Does alloy rust?

elcaito69 said:

Stupid question, sorry, but I saw a 2nd hand bike recently where the guy claims the wheels are made of alloy, including the hubs and yet there is spot rust on the hubs and not the rims. Could it be that the wheels are a home made job of steel hubs and alloy rims? It's not heavy rust, but it's red and not black rust, which is also a worry.
Thanks

Afraid you will need to specify what type of alloy you are talking about... fact is pretty much anything metal you buy will be an alloy of some type... all alloy means is a mixture of different metals. Steel is an alloy, so are aluminum rims.
Pure metals are pretty crappy for most purposes, so we mix them to give different attributes. And yes steel does rust.

usually, the only rust you'll see near a hub body is associated with the spokes, which are steel, 95% of the time. Even stainless steel spokes will get some rust spots appearing where the surface of the spoke is worn, which is usually at the spoke cross-over points, but I guess it could also occur at the hub spoke holes if the wheels have had a fair bit of use.

elcaito69 said:

Stupid question, sorry, but I saw a 2nd hand bike recently where the guy claims the wheels are made of alloy, including the hubs and yet there is spot rust on the hubs and not the rims. Could it be that the wheels are a home made job of steel hubs and alloy rims? It's not heavy rust, but it's red and not black rust, which is also a worry.
Thanks

only ferrous metals rust such as steel and iron, alloy is generally an aberviation of aluminium alloy which technically doesnt rust but will corrode over time unless protected.

If there is orange/brown coloured rust on the hubs then you can conclude one of two things. 1. The hubs is made of steel and has rusted or 2. the hub has had something made of steel resting against it and may have stained it rather that actually making it rust.

personally i suspect BS, the guy may know very little about bikes and is selling you a steel hub.