Tire Test - CST E-Series Reach

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Test Summary

Conclusion: 3 / 5 Recommended
Weight: 734 grams
Rolling Resistance: 21.9 watts
Puncture Resistance: 10 / 6

CST E-Series Reach road bike tire on a rolling resistance test machine

The CST E-Series Reach is an E-bike tire from the world's largest bicycle tire manufacturer. CST (Cheng Shin Tire) is a Taiwanese company with factories in Taiwan and China. There's a big chance you've ridden on CST tires without knowing, a lot of tires from smaller brands are actually rebranded CST tires. They also own the Maxxis brand, which is their high-end brand. The CST branded tires are marketed as the more value-oriented tires.

The E-Series Reach comes with a 22 TPI carcass, single compound rubber, ECE-R75 certification (up to 50 km/h), and the CST APL technology. The APL system is basically a 1 mm thick layer of rubber that is harder to penetrate. Although 1 mm is better than nothing, there are also tires on the market that come with 3 - 5 mm thick AP layers. Maybe this layer is extremely hard to penetrate while at the same time keeping rolling resistance at a low level? Let's put this tire on the test bench.

Manufacturer Specs
Brand CST
Model E-Series Reach
Year 2015
Supplied By Supplied by Continental
New or Used New
Mileage 0 km
Price Range Med
Manufacturer part number
Bead Wire
ETRTO 37-622
Size Inch 28"
Width mm 37.00
Specified Weight 734 grams
Max Pressure 75
Made In China
Available Sizes 37-622 (28x1.40)

Test Results

CST E-Series Reach Touring/E-Bike on a rolling resistance test machine

Size and Weight Measurements

Size and Weight Measurements (Bike Wheel: 622-17C, Pressure: 60 psi / 4 bar)
Specified Weight 734 grams
Measured Weight 734 grams
Measured Width 37 mm
Measured Height 34 mm
Tread Depth 1.1 mm
Total Tire Thickness Center 4.4 mm
Total Tire Thickness Sidewall 1.80 mm

CST specifies the weight should be close to 715 grams, my sample comes in at 734 grams. On a 17C rim, at an air pressure of 60 psi, the 37-622 E-Series Reach measures 37 mm wide and 34 mm high. It's nice to see a tire actually measure close to its rated size.

The E-Series Reach comes with an almost slick tire profile, there are only some slight grooves at the edge of the tire. I've measured these grooves at 1.1 mm deep. This definitely is less that most other touring tires that come closer to 2 mm tread depth. The total tire thickness at the center of the tire is also quite thin with a thickness of 4.4 mm. The sidewalls do are thick with a measured thickness of 1.8 mm.

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Rolling Resistance Test Results

Rolling Resistance Test Results (Speed: 29 kmh / 18 mph / 8 m/s, Load: 42.5 kg / 417 N)
Inner Tube Conti Tour 28 (170 gr butyl)
Rolling Resistance 90 psi / 6 Bar No Data Watts
CRR: No Data
Rolling Resistance 75 psi / 5 Bar 19.0 Watts
CRR: 0.00570
Rolling Resistance 60 psi / 4 Bar 21.9 Watts
CRR: 0.00656
Rolling Resistance 45 psi / 3 Bar 26.6 Watts
CRR: 0.00797
Rolling Resistance 30 psi / 2 Bar 36.2 Watts
CRR: 0.01085
Use the formula: RR (watts) = CRR * speed (m/s) * load (N) to calculate rolling resistance at a given speed and load

At the maximum rated air pressure of 75 psi, rolling resistance comes in at a low 19.0 watts. This is actually the lowest rolling resistance of all touring tires that have been tested to date. At 75 psi, it outperforms the Schwalbe Marathon (read review) by 0.6 watts. At lower air pressures, rolling resistance starts rising much faster than comparable tires. At an air pressure of 60 psi, the Schwalbe Marathon already has a 0.6 watts advantage which increases to 5.6 watts at 30 psi.

Rolling resistance is close to what I expected from the E-Series Reach. It's just unfortunate rolling resistance increases so much at higher air pressures. It's nice to be able to lower air pressure to increase comfort, 60 psi on 37-622 tires already gives quite a bumpy ride.

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Puncture Resistance Test Results

Puncture Resistance Test Result (higher is better)
Puncture Resistance Tread 10
Puncture Resistance Sidewall 6
Puncture Factor Tread * 44
Puncture Factor Sidewall * 11
* Puncture Factor = Puncture Resistance * Total Tire Thickness
Puncture Factor provides a more realistic puncture resistance score for touring tires

While performance in the rolling resistance test is strong, the E-Series Reach performs very poorly in the puncture resistance test. In the tread puncture resistance test, which is the most important measurement, it's the lowest scoring tire to date. It does perform much better in the sidewall test, but I'm sure 90% of real-life punctures are in the tread area.

Puncture Factor Tread also comes in very low because the tread is not only easy to puncture but also very thin. With a score of 44 points, it scores less than half what the Schwalbe Marathon scores (102). Just like the puncture resistance sidewall score, Puncture Factor Sidewall is on the high side as well because the sidewalls are quite thick compared to other tires.

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CST E-Series Reach Touring/E-Bike on a rolling resistance test machine

Rolling resistance at very high air pressures is very good. At lower air pressures, rolling resistance starts rising faster than comparable tires. In the puncture resistance test, the E-Series Reach performs awfully with the lowest tread puncture scores to date. On top of that, it doesn't have much tread depth. We do rate the CST E-Series Reach recommended 3/5 because.. this is Bicycle Rolling Resistance.

There still doesn't seem to be a tire that comes close to the Schwalbe Marathon (read review) in both the rolling resistance and puncture resistance departments. The Schwalbe Marathon is still our nr 1 recommended tire for a low rolling resistance and high puncture resistance. On top of that, you also get a decent tread profile and tread depth.

RATING: 3 / 5


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