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How do you top up air in an inflated tubeless wheel?
Hello all
Lucky enough to have taken delivery of a new steed, set up tubeless - my first such experience.
- How do I top-up the air? Can't find any vids or articles about it, they all address inflating from flat upon set-up. Any air escaping means sealant comes with it, right, and I always get a whoosh of pressurised air when I take my track pump off the Presta valve on other non-tubeless wheels. I suppose whether the tyre was flat to begin with or not is irrelevant really, either way you're facing the same problem of taking the pump off under pressure and some air escaping.
An additional factor is the novel (to me) concept on these rims, with detachable valves that you only put on for inflating and which otherwise stay tucked inside a valve tool (with the resulting hole in the rim covered by a click-on cover). I'd imagine that screwing and unscrewing them when inserting them will also result in sealant being shot out?
Any tips or ideas gratefully received, thank you.
They are Newmen Streem Advanced R50.
Don't know if I can add YouTube links here but their website has a video about set-up, and it skips taking the pump on and off the valve (and also inflated it from empty, meaning you don't have the problem of screwing in the valve when it's under pressure and with sealant already in).
If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.
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27 comments
UPDATE for those wot are "interested"
- kept the valve at 12 o'clock for some hours, screwed in the detachable valve (momentary hiss of air but no sealant), dabbed valve (hiss of air but no sealant), inflated per usual, took Presta head of pump off to usual whoosh of air but no sealant, screwed detachable valve off (mere trace of sealant in detachable valve interface).
Result!
most likely this is air from within the hose and track pump body, and not air leaving the inner tube as the presta valve is designed to prevent that.
screwing or unscrewing the stem should not release air, otherwise as soon as you had them inflated and unscrewed the stem the valves would go flat. certainly the plug cover will not hold air and you could not get it in place in time anyway. There must be a non return valve that remains within the rim.
I'd never heard of those removeable valve stems before - that's not normal for tubeless; it's a particular quirk of the wheels you've got. With most tubeless wheels, the valve remains in place the whole time. So you've definitely made life a bit more complicated for yourself than a typical tubeless set up!
Regarding your question, it helps to remember that the sealant is simply a liquid, and with as any liquid it will flow under gravity. When the wheel is stationary, this means the sealant will pool in the bottom of the tyre. If you've watched videos where sealant is added to the tyre directly prior to seating (cf. being added through the valve to an already seated tyre), you'll see the amount of sealant that is typically present in a tyre - it forms a pool a few mm deep at the bottom of the tyre.
Most sealants are fairly viscous, and so even with your best efforts some sealant may remain in and around the valve area, and so it is somewhat inevitable that when you open the valve, a small amount of sealant may be present (and if you depress the valve briefly, you will notice this being shot out with the air). But if you have allowed the sealant time to drain away from the valve as per the other comments, this amount should be very small and should not cause any problems.
Thanks for taking the time to reply.
From a quick google search of how to avoid sealant in the valves.
Thanks. I didn't search that item specifically as you've got to know it's a problem/search term initially, I guess!
Don't understand it though (hence not searched). How can turning the wheel so the valves are at the bottom drain out sealant - depends what it drains out of (presumably you want it drained out of the valve itself), and from the position it states for the wheel that can only be draining it out of the tyre entirely. Perhaps I've misunderstood, but it's not suggesting surely that you drain your sealant out of the wheel just to add a few blasts of air (which I'll probably do every week)?
Turning the wheel so the valve is in the 6 o'clock position should allow any sealant that may be in the valve to drip out of it into the tyre. I don't bother with that as there's rarely any sealant in the valve, but that might be because I use MilkIt valves which have an extra seal.
I found out the hard way that even after wheel rotation, give the valve a little blip to force some air from the tyre through the valve.
This will help clear the valve ... especially if your Presta isn't the best quality.
If there's still sealant in the valve, it's hard work pumping by hand and if you use a CO2 cannister, the back pressure can unseat the cannister O ring and render the device useless.
Perfect, thanks
So in summary:
1) turn wheel so valve is at the top.
2) Leave for as long as possible to enable sealant to drain from inside of valve.
3) Blip valve to expel what little sealant remains in the inside of the valve.
4) Use normal track pump.
Agreed?
Couple have changes in bold.
Via the valve. Assuming it's a skinny road bike wheel it will use a Schrader valve. If it's a mountain bike it will use a presta valve. Search on YouTube for some videos. Tubeless just means it doesn't have an inner tube like a car but like a car you still need to add air and generally more often than a inner tubes wheel.
Schrader & Presta are the other way round.
I can never remember which one is which. I tried to associate "Presta" with "pressing", but both valves involve pressing the core bit so it doesn't really help.
Mountain bikes shred the Schrader!
Funny how some things stick with one: forty years ago I heard a mechanic saying to a customer, "Presta's a skinnier word than Schrader and it's the skinnier valve" and I remember it every time I buy new inner tubes.
Presta takes more pressure...
You can just use an ordinary pump to top them up and inflating when the bead has already been popped into place. Usually the only time you need a special tubeless pump (or air canister) is when the bead isn't readily sealing and you want to put a load of pressure in quickly to seat the bead (often with a satisfying "bang"). It's rare for sealant to come out of the valve when inflating them, so you shouldn't have any issues.
I hadn't heard of detachable valves before, though I expect they've got some kind of seal so that sealant doesn't come out.
Found a pic of the valve:
Thank you very much for your time.
I'd not heard of the detachable valves before. Sounds more hassle than it's worth to me, in particular as it leaves you with something small to forget/lose.
But tubeless wouldn't be possible without them.
I think Steve K is referring to the detachable nature of this valve and rim set-up, which valve is designed to be taken off in its entirety when not using a pump on them. I therefore have to take the valve and tool with me whenever I ride, separately. So yes, something I could easily misplace or forget.
My understanding is that the more usual arrangement is that the valves are a permanent fixture once the wheel's set up, although they can be unscrewed when taking the whole thing apart when the tyre's off etc.
That detachable valve stem is bonkers - a solution looking for a problem.
All about the aero, innit.
Which of course is crucial to amateur riders, being as they generally are as aero as a garden shed.
either that or some one has bought in hard to the rotaing mass is worth double argument and moving the valve stem from the wheel rim to the pocket is a saving due to less rotational mass.
Depends what the valve is like inside the rim. Maybe they seal under pressure and so it's a one way system.
Yes it's got to be hasn't it, or else they'd be impossible to to up with air.
Bit of a drag having to have yet another item (this valve tool with valve inside) to take on a ride to be honest. Also got to buy a plug repair kit it seems, so haven't lost any 'must take with on ride' items at all!
I've got Fillmore valves which seal and they are great and quick to inflate (although a little pricey).