chain tensioner
device for tensioning a chain to compensate for the shifting of gears or elongation of a chain due to wear
en-GB/ˈt͡ʃeɪn tɛnʃnə/
en-US/ˈt͡ʃeɪn ˈtɛnʃənɚ/
device for tensioning a chain to compensate for the shifting of gears or elongation of a chain due to wear