Bikes Del Pueblo:

San Diegos Non-Profit Do-It-Yourself bike repair
Open Sundays 10am-3pm
Used bikes for sale and Parts for fixing your bike
Donations appreciated.  
Volunteer Opportunities Available.
Located at the PopUp15 Lot:
4050 El Cajon Blvd, City Heights, San Diego 92105

Ebike Store at 2907 Shelter Island Blvd opening November 2021

Sheldon Brown
Website with a very comprehensive guide to bicycle repair

Bike Index
Website to register your bikes Serial Number, report a stolen bike, check the S.N. of a bike before purchasing to make sure it is ‘clean.’