The small market on the right hand side North of the Chiang Puak bus terminal (Chotana Rd) has some fairly good riding jackets and heaps of other stuff, the jackets range between 1,500-2,500 Baht and have armour in them, they are manufactured in China but they look OK for the price, he may even have pants now. Its the stall that has all the helmets on display out the front. He also has another outlet in Si Donchai Rd.