Sram apex wifli 10 speed rear mechsram again raises the bar on rear derailleur performance with the apex rear derailleur the apex wifli rear derailleur represents the same design philosophy that has delivered our best in class products for the road market the sram apex wifli rear derailleur lengthens its cage and gets a slight variation in geometry to accommodate an 11 32 cassette the range of gears is wider than the standard triple chainring system and saves a significant amount of weight fe