MBP Alloy Tubeless 40mm Bicycle Presta Valve Stems Fits Most Rims with 2 Types of Grommets Included for Each stem.

These tubeless valve stems are very nice. They feature toolless installation of the presta valves by hand into the stem itself. This can also be done via an adjustable wrench because the presta valves have two sides that are intentionally flattened to allow a wrench to achieve grip. They come with two different rubber seals which can sit inside the wheel which was a nice touch. The valve caps are also aluminum and have a rubber piece on them to allow for easier removal and installation when adding or removing air. Overall these are a quality pair of valve stems that do not leak and work well.

I bought another brand 1st but it would not seal my DT Swiss rims with my Grand Prix 5000 TL tires. It had a cone shaped bung which was a little too wide to seal the stem hole. These stems have two bung options. The block shaped bung fit my DT Swiss perfectly and achieved a good seal. They also are better made than my previous. The lock nut is a little bigger and the rubber washer is wider making it easier to screw the stem on tight. Very pleased.

I really like these as there is an aluminum lip at the base of the valve, under the rubber gasket. This makes it effectively impossible to tighten the valve so much you pull the rubber off the stem. Its not the sort of mistake you make often, but it can happen. This design makes that impossible to happen in the first place. Worked perfectly with my DT FR560 rims as well as my Weinmann 80mm double-wall rims. A little short with the DT's but still plenty of room to attach an air chuck.

These are closer to 35mm once you account for the thicker than average rubber seals. I bought these for my Specialized Roubaix after trying regular old Stans tubeless valve stems for a season and experiencing intermittent leaks. My bike has DT Swiss R470 tubeless ready aluminum wheels. The DT swiss brand tubeless stems use the "mailbox" shaped rubber gaskets inside the rim, so I figured these MBP stems with a similar fitting would work better than the small cone shaped stans. I didn't account for the extra room the thick rubber fittings would take up and using the "mailbox" shaped fittings did not leave enough of the stem sticking out of the rim to attach a pump. I switched to the cone shaped fittings and they worked fine. They are significantly larger in diameter than the Stans and are removable. Overall the stem and fitting seem much more durable than the Stans. The cone shaped fitting actually seals the rim hole and doesn't tear like the stans did. It seems like MBP measures from the bottom of the stem, instead of the top of the bottom rubber fitting, so I would measure these closer to 35mm than 40mm. My old stems were 44mm. Using the cone fitting with my rims I have just barely enough stem sticking out to attach a pump. I wish MBP made a 45mm version of this, then it would be perfect. If you have DT R470 wheels, I would consider a stem at least 5 mm longer than these, but they will still work in a pinch.

Despite being a mountain biker who's been riding for over 35 years, I'm something of a new convert to tubeless tire setups, largely because past efforts at it have failed miserably and I went back to tubes, because they were less hassle. That may be changing, after buying these valves. Why? Because they're vastly better than other brands that I've tried like Stans valves, and create an excellent seal with my Maxxis tubeless ready tires and DT Swiss rims. I think a big part of that is the o-ring that sits on top of the rim and below the locknut. I set up my 2015 Trek Fuel EX7's Maxxis Dissectors this weekend with these and both tires took about 10-15 mins tops using the dry method, with no mess. I'm sure some of the pricier valves like Muckoff work great too, but to my mind $30 for a set of valves is just obscenely expensive for two valves. Can't speak to the long-term durability of these valves as yet, but they seem to be great quality and time will naturally tell.

Very happy with their performance, solid fit, and durability. I’ve removed these stems multiple times when I’ve changed tape/maintenance, and they reinstall just like the first time and provide the same performance. Unfortunately, I did not take a picture of the top before I put the tire back on, but there is a thick tapered rounded rubber “grommet” that seats into the wheel and shows no wear after several re-installations. Same goes for the internal threads for the core. Threads/seals fine. There’s an o-ring behind the nut (you can see in pic), which helps seal the rim side, and the nut stays secured and haven’t stripped or came loose. (Always check them regardless every time you check your tire's psi). The nut is shaped for a small wrench if necessary, depending on your finger's grip. The finishing touch is the metal valve caps that they come with. I would definitely purchase it again. Well priced for what you get. UPDATE 11/12/20 I've purchased two more sets since my original review, and all have worked excellently.

I've converted tons of wheels to tubeless. Can't say enough about these valve stems. The two grommet rim styles included make these a snap to install in any rim. Look great, perform wonderfully. I keep an extra set on hand to give out to friends. This is my "go to" valve stem for DH, Enduro, Trail, XC. Thousands of miles on my fleet and never a problem.

Awesome they work great and seal well. They look good.