Transalp with the E-MTB: Is the range extender finally making the experience possible?

My thighs are burning. The heavy rucksack presses me into the saddle and the intervals in which I have to stand up so that blood can flow through my leg veins again are getting shorter and shorter. There are still 800 metres to climb to Döss Radond, the highest point of today's stage. But firstly, it's almost five o'clock in the afternoon. And secondly, I only have two blue bars left on the display. This means that I've already used up well over half of my battery capacity. That's why I've been back in eco mode for 200 metres of altitude. I actually wanted to complete the whole stage in this lowest support level. To save power.

From Nauders up to the mountain station of the Bergkastel cable car, I pedalled like an ox. For 1000 metres in altitude. But then there were these nasty, steep ramps in the direction of Val Müstair - I just had to add a few more briquettes. But the fact that it cost so much more battery? Doesn't help, keep going. Another 500 metres in altitude. A couple of hikers on their way down into the valley fall silent when they see me. As soon as I pass them, I hear: "How slow he is. Despite the e-bike!" Another 200 metres up to the top of the pass. The colour on the display changes from blue to orange. I dismount, lean on the handlebars and push the rest of the way. Sabine is already sitting at the top of the Döss Radond. I'm completely hypoglycaemic, but I still have enough energy for a frustrated distance shout: "Mission self-sufficient Transalp failed, we've fucked it up!"

E-MTBs can do almost anything, but a full-blown Transalp has never been one of them. At least not without a support vehicle and luggage transport so that there is room for a heavy second battery and charger in the rucksack. Daily stages over 2000 metres in altitude are simply not possible with most bikes and only one battery. But then Claus Fleischer, CEO of Bosch and occasional touring companion, presented me with the supposed game changer: "With this," grinned Claus, holding a black thing the size of a drinking bottle in front of my nose, "you can manage 3000 metres in altitude." All you have to do is mount this "Bosch Power More 250" range extender in a special holder instead of the bottle cage and combine it with an in-built 750 watt-hour battery on the bike. This system would already provide 250 additional watt hours. If this works, a self-sufficient Transalp should actually be possible. It's definitely worth a try.

It's the 5th of October when we set off. The days are already getting short. But we wanted to wait until Marc Schneider, the race director of the BIKE-Transalp, returned from his route research for the 2024 route. Marc sent us a condensed version of this first draft route in four stages in the form of GPS data. From Imst to Boario Therme, near Breschia, with a total of 340 kilometres and 10624 metres in altitude. One thing is clear: we will make it as difficult as possible for the range extender. Or ourselves, as day 2 impressively demonstrated. It all started off so beautifully carefree:

Stage 1 - Imst-Nauders: 81 km - 2327 m altitude difference

The elevation profile of the start stage promises a kind of easy roll-in: Between Imst and Nauders there are a total of 2327 metres in altitude, but without any noticeably steep climbs. We cycle a few kilometres on asphalt into the Pitztal valley and traverse the Pillerhöhe on a steep, slippery path towards the Inn valley. My finger twitches for the support level switch, but I don't allow myself more than Tour Plus. But my pulse is racing. Sabine's economy concept looks different: She simply pushes through technical sections. After a long descent on gravel, we cycle the Via Claudia through the Inn Valley. An easy but steady 30 kilometres uphill. In the Eco, this drains your reserves about as much as a short ramp. After 60 kilometres, it's time for the final climb: another 600 metres in altitude and 15 kilometres to Nauders, but still 50 percent battery. Well managed. Sabine even has 10 per cent more. We look at each other: "Okay, turbo!". And so we fly up to the Mutzkopf in record time and down to Nauders on the finest bike park trails. Shortly before we reach the Neue Burg hotel, my display switches to orange: 30 per cent remaining capacity - that was relaxed. We can easily go one better tomorrow, I think.

Stage 2 - Nauders-Bormio: 104 km - 3032 metres altitude difference

3000 metres in altitude is quite a challenge. If we want to arrive in Bormio tonight, we not only have to economise on our batteries, but also on daylight. In October, you simply have much less time for a marathon like this. The sun currently sets at 18:30. Then it quickly becomes uncomfortable in the high mountains. Theoretically, you could roll from Nauders directly towards the Swiss border. But this is the BIKE Transalp route. Naturally, a few laps of honour are planned on the Reschen Pass. So it's 3.30 pm before we stop for lunch in a bar in Santa Maria - where the kitchen is now closed. "Salad would still be possible," says the waitress, looking at us sympathetically. At least there's power for our bikes, they can plug in.

But only for half an hour, because we're sitting on coals. When we set off, my display at least shows one more white bar, i.e. 10 per cent. But it's still going to be tight. The last 800 metres of altitude difference up to Döss Radond now pile up between us and the day's destination in Bormio. My personal Waterloo, which I have already described at the beginning. But when I finally reach this pass, Sabine doesn't even know why I'm ranting about "messed up" and "mission failed". Her display still shows three blue battery bars. I nibble on a bar and then another. Okay, mission not yet failed, we can carry on. It's already dawn as we cross the Val Mora. The blue hour casts a ghostly light on Lake Cancano. As if in a trance, we knead along the gravel road towards Bormio. Sabine gives me slipstream, she has one more bar than me. My display lights up red. It's a good thing we've packed a small headlamp. That way we can still get a rough idea of the trail in the last, dark stretch of forest. The display flashes as we park the bikes in the ski cellar of the Hotel Baita Fanti. Charge the batteries, shower, eat, sleep - and take a look at the next stage. It really can't get any tougher than today.

Stage 3 - Bormio-Aprica: 98 km - 3232 vertical metres

And it gets tougher. The infamous Mortirolo Pass stretches towards Val di Sole and the Adamello massif. That alone is 1300 metres of steep tarmac in one go. But somehow we are less excited today. Perhaps because we can now better assess our reserves and those of our batteries. It's basically a calculation exercise: we know the altitude and kilometres and the remaining capacity of the batteries. A simple rule of three. Provided you can rely on the battery management of the motor, which is the case with us. What it says on the tin is what it contains. Nevertheless, today's 3232 metres in altitude are a full programme. In Grosio at the foot of the Mortirolo Pass, we want to recharge our batteries during the lunch break. That's why we treat ourselves to Tour Plus mode for the long climb into Val di Dentro.

This allows us to enjoy this secluded high valley with its alpine pastures and small mountain lakes much more. The descent into Valtellina on ancient cart tracks is also fun: 1800 metres down into the alleyways of Grosio. After the planned pit stop at the Hotel Sassella, the Mortirolo Pass with its endless tarmac hairpin bends awaits. The average gradient is 10 per cent. According to Strava, the route record is 46 minutes. We need about twice as long. I arrive in Aprica with an orange-coloured bar, Sabine with two blue ones. 15 kilos less on the ribs simply pays off.

Stage 4 - Aprica-Boario Terme: 67 km - 2033 metres altitude difference

According to the numbers, the last stage should be a piece of cake - but it should contain an "epic monster": the Passo Venerocolo. The lower part of this pass is so steep in places that we can only make progress leaning far over the handlebars - in turbo mode. After that, it flattens out a little, but remains technical. At the "Ristoro Aprica" mountain restaurant, we say goodbye to human civilisation for hours. Section by section, we work our way up. First on a winding root trail, later on high alpine hiking trails secured by wire ropes. A jewel of a trail! The surrounding landscape: as wild as in the Western Alps. As we cross the pass, the vast expanse of the Po Valley opens up before us. "Wow, the end of the Alps," I say to Sabine, who points to her display: "And the near end of my battery." The E-MTB mode, which we had switched on almost continuously in favour of the uphill flow, is now taking its toll. Well, we must have miscalculated today. Never mind, we'll recharge somewhere down in the valley and it should last us until Boario Therme. The uphill flow fun was worth it.

Info: Transalp with the E-MTB

Lightweight makes sense: In a four-star hotel with flip-flops for dinner - a picture that is not uncommon in bike hotels during the Transalp season. Of course, shoes for the evening don't fit in a rucksack and are far too heavy. Anyone planning a self-sufficient Transalp is fighting for every gram. And not just to have less weight on your back.

Weight has a dramatic effect on the range of the batteries. Markus weighs 83 kilos in full kit, i.e. with helmet, shoes and clothes. Sabine weighs 70 kilos, 13 kilos less. On average, this saves between 10 and 20 per cent power.

Here are a few more interesting weights:

Bike with pedals 23 kilos

Range extender with bracket 1.6 kilos

Backpack Markus / Sabine 8.5 / 9 kilos (without water)

Handlebar bag Markus / Sabine 1.7 / 1.5 kilos

Bag in frame triangle Sabine 0.65 kilo

Our Transalp e-MTB with range extender

As light and efficient as possible: For our Transalp self-sufficient project, we chose the Canyon Neuron On CF 8 as standard equipment. At less than 23 kilos, the bike is quite light thanks to the permanently installed 750 watt-hour battery, the geometry is not too flat and therefore good for neutral steering behaviour on long tours. The tyres (Schwalbe Nobby Nic), which we would normally have swapped for heavier and grippier ones, save us valuable energy on the Transalp thanks to their lower rolling resistance. Thanks to the tubeless system and defensive riding style, we didn't have a puncture even on rough passages. Clipless pedals and shoes with good power transmission also save us a few ounces of energy. Markus, who usually prefers flat pedals, had fitted these especially for the Transalp.

However, the most important feature for us is the Bosch CX drive. In our experience, this is one of the few drives with a reliable, linear capacity display. This prevents nasty surprises when calculating the remaining range. Sabine used her Iphone 13 Pro Max for navigation, mounted on a Fidloc Vacuum stem mount. A large power bank (Otterbox, 15,000 mAh), stowed in the frame bag under the top tube, served as the energy supply. The Bosch Power More 250 Range Extender sits in a special holder instead of the bottle cage. It is connected to the bike's charging socket via a supply cable and remains wired to the main battery during the stage (except when charging, of course). The advantage of this setup is that you charge the range extender immediately after the tour. It is then fully charged after dinner (charging time 1.5 to 3 hours). Then you plug the bike into the main battery overnight. This ensures that you have full capacity again the next day.