Stock part photos used for the home-page category tiles and the waterfall preview (?fallpreview=1).
All from Wikimedia Commons; resized to 360px wide. Licenses as stated by each file page.

tektro.jpg    "Bike disc break disc pads and caliper.jpg" by Alextredz, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:Bike_disc_break_disc_pads_and_caliper.jpg
rotors.jpg    "Magura Julie disk brake rotor 160 mm.jpg" by Petar Milošević, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:Magura_Julie_disk_brake_rotor_160_mm.jpg
gates.jpg     "Booda-Bike-Tailor-Gates-Carbon-Drive-System-CDX-Belt-small.jpg" by MezriczkyM, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:Booda-Bike-Tailor-Gates-Carbon-Drive-System-CDX-Belt-small.jpg
cues.jpg      "SHIMANO RD-TY20 (rear derailleur, 1989).jpg" by Petar Milošević, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:SHIMANO_RD-TY20_(rear_derailleur,_1989).jpg
kenda.jpg     "Fat Tire Bike by Ensey Motorized Bikes.jpg" by Nzmb, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:Fat_Tire_Bike_by_Ensey_Motorized_Bikes.jpg
wheel275.jpg  "Ritzelpaket am Hinterrrad.JPG" by Miriam Guterland, CC BY-SA 3.0
              https://commons.wikimedia.org/wiki/File:Ritzelpaket_am_Hinterrrad.JPG
fork35.jpg    "2015 RockShox RS-1.jpg" by Duncanriffle, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:2015_RockShox_RS-1.jpg
pack52.jpg    "Bosch Pedelec Battery.JPG" by Stefan Bellini, CC0
              https://commons.wikimedia.org/wiki/File:Bosch_Pedelec_Battery.JPG
torque.jpg    "BLDCBicycleHubMotor.jpg" by Ken962, CC BY-SA 3.0
              https://commons.wikimedia.org/wiki/File:BLDCBicycleHubMotor.jpg
kqilever.jpg  "Bicycle brake lever with adjustable mechanical advantage (leverage).jpg" by KaiKemmann, CC BY-SA 4.0
              https://commons.wikimedia.org/wiki/File:Bicycle_brake_lever_with_adjustable_mechanical_advantage_(leverage).jpg
sabvoton.jpg  "ELECTRIC VEHICLE CHRYSLER ADVANCED DC MOTOR CONTROLLER - NARA - 17499077.jpg", public domain
              https://commons.wikimedia.org/wiki/File:ELECTRIC_VEHICLE_CHRYSLER_ADVANCED_DC_MOTOR_CONTROLLER_-_NARA_-_17499077.jpg
thud.jpg      "Cane Creek eeSilk.jpg" by Glory Cycles, CC BY 2.0
              https://commons.wikimedia.org/wiki/File:Cane_Creek_eeSilk.jpg