The 2024 R 1300 GS Is a Change in Thinking at BMW

[Hugh Janus]

BMW has simplified and lightened its big-bore boxer adventure bike. The 2024 R 1300 GS is 26 pounds lighter than the R 1250 GS. (BMW/)

“The bike looks smaller, very clean. It has a modern, easy shape.” Thus spoke Edgar Heinrich, BMW Motorrad’s design director, of the 2024 BMW R 1300 GS. He has been through four or five generations of the GS, saying, “I ride the bike often. Every time, the new one was so much better. Can we do this again?”

He was speaking to me in a phone meeting last Friday, accompanied by Reiner Fings, production manager, boxer models. When the photos of the new bike arrived, I saw that this 1300 is a new beginning. I saw a simple linear design, its engine very far forward. I saw all elements integrated. Previous machines have been workmanlike and capable, but seemed to have grown by addition—collections of separate elements.

“Is this a revolution?” I asked. Heinrich replied, “I would not say a revolution, but a bigger evolution.”

What has driven this comprehensive redesign, this “big evolution”? Heinrich replied, “Everybody is chasing, trying to do a GS.”

BMW’s R 1300 GS is slimmer thanks to a new engine and frame. (BMW/)

He was referring to Harley’s new Pan America and Triumph’s Tiger 1200, among other newcomers. There is competition!

“The situation has always been the same,” he continued. “Everything adds weight. Performance is good but the bikes are heavy. We don’t want this circle! So at the top of the list is to lose weight.”

To accompany fundamental changes, there had to be a simpler, cleaner design.

BMW’s GS has for years defined the on/off-road segment, but others are seeking a share of that market. This means it is time for BMW to move the goal posts.

The new bike is 26 pounds lighter than the 1250 GS (“unladen” weight is 523 pounds), and now makes 145 hp at 7,750 rpm from its new bore and stroke of 106.5 x 73mm. Dimensions of the predecessor 1250 GS were 102.5 x 76. Although peak torque is 110 lb.-ft. at 6,500, the real story on torque is its width: From 3,600 to 7,800 rpm, more than 96 lb.-ft. of torque are continually available. Broad and strong. As the press release says, there is a “notable torque increase across the entire rpm range…”

Quoted performance is 0–100 kph in 3.39 seconds and a top speed “over 124 mph.” Others have estimated this as 140 mph.

Maximum engine speed is 9,000 rpm.

I was especially impressed that this engine, with its high 13.3 compression ratio and ShiftCam-driven four valves per cylinder, produces stroke-averaged net combustion pressures worthy of purpose-built racing engines. This is a solid benefit because it’s always more efficient to make power from combustion pressure than from friction-generating high rpm.

Two revolutionary changes are 1) the six-speed gearbox is now below the engine rather than behind it, allowing a modern forward weight bias and a longer swingarm. Lowering the gearbox has usefully reduced the angles through which the U-joints in the enclosed drive shaft must operate. This reduces the speed variation generated by Cardan joints.

And 2), the former tubular frame has been replaced by a sheet-metal shell frame that is stiffer while at the same time “optimizing installation space.” This means that the frame encloses necessary components, rather than competing with them for space.

Remember the principle of efficient structure: Move the material outward, away from the centerline. A tube is stiffer than a rod, and best of all are the fuselages of large aircraft—thin, large-diameter tubes.

How the R 1300 GS Makes More Power With the Same Efficiency

How can this large-bore twin breathe and burn as well as it does across a wide rpm range? The answer is not only BMW’s ShiftCam, but also in the way ShiftCam’s low-power mode is implemented. We expect engines that breathe especially well—as this 1300 does—to have narrow power because that requires tuning all design elements to work in the same narrow range. But ShiftCam gives this engine two natures by providing two different intake timings and valve lifts.

BMW chose to enlarge the bore and shorten the stroke for a specific reason: to make room for bigger, higher-flowing valves. Intakes were 40mm in the 1250, but have grown to 44mm in the 1300. In traditional design, big valves and ports often equate to weak bottom-end and midrange power, caused by the lower intake velocity being unable to fill the cylinder as well or to produce combustion-accelerating turbulence. ShiftCam prevents that loss by shortening valve timing and reducing lift at lower revs. Both increase intake velocity.

There is more. When ShiftCam operates in low rpm mode, the intake valves are given staggered opening timings that cause mixture entering the cylinder to swirl around the cylinder axis. This also contributes to speeding combustion, helping to maintain high torque.

Throttle bodies are 52mm and fuel capacity of the tank is 5 gallons.

A shorter engine unit makes for tighter packing. (BMW/)

Because we may occasionally get a tankful of substandard gas, the engine has a combustion knock protection feature; the shock waves of abnormal detonating combustion (knock or tinkle) are detected and the BMS-O engine control computer retards ignition timing whenever it occurs.

A rule of thumb tells us that peak combustion pressure is roughly seven times the pressure at the end of compression. This means that we can extract more useful energy from the fuel by raising compression ratio. Compression ratio is normally limited by the onset of detonation, but the 1300 GS engine has two strong defenses against this: 1) the fast combustion described above, and 2) the knock protection system. This has allowed the 1300′s compression ratio to be raised to 13.3:1. This increases torque (by boosting combustion pressure) and also makes the engine more efficient by taking more energy from the combustion gas, rather than letting that energy be wasted as exhaust heat. Mainly because of this, the 1300 gives the same fuel mileage as the 136-hp 1250. As the press release puts it, the result is “exemplary fuel consumption, emission levels, smoothness, and refinement.”

The closed-loop three-way exhaust catalyst (located under the engine) meets Euro 5 in its ability to reduce levels of unburned hydrocarbons, CO, and nitrogen oxides. Each cylinder’s stainless exhaust header pipe has its own oxygen sensor.

A wet slipper/assist clutch at the front of the engine has 10 friction discs. The assist feature, by using engine torque to increase pressure on the plates, allows a softer clutch pull. The slipper feature uses reverse torque to soften clutch engagement when rapidly decelerating to prevent engine-braking from dragging or hopping the rear tire.

A Lighter and Stiffer Chassis With Improved Rider Response

The managers I spoke with earlier emphasized the more precise feel and control of the new model. Recent motorcycles are a huge advance over what went before in this respect. We talked about the rider of the past, making a control movement on a bike of that time. The bars turn, but because they are rubber-mounted, the steering-crown at first does not. When the crown does turn, the fork tubes shift in their clamps (single pinch bolts). Finally the “message” reaches the tire footprint and the motorcycle begins to respond. That is steering delay. The new bike brings control “feel” and response closer to feeling like the bars are extensions of the front axle.

As one example, know that the front axle, which was 20mm in diameter, has become 25mm. Bending stiffness of tubes (for constant wall thickness) increases as the fourth power of diameter, so the new axle is potentially 2.4 times stiffer than the old.

Looking at the photos I noticed I could see right through the big hollow stub axle of the 1300′s single-sided swingarm. Looks like diameter (and therefore stiffness) is increased at that end as well. BMW describes the new swingarm as having a stiffer connection to the frame.

With the shorter engine comes a longer swingarm. Take a look at the diameter of that rear axle. (BMW/)

Think of the change in chassis structure, from steel multi-tube to a sheet steel shell as analogous to enlarging a tubular axle.

The seat frame, formerly a tube structure, has been changed to an aluminum die-casting. In its stiffer bond with the main frame [there is an] increase in riding precision and stability. This is more of the same—making the motorcycle “more of a piece” gives prompt, accurate control.

There has also been a concerted effort to move components inward, to be grouped closer to the machine’s center of mass. This mass centralization reduces the effort required to set maneuvers into motion or to arrest them.

Past BMW boxer engines have had air/oil-cooling but the share of cooling performed by liquid has been increased in 1300. Where most liquid-cooled bikes have their radiator interposed between engine and front tire, on the 1300 GS rad location is offset to allow the more forward engine location.

The R 1300 GS’ Suspension Evolution

In the past the handlebar has attached directly to the upper fork crown of the Telelever front suspension and with suspension motion there has been a small amount of upper crown tilting (it attached to the frame with a ball joint). That was imperceptible on road bikes with less suspension travel and lower bars. Adventure-tour bikes require longer suspension travel and may have higher bars, accentuating the tilting of the upper crown. To prevent that, the 1300′s EVO Telelever upper crown cannot tilt as it turns on its own pair of bearings. Steering motion is linked to the fork tubes by a flexible stainless steel plate.

Steering geometry is rake 26.2 degrees, trail 4.4 inches. Wheelbase is 59.8 inches.

Front suspension travel is 7.5 inches. (BMW/)

Suspension travel is unchanged from 1250 at 7.5 inches front, 7.9 inches rear. A Sports Suspension option adds 0.8 inch of extra travel front and rear, and is firmer. Three types of wheels are available in the 3.0 x 19F, 4.5 x 17R rim dimensions—cast aluminum, forged enduro, or cross-spoke (wire) wheels.

At the front are twin 310mm brake discs with four-piston calipers, and at the rear is a single 285mm disc. Integral ABS Pro and Dynamic Brake Control are standard.

Seat height tends to increase with suspension travel, and is 33.5 inches on the new model. With optional Adaptive Vehicle Height Control this reduces to 32.3 inches when stopped or moving slowly, allowing the rider’s feet to more easily reach the ground. City buses (and other ADV bikes) have had a similar height control feature for many years; R 1300 GS owners can now enjoy it as an option.

We have seen systems which allow suspension damping curves to be electronically altered either by rider choice or automatically, but such systems ignore the fact that for best performance, damping and spring rate must remain in correct proportion. The 1300′s optional Dynamic Suspension Adjustment alters spring rate as well as damping.

The optional Shift Assist Pro eliminates motion formerly lost in triggering the switch, making its action more direct.

Getting “bigger and bigger” is no longer the way forward for BMW’s big boxer GS. (BMW/)

I’m leaving most of the description of the electronics control and display to others, save to say that my informants Heinrich and Fings told me the goal in these areas was to simplify what can be a confusing task—finding what you want among so many choices.

In the words of 1300 Project Manager Jochen Beck, this machine stops the trend in adventure-tourers of “getting bigger and bigger.” The new 1300 GS is a balanced combination of valuable technological change with a fresh look.

Source

[Pedro]

I'm curious about this, they seem to have gotten a little heavier from the 1200 to the 1250 by adding the shift cam weight. Now they make a big revolution all about loosing weight and 26 pounds is all they get?

Hmmm

 

[Pedro]

26 pounds is 11kg.

My 2015 R1200GS Adventure is supposed to be 260kg with fuel, a 2021 R1250GS Adventure is supposed to be 268kg with fuel, so basically they added 8kg with adding clever valve wizardry. They now go through all that effort and revolution to drop 11kg, and that includes a lithium battery that by itself saves a good 2 or 3kg?

In effect their revolution makes the ultra light new bike similar in weight to my bike, and ditching a steel rear frame for a pressed sheet one? I see a revolution in profit margins, that what I see