Shimano 105 chain replacement?

thirded

KMC X10 are frequently cited as reliable 10-speed chains (same for X9-93 in 9 speed).

Don't lay the new chain beside the old one, you should always count the links.

Personal choice here but works for me cheapest SRAM chain I can find on e bay anf change it every 3 months

Wear not stretch

Oh and when you trim your new chain lay out your two chains next to eachother like so:
|
||
||
||
And then trim the new chain to match the old chain -1 link to account for "stretchage" !

There are only two brands of chain I would ever buy again

SRAM or KMC

So whatever speed your chain is, just search google

For example, its a 9 speed. Then just put in 9 speed SRAM chain

SRAM chains are also shimano compatible and i've always found them excellent as an alternative to shimano, usually some good deals to be had online for one. As SammyG said just make sure you get the 10 speed or 9 speed specific one to suit your setup.

If your existing chain has stretched significantly you might find that it's worn the teeth on cassette / chainrings and when you fit a brand new chain it skips/jumps on the worn sprockets/rings. Depends whether you've caught the chain wear in time.

The 5701 is to fit a double chainset only and has to be fitted in the correct direction. The 5600 will do a double or triple. You don't have to use a Shimano chain, you could use KMC which has the benefit of a reuseable magic link for easy fitting, removal and cleaning or any other Shimano compatible 10 speed chain. The 5600 is very durable according to the Tour Magazine group test at the end of 2011.

If it's 10 speed get a 10 speed shimano compatible chain.

Chain Reaction have one cheapish (£13).