Which is the best road bike? Giant Propel Advanced SL vs. Specialized S-Works Tarmac SL9

The club of the best road bikes and all-round racing bikes has so far been made up of the elite group of bikes that have achieved the top mark of 1.5 in the TOUR test. Alongside the Specialized Tarmac – in the form of its predecessor, the SL8 – this group also included the Scott Foil RC Ultimate and the Addict RC Ultimate, the Canyon Aeroad CFR, and the predecessor to the Giant Propel Advanced SL. The latest version of the latter has overtaken the competition by achieving the new TOUR top mark of 1.4. The Specialized SL9 has been hot on its heels and recently drew level with it in the TOUR test. Reason enough to pit the world’s best all-round racing bikes – as rated by TOUR – against each other in the ultimate showdown. Given the tie in scores at this exclusive level, is it even possible to spot any differences at all? The result of the comparison is surprising and, at the same time, highlights just how distinct and pronounced the differences between the bikes are. Let’s take a closer look at the key figures and the various categories.

Key figures at a glance

Differences in detail

Weight

Weighing in at 6.43 kg, the Giant Propel is the lighter of the two bikes and is likely to be the lightest aero bike in the world. This is particularly impressive given that the Propel was originally launched as a pure aero road bike; outstanding aerodynamics usually require a specific design that stands in the way of the quest for low weight. However, the current Propel, as an all-round racing bike, is around 60 grams lighter than the Tarmac SL9, which has been refined for what feels like an eternity as the ideal, lightweight professional racing bike. Giant achieves this weight advantage primarily through the consistently refined Cadex wheelsets with carbon spokes, carbon hubs and a laminated construction – the wheelset alone saves almost 200 grams compared to the previous model.

Weighing 6.49 kilograms, the Tarmac SL9 is 60 grams heavier, but it comes fitted with wider – and therefore slightly heavier – 30-millimetre tyres; according to Specialized, around 150 grams have been saved on the frame and wheels.

Conclusion: Weight – Giant wins by a narrow margin

Aerodynamics

Here, Specialized turns the tables. In the GST wind tunnel, the SL9 requires 205 watts to reach 45 km/h – four watts less than the Giant Propel, which requires 209 watts. For the Propel, with its pedigree as an aero specialist, this may be a slight disappointment depending on your point of view, especially as it sits exactly on a par with its predecessor. Specialised’s aero bikes now achieve around 195 watts – so, at least in terms of aerodynamics, the Giant hasn’t made any overall progress.

The SL9, on the other hand, has been significantly improved thanks to targeted refinements such as a slimmer head tube, a redesigned fork, a more aerodynamic seatpost and new Roval wheels with carbon spokes.

Conclusion on aerodynamics: Specialized is the clear winner – and leads the field among all-rounders.

Comfort

The Giant is a pleasant surprise: the rigidly laminated seatpost offers good suspension, as is typical for this class, and is significantly better than on its predecessor. In this respect, the SL9 must give way to the Propel according to the measured values (rear comfort 109 to 160 newtons per millimetre (N/mm); at the front 96 to 122 N/mm) and ratings (front/rear 1.7/2.7 versus 2.3/3.7). However, the Specialized brings its 30-millimetre-wide tyres into the fray as a factor enhancing comfort, as well as its consistently impressive and confident ride feel, which also contributes to overall comfort.

Conclusion on comfort: Giant has a slight edge; Specialized is catching up again with wider tyres.

Driving dynamics & handling

Both bikes are fascinating machines to ride – but with very different characters that are clearly evident when you’re in the saddle. The Giant Propel is an agile, responsive bike that’s easy to manoeuvre and always remains under control. It’s often described as ‘explosive’ and ‘playful’. The Tarmac SL9 rides with excellent directional stability and precision, providing direct feedback at all times and inspiring confidence through corners. The supple tyres with a cotton carcass offer a riding experience all of their own. In contrast, the narrower, aerodynamically optimised tyres on the Giant feel a little wobbly.

Conclusion on handling: A matter of personal preference – Giant is agile and playful, whilst Specialized is precise and stable.

Facilities & Pricing Structure

The Giant stands out with a comparatively wide range of models: you can get started in the Propel range with Shimano 105 components and aluminium wheels for as little as 2,999 euros. The Advanced Pro has a slightly heavier frame than the top-of-the-range model, a classic clamped seatpost and different wheels. It should still weigh just under seven kilos and costs 7,999 euros with Dura-Ace and Cadex wheels featuring carbon spokes. The frame set (SL only) is available for 3,899 euros. A power metre is included with the top-of-the-range model featuring SRAM Red.

The Specialized is currently available exclusively at S-Works level; both available specifications (SRAM Red AXS and Shimano Dura-Ace Di2) are priced at 13,999 euros. The frame set costs 5,799 euros; a 200-euro surcharge applies for the Replica version in various professional team liveries.

Conclusion on pricing structure: Giant is significantly more accessible and inclusive.

An overview of our strengths

Giant Propel Advanced SL

• The world’s lightest aero race bike (6.43 kg)
• comfortable
• an agile, explosive driving experience
• a wide price range – from €2,999 up to S-Works level

Specialized S-Works Tarmac SL9

• aerodynamically superior (205 W – best all-round result)
• the most well-rounded overall package
• wide tyres (30 mm)
• precise, stable handling
• versatile

Target groups

Giant Propel Advanced SL

Target audience: Cyclists looking for a lightweight aero bike that’s suitable for everyday use and who don’t need the absolute maximum in aerodynamics. Ideal for:

• Amateur racers and ambitious athletes who regard weight as a crucial factor
• Riders who want a combination of comfort and agility
• Budget-conscious buyers who wish to get started gradually (various price points)
• DIY enthusiasts looking for a frame as a base
• Drivers who prefer a playful, agile ride

Specialized S-Works Tarmac SL9

Target audience: Competitive cyclists who The most well-rounded overall package, with no compromises who want to and are willing to pay the premium price. Ideal for:

• All kinds of racing ambitions – criterium, granfondo, stage races
• Riders who prioritise aerodynamic performance but do not want a pure aero bike
• Long-distance drivers who want to combine speed and comfort
• Tech enthusiasts who want to own the world’s best all-round road bike
• Cyclists who are looking for a bike with no weaknesses whatsoever and don’t want to compromise on any aspect

Conclusion

Both bikes share top spot in the TOUR test with a score of 1.4 – it’s a real dead heat at the very highest level. The choice ultimately depends on personal priorities:

Giant Propel: For anyone who wants the world’s lightest aero bike with a surprising level of comfort – and doesn’t need every last watt of aerodynamic performance.

Specialized Tarmac SL9: For those looking for the most aerodynamic and all-round best-balanced road bike, one that doesn’t fall short in a single category – and who are prepared to pay the premium price for it.