L-bolt and knob combinations are available in two sizes. Please follow the links to order the right part for your specific trainer.
Click here for a replacement part for any gray trainer manufactured prior to 2007 with a serial number smaller than 50000.
Click here for a replacement part for any Green trainers manufactured between 2007 and 2013 with a serial number over 50000. Note that the L-bolt only works on pre-2013 "V-shaped" frames.
NOTE: If you're trainer is a newer, "U-shaped frame," or T-2000-series, you'll need this part if you have a broken tension knob.