Which dual ring chain guide should I get: ethirteen drs oe black spire chain tensioner. I already have a nice bash gaurd (raceface evolve),but I have a bike in need of a new bash gaurd. It would be nice to know that I could save $100 with the spire. Its going on a faith. Ultimately, which is going to be the smoothest for shifting, provide the least resistance and keep the chain on the best?