help with dropping chain
 

newbie here...

i recently picked up a 2004 Specialized Allez Elite road bike. Seems to be in pretty good working order except for a worn chain that i'll be replacing soon.

however, when i shift from the smallest chainring to the middle chainring my chain drops about half the time. i'm not shifting under heavy load or on a particularly steep decline or incline. anyone able to educate me on what could be causing this and what the possible fixes could be? will a new chain help at all?

i know i can take it up to my LBS, but i'd like to learn to do much of the maintenance/repair work on my own.

thanks!

Umm, since you need to replace the chain, why don't you do what you know needs to be done first then see how it works?

If the chain has been allowed to wear too much it may have worn the cassette with it. If your chain skips on the cassette after you change it, the cassette may be worn and need to be changed as well.

that is the plan - replace the chain and go from there. cassette appears to be ok...to my untrained eye anyway. thus far i dont have any skipping on the cassette even with the older chain.

is it possible that a chain could drop when going from small to middle chainring just becuase the chain is worn? or is it more likely that something else is going on?

What do you mean by "chain drop"? does the chain actually come off the chainrings completely or does the chain derail back to the inner ring? Does the chain make it all the way up onto the middle ring at all?

The first thing I'd look at is the ability for the ft der. to move far enough to have the chain lift completely on to the middle ring. You could place the chain on the middle ring by hand then see if the der cage is centered on the chain. A common problem is the cable tension is not quite enough to have the lever move the cage enough. Shimano ft ders are sensitive to cable tension in a variety of ways, this is but one of them. One of the complaints that we get at the shop is that the ft der doesn't shift well after a while, like after warming up things change. Well the only thing that changes is the rider's awareness. If the lever is not thrown to a full amount, as can happen after a rider tires, then the shift might not be completed.

Of course making sure there's no bent or twisted links or teeth is good advice. Worn chains get more side to side play and the need for cage movement increases over time, to compensate for this added slop.

While condition and tune condition are factors in ft shifting there is a LARGE technique aspect and it is the largest variable. Andy.

What do you mean by "chain drop"? I'm having trouble picturing how the chain could fall to the outside of the chainrings if you're shifting from the granny to the middle ring.

EDIT: Simul-post!

" i dont have any skipping on the cassette even with the older chain." That is expected, as chains and cassettes wear together. If the chain is allowed to become too worn, the corresponding wear on the cassette will make it skip when a new chain is installed. If this happens a new cassette is needed.

You should not expect to be able to judge the state of wear of a cassette by eye; its performance with a new chain will dictate whether it needs replacement. Get yourself a good steel rule and use that to check the state of chain wear; the so-called "chain checkers" are generally misleading.

As I suggested earlier, change out your chain and then see how it works. You will have saved yourself some pointless troubleshooting if the "chain drop" problem goes away with a new chain.

I'd suggest that you get a chain which connects with a master link as opposed to the Shimano chains which require the special connecting pin. The link can be opened for cleaning or other work much more easily and you do not need a new pin each time.

by chain drop, i mean it came completely off the chainrings to the inside.