Purchased a mountain bike that came with rims — similar to the Alex 26-in G6000 — that used Schrader inner tube valves, which I wanted to convert to Presta. Although first used a 1" square scrap piece of inner tube, with a hole punched in the center to protect the Presta valve base from the larger diameter hole in the rim, and although that seemed to work well, thought it would be great to design an adapter for the conversion of the rim from a Schrader to Presta valve. Previously had purchase an aluminum Presta valve adapter that only seemed to work on the exterior of the rim — yet was too small for the rim interior valve hole, which measures about 3/8" (9.5 mm). Since having a flat tire, which appears to have been partly due to high inflation pressure and the inner tube being damaged from one of the spoke holes that were only covered with a rubber rim strip. Purchased some Velocity Veloplugs (8mm) for the spoke holes in the rim and decided to design the valve adapter similar to that product — and although not externally visible, even had the option to print the Presta adapter to closely match the color of the plugs. Although have yet to test on other rims, this Presta valve adapter might also work with different or flatter rim design cross-sections — as long as the rim valve hole is about 3/8" (.375" or 9.5 mm) diameter. Just align adapter lengthwise, parallel with the rim and insert with pressure into the valve hole. In addition, what is really great about this adapter is that it can be reused for another rim and/or removed so that a Schrader valve inner tube can be used again! Removal can be done with a small flat screw driver and gently prying up the adapter equally around the edge. Thank you for visiting the NRB Spatialty shop!