Yes, switching to an 18 will be noticably easier. You may need to add links to your chain, or simply buy a new chain cuz you're going bigger. Possible tool needed for this is a chain tool. You can probably re-use the lockring ya got on your hub now, and just get a new cog.You will need a chainwhip ( make sure it's the right size as your cog, there are two sizes) to get the cog off and a lockring tool for removal and installation of....well...the lockring. G'luck. Oh...and get some good grease. Clean and re-grease your parts before installation.I mean bike parts, of course.
