Road Bike Tire Test: Specialized Turbo Cotton

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  • Specialized Turbo Cotton
Performance compared to all other road bike tires
(100% is best)
Pro Members get 11-point radar charts

Specialized Turbo Cotton road bike tire on a rolling resistance test machine

The Specialized Turbo Cotton is a road bike tire optimized to provide the lowest possible rolling resistance, highest grip, and most comfortable ride at the cost of tire life and puncture resistance. The Turbo Cotton comes with a 320 TPI cotton casing, and the Specialized GRIPTON compound which they claim is the best compound in the world. It also has a layer of Specialized BlackBelt puncture resistance material to get the puncture resistance to an acceptable level.


I'm testing the 24-622 version of the Turbo Cotton as that comes closest to the other tires I've tested previously and will test in the future. A slightly bigger 26-622 version is available as well. The main competitor of the Turbo Cotton is the Continental Grand Prix TT (read review) that I've tested recently as well. Both the Turbo Cotton and Grand Prix TT are tires that provide the ultimate performance in speed. Both these tires are not made to last thousands of miles or provide a very high puncture resistance.


As the name suggests, the Turbo Cotton has a cotton casing with skin-colored sidewalls (a black version isn't available). Some people swear by cotton tires like the Turbo Cotton and Vittoria Corsa because they are supposed to offer a more comfortable ride. I can't do a complete road test of every tire I test, but I'm very curious how the Specialized tires perform on our tests...

Manufacturer Specifications


Manufacturer Specifications
Brand Specialized
Model Turbo Cotton
Year 2016
Tire Type Tubetype (clincher)
Supplied By Bought in store
New or Used New
Mileage 0 km
Price Range Very High
Buy At
Manufacturer part number 00015-1503
TPI 320
Compound Gripton
Bead Folding
ETRTO 24-622
Size Inch 28"
Specified Width (mm) 24
Specified Weight 220 grams
Max Air Pressure (psi) 125
Made In Members Only
Available Sizes 24-622 (700x24C)
26-622 (700x26C)

Specialized Turbo Cotton Test Results

Specialized Turbo Cotton road bike tire on a rolling resistance test machine

Size, Weight, and Thickness Measurements


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Size, Weight and Thickness Measurements
Specified Weight 220 grams
Measured Weight 224 grams
System Adjusted Weight
(tire + inner tube (100 gr)
324 grams
Measured Width 25 mm (un-round)
Measured Height 22 mm (un-round)
Total Tire Thickness Center 2.1 mm
Total Tire Thickness Sidewall Members Only
Unmounted Casing Width No Data
Unmounted Tread Width No Data
Tread Cover (Tread / Casing Ratio) No Data
All size measurements are taken at an air pressure of 100 psi / 6.9 bars on a 17.8 mm inner width rim.

Specialized claims the weight of the 24-622 to be approximately 220 grams; my sample comes in at a nice 224 grams. With a maximum width and height of 25 and 22 mm respectively, the Turbo Cotton comes close to its rated size, but measures smaller than tires from other manufacturers. I'm not sure why Specialized has gone with the non-standard tire sizes, the 24 comes a lot closer to 23 mm tires from other manufacturers. The 26-622 Turbo Cotton should be similar in size to 25-622 tires from other manufacturers.


Just like the Continental Grand Prix TT, the Turbo Cotton is a very thin tire. Total measured thickness at the center of the tire is 2.1 mm, which is a bit more than the Grand Prix TT (1.9 mm). Most other all-round tires come in closer to 3 mm thickness at the center of the tire. The low thickness of the tires means they will wear out quickly. Because the cotton casing is constructed in a different way when compared to nylon casings, the 0.75 mm sidewall thickness is the average between the bottom half of the sidewall (1.0 mm) and top half of the sidewall (0.5 mm).

Rolling Resistance Test Results


Rolling Resistance Test Results
Inner Tube Conti Race28 (100gr butyl)
Measured Width 25 mm (un-round)
Rolling Resistance
Real tire width in mm:
22-24 = 132 psi/9.1 bar
25-27 = 120 psi/8.3 bar
28-29 = 108 psi/7.4 bar
Ultra High Air Pressure

(120 psi / 8.3 bar)
10.1 Watts
CRR: 0.00303
Rolling Resistance
Real tire width in mm:
22-24 = 110 psi/7.6bar
25-27 = 100 psi/6.9 bar
28-29 = 90 psi/6.2 bar
Extra High Air Pressure

(100 psi / 6.9 bar)
11.1 Watts
CRR: 0.00333
Rolling Resistance
Real tire width in mm:
22-24 = 88 psi/6.1 bar
25-27 = 80 psi/5.5 bar
28-29 = 72 psi/5.0 bar
High Air Pressure

(80 psi / 5.5 bar)
Members Only
Rolling Resistance
Real tire width in mm:
22-24 = 66 psi/4.6 bar
25-27 = 60 psi/4.1 bar
28-29 = 54 psi/3.7 bar
Medium Air Pressure

(60 psi / 4.1 bar)
Members Only
The Road Bike section is a multi tire size section, air pressures have been adjusted to the measured casing width.

All numbers are for a single tire at a speed of 29 km/h / 18 mph and a load of 42.5 kg / 94 lbs.

Use the formula: RR (Watts) = CRR * speed (m/s) * load (N) to calculate rolling resistance at a given speed and load.

As expected from a tire that is supposed to be one of the fastest tires in the world, the Turbo Cotton has a very low rolling resistance. At an air pressure of 120 psi, rolling resistance is 10.1 watts, which is just 0.2 watts higher than our current fastest tire: Continental Grand Prix TT 25 mm (read review). At lower air pressures, the relative performance of the Turbo Cotton is a bit worse when compared to its performance at very high air pressures.


Because the 24-622 Turbo Cotton measures small compared to the 25-622 Grand Prix TT, It might have been better to test the 26-622 Turbo Cotton as it should be the same size as 25-622 tires from other manufacturers. I expect the 26-622 Turbo Cotton to slightly outperform the 25-622 Grand Prix TT at 120 psi (~9.7 - 9.8 watts) and close the gap a bit at 100 and 80 psi. Keep this in mind when buying Specialized tires: 24 = 23, 26 = 25.

Puncture Resistance Test Results

Specialized Turbo Cotton road bike tire on a rolling resistance test machine
Puncture Resistance Test Results (higher is better)
Total Puncture Score Tread 36 Points
Total Puncture Score Sidewall Members Only
Tread Puncture Force Sharp Needle 9 Points
Tread Puncture Force Blunt Needle No Data
Tread Total Tire Thickness 2.1 mm
Sidewall Puncture Force Sharp Needle Members Only
Sidewall Puncture Force Blunt Needle No Data
Sidewall Total Tire Thickness Members Only

Does the Specialized BlackBelt puncture resistance material provide enough puncture resistance? With a score of 9 points in the tread puncture test, puncture resistance is slightly better than the Grand Prix TT which scored 8 points. Compared to the more all-round tires which mostly score 11-12 points in our test, performance is as expected from a tire with a very low rolling resistance and thin tread.


At 4 points, sidewall puncture resistance is similar to most other high TPI tires which generally come in at a sidewall puncture resistance score of 4-5 points.

Static Grip Test Results


NOTE: Grip test data is only available on tires tested after November 2018. You can find more information about our grip test here: Introducing Grip Testing

Static Grip Test Results
Wet Grip Average No Data
Wet Grip Center No Data
Wet Grip Edge No Data
Grip in points = coefficient of friction * 100

Conclusion


  • Specialized Turbo Cotton
Performance compared to all other road bike tires
(100% is best)

Pro Members get 11-point radar charts

Just like the Continental Grand Prix TT (read review), the Specialized Turbo Cotton is a very, very fast tire with limited puncture resistance and tire life. These tires will save you 5+ watts for a pair of tires when compared to the most popular all-round tires that provide better puncture resistance and will last a lot longer. If you fit these with latex tubes, I'm convinced it will be very hard to find faster tires.


Most bicycle shops don't sell the Specialized tires, but they are available at (local) Specialized dealers at prices that are a bit higher than the Grand Prix TT (read review) or other top-of-the-line clincher tires. Have you used these tires or have any experience with the Specialized GRIPTON compound? Please consider writing a comment as I'm curious to your opinion.

RATING: 5.0 / 5
TEST VERDICT:
Highly Recommended


Comments



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