Chains for hub gears

Most of the chains sold for bicycles are for derailleur systems, and they are not the best choice for hub gears. Let me explain.
Chains designed for derailleur gears have to be flexible sideways so that they come off the sprocket when required to and can run comfortably when the chainring and sprocket are not aligned. They also need to be narrow enough that they don't touch the adjacent sprocket(s).
In contrast, chains for hub gears need to resist coming off the sprocket as there is (ideally) no chain guide/tensioner. Any lateral flexibility or other features that aid the chain in coming off the sproket is undesirable.

The inner link of a normal chain consists of a pair of plates that are fastened together by tubes known as bushes. The rollers that the sprocket teeth touch are sandwoched between the paltes and run on the outside of the bush. The pin that fastens the outer plates together passes through the middle of the bush.
To gain the requred flexibility, the designers of derailleur chains eliminated the bush. Without the bush, the inner plates are free to move independently. Inner plates simply have a shoulder on which the roller sits.
Why is this bad? Many reasons:

The extra flexibilty increases the chance of the chain coming off
There is less bearing surface for the roller to contact resulting in more wear
There is less bearing surface for the pin to contact, resulting in more wear
The extra side play allows the inner plates to separate giving the roller even less bearing surface
The extra play in all parts of the chain allows more dirt into the chain, increasing wear
The pins protrude beyond the outer plate by a minimal length, if at all. This makes it necessary to be more accurate when joining chains.

How do I tell?

Find the end of the chain that is an inner link. There are two giveaway features; the bush is visible on the outside and if you look down the hole that the pin fis in you can see the split between the two halves.

Details of chains

Make	Model	Width/in	Bushed?	Overall width/mm	Finish
		3/32	N
		3/32	N
		1/8	N
		1/8	N

Vertical dropouts and no chain tensioner?

By choosing the size of chainring and sprocket carefully it is possible to fit a hub gear to a vertical dropout bike frame without using a chain tensioner. FixMeUp! makes it easy to work out what's best for you, and is as relevant for hub gears as fixed gear. Highly recommended.