Review on 🚲 MBP Alloy Tubeless 40mm Bicycle Presta Valve Stems: Fits Most Rims, 2 Types of Grommets Included! by Ham Channell

. I bought these for my Specialized Roubaix after trying regular old tubeless Stans valve stems for a season and encountering intermittent leaks. My bike has DT Swiss R470 tubeless aluminum wheels. Swiss brand DT's tubeless stems use letter box style rubber grommets in the rim so I figured these MBP stems would work better with a similar fit than the small tapered stems. I didn't take into account the extra space of the thick rubber. The connectors take up space, and using "letterbox" connectors doesn't leave enough stem protruding from the rim to attach the pump. I switched to cone fittings and they worked fine. They have a significantly larger diameter than Stans and are removable. Overall, the stem and armature seem a lot more solid than the Stans. The tapered fit actually seals the hole in the rim and doesn't crack like the mills do. It looks like the MBP is measured from the bottom of the stem and not the top of the bottom rubber fitting, so I would measure them closer to 35mm than 40mm. My old stems were 44mm. With a cone that fits my rims, I barely have a stem sticking out to attach the pump. I wish MBP would have made a 45mm version of this then this would be perfect. If you have DT R470 wheels I would think the stem is at least 5mm longer than these, but they still work in a pinch.