2021 Giant TCR Advanced SL Disc first-ride review: An aero evolution

by James Huang


Giant’s ninth-generation TCR family follows in the footsteps of other major players in the industry in that it now adds a generous dose of aerodynamic shaping to its previously light-and-stiff formula. However, the family of carbon fiber frames has also gone on a diet, gains a newly refined geometry, and — of course — has room for bigger tires, all while still retaining its superb stiffness and composed ride quality.

We got our hands on one of the very first production flagship samples worldwide, and those of you who have been waiting in anticipation for this day to come will be happy to hear that it’s one hell of a good bike.


Story Highlights

  • What it is: The latest generation of Giant’s flagship all-around road racer.
  • Frame features: Premium carbon fiber and resin materials, laser-cut swatches and robotic ply placement, ultra-low weight, newly added aerodynamic shaping.
  • Weight: 765 g (claimed, medium painted TCR Advanced SL 0 Disc frame only); 330 g (TCR Advanced SL 0 fork only); 6.69 kg (14.75 lb, as tested, small TCR Advanced SL 0, without pedals.
  • Price: US$11,000 / AU$13,999 (pricing for other regions TBC)
  • Highs: Exceptionally low weight and high stiffness, bonus aerodynamic shaping, refined ride quality, newly composed handling, standard power meter.
  • Lows: Integrated seatmast has to be cut to size, press-fit bottom bracket.

A measured approach to aerodynamic gains

In a move that will surprise precisely no one — if only because we saw the new TCR at races months ago — the new TCR has been reshaped with aerodynamic efficiency in mind. “Truncated ellipse” cross-sections are now used on nearly every frame section to help air flow more smoothly around the frame at a wide range of effective wind angles, without adversely affecting other attributes like weight and stiffness.

Giant says the frame’s new shape was also designed specifically with two round bottles in place (since that’s how the bike is most likely to be ridden), and wind tunnel testing not only includes those bottles in place, but also a mechanized mannequin to better simulate real-world performance (in case you’re wondering, the mannequin’s nickname is Grischa since it was modeled after former Rabobank rider Grischa Niermann.)

The aero tube shaping on the new TCR is fairly subtle, but it’s still there when you look for it. Note the rather flattish-backed profiles on the head tube and down tube, for example.

Interestingly, one of the by-products of that sort of testing is that while the down tube, head tube, seat tube, seatmast, and fork blades all feature the new profile as you’d expect, the seatstays do not. According to Giant, that area of the frame was confirmed through wind tunnel testing to reside in highly turbulent air, so it wouldn’t stand to benefit from an aero profile, anyway.

Giant also hasn’t gone over the top in terms of seeking out those gains, either.

For example, Giant is sticking with separate stems and handlebars instead of following the herd and using a one-piece front end. Although modest aero profiles are featured on the tops of some of the handlebars — depending on model — and the headset spacers are profiled to match the head tube, the more traditional two-piece layout still affords more adjustability and customization in a key area.

The brake and shifter lines aren’t fully internal, either. They’re exposed between the handlebar and frame/fork as usual, primarily for easier servicing.

“The main goal was to make an efficient bike, which also means ‘consumer friendly’ for service,” said Giant senior global product marketing manager Andrew Juskaitis. “Many consumers (mainly the amateur racers) don’t want to spend a lot of money in a bike shop for service or just to change a stem or handlebar, which is the main reason why we don’t go for fully internal cable routing.”

The seatmast profile isn’t hugely different from before, but there’s now more of a flattened trailing edge whereas it used to be closer to a proper teardrop.

Either way, Giant isn’t really making any extraordinary claims about the new TCR’s aerodynamic performance in comparison to some other bikes that have also been designed with similar blends of attributes. According to the company’s in-house wind tunnel testing, the new TCR Advanced SL Disc saves a scant 0.5 watts over the latest Specialized S-Works Tarmac, and 0.4 watts relative to the current Cervelo R5 Disc, both taking into account a weighted total performance at wind angles between +15° and -15° of yaw.

Notably missing are a few other key models, however, such as the Scott Addict RC, Canyon Ultimate CF SLX, and Cannondale SuperSix Evo. Nevertheless, it’s still somewhat reassuring that the differences between the Specialized and Scott are so small since anything vastly more dramatic would seem less believable.

As compared to a more traditional light-and-stiff model that hasn’t been designed with aerodynamics in mind, though — in this case, the Trek Emonda SLR Disc — the difference is also as you’d expect, with the gap widening to 13.9 watts. Interestingly, the previous TCR Advanced SL supposedly wasn’t all that bad, either, registering 252 watts of drag using the same protocol — worse than the Tarmac or R5, but still better than the current Emonda.

The seatstays are still rather slender for ride comfort, but they don’t seem to have much of a traditionally aero shape to them. Then again, much of the air they’d encounter would be more than a little “dirty” seeing as how the rider’s legs are churning away right in front of them.

Keep in mind, too, that Giant’s testing was done at a more realistic wind speed of 40 km/h (24 mph) instead of the more common (but less attainable) 50 km/h (31 mph). Assuming the numbers hold true, that means those figures are more likely to be experienced by actual riders on a real road.

Also interesting is that while Giant admits to only having tested the disc-brake version of the TCR in the wind tunnel, its computational fluid dynamics simulations suggest that the rim-brake models are actually slightly less efficient.

The traditional fundamentals still matter

When it comes to going fast, numerous studies have proven that aerodynamic efficiency is usually the most important factor. But that said, it’s not the only thing that matters, and given that low weight and high chassis stiffness were two of the attributes that people found most appealing about the existing TCR, Giant wisely didn’t want to mess with a good thing. Even better, Giant says the new bike has actually improved in both areas.

It’s worth noting here that Giant is one of the only major brands that still manufactures all of its own frames in-house, and its composite frames begin life from rolls of raw fiber. The company even makes its own pre-preg sheets instead of purchasing it elsewhere — using resins that are blended in-house — and that level of control affords some additional freedom in how the frames are made. For the latest TCR Advanced SL, the company has instituted a few rather interesting-sounding manufacturing innovations.

The down tube is still extremely wide like the previous version, but the shape is less overtly rectangular than before.

According to Giant, the new frame is built with updated carbon fiber materials that apparently offer better structural properties than what was available previously, and — as it’s been since at least the 2014 model year — they’re held together in a resin matrix that’s reinforced with carbon nanotubes. Individual pieces of those pre-preg sheets are now cut by laser instead of the usual hydraulic press and steel blades for smaller and lighter pieces, too, and of the 500 or so pieces that are typically used in a single frame and fork, Giant says about 150 of them are now put into place by robots for greater precision before the whole assembly is clamped in a mold and baked.

Conversely, certain sections of the TCR Advanced SL frames are made with fewer, but bigger, plies that prioritize longer continuous fiber runs for more efficient (and, thus, lighter) use of material.

At least for the flagship TCR Advanced SL Disc model, Giant claims to have cleaved a substantial 140 grams off of last year’s already-light version utilizing all of those new processes, with 54 g shaved from the frame and fork structure itself, 65 g saved thanks to a new minimalist paint job (exclusive to the flagship SL 0 model), and the rest coming from smaller ancillary bits.

Giant graces the flagship TCR Advanced SL 0 model with a “Thinline” paint job that leaves much of the frame covered in just a bare-bones layer of clearcoat.

Claimed weight for a medium frame with full-length integrated seatmast (but without the head) and paint is now just 765 grams, with the matching fork adding another 330 grams. For the sake of comparison, Giant claims the new TCR Advanced SL Disc is 105 grams lighter than the similar Specialized S-Works Tarmac Disc and 322 grams lighter than the Cervelo R5 Disc. The Trek Emonda SLR Disc is lighter, but only by 17 grams.

In terms of absolute stiffness, the new TCR frame loses a slight bit of ground over its predecessor, although given where that bike already was, that’s not much of a criticism. How slight, you might wonder? According to Giant, the old bike posted a bottom bracket deflection of 71.09 N/mm, while the new one measures 70.96 N/mm.

However, the decrease in weight means that the stiffness-to-weight ratio has increased relative to last year’s model, and at least according to Giant’s figures, the new TCR beats the S-Works Tarmac, Emonda SLR, and R5 by significant margins.

The new fork has dropped a single gram relative to the previous one, but torsional stiffness has supposedly gone up, which should (at least theoretically) translate to more predictable handling, especially on the disc-brake models. TCR Advanced SL and TCR Advanced Pro frames get Giant’s 1 1/4-to-1 1/2in OverDrive 2 steerer diameter, while the TCR Advanced models get a more conventional 1 1/8-to-1 1/4in size.

Refined handling and fit, more versatility

Giant’s marketing materials didn’t make a big deal of this, but if you dig into the geometry charts of the new and old bikes, it’s hard not to notice some pretty significant changes.

Bottom bracket drop has increased by 2 mm across the six-size range. Giant says the change was made to keep the overall handling consistent if you decide to run bigger tires (and it’s worth mentioning that the stock 25c tires measure 28 mm in real life). Stack and reach have also been adjusted for a more even progression as you move through the sizes, and smaller sizes get slightly steeper seat tube angles. Interestingly, the small size specifically gets a slightly slacker head tube angle, too.

The bigger stock tire size has the side effect of increasing trail a bit, and wheelbase measurements have grown across the board as well. Chainstay length remains a tidy 405 mm, indicating that virtually all of that wheelbase increase occurs up front.

Somewhat surprisingly for a company with Giant’s resources, though, the same fork rake is still shared across the entire size range.

Taken in total, the changes move the TCR’s handling in a slightly more stable direction, with somewhat calmer handling manners and better high-speed stability relative to last year’s model.

“Our goal was to make more consistent and balanced steps for reach between each size,” Juskaitis said. “We also chose to adopt the trend of a more forward saddle position with a steeper seat tube angle. In order to compensate for [larger tire sizes], we lowered the bottom bracket, and in order to get enough tire clearance at the fork, we increased the fork length by 2 mm, which increases the trail and helps for more stability.”

Speaking of tire sizes, Giant has — of course — bumped up the maximum allowable widths on the new TCR. Disc-brake versions are now officially approved for use with tires up to 32 mm wide (measured width), while rim-brake models are more limited to 28 mm-wide tires. So while the TCR technically remains a road-racing bike, the ability to run larger-volume tires (especially on the disc-brake version) expands its range of capabilities on surfaces other than tarmac, too.

Range overview

As with the current TCR range, the new version will be split into three tiers, all with carbon fiber frames. Exact model availability will depend on region, but most markets will receive some mix of rim-brake and disc-brake bikes.

The top-tier TCR Advanced SL incorporates all of the engineering features mentioned earlier, and is understandably the lightest and most expensive of the trio. In the interest of all-out performance, Giant has built all TCR Advanced SL Disc framesets to work only with electronic drivetrains. Rim-brake models, however, will accept either electronic or mechanical groupsets.

Headlining the range is the TCR Advanced SL 0 Disc model showcased here, fitted with a SRAM Red eTap AXS wireless disc-brake groupset, Cadex 42 mm Disc carbon clinchers, and Giant house-brand carbon fiber finishing kit for US$11,000 / AU$13,999. The TCR Advanced SL 1 Disc moves to a SRAM Force AXS wireless disc-brake groupset and Giant-branded carbon wheels for US$8,100 / AU$10,299.

Certain markets will also see so-called “KOM” variants with 1:1 climbing gears, but every TCR Advanced SL model will come stock with a crank-based power meter (Quarqs for the SL 0 Disc and SL 1 Disc; Giant PowerPros for the rest).

The TCR Advanced Pro replaces the integrated seatmast with a more conventional (but still aero-profile) telescoping carbon seatpost, less expensive carbon fiber and resin blends are used, and the frame is constructed in a more conventional fashion using hand labor instead of the fancy robots and lasers.

There are nine TCR Advanced Pro models in total, starting with the TCR Advanced Pro 0 Disc (US$5,400 / AU$7,999) with Shimano Ultegra Di2, Giant-branded carbon wheels, and Giant-branded carbon finishing kit, and bookended (in the US, at least) by the rim-brake TCR Advanced Pro 1 (US$3,500 / AU$N/A) with a Shimano Ultegra mechanical groupset, but the same wheels and cockpit components.

Finally, there’s the TCR Advanced range, which shares the same frame as the Advanced Pro but downsizes to a more typical 1 1/8-to-1 1/4in tapered steerer diameter instead of the bigger one used on the more expensive bikes.

Up to eight TCR Advanced Pro models will be offered, topped by the TCR Advanced 1 Disc Pro Compact (US$3,200) model that features a disc-brake Ultegra mechanical groupset and aluminum Giant PR-2 disc-brake clincher wheels. For riders on a tighter budget, there’s the TCR Advanced 3 Disc at the opposite end of the pricing spectrum (which won’t be brought into the US, but is available in Australia for AU$3,299), built with a Shimano Tiagra groupset.

Giant will also offer the TCR Advanced SL Disc, TCR Advanced SL (rim-brake), and TCR Advanced Pro Disc as bare framesets.

Pricing for UK, and European markets is to be confirmed.

Still on the road again — at least for now

Our most recent Nerd Alert podcast focused on the interplay between low weight and aerodynamic efficiency. Spoiler alert: the latter usually wins, at least in terms of getting to the finish line first. However, as more than one astute commenter noted, the majority of people who ride primarily just for enjoyment have more to gain from a bike that feels good — and when it comes to road bikes, that usually means one that’s lightweight, efficient in terms of power transfer, and rides well.

Well, here’s some good news for you folks. Admittedly, I only have a couple of weeks in on my TCR Advanced SL 0 test sample at this point, but experience has taught me that my first impressions rarely differ from my long-term conclusions, and the new TCR Advanced SL Disc ticks all of those boxes — meaning the added aerodynamic benefits come with no noticeable penalty to all the other stuff that you usually care about.

In comparison to some other moderately aero road racing bikes that have been introduced recently, the new TCR looks decidedly normal.

Just as it was with the previous-generation TCR, the new one is notably rigid and responsive, with a palpable immediacy in how it picks up speed when you put down the power whether seated or standing. Combined with the bike’s very low weight of just 6.69 kg in my small size (14.75 lb, without pedals), and no doubt aided by the bike’s standard 1,327-gram Cadex 42 Disc Tubeless carbon clincher wheels (which I’ll cover in more detail later), the TCR Advanced SL 0 is a perfect partner when the road heads upward.

To state it bluntly, I hate climbing — which probably has a lot to do with the fact that I’m not very good at it — and yet this thing nearly makes me want to do it more.

As much as I enjoyed the TCR Advanced SL 0’s superb chassis rigidity and low weight, though, the more noticeable change for me was the revised frame geometry.

My daily-driver road bike is a custom-built, previous-generation TCR Advanced SL, so I’m very familiar with how that bike handles — and I generally like it, which is precisely why it’s my daily driver.

However, the new front-end geometry (and specifically, the increased trail dimension) and lower bottom bracket introduce a newfound level of stability in fast corners that lends a lot of extra confidence, particularly at higher speeds or on particularly steep descents. Overall, I find it more composed and reassuring when rocketing downhill (without feeling at all neutered or sluggish), and while the geometry chart suggests the effect will be more subtle on other sizes, it’s a nice change.

The 42 mm-deep Cadex wheels of my test bike are impressively light and handle decently well in crosswinds. Expect a more detailed report shortly.

Ride quality is superb, too. One key reason Giant has so steadfastly adhered to the integrated seatmast on the top-end TCR Advanced SL family is the way it allows frame engineers to more precisely tune the flex characteristics relative to a typical telescoping seatpost.

While the new bike is extremely stiff in terms of pedaling efficiency and front-end handling, it nevertheless serves up a highly refined ride. It’s talkative and very lively, but yet also pleasantly damped and never overly harsh. Impressively, that even carries through to the front end, despite the oversized steerer dimensions.

Bits and bobbles

Any downsides related to the TCR’s new aero features are arguably only aesthetic (and I’m splitting hairs here). While this ninth-generation TCR has changed little in terms of the basic shape, the stem and headset area still strike me as a little awkward — not nearly as weird as Giant’s full-aero Propel, but still not as elegant as the previous version. So be it. If it really bugs you, swap out the upper headset cover and exchange the profiled headset spacers for round ones.

The stack of spacers makes for a rather ungainly look, but lots of that goes away if you run an aggressive position and trim away the excess steerer tube. This is a loaner, however, so I’m not about to lop off a bunch of steerer tube that the next person in line might need.

There’s also the perennial issue of the integrated seatmast on the TCR Advanced SL frame. Yes, there does seem to be tangible benefits in terms of ride quality, as well as measurable ones in terms of weight and aerodynamic performance. However, it’s also nerve-wracking to take a hacksaw to your brand-new (and expensive) carbon frame, it adversely affects the bike’s resale value, and complicates traveling with the bike, too.

Trek figured out more than 10 years ago how to do this without having to cut anything, and it’d be nice if Giant could follow suit.

And then, yes, there’s the press-fit bottom bracket. Granted, the PF86 format that Giant has long preferred is one of the least problematic of all the press-fit formats — and Giant has a very good track record for long-term, noise-free performance —and the wider shell is what allows the adjoining tubes to be so wide, and thus, what helps the frame be so efficient to pedal. That said, no one will ever convince me that press-fit is easier to work on than a threaded shell, or that it requires fewer specialty tools. It’s also harder to use a 30 mm-diameter spindle in here unless you settle for a so-so bearing setup.

The wide-format T47 system was conceived specifically for cases like this. Yes, minimizing weight was one of the key design goals for this latest TCR, and yes, incorporating a T47 threaded shell (with its requisite aluminum insert) would add some weight. But in my opinion, it’d be weight well spent, and I doubt many people would complain about the trade-off. I’m a little bummed Giant didn’t go that route, but hey, at least it’s not PF30 so it could have been a lot worse.

Giant wasn’t willing to sacrifice the previous TCR’s superb chassis stiffness as it chased aerodynamic goals. Many areas of the frame are still incredibly wide, particularly down by the PF86 press-fit bottom bracket shell.

And finally, there’s the comparatively traditional cable routing. Giant obviously could have chased every watt and second by hiding everything away tip to tail, but there’s a lot to be said for the bike’s designers having the courage to prioritize serviceability over marketing. I’ve personally changed a number of fully internal one-piece cockpits in recent years, and each one scarred me to varying degrees. Sure, I think certain user groups will be disappointed that Giant left a few small time savings on the table here, but no one will complain about the time and frustration saved in the workshop with this setup.

The continuation of a legacy

It’s admittedly too early for me to declare the new TCR as some sort of world-beating, “best-in-class” machine. And I can’t verify at this point that Giant’s aerodynamic claims hold true, either.

But for now, I can at least say that Giant’s stated targets for weight, stiffness, and ride quality seem to hold true, the revised handling is a change in the right direction, and from a visual standpoint, the more traditional profile (yes, the TCR can ironically now be considered “traditional” relative to much of its competition) will undoubtedly be appealing to plenty of potential buyers.

Is it the “total race bike” that Giant’s marketing materials boldly declare it to be? At this point, it’s hard to argue that it’s a very well-rounded machine designed for going fast. But what I can say for sure already is that it’s an awfully entertaining machine to ride.

www.giant-bicycles.com

Editors Picks