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-   -   New tires roll better? (http://www.bikeforums.net/general-cycling-discussion/941696-new-tires-roll-better.html)

Fingerpicker 04-04-14 06:12 PM

New tires roll better?
 
Am I nuts? Over the winter I replaced the so so tires that came on my Specialized Allez. It was purchased new 18 months ago. Today was the first ride of the year and the first on the new tires (Michelin). The bike seemed to roll smoother and faster.. A lot smoother and faster...is that possible...all tires are 700x25

wahoonc 04-04-14 07:18 PM

What were the original tires? I have some brands that rolled out better than others. Also a noticeable difference between tire models within a brand line up.

Aaron :)

Landofnone 04-04-14 07:27 PM

Tires are like women and men each produce different types of riding style's. :roflmao2:

cruiserhead 04-04-14 08:02 PM

As tires age, the rubber hardens and wear and tear changes the roundess and cross section of the tire.
The softer durometer of new tires makes them smoother and faster.

Fingerpicker 04-05-14 06:36 AM

Thanks that makes sense..is there a rule of thumb for when to change tires? I don't know what the old ones were ..they came with the bike, probably a place where're they cut costs


Quote:

Originally Posted by cruiserhead (Post 16643035)
As tires age, the rubber hardens and wear and tear changes the roundess and

cross section of the tire.
The softer durometer of new tires makes them smoother and faster.


Wanderer 04-05-14 09:17 AM

It's probably much more simple than all that ----- you just put higher quality tires on your bike. OEMs are usually mounted to a price, and very cheap and low quality.

Retro Grouch 04-05-14 10:15 AM

Lots of people talk about bicycle tire rolling resistance but I don't think that very many folks understand it.

When you sit on your bicycle a portion of your tire flattens against the ground. As you ride, that flat portion is constantly moved to a different section of the tire. Take a bare tire and try to flatten a section of it with your fingers. You can do it easily enough, but it obviously takes some effort. As the bike rolls along that effort ultimately has to come from the rider. Old hard tires are always going to be harder to bend. Tires with thick puncture resistant belts are always going to be harder to bend. Thin, supple tires are always going to be easier to bend but will cut or puncture more easily.

To a point, inflating your tires harder will reduce the size of the flat spot and, since you have to bend them less, the rolling resistance of the tire. Exceeding that point, however, will make your whole bike bounce upward over every tiny little pebble in the road. The energy that's required to lift the bike and rider also has to ultimately come from the rider.

fietsbob 04-05-14 10:45 AM

that new car smell

Drew Eckhardt 04-05-14 10:56 AM

Quote:

Originally Posted by Fingerpicker (Post 16642831)
Am I nuts? Over the winter I replaced the so so tires that came on my Specialized Allez. It was purchased new 18 months ago. Today was the first ride of the year and the first on the new tires (Michelin). The bike seemed to roll smoother and faster.. A lot smoother and faster...is that possible...all tires are 700x25

Carcass flexibility varies with effects on feel and rolling resistance with a factor of 2 between the fastest and slowest road tires.

Unfortunately most of your power is going into overcoming aerodynamic drag, so the impact on speed is much lower.

Assuming .4 m^2 Sd, .760 Cd, and 165 pound bike + rider weight going from .007 Crr to .0035 your speed would increase from 15.7 to 16.9 MPH at 100W and 20.8 to 21.9 MPH at 200W.

chaadster 04-05-14 11:20 AM

I disagree with a lot of what has been posted, and would answer the OP's question simply by saying no, new tires do not roll faster than worn tires of the same make.

However, what the OP has done is to switch brands, so in that case, the more likely explanation is better casing and tread on the new tires.

Harder durometer rubber, more supple casings, and higher pressures generally have lowest rolling resistance. Look for tires with high thread count casings, dual compound treads (hi-duro in center, lower on shoulders), and light weight (indicating less treading) if rolling efficiency is a priority.

Homebrew01 04-05-14 11:32 AM

Quote:

Originally Posted by Fingerpicker (Post 16643621)
Thanks that makes sense..is there a rule of thumb for when to change tires? I don't know what the old ones were ..they came with the bike, probably a place where're they cut costs

I don't replace a tire until the rubber is worn enough that I start to see the cords underneath.

I have a few new tires on hand so I can replace immediately when needed.

chaadster 04-05-14 11:39 AM

I should hasten to mention that determining whether a tire rolls better in actual use is highly subjective, and a tire that feels better may help you pedal further, harder, and with less fatigue, irrespective of relative Crr value, and in which case, a new tire of a given type is almost certainly more comfortable and better feeling than a very worn one, if only due to vibration damping of thicker tread.

longbeachgary 04-05-14 11:43 AM

Quote:

Originally Posted by Fingerpicker (Post 16642831)
Am I nuts? Over the winter I replaced the so so tires that came on my Specialized Allez. It was purchased new 18 months ago. Today was the first ride of the year and the first on the new tires (Michelin). The bike seemed to roll smoother and faster.. A lot smoother and faster...is that possible...all tires are 700x25

You may be nuts but different tires of the same size roll differently. Some tires make a tremendous difference.

chaadster 04-05-14 12:55 PM

Quote:

Originally Posted by Fingerpicker (Post 16643621)
...is there a rule of thumb for when to change tires?

Quote:

Originally Posted by Homebrew01 (Post 16644176)
I don't replace a tire until the rubber is worn enough that I start to see the cords underneath.

I wouldn't recommend using exposed casing as the rule of thumb; the increased likelihood of flats and the potential for loss of critical traction make waiting that long to replace, in the face of what a tire costs, seem unnecessarily risky.

My rule of thumb would be to replace the tire when the tread is heavily worn.

What does that mean? Well, in the case of a grooved or blocked tread, when those elements are worn away in the center of the tire. For a smooth or textured tread, when the rounded crown of the tread is worn flat shoulder to shoulder.

cruiserhead 04-05-14 01:41 PM

http://weknowmemes.com/wp-content/up...d-carry-on.jpg

rydabent 04-06-14 08:00 AM

Retro +1

It is indeed the tires ability to absorb road irregularities that reduce rolling resistance. If a tire can absorb a bump, it does not have to lift the bike. Of course lifting the bike takes energy and in effect slows down the bike a small amout.

Walter S 04-06-14 08:10 AM

Quote:

Originally Posted by rydabent (Post 16646094)
Retro +1

It is indeed the tires ability to absorb road irregularities that reduce rolling resistance. If a tire can absorb a bump, it does not have to lift the bike. Of course lifting the bike takes energy and in effect slows down the bike a small amout.

That's interesting in concept. You do also need to consider that the tire absorbing the bump, itself requires energy. In that case it is energy is consumed by flexing the rubber of the tire instead of lifting the whole bicycle. But hitting that bump involves the same amount of energy to be dealt with whether it's a soft tire or not.

My intuitive feeling is to agree with you, that lifting the whole bicycle rather than flexing the rubber of the tire will have a more slowing effect. But I don't think I understand the physics involved well enough to prove that.


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