(Test from EMTB 2/2016) "Jo, look here, the 500 Wh battery is exactly empty." Christian "Picco" Piccolruaz, Stubai mountain guide and EMTB tester, and I roll out in front of a picturesque hut 2200 metres above the Stubai Valley. The Bosch Performance CX motor on Picco's bike has switched off, while the battery indicator on my bike has jumped to "- -". This means: two more minutes of weakening thrust, then the pedelec motor turns blue.
Never mind, we always ride in the Tyrolean mountains with a second battery in our rucksack. This also comes in handy this time, because after the hut we continue along a mountain ridge for around 500 metres until we turn into a long descent. To save the batteries' honour, it should be noted: After work, we cranked up to the hut in sport and turbo mode to enjoy the evening sun. Not easy on batteries and motors. It's just under 1200 metres in altitude from the valley village to the hut, first asphalt, then forest road with some rough gravel and hefty ramps, perfect for powering up and clearing your head.
It's "eternal autumn 2015" and the shadows in the valley are getting longer. Nevertheless, apple strudel and elderberry schnapps are always a good idea. On the sun terrace, we start to ponder. How many more metres in altitude could be squeezed out of the batteries with narrower tyres? How much worse would the downhill performance or puncture protection be? Do wider tyres suck up much more power? Are plus-size tyres the solution?
What is measurable? We wanted to find out and set up camp on Lake Garda in spring 2016. Our mission: four different tests with five different pairs of tyres. The aim is to find out to what extent the rolling resistance of the tyres on the E-MTB affects the range. At the start: Conti's fast X-King ProTection 2.2 as the narrowest tyre, Vittoria's new E-Goma 2.25, Schwalbe's Nobby Nic in 2.35, the almost one kilo heavy enduro tyre Der Baron in 2.4 width and the widest tyre, the Schwalbe Nobby Nic in 2.8 inches, i.e. in B-Plus width. Also in the luggage: highly sensitive Look power measurement pedals.
We outline four test scenarios with a fixed total rider weight of 90 kilos. We test the tyres with 2.3 bar air pressure for the narrower rollers and 1.3 bar for the wider ones. We ride the bike in turbo mode, applying 130 watts of power ourselves, controlled by the power measurement pedals.
First test: Pedal 350 metres on a set tarmac route, then roll back and measure the power consumption during charging until the battery is full again. In the meantime, change tyres and repeat the same procedure with new tyres - until all tyres have been tested.
Second test: Rolling resistance test without pedalling. To do this, we roll slightly downhill on 50 metres of asphalt. The time taken is recorded. The rolling test is repeated five times per pair of tyres and the times are then averaged.
Third test: completely drain the battery on a long tarmac hill climb. To save time, five 500 Wh Bosch batteries are available, as good as new and full to the brim.
Fourth test, to round things off: the classic Innsbruck low mountain circuit (1200 m elevation gain, 25 km, single trail, gravel, asphalt) to check the tyres for puncture resistance, traction (uphill/downhill), braking and cornering behaviour.
Christian completes precise laps for the first test, only coming into the test cellar to change tyres and charge. We eagerly note down the consumption figures. The charging times vary and the first differences become apparent. The next day: 50 metre rolling test on a lonely mountain road. We tirelessly record the times - roll, measure, repeat. In between: Changing tyres, pumping up, upper arms like Hulk. On the third day - Christian has to return to Stubai - I change to Latsch in Vinschgau, the mountain road to St. Martin am Kofel is calling. Altitude difference: 1137 metres - that's not enough for a full unload. So on every test ride, I roll back at 1100 metres in altitude and ride up again until the battery electronics switch off. Over two days, including the roll-in, the Polar logger adds up to almost 7500 metres in altitude.
Now it's time for the evaluation. In terms of rolling resistance, the narrow X-King and the slightly wider E-Goma naturally perform very well. The hard currency, however, is the metres in altitude covered. The altitude metres and battery consumption test correlate well, and in addition to the rolling resistance, the tyre weight is of course noticeable here. The maximum difference in range is 130 metres in altitude between the 2.2 cross-country and 2.4 enduro tyres. Surprising for us: The performance of the 2.8 Plus tyre: In terms of metres of altitude covered, the 2.8 Schwalbe is practically on a par with its little 2.35 brother (25 m), but also with the Conti Der Baron.
The Plus tyre is 80 vertical metres short of the Vittoria and 125 short of the 2.2 race tyre (Conti X-King). One thing is certain: For its width, the 2.8 Nobby Nic performs excellently! For us, this means that we can finally ride wide tyres without regret.
CONCLUSIONThis test clearly shows that the future of E-MTBs belongs to wide, puncture-proof tyres that roll sensibly. The distance between the Enduro and Plus tyres and the 2.35 Nobby Nic is hardly relevant - but Plus and Enduro offer more puncture protection and traction. We would certainly prefer the wide tyres to the two narrow tyres from Vittoria and Conti. In terms of riding characteristics, they are clearly superior, and the maximum 130 metres lower range is bearable. Of course, anyone planning to cross the Alps will have to do the maths again: You can save up to 130 metres in altitude per day - up to 900 metres in seven days. For normal e-MTB tours, however, the rule is: wider is better. Our favourite for this: the Plus tyre from Schwalbe. The 2.8 Nobby Nic is the new benchmark with top riding performance and very good range values.
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CONSUMPTION
We measure the watt hours charged after a 350-metre tour on asphalt until the battery is full.
ROLLING WIDER STAND
On asphalt, we measure the time for 50 metres of rolling distance five times per pair of tyres. Without motor and pedalling.
HEIGHT METER
On tarmac, we drain the batteries with a steady 130 watts of power and determine the range/hour.
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CONTINENTAL DER BARON 27.5 x 2.4
High-quality, stable (985 g) enduro tyre with grip on any surface and low wear thanks to the Black Chili compound. Good self-cleaning properties. Moderate puncture resistance. Good limit range.
CONTINENTAL X-KING PROTECTION 27.5 x 2.2
Lightweight 655 g touring file that cuts a fine figure on dry surfaces. Quickly overtaxed in wet conditions, very narrow for E-MTBs. Smooth-running tip for easier Alpine crossings.
SCHWALBE NOBBY NIC 27.5 x 2.35
Top all-rounder (720 g) with acceptable puncture protection and good performance on all surfaces. Goes well with the 2.8 Nobby Nic at the front on tighter rear triangles.
SCHWALBE NOBBY NIC 27.5 x 2.8
Lighter (860 g) and better than its 3.0 brother in terms of grip, control and steering precision. Perfect front tyre for everything except mud and snow. Also a blast on the rear wheel. Rolls well, feels comfortable almost everywhere.
VITTORIA E-GOMA 27.5 x 2.25
Old acquaintance, reinforced for E-MTB (820 g). Very good rolling characteristics and wear values. Moderate grip and puncture protection. Likes dry ground, but not mud. There it clogs up quickly.
