Individual test Specialized Diverge STR Expert
Modesty is not exactly the hallmark of the Diverge STR. On the contrary. The Specialized attracts attention, or more precisely the frame - because where the top tube and seat tube of a diamond frame are usually firmly connected, a carbon and metal construction stretches into the gap: a hydraulic shock absorber. In combination with the suspension element on the handlebars, this makes the Diverge STR the first full-suspension racing bike from the Americans.
Purists who value the gravel bike as a robust and uncomplicated companion on gravel tracks and roads will probably question the point of a gravel full-suspension bike at this point. Complicated technology definitely makes gravel racers heavier, generally more maintenance-intensive and possibly more susceptible to defects. But does this also apply to the 2023 newly presented Diverge STR Expert?
Complicated technology on the Specialized Diverge STR Expert
Gravel bikes with full suspension, which almost resemble mountain bikes, are nothing new in the increasingly colourful gravel segment; prominent examples include the BMC Urs LT with suspension fork and elastomer bumpers on the rear triangle (TOUR 5/2022) or Cannondale's Topstone Carbon Lefty (TOUR 10/2020). On the Diverge STR, Specialized has now added a new technical approach to the familiar Future Shock suspension on the handlebars - namely an active hydraulic damper element on the rear triangle that keeps the springy seatpost in check.
The development department in Morgan Hill put a huge amount of effort into this, with the Americans spending around five years tinkering with the frame. "It was literally blood, sweat, tears and overtime - peppered with nagging doubts as to whether the technology would ever make it across the finish line," head developer Luc Callahan is quoted as saying on the Specialized website. After several prototypes, the result was a frame with rear suspension, the centrepiece of which is the hydraulic damper on the top tube. The seat post itself is located in a second carbon tube, the end of which is clamped low down in the seat tube, roughly at the height of the bottle cage.
The seatpost springs backwards/downwards over its entire length, resulting in up to 30 millimetres of travel at the saddle; the shock tames this travel so that the seatpost does not bob annoyingly when pedalling. The firmness of the system can be adjusted: On the shock in three stages while riding or in the workshop by turning the carbon insert. The carbon insert has two different degrees of hardness depending on the mounting position and is supplied in two versions.
In the style of a mountain bike
Not only does this sound complicated in theory, it also takes some time in practice to understand and adjust all the setting options. Even Specialized point out that the system should "only be fitted by a professional mechanic" due to its complexity. During the ride, however, the gravel bike from Morgan Hill is completely convincing and irons over bumps impressively and gently.
The Diverge STR absorbs particularly rough impacts with the suspension at the front and rear, whereby the Future Shock System raises the handlebars relatively high and puts the rider in an emphatically upright riding position. If you have to take your foot off the accelerator on an unsprung gravel bike when you hit potholes or roots to prevent the handlebars from being knocked out of your hands, the Diverge simply skips over them in the softest setting of the shock. No bobbing, no creaking.
The system simply works. Despite the high wheel weight of 9.7 kilograms, the Diverge STR is surprisingly fast on the road, even on asphalt with the suspension system locked; the 42 millimetre wide tyres, which were fitted to our test bike without a tube, provide more than sufficient damping. It remains to be seen which target group the bike and its sophisticated technology will appeal to - but it is likely to remain comparatively small: The Americans have put a price tag on the Diverge STR that excludes many potential buyers from the outset.
The cheapest model we tested with a combined SRAM Rival and GX Eagle drivetrain costs € 7500, and Specialized are even charging € 15000 for the S-Works version - a little more than for one of the best road bikes, the S-Works Tarmac SL 7. Do you really want to regularly expose such a fine piece of technology to mud and dirt and the bombardment of swirling gravel?
Facts about the Specialized Diverge STR Expert
- Price7500 Euro
- Frame/fork/steering bearing weight* 1652/452/64 grammes
- Frame sizes** 49, 52, 54, 56, 58, 61
- Seat/top tube/head tube 490/570/131 millimetres
- Stack/Reach/STR*** 618/388 millimetres/1.59
- Wheelbase/caster 1045/53 millimetres
Equipment
- Drive/Circuit SRAM Rival eTap/SRAM GX Eagle eTap (1x12; 40, 10-50 t.)
- Brakes SRAM Rival (160/160 mm)
- Wheels/tyres (weights)**** Roval Terra/Specialized Tracer Pro 42 mm (f./h. 1525/2317 g)
Measured values & individual notes*****
- Weight of complete wheel 9.7 kilos Grade: 3,7
- Steering head stiffness 112 Nm/° Grade: 1,0
- Lateral stiffness Fork 01 N/mm Grade: 1,0
- Bottom bracket stiffness 64 N/mm Grade: 1,0
- Seatpost spring stiffness 35 N/mm Grade: 1,0
- Spring rate fork 01 N/mm Grade: 1,0
Overall grade Specialised Diverge STR Expert - 1.8
*Weighed weights
**Manufacturer information Test size bold.
***Stack/Reach Projected vertical/horizontal measurement from the centre of the bottom bracket to the top of the head tube; STR (Stack to Reach) 1.36 means a very stretched, 1.60 an upright riding position.
****Impeller weights incl. tyres, cassette, quick release/threaded axles and brake discs if necessary.
*****Single noteswhich are included in the overall grade with different weightings, are only partially printed for reasons of space. The grades are calculated with all decimal places up to the final grade; however, for the sake of clarity, all grades are shown with rounded decimal places.
1The lateral stiffness of the fork cannot be determined with the TOUR test stand due to the design. In addition, the comfort measurement of the fork does not provide any indication of the actual suspension travel on the handlebars due to the design. The evaluation takes into account both the design and the measured value on the handlebars.
Julian Schultz
Editor
