Slime vs normal tube
w7london
Posts: 37
I just changed to slime on the rear wheel, and I *think* there's a lot more drag (I mean I'm doing more work than I used to) - but I'm not sure if that's just psychological!
Would I really be able to feel a difference?
I also changed to Smart Sam tyres a few weeks ago, so I guess that's adding to the weight.
My question is just: is my mind playing tricks, or should I just shut up and learn to love the slime?
Would I really be able to feel a difference?
I also changed to Smart Sam tyres a few weeks ago, so I guess that's adding to the weight.
My question is just: is my mind playing tricks, or should I just shut up and learn to love the slime?
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Have you adjusted anything else? Lowered tyre pressures?
I run my road tyres about 70-90 PSI but my off-road ones about 20-25
It's a long time since I even used tubes, let alone weighed them, which is why these figures are for 26" tubes.
Plain, presta valved inner tubes 26” (1.75 – 2.125) weigh 192g .
Similar 26” (1.9 - 2.125) weigh 160g
Ie inner tubes can vary in weight quite a bit.
The Slime, inner tubes that I bought weighed 315g each, ie 123g - 155g extra weight per plain tube.
Scale that up for a 29er and you get 137g - 173g extra weight.
Don't forget that weight is in the tyre, right where you can feel it the most. Weight at the wheel not only has to be accelerated horizontally, but rotationally as well. That extra resistance you feel is you having to provide extra power to overcome the extra rolling moment of inertia of a heavier wheel. It's a lonnnng time since I did that sort of maths, but I'm fairly sure that the effect goes up with the square of the diameter.
You will feel it every time you try to accelerate or slow down, and when you are trying to change direction, especially when doing quick left - right - lefts.
If you were to go tubeless, you would replace that Slime tube with maybe 80-100gms of sealant, depending upon tyre size.
I ride an MTB but mainly on road (I know, I know!) so I keep the pressure at the high end. I'm using Smart Sams which I think are rated at around 30-54psi.
They're 27.5 wheels.
But yeah I think I feel a weight diff (and i only have Slime on the back wheel). I'm not sure whether to stick with it or go back to normal tubes.
I've ridden over 5,000 km in the past 12 months on the road, in all weathers and all conditions, with road tyres, with non-slime tubes and I've not had a puncture. Now maybe I've got a bit lucky, but you shouldn't be getting that many.
But if you want fast tyres for riding a 27.5" wheel on the road only then you may want to consider some slicks. There's a lot of 27.5" / 650b slicks coming out now as the number of gravel bikes and adventure bikes are increasing.
No way should they be happening that frequently.
But the rest of them, I'm not sure about. I even went to extreme lengths of changing both the tyres and tubes at the same time to make sure everything was fresh and undamaged (and I checked the wheel rim too). Which is why the next puncture (about 3 weeks in to the new set) was so disappointing.
The latest puncture was a pointy stone that went straight through the rear tyre.
I think I'm quite careful about not riding over dirt on the side of the road/avoiding glass. But i don't know.
Maybe it's the above, maybe rim tape has moved and a spoke or sharp end is poking through.
I won't ask if your tyre pressures are too low as we've already established that they are in fact quite high.
You know the reason for latest puncture - a pointy stone - but it's important to try to find the reason for every puncture. Like my experience with the flint, if you can't find the reason, then you can't be sure it won't just happen again.