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I have been experiencing a lot of flats lately (proportional to the increase in time/distance I have been doing), so I am thinking of adding a tube protector (e.g., one of these) to each tire.

Will this alter rolling resistance or just add weight to the wheel? I'm not sure what goes into rolling resistance aside from tire material and pressure. I expect a slight slow-down, but I'm not sure what to expect. I'm willing to trade slower speed for the time fixing flats.

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What kind of bike for what kind of riding? –  cmannett85 Dec 24 '11 at 9:47
    
Seconded on the question. Getting flats even reasonably often is a symptom that something else is wrong (low tire pressure, extremely poor tire quality, improper rim tape installation, etc.). Properly-chosen tires ought to last thousands of miles. –  Stephen Touset Dec 25 '11 at 1:57
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5 Answers 5

up vote 2 down vote accepted

It likely depends a lot on your tire pressure. For high-pressure tires the liner just adds to the stiffness of the tire and might actually reduce rolling resistance slightly.

For lower pressure tires, the liner must flex and, to a degree, slide against the tire and tube with every revolution, increasing internally dissipated energy and hence rolling resistance. But the effect would be slight.

A better solution is to use Kevlar (or equivalent) belted tires. These have about 10x the puncture resistance of standard tires, have negligible effect on rolling resistance, and are much easier to deal with than the separate liner. But of course they're 30-50% more expensive, and hard to find in certain sizes.

(NB: Don't confuse "Kevlar belted" tires with "Kevlar bead" tires -- Kevlar bead is used in folding tires, some of which are Kevlar belted and some not. And I personally find folding tires a PITA to install the first time -- though some people love them.)

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I looked around the internet to find any evidence of the effects of tire liners on speed, but couldn't find any. I was considering using them while touring. So, I did my own test.

My bike is a mid-range steel framed tourer with Schwalbe 26" x 1 3/8 Delta Cruisers. The tubes are Bontrager. I installed the liners as per instructions and took the bike out for a spin. It was like riding through treacle. I wasn't carrying panniers and luggage, but it felt the same. I thought I had fitted them ok and therefore was at a loss as to how these really light nylon liners could have the effect of a fully loaded bike, but worse.

So, the next day, I thought I'll try again - maybe it's just me. I'll take the bike on a training route I use a lot. Here are the results: 24 kms., 16.1 kph average, 1 hour 30 min. And I didn't enjoy it. My bike had turned into a turkey overnight.

Next morning, I headed out again on the exact same route (no traffic lights, country roads, no hills) without the liners, same tire pressures. What a pleasure - lovely ride, responsive, gliding. Results: 24 kms., 20.3 kph average, 1 hour 12 min. That's a 25% difference in speed and time. And I would need a flat every 20 kms. to make up the difference. Hard to believe, isn't it?

When I examined the liners they had turned black,, on both sides, from bright orange, which I assume was from the tire and tube rubbing on it. It had also stuck to the tube in one or two places, necessitating me to peel it off. I will never be using them again. It would be interesting to hear of any other people's research into tire liner use. Is this just a one off? What about thick tubes and reinforced tires? How do they affect performance?

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What tire pressure do you typically run? –  Daniel R Hicks Feb 2 at 13:14
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yes, it will increase rotational weight and slow you down just a bit. But if you experience flats often, this minor slow down will be better than flat repairs road side.

I use tire liners on my daily riding, training and commuting routes. Then if i race or do a semi-competitive event, take them out for a nice feeling of being lighter and faster.

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Increasing rotational weight has a significant effect on acceleration and making the bike feel a bit more sluggish. Rolling resistance is a function of tire casing deflection, not so much added weight. Supposedly adding one ounce of weight at the rims is like adding 7 ounces of frame weight. I prefer to run stans sealant in my tubes as opposed to liners. Liners do work, I recommend the Rhinodillo brand.

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Since the issue has come up several times, I asked over on the physics Stack Exchange what effect adding a mass to a wheel has vs adding the mass to the bike frame (or rider). The answer was 2x -- adding one ounce to the wheel is like adding 2 ounces to the frame. –  Daniel R Hicks Dec 27 '11 at 3:10
    
Excellent, thank you for taking the initiative. 7x was what I heard early on in my shop days. This doesn't eliminate the fact, however, that putting $ into a lighter wheelset instead of components is still a good idea. –  802bikeguy.com Dec 27 '11 at 5:04
    
Yes, but added wheel weight is not as disastrous as others would have you believe. –  Daniel R Hicks Dec 27 '11 at 18:05
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I've been using tire liners, 700-23 / 120 psi, on my bike for about 3 months now and have noticed an increased rolling resistance. It isn't much, about 1 mph. But it is there since I put the liners in. That being said, its much better than the flats I was getting every other ride.

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