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Is it normal to lose air pressure with tubeless tires during an event?

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Is it normal to lose air pressure with tubeless tires during an event?

Old 10-22-17, 10:47 AM
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Is it normal to lose air pressure with tubeless tires during an event?

I lost more than 10 psi while riding 50 miles of irregular loose gravel. I had to top-off the rear tire prior to finishing. These are tubeless tires on tubeless rims. I might just need to replenish sealant? Any suggestions?
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Old 10-22-17, 12:04 PM
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I think it's most likely a sealant refresh is in order. The other small possibility is leaky Presta core-- either to it just wearing out, or getting a bit of sealant in the core and not sealing fully. Dropping 10psi in a day is too much, even if starting from road pressures.
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Old 10-22-17, 12:13 PM
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Another possible source of the leak is the rim tape.
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Old 10-22-17, 12:58 PM
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Tubeless rim should only have a valve hole,in it.
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Old 10-22-17, 01:25 PM
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I've filled the tires to 60psi and I'll check to see how much loss exists after 20 hours.

I'll add sealant before the next local ride and check if that takes care of the air pressure loss.

It looks like manufacturers expect sealant to dry out several months after the initial dosage.
https://www.bikerumor.com/2014/02/19...cked-replaced/
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Old 10-22-17, 01:32 PM
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Wipe the dried sealant out every 2-4 months? LOL. What's the trick to getting a tire to last 4 months? Oh, right-- ride less, I suppose. I generally wear the tires out before the sealant has a chance to dry up (except for the mid-summer months, where the tires will go bone dry in 2 weeks.)

I forgot about the possibility of rim tape, because I've only had rim tape develop a leaky seam once, and it would drop 40psi in a day. The current rims are the proper kind, with only the one hole in them.
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Old 10-23-17, 03:20 PM
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Did you burp them at all during the ride?
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Old 10-24-17, 06:30 AM
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I found that a luer lock syringe without a needle will perfectly fit in a presta valve without the core. Makes refilling sealant a lot easier. I get them from McMaster Carr.

I feel like sealant drying out is probably not the cause of air loss though. However, it's certainly worth a try. My problems in the past have stemmed from my less than stellar rim tape application.
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Old 10-24-17, 07:34 AM
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Originally Posted by Barrettscv
I've filled the tires to 60psi and I'll check to see how much loss exists after 20 hours.

I'll add sealant before the next local ride and check if that takes care of the air pressure loss.

It looks like manufacturers expect sealant to dry out several months after the initial dosage.
https://www.bikerumor.com/2014/02/19...cked-replaced/
How old is your sealant? Typically it has to be refilled every 6 months or so. I know I need it when it looses more air than normal just sitting in the garage.

Could it be burping? That could happen if you are running low pressure, but not so much at higher pressure. I use skinnystrippers to prevent my tires from burping at any psi. Keeps the latex off my wheels too.
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Old 10-30-17, 09:39 AM
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Originally Posted by chas58
How old is your sealant? Typically it has to be refilled every 6 months or so. I know I need it when it looses more air than normal just sitting in the garage.

Could it be burping? That could happen if you are running low pressure, but not so much at higher pressure. I use skinnystrippers to prevent my tires from burping at any psi. Keeps the latex off my wheels too.
It looks like the tires only needed a replenishment of sealant. I added two ounces and the tires are hold air perfectly again. I’ve ridden 60 miles with no significant air loss over a 48 period.

I’m a little surprised. The tires were installed with sealant at the beginning of summer. However, I only used a minimum of sealant at the time.
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Old 10-30-17, 09:44 AM
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It is not unusual to need to replenish sealant after 3 months just as it is not unusual to go 6 months with no problem.
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Old 10-30-17, 10:45 AM
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Sometimes new tires need extra sealant after a month or two because the sealant is finding all the holes/micro holes. After the a refill I would expect much longer before needing more (assuming you used new tires).
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Old 10-31-17, 01:32 PM
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Originally Posted by Barrettscv
It looks like the tires only needed a replenishment of sealant. I added two ounces and the tires are hold air perfectly again. Iíve ridden 60 miles with no significant air loss over a 48 period.

Iím a little surprised. The tires were installed with sealant at the beginning of summer. However, I only used a minimum of sealant at the time.

Yeah, my sealant from late spring was dried out about a month ago.
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