Just bought a chain (on sale at good price so bought it to make up cheap P + P for online order), so got to thinking about actually changing a chain for the first time ever. I have a couple of questions: 1. I have probably done about 1000 miles - is it likely to need replacing? 2. Should I buy a chain checker? 3. Does the Alien II chain tool, work with Shimano chains? The Haynes manual says that Shinmano needs a different tool to the 'normal' one.