Flat out - for when you get the 1/2 inch puncture.
Besides that claim to fame they say it washes up with water better and lasts an inordinately long time before needing a refresh. (They used to advertise forever as I understand it)
They still do. Officially its 'up to 10 years' but that translates to 'life of the tire'
FlatOut is, hands-down, better than Slime. After some major events where I know Slime couldn't have coped, I replaced my Slimed tubes I have with others that have FlatOut in them.
- a strip of 6 roofing nails from a nailgun. SIX nails. Tires were Snowshoe XLs (and they were running tubeless) on a cargo bike coming back loaded from a Home Depot run. Thankfully my bike-battery-powered air compressor always goes with me as I spun the tires but was losing so much air, I needed a refill. Then rode the bike about a block until I needed another refill, and repeated that three times as the air escaping slowly decreased. On the fourth air refill the last of the hissing stopped and the tires have stayed inflated ever since. No repairs necessary.
- A big jagged piece of metal. Oddly it was the same cargo bike a few weeks earlier on my street wheels which were running with tubes. Big nasty piece of jagged scrap metal. Dark night time commute home. By the time I got stopped, the 4.3" Surly Edna tire was essentially flat. Used my trusty compressor to refill. A block later refilled again. That was it rode home. When I changed wheels a few weeks later, I found the hole in the tube had dried into a hard nub, unlike Slime which leaves an often-weepy soft plug that may be still leaking air very slowly.
I called FlatOut on the phone and got their product manager in charge of dealing with bike compatibility. He confirmed the Sportsman Formula was the one they had tested with BackCou ebikes. This conversation, which I reported pretty widely at the time, is where the 16 oz dose for a fat tire comes from. I also sounded him out about using it as a tubeless sealant and he stated they had never heard of it being done, and it should work if I painted the tire beads in advance with some to help ensure a seal. In the end I didn't need to do that and it still worked like a charm. No leakage and no top-ups needed after weeks, and as I found out the hard way, it works to seal tires great. I had one more on the tubeless wheels. I heard hissing up front and got the bike stopped to try and pull out whatever it was. Found nothing but a half-dry wet spot with no visible hole and no air leakage.
As for Kenda tubes, I slimed them back in the day and they worked fine. BUT since the valve cores were not removable, you had to stab a hole in the tube and inject slime with a meat marinade injector, then patch the hole. Maybe thats what Kenda was getting at as no you cannot inject Slime thru the valve given the non-removable core.
Got an ebike? Use the big battery you are already lugging around to power a small portable pump.
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