i got some nice Dura Ace 7850 wheels On eBay for under $200 and they seem to be in great shape. I’m dying to get them set up full tubeless and try them out with Hutchinson 700x23 tubeless tires.

They had had been run with tubes and did not come with valves so I tracked down some Shimano road tubeless valves. The valves were missing a little contoured plastic peice that maybe seals slightly better with the little o-ring between the knurled nut. I used a second o ring instead which rides in the groove of the knurled nut so there is no metal to metal contact when tightening down the valve.

I’m using a high pressure inflation canister “Airshot” which I was inflating up to about 160 psi to try to force the square tubeless bead up onto the shelf. This system worked like a champ with some DT Swiss R460 rims that I mounted some Panaracer tubeless tires onto earlier today.

But it no such success with these Dura Ace 7850’s and their weep holes. Air is somehow getting inside the rim extrusion and exiting through these weep-holes ( there is one on each side of the rim). These wheels have the spokes that thread into integral spoke nipples on the outside of the rim leaving the rim bed smooth and devoid of holes. This makes me think that the valve is he point of entry for air then - but I’ve got the valve tightened down nice and tight. Could someone please advise on where I am going wrong or things to check? I would appreciate your help.

BTW: I even tried putting some tubeless tape over these 2 weep holes hoping that if I could block them just long enough to let the tire bead pop out onto that shelf - then it would mount and begin holding air. But to no avail.

I also tried mounting a butyl tube & inflating the tire to get it to mount halfway. I then deflated the tube and removed it, then re-installed the tubeless valve, remounted the one bed (applied soapy water as a lubricant) and get it another blast with the airshot. No luck - air is just rushing out of these weep holes...

Yeah, I noticed the non-removable core. This was going to make adding sealant a challenge I would think since it might clog the valve. I thought the Shimano valves would work the best since these are narrow rims and the “cone” type valves hit the sides of the inner rim well. I might stack a coupe more O-rings under the knurled nut and also use sealant as you suggest under the valve to try to get it to stop leaking there.

Thanks for for your help.

I just thought of something that might work - How about cutting a tiny bit of latex inner tube into a small rectangle to go under that half round, rectangular road specific valve? I have a Vittoria latex tube that is unrepairable that I ruined while self learning latex tube non-pinch installation.

i would set the flexible little rectangle of latex on the valve hole and mark for a clean through hole with a sharpie. The valve hole could be punched through using a paper hole punch I would think since the latex material is quite thin and flexible.

I don’t believe that mine have the carbon laminate. They appear to be matte black anodized aluminum (inside and out). The interior of my rims had some dried sealant residue but no real corrosion.

At at this point I’m hoping that the issue is a problem with my Shimano valve not making a good seal.

I will I’ll post back here with an update about whether I succeed (or fail again) at getting this thing to hold air.

Today I made my little pink latex valve gasket, put a 3rd O-ring on the valve and snugged up the valve after first mounting the tire. I was really hoping that this would have sealed off the valve hole and permitted my airshot to blast the tire onto the rim interior shelf so as to permit it to start holding air.

No no such luck! Air is still somehow escaping. This is turning out to be quite the puzzle. I will try my air compressor just for the heck of it and use my LED headlight to visually inspect and feel for leakage - then report back. Whew! - tons of fun doing winter mechanic work and making NO real progress.

Are you using soapy water on the beads, or just trying to mount it dry? I’m starting to think the air isn’t coming out of the weep holes, but just from sections of the bead that aren’t seating.

I do have the little Schwalbe soapy bead thingy that I used for mounting the tire. The suds seem/moisture seem to dry pretty quickly so I didn’t think it played a role during the inflation stage, just the installation part.

Well I just tried my Schraeder tire inflater with my air compressor dialed up to 120 psi. Air is rushing from these 2 weep holes. This is preventing the beads from being expanded out like they should. I’m going to try a Mavic valve that I’ve got to see if it produces any different results.

OK -so I tightened the knurled nut that holds the valve stem a lot tighter. Now I can no longer hear air rushing from the weep holes. Now it is just rushing from around the edges of the tire too fast, still not mounting. The non-removable presta core now appears to be an impediment to blasting more air in there.

So out with the Shimano valve (even though I did appear to resolve the riddle of the weep holes), arghh...

Thanks for the tip. I will check this.

I took the wheel down to my LBS mechanic last night to have him check my (lack of) progress with the Mavic road valve installed. The half round profile of the valve grommet did not match up to the rim interior. He sold me 2 Origin-8 branded road valves that have a tapered rectangular profile that he thinks will squish into place. These do have a removable presta core which the Shimano ones lack. If this rectangular style is a no go, then I’m back to the Shimano valves which I wish I could tighten even tighter than finger tight.

Update: the Origin8 valve isn’t sealing. So it is back to the Shimano valves but now I’m stuck for ideas since the non-removable core just does not permit enough pressure in to mount the tire. As a late-adopter to (this generation) of tubeless road wheels, I’m not impressed. It is a sunny mid 40’s day today & I’m not out riding.

The compressor is a single stage Campbell-Hausfeld that was given to me as a gift. I think it says 5 HP on it, the pressure seems to go no higher than 120 psi. I like the idea of using a rubber tipped air gun. Unfortunately, the best fitting valves I’ve got are the Shimano ones. As the correct valves for these wheels, why in the world would I not be able to get them to seal?

I tried a little rubber rubber gasket made from a spent latex inner tube and it leaked. I guess I’ll try using some clear silicon caulk or RTV sealant next but I don’t like the idea of making the valve more difficult to remove out on the road when it’s dark and I need to swap in a tube.

I wouldn’t say tubeless is not for me. I have 2 sets that are just about good to go (a new Mavic Cosmic Elite UST disc set and a Dura Ace 7800/DT Swiss R460 set - both of which appear will work out quite nice).

It’s this 1st gen tubeless Shimano Dura Ace 7850 that is being difficult. I mean - I have the correct Shimano valves and I positively cannot get them to seal enough to permit the new Hutchinson Atom tubeless 700x23 tire to pop onto the bead. I’ve tried numerous ways to squish these Shimano rectangular/rounded bottom tubeless valves to conform better to the rim interior. I noted one tiny area of abrasion near the valve hole where a slight amount of the anodization is scratched a bit. This last time I put a tiny bit of tubeless rim tape over this and re-tried my Airshot inflation tool with 160 psi only to have the same problem of most of the air rushing out the 2 weep holes on the rim extrusion. The tire actually does partly mount with what little rush of air is left to push the tire bead outward.

I really don’t like throwing in the towel on an installation that should be doable. I’m going to look into the Milkit system possibly or I may just scratch the tubeless idea for these wheels and install some nice 700x23 Deda Tre open tubulars that I’ve got kicking around along with Vittoria 19-24mm latex tubes. This combination would most likely be lighter, permit higher inflation pressures and give a great (but fast wearing) ride.

BTW: The 7850 rear wheel slides right into my 128mm spaced 1988 Klein Quantum that I’m restoring. Having these 2008 era wheels running in a 1988 frame in 2019 is challenging and makes me curious if sensibilities crossing 4 decades time can be collated into a relevant 2019 size 57 road bike.

Update on inability to mount front tire due to leakage around the valve - I just got off the phone with Shimano customer service and gave the person the part number for my Shimano Dura Ace 7850 valves - it turns out that the 3 pack of Shimano 7850 tubeless valves are all rear specific.

I feel embarassed for wasting so much time trying to get Shimano, Origin8, Mavic UST valves to seal over the past 3 or 4 days and just wasting my time. The Shimano person said that you must use the correct Shimano valves in order to have success and that the curvature between the front and rear of the rim well is different. Not having any real world tubeless experience, I really thought getting a squared grommet road style tubeless valve would be sufficient and it could be made to seal by squishing it tightly. Obviously this is not true as I have put my air compressor and my Airshot canister through so many cycles (for naught) that my arms are sore.

So, here I go. I just ordered a front valve so the front wheel is being set aside for now.

On to the rear wheel. If this mounts without leakage then I think I will pass out from relief!

Success (on the rear) !

I just installed my Shimano 7850 valve on my rear wheel. There was some old sealant on the bead of the rim which I scrubbed away with a scrub brush, a Scotchbrite kitchen sponge and dish soap. I rinsed it off, let it dry then , mounted a new Hutchinson Fusion 5 All Season road tubeless 700 x 23 directional tire. I used Schwalbe “Easy Fit” soapy solution and worked it in between the rim/tire bead on both sides. I used my Zefal Husky track pump and pressurized my Airshot canister to 160 psi.

I took a few few deep breaths to recover from the pumping and said a little prayer that this would work.

Well it worked on the first try! How gratifying! I mean it just popped on there immediately and I hear no air hissing out anywhere! After all those fails on the front, having success the first try is great. I checked the pressure and it is currently at 78 pounds and no sealant.

I’ll recheck the pressure in the morning.

Now I’ll be eager to get my Shimano front valve in the mail. The Hutchinson Atom tire that I have chosen for the front is a bit tighter than the Fusion 5 All Season but still I expect it to install easily now that I know it is a valve issue.

I swear the rear mounted so easily that if it holds pressure, I might ride them sans sealant. I have my fingers crossed.

I hear ya.
I sort of figured I would be going down a bit of a rabbit hole on this winter mechanic adventure.
As an experienced 56 y/o cyclist who has been doing road biking for 40+ years, I’m looking at trying tubeless as another part of my cycling resume’.
The more I can de-mystify it, the more proficient I become. I would love to put a full season on tubeless road clinchers for 2019 and sort of chronicle the results. Even if it is rejected, I believe it will not be a fail.

Riding some nice tubulars does sound fun as well. I’ve got a mini stash of some new 700x25 Conti Grand Prix 4000 tubulars just waiting to be glued onto Campy Bora Ultra tubular wheels that are new in the box.

With a full time job and numerous family responsibilities, achieving small steps towards getting one bike roadworthy gives you heightened enthusiasm that all the little bugs really can be addressed, one at a time...

Thanks for that. On these forums it is always appreciated when the original poster (me in this case) is given a bit of leeway as we outline our process and seek suggestions or feedback from others. The dialogue that ensues is constructive. It is much appreciated when there is an exchange of ideas that is more open minded and not as dogmatic.

Tubulars are kind of like tubeless in that you need to be patient and pay attention to details for the initial installation.