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Discussion Starter · #1 ·
Hi,

What your looking at in the picture is me pulling my tire over to see the stem hole. I'm wondering if the round looking piece is supposed to be there or does that come out? Keep in mind that these stems have been in the bike for probably 10 years. It kind of looks like the old piece of rubber that form fits to the inside of the tube is still there and the circle shape is from being depressed for so long, but I'm not sure. Thoughts?

Thanks!
Scott
 

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That looks like a plastic rim strip (Bontrager/Trek?) for a tubeless setup. The circular depression is for seating a flat valve/o-ring rather than the more common conical valve seat.
 

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From what I can tell the air is only leaking from the valve stem base.
That usually equates to air leaking behind the tape and exiting the valve hole (least resistance for air to travel and exit.

I can't tell anything from the picture but valve stem area leaks are probably tape related. As long as you have secured the stem I should add.
 

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Discussion Starter · #9 ·
I went ahead and purchased the Bontrager valve, but it's still leaking around the valve. Seems like there just aren't that many things left to check. Could the rubber rim strip be going bad? If you look at the picture above, the rim strip seems to have nothing to do with the air leaking around the valve since it's seated in the circular piece. Any ideas....
 

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I went ahead and purchased the Bontrager valve, but it's still leaking around the valve. Seems like there just aren't that many things left to check. Could the rubber rim strip be going bad? If you look at the picture above, the rim strip seems to have nothing to do with the air leaking around the valve since it's seated in the circular piece. Any ideas....
It's time to tape the rim if you are still leaking. In my own experiences I mean. I don't know about the Bontrager rims and what makes them so special.

However, the Specialized rim tape that was stock was garbage when I bought the bike used. One wheel sealed fine, one wheel was leaking like somebody drilled a hole in the wheel.
 

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Thanks...Do you happen to know if that round, hard plastic piece in the picture will come out when I remove the rubber rim strip?
No I do not know about the round piece. I'm not familiar with what that piece is exactly -it's not the same as the 2 different types of wheels I have. Sorry. It's difficult for me to tell what all the grooves are there, including the 'notch' around the valve stem area. Must be something unique to the Bontrager wheels, or there is an optical illusion.

I'm not too sure how finicky a valve stem seal is. I mean I am, but there could be a variance. The Specialized valve stem with an o-ring seal is prone to leaking in my one experience, but also from others on the internet.
I've got Stans (I think) valves in the wheel now. For the past few months I've had to tighten the jam not for some reason (outside). Honestly, I'm not sure why it hasn't vibrated off considering the amount of turning I can do once it has loosened, maybe a full rotation.

I installed a new tire over the weekend and did the typical, press down on the stem from the inside and tighten the lock nut. Unbelievably loose. The point though is that I was not leaking air from a valve stem with a loose lock nut.
 
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