Lachlan

First, if this has been addressed before I apologize. I tried searching the forums, describing the problem as best as I can, but when you aren't sure what is wrong it's hard to look intelligently for an answer

So, 2 questions:

1. When I have the bike shifted onto the smallest ring in the back, the chain slips off and gets stuck between the chain ring and the frame. Is there anything I can easily do to fix this?

2. What is the least likely way to damage the frame for me to get the chain unstuck?

And, I suppose, 3, with the Shimano 105 shifters where you push the small lever in to go to a smaller gear and the larger lever in to go to a larger gear, is there an easy way to tell what gear you are currently in?

Thanks for any help

operator

1) High limit screw adjustment needs to be turned clockwise. Until it doesn't jam or until it doesn't want to shift into the smallest cog, then start backing it off (counterclockwise) until it does.

2) There isn't one.

JiveTurkey

#1: If I understand question 1 correctly, I do not think this is a mis-adjusted rear derailleur. It's just less than ideal form. It sounds to me like you are using the small chainring/small cog combination. The chain may be falling off the inner chainring due to insufficient chain tension and/or cross-chaining. In general, you should not use this gear combo (nor big/big).

Also, make sure the LOW limit screw of the front derailleur is tight to the point that it JUST allows the small chainring/largest cog combo.

#2: Probably the safest way to do it is remove the right crank arm, though that's impractical on the road. Using a chain tool may work too.

#3: Just look down. Or you can shift to the lowest gear, then count up from there.

operator

Sorry, I don't see how chainline causing a chain jam on the lowest cog doesn't fit under "misadjusted RD". This is what the high limit screw was DESIGNED to do.

If you want to play the what else can cause this problem assuming nothing is working properly/not bent/compatible then you better start an encyclopedia.

JiveTurkey

The OP said the chain gets jammed between the CHAINRING and frame. If it was falling between the cog and frame then, yes, it would likely be a misadjusted high limit screw on the rear derailleur. It seems more likely that that is what is happening, but I'm only going off what the OP wrote. In either case my advice is not any less sound, as is not yours, so no need to get defensive.

roadfix

The OP probably meant cog.......at least that's how I read it.

Lachlan

Thanks for the help. I did a few quick google searches on cogs and chainrings and it is the cog and not the chain ring. Sorry for the confusion.

operator

[QUOTE=JiveTurkey;5582335]The OP said the chain gets jammed between the CHAINRING and frame..[/
QUOTE]

Even if that were the case, you are still wrong. There is NO reason chains should jam on a properly adjusted, non-damaged, everything compatible bike repeatedley.

There may be that rare instance that a big enough bump while shifting causes the chain to jam between the inner chainring and bb, but it should be a rare occurence.

2_i 

The are other similar accessories on the market, but only the one below in my experience, AJ's Frame Guard,

https://www.cambriabike.com/shopexd.asp?id=14233&page=AJ'S+FRAME+GUARD+FG-1

is of the type 'mount it and forget it'. Cheaper ones on the market principally delay the problem reoccurrence.

greyghost_6

Yeah its your limit screws. I think that Dura Ace made some little shift indicator, that came with their shifters for a while that everyone threw away. It was about the thickness of a pencil and maybe 3" long. that needed to be installed just after the cable comes out of your shifter. I think they are calling it an "Inline Shift Indicator" Looks pretty nifty if you are into functionality instead of performance around 13$. And if you wanted to spit up around $100 for a Flight Deck cyclometer to fit into your shift lever and bars you can fully utilize your shifters buttons and stuff. These are trick! Wish I had one...

Inline Shift Indicator:

JiveTurkey

[quote=operator;5583443]Seriously, take it easy. Not all bikes are properly adjusted (obviously, or else the OP would not have had a cog problem). I was just trying to cover all the bases. If it makes you feel better. You were right. I was wrong. I'm done, let's move on.

cyccommute 

operator had it right the first time. Your high limit screw on the rear derailer is misadjusted. Once adjusted properly, you won't need to worry about it.

Lachlan

Thanks for the help. I adjusted the screw that I'm pretty sure is the high limit till it wouldn't shift to the smallest cog, then turned it counter-clockwise just till it would. Hopefully I won't take anymore chips out of the finish of my bike...