2000 Metres of Climbing on an E-Bike: Who Gets Tired First — the Battery or You?

Aleksei “Lex” Shatilov — certified mountain bike guide (Guida di Mountain Bike, Accademia Nazionale del Ciclismo), MTB Tour Garda, Riva del Garda

You’re choosing a route and you see this number: 2000 metres of climbing. Then you remember your last ride. After 1000 metres of climbing, half the battery was gone. So the answer looks simple: the battery isn’t big enough. But it is, if you ride most of the climb in Eco. The problem usually isn’t the battery. It’s how you use it.

One example is Tremalzo, a famous mountain route above Lake Garda. It has about 2200 metres of climbing. You can ride it on one charge. You’ll find the numbers from one real ride further down.

What this article is about. Electric mountain bikes with the Bosch Performance Line CX motor and an 800 Wh battery. All the calculations are for these bikes. You’ll find three kinds of information here: numbers from real tests and rides, calculations, and advice. The text always tells you which kind it is. The sources are linked in the text. The full calculation is at the end, step by step, under “Where the numbers come from”.

Who does the work: you or the motor?

The motor has several modes. The difference between them is simple. It’s how much of the work you do, and how much the motor does.

Each mode has its own percentage. It shows how much the motor adds to your own power. In Eco, the Bosch Performance Line CX motor adds 60%. So for every 10 you put in, the motor adds 6. In Turbo, it adds up to 340%. For the same 10 from you, the motor adds up to 34. That’s more than three times your own power.

Here’s where these percentages come from. In Eco, you put in 10 and the motor adds 6. That’s 16 in total. Ten of those 16 are yours, and that’s about 62%.

The mountain doesn’t change when you change the mode. It always takes the same amount of work to get you to the top. In Turbo, the motor does more than three quarters of that work, so the battery goes down faster. BIKE magazine tested this on a climb in 2019, with a 400 Wh battery. In Eco, the same battery took the rider almost twice as high as in Turbo.

And weight? It matters too, but not as much. An extra 20 kg costs you about 15% of your range — how far the battery takes you. Changing from Eco to Turbo costs you more than 40%.

Now for the honest part. One battery is enough for a big climb because, in Eco, you do most of the work. On the same climb, your legs do two to three times as much work in Eco as in Turbo. If you always ride in Turbo, a route with 2000 metres of climbing isn’t the best first step. Try a climb of 1000 metres in Eco first. If that goes well, you’re ready for more.

How far will the battery take you?

The starting point is a test by BIKE magazine. The test bike was a Cube with the Bosch Performance Line CX motor and an 800 Wh battery. It went up an asphalt road in Turbo. The road was steep: 12.2% on average. The rider weighed 90 kg with equipment. The battery was empty after 2259 metres of climbing.

These are almost perfect conditions: asphalt, a steep climb and the same speed all the way. So that isn’t your number yet. It has to fit your weight, your mode and a real road. It’s also a good idea to keep 20% of the battery in reserve. Here’s the result.

This is how many metres you can climb on an 800 Wh battery and still have 20% left. These numbers are calculated, not measured. You can see how at the end of the article.

Total weight means you in your riding clothes, your backpack, your water and the bike. The bike alone weighs about 25 kg.

Does this sound familiar? “A thousand metres of climbing and half the battery is gone.” That’s riding in Turbo.

In Eco, there’s so much range that the battery isn’t the limit any more. Your legs are. The second half of this article is about that.

What the table doesn’t know. It only counts the climbing. Long flat sections use the battery too if the motor is on — in Turbo, quite a lot. In cold weather, or with lots of stops and starts, the battery gives you less. So use the table for planning, not as a promise.

Does it work on a real ride?

It’s always good to check a calculation against a real ride. Here are the author’s numbers from Tremalzo.

• 6 October 2026. Dry weather, not hot and not cold.
• The bike: a Cube Stereo Hybrid ONE22 Pro 800. It has the same motor and the same battery as the bike in the BIKE test: Bosch Performance Line CX and PowerTube 800 (800 Wh). Total weight: 120 to 125 kg.
• The ride started at the lake with 100%. No charging on the way.
• Up to the restaurant just below the pass: Eco mode. On the flatter sections, the motor was off.
• There, after about 1700 metres of climbing, the display showed 58%.
• After that: Eco where possible, Tour+ on some sections, and sometimes Turbo. At the end, after about 2200 metres of climbing, the display showed 33%.

Up to the restaurant, the ride used 42% of the battery. That’s about 2.5% for every 100 metres of climbing. The table says the same climb in Eco would use about 55% to 57%. There are two reasons for the difference. The motor was off on the flatter sections. And the table already takes away some metres for real roads. So the table is on the safe side.

The second part of the ride shows the opposite. It has only about 500 metres of climbing. But Tour+ and Turbo were on for some sections, and it’s a long way home. That took another 25% of the battery.

The battery numbers come from the bike’s display. The metres of climbing come from GPS and are rounded.

Tour+ and eMTB: the middle modes that aren’t always in the middle

The table above has Tour mode, which always adds 140%. But new electric mountain bikes with a Bosch motor usually don’t have it. Most of them come from the shop with four modes: Eco, Tour+, eMTB and Turbo. In the Bosch eBike Flow app, you can change one of them to Tour, if Tour is available for your bike.

The two middle modes look like the perfect choice: enough help, and the battery lasts. That’s not quite true. Both modes are “smart”. They decide how much help to add, and that depends on how hard you push on the pedals. When Bosch first presented Tour+, it explained the mode like this. On flat ground, the motor helps less, to save the battery. On a climb, it adds help when you push harder on the pedals. The eMTB mode works in a similar way. It adds between 140% and 340%.

The metres are for an 800 Wh battery and a total weight of 120 kg, with 20% kept in reserve. For eMTB, these are limits, not a test result. Your real number will be somewhere between them. It depends on how hard you push on the pedals. There are no numbers for Tour+ here. Different articles give different limits for it, and no official Bosch numbers for the new motor could be found.

On a long, steep climb, you push hard on the pedals, so a “smart” mode adds more help. Then eMTB gets close to Turbo, and the battery goes down almost as fast. Want to know before the ride how much battery you’ll use? Then stay in Eco on a big climb.

One more thing. Updates can make the motor stronger. With the 2025 update, it can add up to 400%. With the May 2026 update, it can add up to 600% for a short time at speeds up to 15 km/h. An update doesn’t change your settings. The extra help stays off until you turn it on in the app. When the motor does more work, the battery goes down faster. All the calculations in this article are for the standard 340%.

How to ride a long climb

• Start in Eco. The first half of the climb is the time to save battery. Your legs are still fresh.
• Watch the battery percentage, not the kilometres. Here are the calculated numbers for a total weight of 120 kg. Eco uses a little over 3% of the battery for every 100 metres of climbing. Turbo uses about 5.6%.
• Check your numbers on the way. You’ve climbed 500 metres and used 18%? Then every 100 metres costs 3.6%. There are 1700 metres still to climb, and they need 61%. That’s 79% in total, so 21% is left. You’ll get there, but you’ll be right at your 20% reserve.
• Keep 20% in reserve. If you get tired and switch to a stronger mode, your numbers won’t work any more. And there may be climbs on the way back. Riding a 25 kg bike uphill with no motor is hard.
• Save Turbo for the end. When the main climb is behind you and there’s enough battery, switch to a stronger mode.
• Pedal faster, in an easier gear. The motor works better that way. Bosch recommends 60 to 90 turns of the pedals a minute.
• Don’t carry things you don’t need, and check your tyre pressure. Soft tyres eat battery. This is one of Bosch’s tips too.

Charging on the way

• Before the ride, find out where you can charge — and check that the place will be open. A mountain hut at the pass may be closed, so it’s good to have a plan B.
• Take a 4-amp charger. It charges an 800 Wh battery to 50% in about 2.6 hours. That’s about 10% in half an hour, or about 300 metres of climbing in Eco. Some bikes are sold with a 2-amp charger. It’s slower.
• Don’t expect much from a coffee stop. Fifteen minutes gives you only about 5%. A one-hour lunch adds about 20%.
• A low battery charges faster. The numbers above are for the first half of the battery. The second half fills more slowly. Bosch’s numbers for a 750 Wh battery and the 4-amp charger show this. The first 50% takes 2.3 hours. The second 50% takes 3.7 hours.
• Charge everything to 100% the evening before. Every 10% that’s missing means 300 metres less climbing in Eco.
• If the route is a little too long for one battery, you can add a second, smaller one. The Bosch PowerMore is an extra battery with 250 Wh. That adds almost a third to an 800 Wh battery. Before the ride, check that it fits your bike.
• Charging will get faster soon. Bosch has announced a 12-amp charger for the end of 2026. Bosch says it charges about three times as fast as the 4-amp charger. An 800 Wh battery should get to 50% in about an hour.

You’re part of the system too

So far, this has all been about the battery. But an e-bike has two sources of energy: the battery and you. The motor helps, but you still turn the pedals. It’s still real exercise. With the motor, you just go higher and further.

Eco saves the battery, but then your legs do most of the work. So when you’ve planned your battery use, plan your own energy as well. It has a limit too.

The 2019 BIKE magazine test of Eco and Turbo shows how much work this is. In Eco, the rider put 160 watts into the pedals for about three hours. In Turbo, it was 130 watts for 45 minutes. In Eco, the rider climbed almost twice as high and did 4.6 times as much work. The energy for this work comes mostly from carbohydrates, or “carbs”. And your muscles and liver can only hold about 600 grams.

Your body has no battery display

The battery shows you what’s left, as a percentage. Your body doesn’t. Often you only find out you’re empty when it’s already serious. Your legs stop working, and so does your head. And there’s still a long ride down.

So treat your own energy like the battery, and do everything early.

• Eat by the clock. Don’t wait until you have no energy left. Eat at regular times.
• Tell someone as soon as you feel tired. If you’re riding with a guide or with friends, don’t be a hero. Even if you’re only a little tired, tell them.
• Change mode a little earlier. Switch to a stronger mode before your legs stop turning. If there’s enough battery for it, of course.

How to charge yourself

The rules are the same as for the battery. Charge before the ride, add more on the way, and never go down to zero.

• The day before: charge. Eat a lot of carbs all day: pasta, rice, bread and potatoes. And don’t plan a big climb right after another long ride. To fill up again, your body needs at least 24 hours of rest and high-carb food.
• Breakfast: two to four hours before the start.
  • Good: porridge or muesli, toast with jam or honey, a banana, or yoghurt.
  • Not so good: sausage, cheese, or eggs and bacon. Fatty, heavy food is slow to digest. It stays in your stomach for a long time.
• On the ride: recharge. Start eating early, a little at a time. Don’t wait until your energy is gone. A good rule is 30 to 60 grams of carbs an hour. That’s one or two bananas or energy gels. A medium banana has about 27 grams of carbs, and a gel has 20 to 30. On a long climb, go closer to 60. Drink water with a gel. And don’t try anything new on the day of a big climb.
• Water. Drink regularly. On a hot day, add electrolytes or take a sports drink.
• After the ride: recover. Now it’s time for protein: meat, fish, eggs or cottage cheese, as part of a full meal. On the ride, carbs come first. Protein comes afterwards. Eating 20 to 40 grams of protein in the first two hours helps your muscles recover.

This is not medical advice. If you have diabetes or heart problems, or if you take medicine, please talk to your doctor before the ride. Ask about exercise and food.

Quick checklist

• Charge all batteries to 100% the evening before.
• Ride most of the climb in Eco.
• Check how much battery every 100 metres of climbing costs.
• Keep 20% of the battery in reserve.
• Use Turbo at the end, and only if there’s enough battery.
• Find out where you can charge, and take a charger.
• Eat carbs the day before, at breakfast and every hour on the ride.
• Tell someone as soon as you feel tired.

You can do a long climb if you ride with a plan.