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These Slime Lite Smart tubes are effectively the same as the regular Smart tubes reviewed previously on road.cc, but they address the weight criticism with a lighter inner tube. On our scales this 19/25c inner tube weighed 102g, a 68g saving.
Using a lightweight butyl tube has allowed Slime to reduce the weight. Inside is the same green fluid that is claimed to be able to seal a puncture up to 3mm. I've seen a demonstration with a nail and it's highly impressive, but that's nothing compared to real-world testing. I've had them fitted to my steel touring/training bike, a bike that gets some seriously heavy miles on rough rides, and in three months haven't had one flat.
To thoroughly test the tubes, I've been taking to gravelled byways and bridleways, deliberately trying to inflict harm on the inner tubes. Despite trying, I've not managed to run out of luck yet. Tyre choice and pressure is a factor, and for the record I was using Hutchinson Fusion 3 x-Light tyres with 90/95 psi front/rear.
With the weight penalty over a regular inner tube it's no surprise there is a slight difference in ride performance compared to the previous setup with normal butyl inner tubes. The difference with these new lighter Slime tubes is much smaller and you'll be hard-pressed to notice the difference, unless you really search for it on climbs and hard accelerations. There's little difference in ride feel too.
You might not want to fit them to your race bike, but for commuting and training purposes they're fit for purpose. The small weight increase is offset by the reduced possibility of puncturing, and as we head into autumn with the higher risk of flat tyres - due to more frequent rain washing glass and crap into the road and water acting as a particularly good lubricant for sharp flints to penetrate rubber - they could be worth fitting to your bike.
The reason for buying these inner tubes is obviously to avoid punctures, but unfortunately I haven't yet suffered a flat in my time testing them. So it was into the garage that I went to conduct a workshop test to find out how they handle being punctured. With the bike in a stand, I pushed a drawing pin through both front and rear tyres. Nothing happened. Pulling the drawing pins out and giving the wheels a spin, then stopping them, the green goo visibly bubbled out through the holes. Then stopped. A couple more revolutions. The Slime had sealed the holes. A pressure gauge revealed the tyres had dropped just 15 psi during this process, from 100 to 85 psi.
I then went for a one hour bike ride, without incident. With the pressure gauge out again once I was back home, the tyres were holding the same 85 psi. That's a small enough pressure drop that you could puncture during a ride and not even realise.
The upfront cost is higher than a regular inner tube, but you should see a reduction in punctures.
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Make and model: Slime Pro Pre-filled Lite inner tube
Size tested: 700 x 19/25c
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
The lightest self-healing tubes on the planet instantly seal punctures up to 1/8in (3mm). Slime Lite Tubes combine a lightweight butyl tube with revolutionary sealant technology to provide flat protection without adding significant weight. Go lite!
Tell us some more about the technical aspects of the product?
Instantly seals punctures
The longer valve is ideal for deeper section rims.
I've been nothing but impressed with these Slime inner tubes. The weight is good, and the resistance to punctures is impressive. I've had a lucky couple of months testing these, but considering the pounding I've given them I would have expected a flat or two by now.
Excellent (so far).
A regular inner tube is sub-100g so these are carrying extra weight, but the gap is much closer than Slime's previous version, making these even more appealing.
Impressively, there's little discernible difference in ride feel over regular inner tubes.
How much for peace of mind that you'll hopefully never puncture? That's the promise offered by these Slime tubes, and it seems to be working for me so far.
Tell us how the product performed overall when used for its designed purpose
Tell us what you particularly liked about the product
Good weight for a tube filled with green goo.
Tell us what you particularly disliked about the product
Small weight penalty, but that's being really picking. They're still prone to punctures with anything over 3mm cutting the tyre.
Did you enjoy using the product? Yes.
Would you consider buying the product? Yes.
Would you recommend the product to a friend? Yes.
Age: 31 Height: 180 Weight: 67
I usually ride: My best bike is:
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, mtb,
David worked on the road.cc tech team from 2012-2020. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes.