I am upgrading a vintage 10speed, new chain was purchased. The new chain was a couple of links shorter than the original that I removed. I currently have the new chain connected with a piece of wire. See picture below:
It seems that it fits, I had the chain on both lower sprockets, front and rear and it seems to function fine when I move the chain on different gear combinations. Once I remove the piece of wire it will be a little tighter but it seems there is some play in the length. The rear derailleur just moves if I increase or decrease the chain length slightly. Just wondering if this is correct, is there some degree of flexibility in terms of how long the chain can be ? Does the new chain have to be the exact same number of chain links as the old one ?