Electric Mountain Bikes: Gen 5 CX Is 120 Nm. Gen 4 Stays 85.

An electric mountain bike is a bicycle with a motor, a pack, and a suspension number, sold into a trail that may not want it. Bosch’s own upgrade page splits the Performance Line CX in two. The Gen 5, part BDU384Y, left the factory at 85 newton-meters and 600 watts. The 2025 update takes it to 100 newton-meters and 750 watts. The 2026 update, which Bosch calls 2.0, takes the torque to 120 and leaves the peak at 750. The Gen 4, part BDU374Y, stays at 85 newton-meters and 600 watts through that same 2026 row. One hundred twenty minus 85 is 35. A page that says “a CX is 85” and a page that says “a CX is 120” can both be quoting Bosch. They are not quoting the same part. This desk did not ride either one.

Full-Power vs Lightweight

Full-power, in this sheet, is the CX Gen 5 after the update: 120 newton-meters and 750 watts. Lightweight, on the same sheet, is the SX: 60 newton-meters and 600 watts, and the 2026 row does not give it the 120 or the 600 percent. Bosch’s footnote 4 says the 60 newton-meter standard applies to SX bikes produced from October 2025. Older ones were 55, and an update in the Flow app can take those to 60. Fifty-five to 60 is 5 newton-meters. It is not the 35 between a factory Gen 5 and the 2026 Gen 5. A Shafer HP with a TQ at 60 newton-meters and 350 watts is a gravel bike. It is not this SX, and it is not a full-power trail bike.

Hardtail vs Full Suspension

A hardtail has a fork and a rigid rear. One travel number. A full-suspension bike has two, and a shock to service. The e-MTBs this desk has already filed as full bikes are full-suspension: the Obscur at 150 millimeters rear and 160 front, the ePelmo at 170. Those are their pages, not a rule that a hardtail cannot be an e-MTB. The hardtail’s case is fewer pivots and less to rebuild. The full-suspension case is that the motor and the pack are mass, and the rear wheel is what hits the square edge. Neither layout changes the newton-meters in the table.

Motor Selection

Read the part code, not the family name. CX Gen 5 and CX Gen 4 share the words Performance Line CX and do not share the 2026 torque. CX-R starts at 100 newton-meters and 750 watts and joins the Gen 5 at 120 in the 2026 row. SX stays at 60 and 600 watts, and its support percent stops at 400 in that row while the CX rows go to 600. The 600 percent is not a hill. Footnote 3 says it applies up to 15 km/h only, and only in Race, Turbo, eMTB+, Cargo, and Auto. Fifteen divided by 1.609 is 9.3 mph. Above that, the percent is a different number, and Bosch says it also depends on the mode and on how hard you pedal. A hub motor is a different machine. The motor page is that split. This table is mid-drive.

Battery Size

The number that matters is watt-hours on that bike’s page, not the motor’s family. The Mondraker film’s SX bike that day carried a 400 watt-hour pack in the downtube. That is one bicycle in April 2025. It is not a law that every SX is 400, and it is not a law that every CX is twice that. A bigger pack is more mass on the descents and more energy on the climbs. The range page is why you cannot turn the watt-hours into a mile by dividing. A light motor sold with a small pack is a different product from a full-power motor sold with a large one. Buy the pair that is on the cart, and write both numbers down.

Wheel Size

The bead is the number that has to match, and the tire page already has it. A 29-inch tire and a 700c tire are both 622 millimeters. A 27.5 is 584. They do not share a bead. A mixed wheelset, 29 in front and 27.5 behind, is what the ePelmo page calls MX and what the Obscur page calls mixed. The front wheel is the one that meets the obstacle. The rear is the one the motor drives. A bigger rear wheel holds speed and can dull a hard kick. It does not change 120 newton-meters into 85.

Suspension Travel

Travel is millimeters of wheel movement, printed twice on a full-suspension bike. The Obscur pair already on this site is 150 rear and 160 front. The ePelmo is 170. A longer number is more room for a mistake and more linkage to service. It is not a higher newton-meter. A trail bike and an enduro bike can share a CX Gen 5 and not share a travel. Read the millimeters on the bike you are buying. Do not import them from the motor table.

Geometry

The chart that matters is reach, stack, head angle, and chainstay, in the size you will actually ride. A slacker head angle is a smaller number of degrees. It is a number on that chart, not a mood. This desk will not print a degree and call it the right one. A long chainstay can calm a bike that has a motor pushing the rear wheel. A short one can make the same motor feel like it is steering from behind you. Sit on the size. A medium on one brand is not a medium on the next.

Brakes

The motor does not stop the bike. One hundred twenty newton-meters is a climb figure. The brake page is rotors, pistons, and pads. A heavier bike wants more rotor and more piston than a pedal bike of the same wheel size, and the brand’s spec is the one to read. Four pistons are not a certification. A cutoff in the lever still has to kill the motor when you pull it. A descent is where you find out the spec was a sentence and the pads were gone.

Tires

Knobs for dirt, a casing that can take the mass, and a pressure inside the range printed on that tire. The tire page already refused a universal PSI. Electric Mountain Bike Network, on 27 February 2026, ran 25 in the rear and 22 in the front on their bike and called it a guide. Those two numbers are not a 29-inch enduro tire and not a 27.5. Tubeless is common because the pressure that holds a root is also the pressure that pinches a tube. It is not a requirement. A mud spike on hardpack is a buzz. A slick on a trail is a slide.

Drivetrain

A mid-drive puts the motor’s torque through the cassette, which is why a CX eats chains and cassettes faster than an analog bike of the same rider. The range of the gears is the bike’s problem, not the motor’s newton-meters. A gearbox is the other arrangement. The GD8 is an 8-speed unit in the motor, with a 480 percent range claimed, and it is not a Shimano cassette. Do not shop a CX bike as if it were that gearbox, or the reverse. A 12-speed and a 9-speed are not the same wear item. The small cog is where a powerful mid-drive breaks teeth.

Weight

Bosch’s upgrade page does not print a kilogram for the CX or the SX. A review that prints one is not this sheet, and this page will not borrow it. The weight that changes the ride is the complete bike, on a scale, in the size you buy, with the pack installed. A light motor with a small pack can still be a heavy bicycle. A full-power motor with a large pack is heavier still. The photo on this page is not a scale. Subtracting two claimed weights from two different brands is how a shopping guide invents a difference.

Trail Access

A trail that allows bicycles does not automatically allow a motor. The post at the trailhead is the rule. This desk will not print a national permission. A Class 1 sticker, pedal assist to 20 mph and no throttle, is the sticker many of those posts name. It is not a passport, and a CX Gen 5 can be built as a class the post does not allow. The class chart is watts, pedals, and speed. The newton-meters are not on it. A throttle makes the argument worse, not better.

Range

Range is the watt-hours, the assist mode, the climb, and the rider. Turbo on a Gen 5 that has been updated to 750 watts spends the pack faster than Eco on an SX at 600. The film’s 400 watt-hour SX bike is not half the range of an 800 watt-hour bike, because nobody rode that pair here. Eight hundred divided by 400 is 2. That is arithmetic. It is not a ride. Use the range page’s method. Ignore a mile count that does not name the mode.

Climbing

Torque is the climb number, and it is why the Gen 5 update exists. Thirty-five newton-meters over the factory 85 is the 2026 claim, on that part, after the update is installed. A bike that never got the update is still the factory row or the 2025 row. Low-cadence push is what the Mondraker film was pointing at when it called 85 more than 55. The 2026 sheet moves the Gen 5 again and leaves the SX at 60. Spinning a smaller gear is still how a lighter motor makes its watts. Mashing a tall gear is how you find out the update was never installed.

Descending

Point the bike down and the motor’s torque is the wrong specification. Mass, brakes, tires, and travel are the descent. A full-power bike that climbed easily is the heavier thing you now have to stop. The cutoff has to work. The pads have to exist. A slack head angle you liked on the way up is the same angle on the way down, and it is still a number from the geo chart, not a skill. If the bike is too much bike when the motor is silent, it was the wrong bike on the climb too.

Setup

Set the fork and the shock to the sag the suspension maker prints, in the percent they print. This page will not substitute a different percent. Set the tires inside the sidewall range, cold, with a gauge. Confirm the motor cuts when each brake lever moves. Then ride. Do not start by flashing a map that asks for more phase amps. More amps are more heat, and on a bike that was a Class 1 they can also be a different class. The update Bosch is offering is their update, for the part codes in the table. It is not a reason to open the controller.

Who Needs an E-MTB?

Buy the part code and the trail post. The family name is advertising.

Buy a full-power bike if the climbs are why you stopped riding, the trail post allows the class on the sticker, and you will service a motor and a suspension. That is the Gen 5 row, after you confirm the update, or a Gen 4 that is still 85 and 600. Buy the lighter motor if you want the bike to feel like a bicycle when you turn the assist down, and you can spin. That is the SX row, 60 newton-meters if it was built from October 2025 or updated, 55 if it was not. Do not buy either one for pavement. A commuter is a different article. Do not buy one for a trail that has already said no. The sign beats the motor.