Bicycle Mechanics - No idea what the problem is, any clues?

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qphysx
02-21-11, 12:35 AM
Sorry in advance if there is a really obvious solution.
I am a noobie mechanic who needs to learn some bike matinence.
Does anyone have an idea whats wrong with my chain, and how i can fix it?
I also just replaced my chain, and it started to act up on my morning ride.

Well the chain seems to be fine when its on the big 53 teeth, but it hangs itself on the small 39 one.
190808190809

Thank you so much!


tomio
02-21-11, 12:42 AM
Looks like you might need to pop out some links.

qphysx
02-21-11, 12:50 AM
it seems to work fine on the big 53 teeth though, sorry if i left this out!


Airburst
02-21-11, 01:02 AM
it seems to work fine on the big 53 teeth though, sorry if i left this out!

It will do that, the big ring takes up more chain than the small ring. It's common to have to shorten replacement chains to fit, usually I just make them the same number of links as the chain I removed.

skilsaw
02-21-11, 01:10 AM
When you took the new chain out of the box, did you check to see if it was the same length as the old chain?

Tomio and I think it is a couple links too long.

Check this internet site http://sheldonbrown.com/derailer-adjustment.html#chain

Chain Length

If you replace your chain or sprockets, you should check your chain length. New chains come longer than they need to be for the vast majority of bicycles. You will almost certainly need to shorten a new chain before installing it on your bicycle. If your large sprocket sizes are anywhere near the maximum your rear derailer can handle, the chain length can be quite critical.
If the chain is too short, it will be at risk for jamming and possibly ruining the rear derailer if you accidentally shift into the large-large combination. Never run with a chain that is too short, except in an emergency.
If the chain is too long, it will hang slack in the small-small combinations. You should never use those combinations anyway, so this is not a serious problem. If you exceed the recommended gear range for a particular rear derailer, you may have to accept droop in these gears.
The best technique for setting chain length is to thread the chain onto the large/large combination, without running it through the rear derailer. Mesh the two ends on to the large chainwheel so that one complete link (one inch, -- one inner and one outer half-link) overlaps. In almost all cases, this will give the optimum length.

twobadfish
02-21-11, 01:15 AM
Chain is too short.

wmodavis
02-21-11, 04:48 AM
Chain is too long. Your picture shows it on the small ring in front and the small in the back and the rear derailer is not supplying any chain tension. It's therefore too long.

TurbineBlade
02-21-11, 06:47 AM
yep, too long. Once you shorten it with a chain tool, problem fixed.

Retro Grouch
02-21-11, 07:47 AM
When you took the new chain out of the box, did you check to see if it was the same length as the old chain.

Bikes come in different sizes so replacement chains come with extra length and always have to be shortened. Usually the fastest and easiest way to size a new chain is to measure it alongside the old one.

conspiratemus1
02-21-11, 08:04 AM
Agree.

When measuring it alongside the old one (assuming the old one was the right length to begin with!), be sure to compress the links, rather than just pulling the old chain taut as you straighten it. This means you have to lay the two chains down on your bench side by side, you can't just hang them from a nail. If the old chain is really worn, by 1%, say, it will be one full link too long after 100 links which will cause you to cut the new chain a full link too short. Even at the usual wear limit for replacement (1/16" in 12" which is ~0.5%), 100 links of chain will be a half-link too long which will leave you scratching your head (and getting chain gunk in your hair) when you find you have matching ends on the old chain, and mismatched ends on the new one.