What makes the chain fall off?

[drplasma64]

Today, my chain fell off 3 times in a 7 mile ride. At least 2 of 3 times it happened when I was shifting the front from the big chainring to the little (I have a double) at the bottom of a hill when I was preparing to either go up again or to stop at a light and wanted to be in an easy gear to cross. I *think* I was in a middle gear in the rear (but could have been on the 2nd out of 6). I'm thinking I shifted too soon and was going to fast and couldn't keep enough pressure on the pedals, does that make sense?

[Trek420]

hey there dr.plasma.

first read this thread about shifting under load, then take two asprin and call...just kidding, start here and see if this helps.

It sounds like you're shifting under load, you can shift under the stresses of climbing but it takes skill and practice and ..... tips from TE...start here:

http://forums.teamestrogen.com/showthread.php?t=2868&highlight=shifting+load[/url]

[drplasma64]

Trek, actually it's exactly the opposite...I think I'm shifting without ENOUGH load. I've read threads about downshifting before you stop so you are prepared to start up again, and I think I'm going to fast when I do it. Would that make sense? I did better when I didn't think so much about shifting It's easier in a car, just shove that baby into neutral!

[runnergirl]

Chains shouldn't fall off-I'd say there's something outa whack with the front dr. or there's a compatability issue of some sort. What kind of bike/components do you have?

[Wendy]

I had this problem for the first several weeks after I got my new bike. After taking it back to the shop twice for adjustments, I took it to a closer LBS, and the owner took one look at it and said the derailleur was too high. I've only been out on it once since I got it fixed, but it's been perfect so far.

Park Tool has some info on this; scroll down for a photo of how close your derailleur should be to the chainring. It really can make a difference.

I have front-derailleur confidence again!

[bikerchick68]

I agree to get the bike checked! I had an issue with my chain falling off te first bike I owned and as it turns out when they tried to do a "tune up" they found that the frame was 6mm out of alignment and they had to replace the frame with a new one!

Chains should not fall off that much no matter how good/bad a shifter you are... good luck with it!

[drplasma64]

Yeah, something is out of whack for sure. The chain had only fallen off once since I started riding again, and then all of a sudden it's having huge problems. All the components are the originals...(except for the chain) shimano SIS derailleurs, biopace crank.

It really has gotten bad since my first ride after I changed my tires. Tonight I just rode on the small chainring after the first time the chain fell off (a block from my house). I had two ideas:

1. My frame pump fell off on that first ride with the new tires...could it have hit the FD and put it out of alignment?

2. I read that the RD has to be aligned first before adjusting the FD...is it possible that when I put the back wheel back on, the RD is no longer where it should be (relative to the freewheel), and so that's affecting the front shifting?

Or could it just be that cables are stretching? I had a tune-up about 60 miles ago.

Also, I checked that park website...it sure looks like the FD is WAY too high to me, but that isn't something that has changed recently.

Sorry, I guess this should have gone into the maintenance forum. And I'm definitely going to sign up for a bike maintenance course!

[CorsairMac]

you said the chain really started having problems after you changed your back tube??

Forgive the duh question but are you sure your back tire is fully seated?? I was having major problems with shifting one day last winter - could NOT get the chain to shift or when it did it kept jumping the cogs. When I got home and looked at the rear cassette I noticed my back tire wasn't seated on the hub. Oops! Once I reseated the tire, my chain issues went away.

[drplasma64]

Not a "duh" question at all. I think it was OK. I took it to LBS yesterday, and told them about both the tire changing (explaining that I was a totally newbie at that, and also wasn't too swift with the quick release) and the pump falling. She seemed to think it was just a FD adjustment that was needed. We'll see! Hopefully I'll get a chance to pick it up tomorrow.