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Discussion Starter · #1 ·
I'm running Nokian NBX 2.0 Lights now and spend a fair bit of time out of the park on the nearby roads where the roadies hang out. So, I'm in and out of the park....pavement and trails.....

Now, I am thinking of fooling around with some road only tires on this hardtail.
Specialized makes a 26x1.0 115-125 psi tire that weighs 285g

I know the Nokians are 21.2 watts..
Any educated guess as to what the 26x1.0 tire at 115 psi might rate in watts?

here is the tire......
http://www.specialized.com/SBCEqProduct.jsp?minisite=10080&spid=7020&=

Certainly it will have lower watts and is lighter.....
I'm also wondering how much faster it will be. Say a guy is doing 20.0 mph on the road using the Nokians at 47 psi rear and 43 psi front, then how much faster than 20.0 mph would he do using the 26x1.0 tires...."all other factors being equal" on a paved road?
 

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Doesntplaywellwithmorons!
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well coasting I regularly pass roadies on 700x23C continental grand prix 300 tires, and I'm on the umma gumma compound Specialized Turbo/S 26x1.0 tires.
 

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2.35" Schwalbe SuperMoto's will probably roll even faster, as well as offer a semi-offroadable ride. More like 600g, though, so the skinny ones will for sure feel faster.
 

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Chester said:
I'm running Nokian NBX 2.0 Lights now and spend a fair bit of time out of the park on the nearby roads where the roadies hang out. So, I'm in and out of the park....pavement and trails.....

Now, I am thinking of fooling around with some road only tires on this hardtail.
Specialized makes a 26x1.0 115-125 psi tire that weighs 285g

I know the Nokians are 21.2 watts..
Any educated guess as to what the 26x1.0 tire at 115 psi might rate in watts?

here is the tire......
http://www.specialized.com/SBCEqProduct.jsp?minisite=10080&spid=7020&=

Certainly it will have lower watts and is lighter.....
I'm also wondering how much faster it will be. Say a guy is doing 20.0 mph on the road using the Nokians at 47 psi rear and 43 psi front, then how much faster than 20.0 mph would he do using the 26x1.0 tires...."all other factors being equal" on a paved road?
Hey,

if you do a google search for rolling resistance bike tire and such keywords you'll find a lot of actual test data for road tires which includes a lot of 26" slicks too. From my memory the best tires had Cr ~ 0.004 (11 watts). I remember earmarking Schwalbe Marathon to buy as the 26" slick with the best rolling resistance from those tests. Don't know what it weighs though.

Anyway a quick visit to analyticcycling.com gives 1-1.5 mph increase in speed for your case if you swap both your tires to slicks.
 

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Discussion Starter · #5 ·
Even 1.0 mph is huge

Boj said:
Hey,

if you do a google search for rolling resistance bike tire and such keywords you'll find a lot of actual test data for road tires which includes a lot of 26" slicks too. From my memory the best tires had Cr ~ 0.004 (11 watts). I remember earmarking Schwalbe Marathon to buy as the 26" slick with the best rolling resistance from those tests. Don't know what it weighs though.

Anyway a quick visit to analyticcycling.com gives 1-1.5 mph increase in speed for your case if you swap both your tires to slicks.
Well, even 1.0 mph is simply huge.....although one section I have in mind now averages about 15 mph instead of 20 mph so that 1.0 to 1.5 mph increase may be cut by to .75 times the 20 mph mark.....I'll go to analyticcycling and run it.
Still, even if I picked up .75 mph over this particular 30 minute run where I chase roadies, it would still mean about .375 miles of advantage. Not many of the ones I can't catch now pull ahead of me by that much over that distance......except the young well trained ones.... Young to me means under 40, me being well past 50...
I suppose I should just break down and get true road bike, but its fun to have a disadvantage and still make up for it.
Next thing I know, I'll have 1.0 tires and drop bars with aero arm rests and TT helmet...

The most fun thing I like about chasing roadies, is if I tuck right in behind them, and draft on my Nokians, .....man, its just like a free ride. I can keep up without even straining even on my knobbies.
That draft, something I never really experienced on the trails, is simply amazing.
I could ride all day like that.
Only left for me to do is to shave my legs...... :)
 

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Actually, 700c tires only have a 10% mechanical advantage over 26", although of course there are more superfast, lightweight 700c tires available. The 26x1's might well be aerodynamically better. Traithletes still often choose 650c as to them aerodynamics (flats) and weight (moutains) are more important than rolling resistance and cornering speeds.
Even if you get a chi-cchi road bike, NEVER shave your legs!! In my inregular crit appearances, I make a point of riding with a helmet visor, unshaves legs, and dirty mtnbike shoes. Makes the roadies a bit more fanatic chasing you, so you know they're not holding back anything.
 

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Discussion Starter · #7 ·
I've wondered about this "10% advantage"

Cloxxki said:
Actually, 700c tires only have a 10% mechanical advantage over 26", although of course there are more superfast, lightweight 700c tires available. The 26x1's might well be aerodynamically better. Traithletes still often choose 650c as to them aerodynamics (flats) and weight (moutains) are more important than rolling resistance and cornering speeds.
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10% mechanical advantage?
I know about the rolling resistance of road tire over mountain (fat) tires, and I know about the weight advantage that a smaller 26 inch tire could have over a 700 tire and I can figure out the smaller aero profile of a shorter tire.....

But I believe you are talking about something different when you say "mechanical advantage"....
Now, I can see if a tire was only 3 inches it would have a terrible time rolling along over even tiny changes in road surface......and I can see how a 60 inch tire wouldn't even notice small bumps in the road........
But is what is the "mechanical advantage" between a 26.0 and 700 tire that could possibly account for a 10% mechanical advantage?

And what exactly does 10% mechanical advantage mean?
I don't understand how to quantify it such that I can figure out what that aspect of tires means. Is it something beyond rolling resistance or does rolling resistance incorporate that data?

700 is about 28 inches right.......
 

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Don't forget that the small diameter of 26 inch tires and low off-road gears will make for a very low high-gear when you are chasing roadies down. Using skinnier tires is going to decrease the effectiveness of your high-gear. It's probably a better idea to get a road bike with road gearing and drop bars, then you too could actually do some pulling and stop sneaking into the draft so much. :p

And 115 psi is a little bit high unless you are racing in cat 2. For training 100 to 105 psi should be just fine depending on your tire and weight. Above a certain pressure the ride becomes much less comfortable, for me that's about 110 psi. I've done just fine running 100 psi (I weigh 165 pounds) in rainy races with speeds around 26 mph, so it should work fine for you too.
 

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Chester, click my profile to check out my bike set-up.

I'm guessing I use and set-up my bike similar to yourself.


I'm running a HT mtb with 26 x 1 Conti GP slicks. I run them at 120psi. I weigh 175lbs. In the wet I drop the tyres down to 100 to 105 psi for the extra grip.

I do a regular commute to work across 15.5miles - mixture of country lanes and dual carriageway and city type roads. The route in isn't flat. At points, I drop down to 12mph on long uphill sections and cruise at 27mph on the flat. My gears do not help. 44/34/22 front 11-23 rear. Gives a shorter chain with only 11-23 rear (100 links). I also find I can climb most hills off road in 34 front 23 rear. Only on extended climbs do I need the granny.

Not sure what the scientists would say. Experience, has shown that my Conti GP 26 x 1 at 120psi are 2mph faster than Conti Twister Supersonics 26 x 1.9 at 45psi, over a road route of 15.5miles long.

I too like to chase down roadies. The looks of surprise when a roadie crusing at 22 to 27 mph on the flat only to look round and see a mountain bike on their back wheel getting a free draft!
 

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nightriding is fun !
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At the moment I'm using Ritchey Tom Slick 1.0 tyres and I average 1-2kph faster than with my Fast Fred 2.35 tyres (also good rollers) on 40-60K rides
What I lose in comfort (and the ability to wander along th eoccasional offroad section) I gain in speed .
The gears don't seem to fit as well as with normal mtb tyres even using a dura ace 12-25 cassette
 

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Discussion Starter · #11 ·
Did you adjust the computer?

Tippster said:
Chester, click my profile to check out my bike set-up.

I'm guessing I use and set-up my bike similar to yourself.
Not sure what the scientists would say. Experience, has shown that my Conti GP 26 x 1 at 120psi are 2mph faster than Conti Twister Supersonics 26 x 1.9 at 45psi, over a road route of 15.5miles long.

I too like to chase down roadies. The looks of surprise when a roadie crusing at 22 to 27 mph on the flat only to look round and see a mountain bike on their back wheel getting a free draft!
Just curious, did you adjust the setting on your cyclo-computer when switching from the Supersonics to the Conti's....being that the tire is smaller?
 

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Discussion Starter · #12 ·
Same calculator question....

Big Bad Wolf said:
At the moment I'm using Ritchey Tom Slick 1.0 tyres and I average 1-2kph faster than with my Fast Fred 2.35 tyres (also good rollers) on 40-60K rides
What I lose in comfort (and the ability to wander along th eoccasional offroad section) I gain in speed .
The gears don't seem to fit as well as with normal mtb tyres even using a dura ace 12-25 cassette
Just like I asked Tippster above....when you switched from the Fast Freds did you adjust the calculator to allow for the smaller Tom Slicks?

1 to 2 mph is lots......I'd catch heaps of roadies with those :)
 

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Chester said:
Just curious, did you adjust the setting on your cyclo-computer when switching from the Supersonics to the Conti's....being that the tire is smaller?
You did not ask me but I will answer :D
Of course, you have to measure the tyre and adjust your computer accordingly, common knowledge that.
 

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I'm using a cateye cordless 2 cyclo computer.

It has 2 tyre settings. You simply measure the circumference of both your tyres and input them into the unit.

Yes 2 mph is a lot. Its based on my own personal experience. Over 15.5 miles of road, I average 20.2mph. With a road tyre I get 18 to 18.5mph. I put it down to more direct power transfer. With a 2 inch tyre you have a lot more rubber and air to flex as you apply power to the pedals.

Going back to my teenage year maths classes:

Area of a semi circle (from the rim to the road - half the area of a circle Pi, R squared, where R is the radius and Pi = 3.142)
Pi x r2 / 2
3.142 x 0.5 inches (radius of a 1inch slick) squared / 2 = 0.39275

3.142 x 1 inches (radius of a 2 inch mtb tyre) sqaured / 2 = 1.571

You can see from teh above numbers that you have 4 times the amount of rubber and air to flex with a 2 inch tyre than a 1 inch.

Having riden 15 miles on road with both a 1.9 semi slick and a 1 inch slick. I would now NEVER DREAM of using a semi slick to cover any distance over say 5 miles without road tyres on.


Enough of the Math, WOLF, your Richey Tom slick tyres weigh 250g a piece. Switching to Conti Grand Prix floding tyres will save you 50g per tyre. Conti claim 195g per tyre, mine weighed in at 200g.

You may also want to check Richey and Conti websites for the Threads per inch on each tyre to compare puncture proofness. Couldn't find the Tom slick tyre on the Richey website. Conti use 5 ply threads in their rubber to protect againsts punctures.

WOLF, you may also want to think about switching your cassette to a 11-23 DA. I'm guessing you have 44 teeth front. with 12 teeth rear, you are limiting your max speed on the flat and downhill. My 11-23 Da cassette weighed in at 156g. If you are fit, you can climb any off-road hill in the middle ring and 23 teeth rear. Only for extended climbing do you need the granny ring. 11-23 DA is half the weight of 11-34 XT (300g).

Hope that helps.
 
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