get the right footing, and my chain drops from the gears.

Is the chain coming off the front gears (chainrings), or rear gears (cogs)?

Does your rear hub turn freely when you backpedal, or is it sticky?

Does your rear derailleur cage point more or less at the chainrings, or does it kind of point toward the wheel?

[EasyRider]

Silly question, but are you leaning the bike against something when you put it away that is moving the shifter? Or maybe a worn spring is making the cage move in the wee hours.

[JanaeBixby]

@bentbike33 146117 wrote:

Is the chain coming off the front gears (chainrings), or rear gears (cogs)?

Does your rear hub turn freely when you backpedal, or is it sticky?

Does your rear derailleur cage point more or less at the chainrings, or does it kind of point toward the wheel?

The chain is coming off of the front gears, not the rear gears. Well when I first back pedal (for less than a second), it is not sticky, it is just fine until the chain drops, but that is just such a short time as it is almost immediate. If I am out riding and back pedal, no issues- does not drop, not sticky.

Does your rear derailleur cage point more or less at the chainrings, or does it kind of point toward the wheel? No clue. I don’t know what this means exactly but will check this afternoon when I get back to my bike! Thanks.

The bike is not resting against anything that is nocking it.

[huskerdont]

Gremlins?

I’d have to guess that right before you get off the bike, coming up to your house, you downshift and probably do less than one turn of the crank afterward. Then, when you first get on your bike and turn the crank back, it’s trying to go back to where it was and is falling off.

Either that or gremlins.

[tnelson]

Are you cross-chaining at all? (In the big ring up front and one of the big cogs in back.) Derailleurs can be finicky if you pedal backwards when cross-chaining. If you normally ride in a chain ring-cog combo like that, just try using a smaller cog in the back.

[bentbike33]

You should probably ride your bike to the Crystal City Coffee Club (CCCC) tomorrow for a diagnosis from the collective wisdom of the attendees.

[JanaeBixby]

@tnelson 146123 wrote:

Are you cross-chaining at all? (In the big ring up front and one of the big cogs in back.) Derailleurs can be finicky if you pedal backwards when cross-chaining. If you normally ride in a chain ring-cog combo like that, just try using a smaller cog in the back.

I am starting to think it is gremlins! I in fact yelled at my husband this morning that someone is playing an awful trick on me, except I would have evidence of a perpetrator based on all the grease they would get everywhere doing so! Ha! I do not do any shifting towards the end of my ride, as all of the area is pretty flat. I am sure this is not the issue. Because it is so flat around both work and home, I keep my gears pretty even, about midrange one the back gear, and on the large of the two gears in the front. I think that is what you mean by cross-chaining?

In general, I have been doing this commute for years, and it is only in the last few weeks/months this issue started. I can only think it is somehow gear related, as I haven’t changed how I ride, where I store my bike, or the bike itself (other than routine maintenance). I even had my bike get a 1-year tune up done- if I think about it, I am pretty sure this issue started post tune-up.

Based on your comments, maybe its with the derailleur? I think that’s where I will focus my investigation! Thanks.

[Emm]

You mentioned it’s a new chain–has the cassette been changed recently too? Sometimes if they’re worn differently they can cause dropped chains in my experience (eg a worn cassette but new chain). But the bike shop should have caught then during the tune up…

Often if it’s a small issue a bike shop will look, diagnose, and fix within a minute and not charge you, esp if you say it began occurring right after a tune up you had there. Worst case they may charge $20 and then it stops.

[tnelson]

@JanaeBixby 146125 wrote:

I am starting to think it is gremlins! I in fact yelled at my husband this morning that someone is playing an awful trick on me, except I would have evidence of a perpetrator based on all the grease they would get everywhere doing so! Ha! I do not do any shifting towards the end of my ride, as all of the area is pretty flat. I am sure this is not the issue. Because it is so flat around both work and home, I keep my gears pretty even, about midrange one the back gear, and on the large of the two gears in the front. I think that is what you mean by cross-chaining?

In general, I have been doing this commute for years, and it is only in the last few weeks/months this issue started. I can only think it is somehow gear related, as I haven’t changed how I ride, where I store my bike, or the bike itself (other than routine maintenance). I even had my bike get a 1-year tune up done- if I think about it, I am pretty sure this issue started post tune-up.

Based on your comments, maybe its with the derailleur? I think that’s where I will focus my investigation! Thanks.

Yup, doesn’t sound like cross-chaining so my next guess would be the front derailleur. May be worth it to just take the bike by a shop for diagnosis. Otherwise, I don’t know any natural predators of gremlins. (I think sunlight?) Good luck!

[Steve O]

Is it dropping to the inside or the outside?

Tomorrow, before you do anything with your bike, kneel down and look at the how the chain is engaged on the front chain ring. Particularly at the bottom. Since this is happening when you reverse pedal, it means that the chain is disengaging from the teeth on the bottom of the ring. (not caused by front derailleur)

If your chain is long and loose (rear derailleur spring going bad?), I suppose it could hang slightly to the side of the ring–just enough to disengage.
Do you pull up with your right foot or your left when you get on the bike? Try the other foot next time. To do so, you’ll have to lean the bike the other way. It will be interesting to see what happens.

Also, try this. Before you get on your bike, stand it up, kneel down and very slowly reverse pedal with your hand. Watch the bottom of the front chain ring to see what the chain is doing. If it stays engaged, try faster to see if that does anything. If it stays on, then you’re good for the day. Come back tomorrow and try again.

One more question: do you ever reverse pedal while riding? If so, does it drop then, too?

[BobCochran]

Here is my idea. Have you used this chain for a long, long time without ever cleaning it and lubing it? If so, you might have worn out the chain and the cassette (the little cogs on the rear) and the chainrings (big rings up front.) Not cleaning the chain, casette, and chainrings can cause them all to wear out. And the chain skips or otherwise misbehaves. I am really bad about drive train cleanings myself, and the last time I brought my Giant bicycle into the shop for a tune up, the chain and rear cassette had to be replaced. I’m trying to do better in terms of frequent cleanings.

Bob

[Steve O]

I am now ready to declare my “Stump the Chump” answer. I had time to think about this on my ride home, and I am confident that I know the solution.
All the clues are there in your original post and your follow ups.

Ready?

Your new chain is too long. When the shop gave you the new chain, they did not adjust it for your drive train. I bet if you look at it when you park the bike, it is not nice and parallel to the ground, but a bit saggy. When you lean it at work or overnight it moves over a little bit against the front chain ring–just enough that when you turn the pedals backwards, the first tooth doesn’t quite engage right and then the chain gets pushed over and off. I suggest you remove a link or two or three from your chain and your problem will be solved. No gremlins involved–just a sloppy mechanic at the shop.

I am willing to put this theory up against any other “Chumps” on the forum who think they have a competing theory that is better. If yours is “righter” than mine, I will buy you your next coffee at coffee club or beer at happy hour.

[mstone]

Booo-gus

[Vicegrip]

1. A worn and or dry loose chain will be more prone to dropping when cross chaining. I see this on my day to day bike. when it is close to the .75 mark it will drop on a crossed up back pedal.

2. Don’t back pedal. Poor form and 100% not reason to do so other than being human.

3 “B” setting on the RD pivot and or it sticking can cause a slack chain. Overly slack chain can cause drops. Add in crusty jockey wheels for the back pedal win.

bkes are not complex. Dirt, wear and adjustment are most of any issue.

[FFX_Hinterlands]

OK, now I’m on the edge of my seat. This is the BBS/bike version of “Car Talk.” Someone figure this out and post it back here already!

[Author]

Posts