First tubeless problem

[LegendRider]

I've been riding the DA 7850 wheels with a tubeless set-up for nearly a year. I love 'em and strongly believe all clinchers will soon become tubeless within a few years.

However, I've recently started to have a problem losing pressure through the Shimano valve. I'm certain it's not the tire since it's happening with two different tires (one of which is new).

I'll lose 25lbs of pressure in a three hour ride and/or all pressure overnight. I've pulled the valve out and saw no obvious defects. And, after reassembling, it held pressure better but not satisfactorily. I don't use sealant as a rule - perhaps that will do the trick.

A replacement valve appears hard to find. Anyone know where I can get one via mail order?

[SpeedyChix]

Stans makes a valve that works great in those rims. Plus the valve core is removable (unlike Shimano's valve).

For use with Mavic UST, Bontrager, and Shimano tubeless rims This custom made Presta valve stem features a removable valve core which allows for easier application of our tire sealant.

http://www.notubes.com/product_info.php/cPath/21_59/products_id/41

[gemship]

Stans makes a valve that works great in those rims. Plus the valve core is removable (unlike Shimano's valve).

For use with Mavic UST, Bontrager, and Shimano tubeless rims This custom made Presta valve stem features a removable valve core which allows for easier application of our tire sealant.

http://www.notubes.com/product_info.php/cPath/21_59/products_id/41


I wonder if someone could make their own by cutting the stem out a tire tube?

[LegendRider]

Stans makes a valve that works great in those rims. Plus the valve core is removable (unlike Shimano's valve).

For use with Mavic UST, Bontrager, and Shimano tubeless rims This custom made Presta valve stem features a removable valve core which allows for easier application of our tire sealant.

http://www.notubes.com/product_info.php/cPath/21_59/products_id/41

Are you sure the Stan's valve will work? I have a couple and the profile of the rubber base is very different from the Shimano valve. When I put it in the rim there was a gap between the base and the rim bed.

[SpeedyChix]

I'm using that Stans valve in my Shimano tubeless road setup. Though I'm running that set for CX so it has some sealant in there. Next to impossible to get the sealant in w/o the removable core.

Pics to come shortly.

btw, that valve is a late add in their line. They don't all work in there.

[LegendRider]

I'm using that Stans valve in my Shimano tubeless road setup. Though I'm running that set for CX so it has some sealant in there. Next to impossible to get the sealant in w/o the removable core.

Pics to come shortly.

btw, that valve is a late add in their line. They don't all work in there.

OK. I have an old Stan's valve. So, the UST model is the one that will work?

[SpeedyChix]

It 'might' ... they started to make a 44mm valve stem that's actually long enough to work in the Shimano road rim. I think the one I have in there is a UST that I reshaped (wouldn't want to use that one w/o sealant.

But now they have a 44mm tubeless road valve stem (Stans 44 road valve stem on the left, Shimano on the right in the photos). This one is the right one to use.

They made the valve stem longer and you can see in the pics that they made the base more of a rectangle (to fit into the deeper/narrow channel of the rim).

http://i159.photobucket.com/albums/t137/RiverKnife/Forum%20Help%20Images/IMGP0972.jpg

http://i159.photobucket.com/albums/t137/RiverKnife/Forum%20Help%20Images/IMGP0973.jpg

http://i159.photobucket.com/albums/t137/RiverKnife/Forum%20Help%20Images/IMGP0975.jpg

[feta99]

Stans makes a valve that works great in those rims. Plus the valve core is removable (unlike Shimano's valve).

For use with Mavic UST, Bontrager, and Shimano tubeless rims This custom made Presta valve stem features a removable valve core which allows for easier application of our tire sealant.

http://www.notubes.com/product_info.php/cPath/21_59/products_id/41

I don't think Stan's valve works with the Shimano tubeless wheels. I tried a valve on a pair of 7801SLs and it did not seal properly. I'm assuming the 7801 and 7850 rims are similar if not identical.

-A

[SpeedyChix]

Those are both Shimano 7801 tubeless road wheelsets in pic above. I do have sealant in the CX wheel but that's a Stans valve. Not running 90 psi in there either, but would expect their 44mm road-specific valve to work.

If you want the Shimano, it looks like Excel carries them:
http://www.excelsports.com/new.asp?page=8&description=UST+Valve+Stem+WH-7801+SL&vendorCode=SHIM&major=1&minor=23

[dekindy]

You can always ask Stan's directly. They have promptly responded to my questions in the past. Ask them when they are finally going to make a stem for my Velocity Deep V's so I can convert them to tubeless.

[Ray]

In this picture from earlier in the thread, the Shimano valve (on the right) shows a funny little asymmetrical piece that's not the valve or the O-ring or the metal O-piece that threads down and holds the valve in place. What's up with that, for those who've been using the Shimano wheels longer than I have? Shortly after I had mine, I developed a leaky valve in the rear wheel. I took it apart and that little piece fell out from somewhere, but I'll be damned if I could tell where. It didn't seem to fit anywhere, so I put the valve back together with just the rubber O-ring outside of the rim and the threaded piece holding the O-ring down against the rim. Filled it up and its been doing just fine since. I ordered a couple of replacement Shimano valves (I don't see any way the valves I had from No Tubes were gonna seal inside of that rim) and they came with those same pieces, except they're symmetrical on the replacement valves. They don't even begin to fit over the outside of the rim and there's noplace INside the rim to put them. Do they have a purpose? Are they necessary?

Thanks for any advice. I think I'm fine as is, at least so far. But if I'm overlooking something key that's gonna cause me problems down the road, I'd rather find out now.

-Ray

http://i159.photobucket.com/albums/t137/RiverKnife/Forum%20Help%20Images/IMGP0972.jpg

[benb]

I'd just use Stan's sealant.. it will easily seal up something like a valve stem being not quite right.

Stan's "injector" does not seal up correctly with the Mavic valve stems that I have for my MTB wheels.. but the sealant works so well I just stuck the injector on the valve as best I could and it sealed up the gap and only spilled about a drop of sealant.

[Keith A]

Ray -- Here's what I know from my Dura-Ace 7850-SL wheelset. Neither of my front wheels have a plastic piece that goes in between the O-ring and threaded cap which matches Shimano's documentation (http://bike.shimano.com/media/techdocs/content/cycle/EV/actionsports/WH/EV-WH-7850-SL-F-2721B_v1_m56577569830638016.pdf). However, one of my rear wheels does have the asymmetrical plastic piece that you mention, but the other does not. Interestingly, the rear that doesn't have this piece leaks more air than any of the other wheels. Shimano's documenation shows this piece on the PDF of the rear wheel (http://bike.shimano.com/media/techdocs/content/cycle/EV/actionsports/WH/EV-WH-7850-SL-R-2722C_v1_m56577569830648621.pdf).

I also found this tubeless installation PDF (http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Wheel/ROAD/InstallingROADTubelwssTires/SI-0028A-ENG_v1_m56577569830607782.pdf) that clearly shows the asymmetrical plastic piece.

[Keith A]

...I ordered a couple of replacement Shimano valves (I don't see any way the valves I had from No Tubes were gonna seal inside of that rim) and they came with those same pieces, except they're symmetrical on the replacement valves. They don't even begin to fit over the outside of the rim and there's noplace INside the rim to put them....Just curious, where did you buy these? I was planning on ordering a couple from Excel Sports, but it sounds like I need to make sure the ones they have in stock have the assymmetrical plastic piece or not. I am hoping that this piece will help maintain better air pressure in my rear wheel that is missing this piece.

[Ray]

Ray -- Here's what I know from my Dura-Ace 7850-SL wheelset. Neither of my front wheels have a plastic piece that goes in between the O-ring and threaded cap which matches Shimano's documentation (http://bike.shimano.com/media/techdocs/content/cycle/EV/actionsports/WH/EV-WH-7850-SL-F-2721B_v1_m56577569830638016.pdf). However, one of my rear wheels does have the asymmetrical plastic piece that you mention, but the other does not. Interestingly, the rear that doesn't have this piece leaks more air than any of the other wheels. Shimano's documenation shows this piece on the PDF of the rear wheel (http://bike.shimano.com/media/techdocs/content/cycle/EV/actionsports/WH/EV-WH-7850-SL-R-2722C_v1_m56577569830648621.pdf).

I also found this tubeless installation PDF (http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Wheel/ROAD/InstallingROADTubelwssTires/SI-0028A-ENG_v1_m56577569830607782.pdf) that clearly shows the asymmetrical plastic piece.
Hmmm. OK, I can see in this picture how that piece sits flush against the rim and gives the O-ring a flat surface to seal against and it makes sense that it would be asymmetrical, since the wheel has an asym spoke pattern. Which is all consistent with the exploded diagram you linked to. But I have the carbon 7850-C24-TL rims and there's no way in hell that little piece sits flush against the rim (which may be a bit bulkier being formed out of carbon?).

In any case, the valves I ordered were from Excel and that piece is definitely symmetrical, so it might work on the aluminum front wheel but not on the back? Its not gonna work on either of the carbon ones. I'm gonna keep running mine without it since the o-ring seems to form an adequate seal flush against the rim. Assuming the O-ring is even really needed - I think the air pressure pushes the valve up against the inside surface of the rim adequately to form a good seal - the O-ring and that plastic piece might just be to protect the rim from damage from overtightening the nut? Not sure where or if you can get the valves with an asym version of that piece.

http://i159.photobucket.com/albums/t137/RiverKnife/Forum%20Help%20Images/IMGP0975.jpg

-Ray

[LegendRider]

Hmmm. OK, I can see in this picture how that piece sits flush against the rim and gives the O-ring a flat surface to seal against and it makes sense that it would be asymmetrical, since the wheel has an asym spoke pattern. Which is all consistent with the exploded diagram you linked to. But I have the carbon 7850-C24-TL rims and there's no way in hell that little piece sits flush against the rim (which may be a bit bulkier being formed out of carbon?).

In any case, the valves I ordered were from Excel and that piece is definitely symmetrical, so it might work on the aluminum front wheel but not on the back? Its not gonna work on either of the carbon ones. I'm gonna keep running mine without it since the o-ring seems to form an adequate seal flush against the rim. Assuming the O-ring is even really needed - I think the air pressure pushes the valve up against the inside surface of the rim adequately to form a good seal - the O-ring and that plastic piece might just be to protect the rim from damage from overtightening the nut? Not sure where or if you can get the valves with an asym version of that piece.

-Ray

I received a replacement valve from the Shimano warranty folks and it came with the symmetrical piece. I was in an XTR package so I assume it's the piece is for their tubeless off-road wheels. I used the asymmetrical fitting from my faulty valve and things seems to be working.