I am assuming that by riding, you meant horseriding. Decathlon is the best place for all types of sportswear and equipment. They have stores in major cities, and also have an online presence. Decathlon is a French sporting goods company. They have quite a selection of horseriding gear, such as breeches, helmet, gloves and boots. You can also check Amazon, for horseriding gear of choice.
Decathlon is the best option if you are interested in bicycle riding gear. The store also sells various types of bicycles, from hybrid cycles to mountain bikes. Other cycling equipment, such as bottle cages, bottles, helmets, gloves, warmers, compact handpumps, multi-tool kits, lights and even bike carrier and knee guards as well as reflective sportswear etc., are available at the store. Check them out or precisely mention what gear you are interested in.