Sir, sa Cartimar maraming bikeshop. try mo sa Cristy's Bike Shop, Velocity, Paulina, and Ross Bikeshop. Basta canvass mo yang mga stores na yan. Sa Quiapo, you can try Kings Bicycel Store and Cycle Art, magkatabi yan, kung galing ka ng quezon city going to quiapo nasa kabilang side yan. Mag overpass ka na lang, katabi nila yung Chowking.
Since from QC ka, meron din sa Marikina, Joven Bike Shop, dyan sila sa may Amang Rodriguez.
Hope this information helps.