Giant TCR Advanced SL 0 Disc 2021

The Giant TCR Advanced SL 0 Disc is a lightweight and hugely responsive road bike with aero features, and it puts in a performance that is absolutely stunning.

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Stiffness to weight

The new TCR (as I'm going to call it from here on in to preserve the world's pixel supply) has a whole bunch of strengths, one of the most obvious being that Giant has managed to cut weight while keeping frame and fork stiffness extremely high.

We often talk about the importance of bike weight being overstated but, all other things being equal, a light bike is more responsive – quicker to accelerate and faster on the climbs. These are key characteristics of the TCR.

Whereas the previous version of this bike was made from Toray T800 carbon fibre, this material accounts for only 30 per cent now, the remainder being a new higher modulus filament that's stiffer and lighter. Giant has also moved from 360-380 swatches of 'cookie cut' carbon to over 500 swatches that are laser cut to size, about 150 of the smallest ones being laid up by robot rather than by hand. The greater precision involved in this method means that less material can be used, meaning a lower weight.

Giant has also switched from seven or eight layers of paint down to just three here, accounting for a saving of about 65g across the frame and fork. You can go to to our launch story for all the technical details. 

The result is a claimed frameset (painted frame, painted uncut fork, integrated seatpost, seat clamp, front and rear derailleur hangers) weight of 1,265g. I've been riding a size L complete bike weighing 6.69kg (14lb 12oz). That's properly light for a disc brake-equipped model.

> Lightweight vs aero: which is best?

I'm not going to tell you that the lack of weight means this bike launches you up the hills like a rocket or any of that stuff, but it all contributes to the greater good.

Giant hasn't chucked stiffness away in the process. People have different views on the importance of frame stiffness in terms of efficiency (yes, we're familiar with the arguments, although it's a whole article in itself) but, at the very least, too much flex feels awful – to me, at least – and is a distraction when you're trying to lay down the power.

Giant's figures say that the TCR's stiffness-to-weight ratio is greater than that of key rivals (by which it means the Specialized S-Works Tarmac Disc, Trek Emonda SLR Disc and Cervelo R5 Disc)... of course! Again, go to our previous article for all the details on this. We've not been to the lab to check those measurements for ourselves so you can accept them or dismiss them as you see fit. What I can tell you is that the TCR feels extraordinarily stiff when you jump out of the saddle and bang on those pedals.

If anything, the front end is even stiffer. Chuck the bike around, brake hard, do whatever you want, you won't cause it to waver or fluster. It's more than confidence inspiring, it's almost freaky.

Aerodynamics

There was a time when you had yer lightweight road bikes, and you had yer aero road bikes, and they were totally different beasts, but over the last few years brands have been merging the two genres. Those bikes listed above are three examples, and the TCR is the latest to join the band.

The Propel remains the true aero road bike in the range but Giant says that every tube shape on the TCR was analysed, engineered and tested to create an overall structure with significantly lower drag than previously at a wide range of yaw angles.

The TCR now features truncated ellipse tube profiles – the leading edge and sides are designed to reduce drag while the trailing edge is cut off square to reduce weight and avoid handling issues – and the huge down tube (up to 65mm in diameter) is designed to work aerodynamically with a water bottle in place (other brands have done the same in the past).

The fork and seatstays are now symmetrical and more open for greater airflow efficiency – along with increased tyre clearance. Again, check out that previous article I keep mentioning for more tech details.

You can't perceive improved aerodynamics – well, not the relatively small differences that we're talking about between one bike and another – you need wind tunnel data here. Giant took the new TCR to the tunnel and tested it with a dynamic mannequin on board and its results say that at 40km/h (25mph), with cages and bottles in place and measured from 15° to -15° yaw, its bike performs marginally better than the Cervelo R5 Disc and Specialized S-Works Tarmac Disc (there's virtually nothing between those three) and significantly better than the Trek Emonda SLR Disc.

Do whatever you like with those results, we're just reporting them. Maybe the other brands will come back with contradictory results in time, but according to Giant the aero improvements to the TCR are greater than the improvements in stiffness-to-weight. It says that the new TCR saves 34 seconds over 40km (25 miles) at 200 watts of pedalling power.

Geometry

One thing Giant hasn't changed radically is the TCR's geometry and that's a good thing because its balance and handling were already excellent. The bottom bracket drop has been increased by 2mm because of the increased clearance for larger tyres I mentioned above (it'll now take 700C x 32mm, whereas the rim brake TCRs will only take 700C x 28mm because of the size of the callipers), with other measurements altered slightly so that stack, measured from the bottom bracket, remains the same.

> How to use bike geometry tables and what it all means

One other tweak has been made to the geometry of the ML model. The effective top tube was previously 570mm, closer to the 580mm of the large than to the 550mm of the medium. Now the effective top tube of the ML is 565mm, splitting the difference between the other two.

It's a race-focused geometry, of course. The head tube and seat tube angles on the L model are both 73 degrees while the stack is 581mm and the reach is 402mm, giving a stack/reach of 1.45. That's aggressive but not radical. The drop on the 44cm wide Giant Contact SLR carbon composite handlebar fitted to my test bike was 140mm (the drop is shorter on the narrower bars fitted to smaller sized bikes) and with my hands down there I felt in a great position to attack or just shelter out of the wind.

If you want to change the stem, your options are limited due to the fact that Giant uses a tapered fork steerer with a 1 1/4in diameter at the top rather than the usual 1 1/8in (it's 1 1/2in at the bottom). That said, I had no worries at all with the Giant Contact SLR stem and it's available in lengths from 70mm to 130mm.

Unlike the other TCRs, the Advanced SL models come with integrated seatposts. You cut it to length and then add a clamp on top. The standard clamp, which comes with a carbon composite cradle to save weight, offers 25mm of height adjustment. You also get a long clamp with 45mm of adjustment (and an aluminium cradle) that'll get you out of bother if you cut the seatpost too short or sell the bike on to a taller rider.

One potential downside is the same as with other integrated seatposts – if you have a high saddle height you might not be able to fit the bike into a hard box when you travel – or it might make life a whole lot more difficult.

Groupset

I'm a huge fan of Shimano Dura-Ace Di2 but Giant isn't offering it as an option anywhere in the TCR range. That's... interesting. What's the thinking there?

Giant believes that SRAM Red eTap AXS leads the way as far as electronic shifting is concerned, saying that it is waiting until the next generation Dura-Ace Di2 is released. That's not going to be this year. We suspect that Shimano must be promising something special for the revamp for a major brand like Giant to be holding off in this way. There's no way it would be doing this for a small weight saving and an updated finish.

SRAM Red eTap AXS is great stuff. The gear ratios are interesting (well, interesting to a lot of people; if you can't be arsed with that sort of thing, hum for a bit and join in again lower down the page).

The TCR is fitted with a 48/35-tooth chainset and a 10-28t 12-speed cassette (whereas you might in the past have expected something like a 53/39t chainset and, say, an 11-28 or 11-30t cassette).

The Giant's drivetrain gives you a range of 33.07 gear inches to 126.99 gear inches (384%), whereas a 53/39t chainset and an 11-30 cassette would give you a range of 34.39 gear inches to 127.52 gear inches (371%).

In other words, the low gear is 4% lower on the Giant's SRAM system while the high gear is just 0.4% lower.

One difference that I noticed in use was less need to change out of the big chainring. The 48-tooth ring combined with the 28-tooth sprocket gives you 45.24 gear inches, as opposed to 46.83 gear inches in a 53 x 30 combo. That might not sound like much but it's over 3% (and although you might want to keep it to a minimum, SRAM reckons that you're fine to run the chain on both the big chainring and the largest sprocket). 

As far as shifting goes, the default setting has your left hand moving the chain to a larger sprocket, your right hand moving the chain to a smaller sprocket, and pushing both paddles at the same time moving it from one chainring to the other, although you can customise that via SRAM's app. You can switch to 'Sequential' mode, for example, where one lever moves you to an easier gear and the other to a harder gear, automatically shifting between chainrings if necessary, or you can go to 'Compensating' mode where the system will automatically shift at the rear when you shift at the front, minimising the difference as much as possible.

Anyway, I won't go into any more depth about SRAM Red eTap AXS shifting other than to say that after half an hour to reprogram your mind away from whatever system you were using previously, you'll love it.

The flat-mount hydraulic disc brakes, working on a 160mm rotor up front and a 140mm rotor at the rear, perform extremely well. In common with similar stoppers from other big brands, they're so consistent that you barely give them a thought after a while, solid braking whatever the conditions becoming the new normal.

You can easily alter reach at the brake lever too, along with the contact point – the position you'd like your fingers to be in when the brakes start to bite.

One other huge factor you need to consider is that the TCR Advanced SL 0 Disc comes with a SRAM Red Quarq AXS power meter as part of the package. This isn't the place to review the power meter but the cranks, chainrings and the power meter itself would cost you over £1,000 if bought separately at full retail price. If you want to train by power, this is a massive draw.

Other components

Giant has stepped up the quality of its in-house components massively over the past few years and you get some exceptional parts here. The Contact SLR carbon composite handlebar I mentioned above, for example, is lightweight (the claimed weight is 248g in a 440mm width) and the top section, designed for aerodynamics, is superbly comfortable when you perch your hands up there.

The Contact SLR stem comes with an out-front computer mount that's compatible with Giant, Garmin and Wahoo computers. It's neat.

Some people might be surprised that Giant has left the brake cables exposed between the handlebar and the frame/fork when many other brands have opted to run them through the stem. This approach makes maintenance a little easier. As for looks, you can make your own mind up.

I found Giant's new Fleet SLR saddle, fitted to all Advanced Pro models, equally impressive. It's fairly short – 248mm – with a carbon composite base, carbon rails and a gaping hole running down the middle, and it features the Particle Flow Technology that Giant has used for the past few years. Two separate pockets within the saddle contain 'high-elastic, free-flowing particles', conforming to your shape and reducing pressure as you ride.

The real highpoint of the in-house spec, though, is the Cadex Disc wheelset (Cadex is Giant's brand, a bit like Trek has Bontrager and Campagnolo has Fulcrum).

The hookless rims, made from Toray T800 carbon filament, are 42mm deep with a 19.4mm internal width. The spokes are carbon composite. What looks like a nipple is the aluminium piece cured on to the end of the spoke to create the thread.

You hold the spoke on that piece and adjust the nipple internally (the new Cadex SLR1 wheels have the same rim profile but do have external nipples with steel spokes).

Giant claims that the hubs offer 69 per cent less drag than DT Swiss's super-popular 240s (again, we're reporting that rather than endorsing it).

The complete wheelset weight is just 1,327g. Bought separately, those wheels are priced £1,099.99 for the front and £1,399.99 for the rear.

They're superb wheels – quick to accelerate and not much bothered by crosswinds – and, as is the case with all TCR disc models with electronic shifting, they come with Cadex Race tubeless tyres in a 25mm width. These have a 170tpi single layer casing.

Running them at a reasonably low pressure, I found the level of comfort on offer here to be high – I didn't give it a second thought even on long rides – and you could always switch to wider tyres (as mentioned previously, up to 32mm) if you wanted.

The money bit

Most bikes equipped with SRAM Red eTap AXS groupsets cost at least £7,500, although Canyon's £6,799 Aeroad CF SLX Disc 9.0 SL aero road bike is an exception.

The Specialized S-Works Tarmac with a SRAM Red eTap AXS groupset is £9,500, the same as our Giant. It also comes with a SRAM Red AXS Power Meter, although its Roval CLX 50 Disc wheels, if bought separately, are considerably cheaper (£750 front, £1,100 rear) than the TCR's. That said, they're first rate wheels. 

> Buyer’s Guide: 21 of the best and fastest 2020 aero road bikes

Trek's Emonda SLR 9 Disc eTap is £9,300. This bike doesn't come with a power meter, and if bought separately the Bontrager Aeolus XXX 2 TLR Disc wheels are £500 cheaper than the TCR's.

> Check out other SRAM Red eTap AXS bikes here

A simple spec sheet analysis can't tell you all you need to know. If you're spending this kind of wedge, try to get a test ride on a few of the models you're considering.

Summing up

The Giant TCR Advanced SL 0 Disc's understated looks disguise a stunningly good performance. This lightweight bike is hugely responsive and handles precisely. Add in aero features and excellent components and it's a real winner.

Verdict

Lightweight and stiff race bike – now with aero features – that puts in a superb all-round performance