bikecommuter13

I have experienced chain drop often recently. When I shift from the big chainring to the small one, the chain will drop sometimes. And I notice that if I keep fast pedaling during the shift, the ring will catch the chain more likely than not. If I forget to pedal during the shift, then it will likely drop.

I have brought the bike into the shop so many times. When they put the bike to the stand, things seem fine. But they can't fix the problem.

I tried to put the front derailleur closer to the ring last time, but it messed up the shifting cable...

Why is this so difficult I am a little frustrated. Is it possible I got a lemon bike?

A side note, I have ridden this bike for about 1300 miles so far, the cassette is worn out according to the shop, but the chain is still ok. How likely is this? Isn't the chain supposed to wear out before the cassette?

RPK79

Huh? The chain can't move from one ring to the other if you aren't turning the crank, let alone fall off.

1983

RPK's sig line made me laugh because it's ironic.

What's the tooth difference between the chainrings in question?

RPK79

/shrug

1983

Your shrug is over?

bikecommuter13

If my legs got lazy and don't pedal fast enough, after the shifting, it will most likely drop. Like when I am coming to a stop, I shift to the small chainring, and just don't pedal after that...

RPK79

So you kind of get it half shifted and then stop. Easy fix is to just stop doing that.

habilis

If you want to try taking control of the situation yourself (instead of being at the mercy of the LBS), there are many good on-line tutorials and videos about derailleur adjustment. As RPK79 said, you have to be pedaling - but not hard - in order for the chain to shift to either a new ring or a new cog. Just keep the pedals gently rotating.

The front derailleur has two limit screws. They control how far the derailleur can move either toward or away from the bike when you shift. When properly adjusted, the derailleur will be centered above the small ring when it's nearest the bike (farthest to the left). It will be centered over the large ring when it's farthest away from the bike (farthest to the right). If the derailleur exceeds these limits and moves left of the small ring or right of the big ring, it's out of adjustment, and your chain falls off.

Improvise a workstand by hanging a rope from you garage/basement ceiling and passing it around the saddle or top tube, and raise the rear wheel off the floor. Fiddle with the left limit screw and watch how the derailleur moves. Line it up with the small ring as described above. Rotate the pedals while shifting and see the effect of your adjustment.

Another possible cause of your trouble is cross-chaining. That's when the chain is on the small ring and smallest cog, or on the big ring and largest cog. This can cause erratic shifting and maybe even throw the chain off one or the other ring; it also cause premature wear of the drive-train components.

Read Sheldon Brown's website for help with bike issues.

TandemJon

Check the ring teeth difference isn't too much.
Check the derailleur isn't pulling the chain over to far. (Adjustment screw usually).
Check the rings aren't out of shape. Spin the cranks with the chain off and view them spinning.

fietsbob

N gear Jump stop .. get one .. N-Gear, Home of the Jump Stop there are others to do the same job.

KLiNCK

^
This.

You've got to keep the crank spinning until the shift is complete!

bikeman715

Part of the problem can be frame ( BB) flex , when you pedaling if it hard pedaling the frame can and will flex ( every bike does it to some degree . ) and when your does it drop the chain . It like having the derailleur not adjusted right . The best thing to do is light pedaling as you change gears . It better for the drivetrain anyway . As far as the chain wearing out before the cassette that normal . You should go thou 2 or 3 chains before you change the cassette .

dsbrantjr

The Park Tool site has one of the better procedures for derailleur adjustments:
Front - Front Derailleur Adjustment - Park Tool
Rear - Rear Derailleur Adjustment - Park Tool

Follow them from the beginning without skipping ANY steps. Do not leave too much clearance when you set the low limit, a millimeter or less is enough.

I also use the N'Gear Jump Stop (and recommend it) but it is more of a belt-and-suspender thing for me; I don't use it as a Band-Aid for improper adjustments.

CliffordK

Also look up Chain Catcher. I'll occasionally drop the chain, but it is so rare that I don't worry about it, so I haven't paid much attention to them.

Oh, I did have some problems recently that was due to a badly worn chain. Replaced the chain (and cassette), and no more dropped chains.

jyl

Details? What model and year bike?

Cassette can't wear out in 1300 miles. Cassette doesn't wear if chain is not wearing. Something is wrong, maybe the bike, maybe the bike shop.

fietsbob

A Pro level chain catcher for Non round Carbon frames is K Edge's chain catcher Road Braze-on Chain Catcher - Road - K-EDGE Chain Catchers

bikecommuter13

2013 fuji sportif 1.3 purchased back in June this year.

It does look worn out right? So I am not sure if they put an old cassette with the bike? Or did it age?

2manybikes

Did you buy this bike new?

Did the shop suggest a chain catcher?

jyl

Hmm. The middle cogs do look worn. Do you clean your drive train, lube your chain?. That seems like a lot of wear for 1300 miles. Unless you never clean/lube. Or, as you've wondered, if the parts weren't new 1300 miles ago.

CliffordK

It is hard to tell from the one view, but that cassette doesn't look too bad to me. The non drive side of the teeth are often rounded from the factory.\

On the drive side of the teeth, I'm not seeing much mashing of the teeth or elongation of the slots.

Retro Grouch 

Are you an idealist or a pragmatist?

My idealist side, in search for the perfect adjustment, won't let me put any extraneous "stuff" onto my bike so I spend my day seeking that adjustment sweet spot and feeling depressed about not riding.

My pragmatic side will slap on the $10.00 "Jump Stop" (or similar gizmo) and spend the rest of the day actually riding my bike but feeling guilty about having that "thing" on my seat tube.

rydabent

If a bike mechanic cant keep this from happening, I believe there is a guide/retainer that can be put on the seat tube to keep this from happening.

Wrenchspinnerjr

Seems like a limit adjustment to me. As far as your cassette, are the tops of the teeth flat or more to a point? It they are pointed then it is likely worn, but at 1300 miles I doubt it.

Retro Grouch 

You might not be talking to the shop's most experienced mechanic.

Cassettes commonly have some irregularly shaped teeth to improve shifting. Lots of folks mistake those funny looking teeth for wear or damage. There is zero chance that you've worn out a cassette in 1,300 miles.

fietsbob

If you replace the chain early the cassettes Last Longer.