So I've just changed up my cassette from a 12-23 to a 12-27 for a long tour and I had a question about the chainguard. It looks like the chainguard is for a 12-21 to 12-24 cassette and it doesn't come all the way out on the 12-27. Is this going to be a problem for me? Is the chainguard really neccesary? Does it actually hold the chain from slipping off the cassette or does it just protect from grease etc??