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Road Racing

2023 Giant Propel Advanced SL 0 long-term review: The complete package

Aerodynamic, very lightweight, great ride quality, solid pricing, and it even looks good – what more could you ask for?

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[ct_story_highlights]What it is:Giant’s flagship aero road bike, transformed into an aero all-rounder.||Frame features:Partially robotic carbon fiber construction, slimmed-down aero tube shapes, drastically reduced weight, fully hidden cable routing, BB86 press-fit bottom bracket shell.||Weight:845 g (claimed, medium frame only); 6.86 kg (15.12 lb), as tested, small size, without pedals or accessories.||Price:US$12,500 / AU$14,000 / £TBC / €11,500.||Highs:Almost as light as non-aero bikes, excellent chassis stiffness, very good ride quality, traditional aesthetics, superb build kit, solid pricing.||Lows:Integrated seatmasts still aren’t everyone’s cup of tea, polarizing wheels and tires, limited component choices.[/ct_story_highlights]

The complete package on paper

Giant created quite a stir when it debuted its latest Propel back in August. Whereas the previous version was obviously intended to be an all-out aero road racing machine, this new one is meant to be more of an aero all-rounder with fewer compromises. I’ve already gone through the changes in detail in my initial write-up, but here’s a rundown of the highlights.

True to that claim, the new Propel is substantially lighter, with 137 g (claimed) lopped off of a now-845 g medium frame. Concurrent decreases in ancillary bits brings the total up to 226 g for the frameset, while improvements in the bar-and-stem shed another 103 g. Impressively, the actual – not claimed – weight for my small-sized sample built with Shimano’s new Dura-Ace Di2 wiredless electronic groupset and Cadex 50 Ultra Disc carbon wheels is just 6.86 kg (15.12 lb) without pedals or accessories. 

That doesn’t quite put the new Propel Advanced SL 0 into the true ultralight category, but it’s an impressive figure nonetheless, and particularly so for an aero bike that claims to be more efficient through the air than its forebear.

This bike is fantastic, full stop.

To go along with the weight savings, Giant is also claiming an 8-10% boost in frame stiffness (and we’re talking in absolute terms, not just stiffness-to-weight) as well as a two-fold improvement in rear-end compliance, at least for the flagship seatmast-equipped Advanced SL version. 

There’s even officially room for 30 mm-wide tires should you decide you want your Propel to be more of an aero all-roader.

As before, the control line routing is fully concealed so as to maximize the bike’s aero profile. It’s a tidier setup this time around with the control lines running along the underside of the stem instead of up top before taking a downward turn into the upper headset cover. That arrangement does away with the goofy bolt-on stem cover, and also makes for shorter paths with smoother bends. The stem can be swapped without having to futz with any hoses or wires, and small changes in bar height are easy too (assuming you have enough slack in the lines). 

The fully hidden routing is much cleaner than it was on the previous-generation Propel.

The stock bar still sees the control lines running inside the bar before popping out of a central port at the stem clamp, but it’s far less of an inconvenience than running them through the stem. Better yet, the stem and routing setup will accept any bar with a 31.8 mm diameter – internally routed or otherwise.

On paper, then, this new Propel presents an enticing and complete package if you’re in the market for an all-round aero road bike that’s fast on the flats and going uphill. And while the US$12,500 / AU$14,000 / £TBC / €11,500 price tag of my flagship test sample is obviously nothing to sneeze at, it’s still an excellent value compared to similar bikes from other major brands. 

All of this sounds too good to be true, no doubt. But after several months on the road with this thing, apparently there are situations where you really can judge a book by its cover because this bike is utterly fantastic.

The complete package on the road

You know how so many people are all-too-happy to say that such-and-such gravel bike is almost as fast as a road bike on tarmac? Pish posh – those people have clearly never spent time on a true aero road bike, because even without instrumented testing, it’s plainly obvious that the Propel is a proper rocket ship. Just like every other properly aero road bike I’ve tested, the Propel Advanced SL 0 is easier to bring up to higher speeds, it’s easier to hold those speeds. Seriously, even if you don’t mean to, you find yourself inadvertently riding away from buddies on non-aero setups unless you make a point of soft-pedaling when you’re on the front.

Sure, it feels “fast”, and there are a lot of factors at play in making it that way. That said, Giant is unfortunately a little opaque in terms of the new Propel’s aero bona fides. The new bike was tested with the newer Cadex wheels (and new tires, which I’ll discuss shortly), the newer Dura-Ace stuff, and the rest of the current finishing bits, whereas the old bike was tested with the then-current (but slightly slower) wheels, tires, and other components. Nevertheless, given the majority of people riding something like this are only after the sensation of speed (rather than actual numerical marginal gains), I’d say the Propel checks this box just fine. 

The top tube is relatively broad up front, tapering slightly as it connects to the seat tube.

Perhaps more important to everyday riders is how the Propel feels in the process of going fast. It’s a glorious bike to ride. It’s tangibly light and stiff – not just for an aero bike, but for a good road bike, period. It’s a wonderful partner on long climbing days and when you’re feeling inspired to attack steep pitches. Sharp stabs at the pedals are rewarded with quick bursts of speed with no hint of delay or hesitation. The handling is precise and responsive. It’s somewhat buzzy and electric-feeling, but without feeling harsh or unwelcoming. It’s the veritable eager puppy, always up for another go and brimming with more energy than you.

Speaking of handling, the small tweaks from the previous Propel serve this bike well. With numbers borrowed from the TCR, the Propel is the consummate do-it-all road racer. The 63 mm trail figure of my small-sized tester (58 mm on larger sizes) is as quick and darty as you’d expect, deftly carving tight corners and easily flicking around obstacles and potholes. But as long as you’re not too fidgety yourself, it’s also suitably stable and confident as you approach terminal velocity on fast descents. 

I can’t confirm Giant’s numerical compliance claims, but I will say that the new Propel is a surprisingly comfortable place to spend your day. The bike’s personality is high-strung, but it doesn’t bite when the road surface is less than ideal. There’s feedback and communication, yes, but also a respectable amount of damping and tangible flex when you unexpectedly nail a pothole, at least out back. I wouldn’t describe the overall ride quality as soft and cushy by any means, but if firm and controlled are more where you’re at, you’ll find a lot to like here.

Last, but certainly not least, can we just talk about how good this bike looks? 

It’s no surprise to see yet another integrated seatmast on the latest Propel Advanced SL. Giant says it’s both lighter and more comfortable, but if you really don’t want to bother with it, just bump one step down on the Propel hierarchy.

Kudos to Giant for the dramatic turnaround in the Propel’s aesthetics. While the previous version was more than a little awkwardly shaped, the new one looks surprisingly traditional. There are no overtly outlandish shapes. The top tube is nearly level. The seatstays are dropped, but they somehow look just right. The proportions are all in harmony. This bike’s shape may very well have been primarily dictated by function, but it’s clear that form wasn’t an afterthought. I’m still coming to terms with Giant’s new corporate logo – and could certainly do with a quieter down tube logo – but all in all, even the paint is flashy yet tasteful.

If it’s not obvious at this point, I’m a big fan of this bike. 

Things I could do without

Alas, as good as I’ve found this new Propel to be, there are handful of things that ground my gears a bit.

Regular readers and listeners of CyclingTips won’t be surprised at all to hear that I’m not a fan of fully internal cable routing (once a mechanic, always a mechanic…). That said, thankfully none of the lines run through the inside of the stem. I could do without the internal routing through the bar (not to mention a normal amount of bar tape instead of leaving the tops bare and slippery), but at least Giant hasn’t limited your options for such a critical contact point. 

Unfortunately, the fact the stem can be swapped so easily makes this next point even more annoying. Just when choices for 1 1/4″ fork steerers was starting to get healthy, Giant has once again limited your options. The nominal steerer diameter on the new Propel is the brand’s usual 1 1/4″, but it’s a proprietary D-shape that Giant says is only compatible with its own stems. To be fair, the molded carbon fiber stem included stock here is both lightweight and incredibly stiff torsionally, but I like to have options nonetheless.  

Speaking of routing, fans of mechanical drivetrains might be out of luck. Although the base-level Propel and the mid-range Propel Advanced will work with both electronic and mechanical drivetrains, the flagship Propel Advanced SL is strictly electronic-only. 

There’s also the issue of the BB86 press-fit bottom bracket shell. Giant does BB86 better than just about anyone with only rare instances of incurable creaking or related issues, and BB86 is also one of my least-hated press-fit formats since the bearings are widely spaced for good spindle support. 

However, the BB86 shell is also much smaller in diameter than most of the newer options. Nearly any crank spindle aside from Shimano will require smaller-than-ideal cartridge bearings, and the diminished durability that goes with that. 

I get it, Giant, you really like Shimano, and at least for you, BB86 works just fine. But again, I like having choices, and in this case, too many people will be forced to choose between their preferred drivetrain components and bearing longevity.

Spec notes

There’s not much I can add at this point about the new 2×12-speed “wiredless” Shimano Dura-Ace Di2 electronic groupset on my flagship test sample. Simply put: it’s amazing stuff. 

Shifts are both lightning-fast and phenomenally consistent out back, and front shift performance continues to be the absolute best in the business, hands down. Lever ergonomics are superb, too, the upgraded hydraulic disc brakes are still plenty powerful and now (very marginally) quieter than before, and although the all-black finish won’t please everyone, I find it more appealing than some of the two-tone setups Shimano has used in the past.

It’s so good.

And for those of you who have questioned the “need” for a 12th sprocket out back, I’ll at least say that I welcome the additional range without having to sacrifice the size of the jumps in between. I didn’t ride this bike long enough to gauge the lifespan of the narrower chain, but history suggests this shouldn’t be an issue (particularly with good chain cleaning and lubrication practices). 

More worthy of discussion are the Cadex wheels and matching tires.

I think my first ride on Lightweight wheels was some time around 2006 or 2007, and I was astounded by how much stiffer and more responsive they felt compared to anything else out there. It’s no wonder so many pros wanted to race on them back then (and still do). Fast forward 15 or 16 years, and it’s a similar experience with these new Cadex wheels. 

So stiff, so responsive.

I’d already felt that with the shallower Cadex wheels I’d used to date, but these new 50 Ultra Disc wheels bump things up another notch. They’re light on the scale at just under 1,350 g (claimed weight), but like all good wheels do, they feel lighter on the road. They’re wonderfully reactive under power and rich with feedback, and unquestionably contribute to the Propel’s super-precise handling. The 22.4 mm inner width is also a solidly progressive figure for the tarmac-only tires these wheels are most likely to see, but the 30 mm external width suggests there won’t be a big aero penalty if you decide to go a little wider, either. Crosswind stability isn’t exceptional, but I’ll take average, all things considered.

But as I’ve mentioned previously, the ride quality of those wheels is very firm – bordering on too-firm, in fact. Although there seems to be a decent amount of damping, there’s very little in the way of actual flex, and swapping to other wheels definitely boosted the Propel’s comfort quotient. Riders who prize quiet freehubs will also want to shove their fingers in their ears when coasting as Giant’s proprietary star ratchet-style rear hub is anything but quiet. It’s not quite as loud as the DT Swiss Ratchet EXP driver, but it’s not far off, either.

More polarizing in my opinion are the stock Cadex Race Aero tires. They roll fast and seem to grip well (at least in the dry – it doesn’t rain much where I am), and Giant says the intentionally ovalized casing profile shows savings as high as 5 W in the wind tunnel compared to more traditional round casings. That may be, but it also comes with quirky handling. Whereas more traditionally shaped tires gradually and gracefully turn into corners, these feel more like you have to consciously work to keep the bike from falling into them. It’s almost like driving a car with a weirdly-tuned variable-ratio steering rack. It’s super darty immediately off-center before settling in later.

These tires may very well be fast in terms of drag and rolling resistance, but I don’t think everyone will love how they handle.

I eventually got used to it, but I can’t say I ever really loved it. Tires are thankfully easy to swap, although that’s not exactly an inexpensive thing to do these days. There’s also the not-so-small issue of the rims being hookless so they’re not compatible with everything. That said, the range of options is at least steadily improving.

I have zero complaints with the rest of the house-brand finishing kit, however. The carbon-railed Cadex Fleet SLR saddle is one of the most comfortable snub-nosed models I’ve tried, and at just under 140 g, it’s very light. And up front, the stock Giant Contact SLR Aero carbon bar sports a pleasantly neutral bend with appropriate drop-and-reach figures, and aero-shaped tops that actually aren’t terrible to hold on to. And again, even if I didn’t like the bend, kudos to Giant for not forcing you into a proprietary bar (I’m looking at you, BMC, and Canyon, and Cervelo, and Scott, and…). 

Giant has even included a pretty decent computer mount that attaches to the stem faceplate bolts. It’s not the most elegant-looking thing, but it gets the job done. It holds fast, it’s adjustable for multiple sizes of computers, there are multiple pucks included for several popular interfaces, and there’s even a GoPro-style accessory mount underneath should you so desire. Works for me.

The elephant in the room

Given how well the new Propel fills the role as an all-around road racing steed, it’s natural to wonder what this means for Giant’s iconic TCR – and I don’t have an answer for you.

Yes, the TCR is lighter still than this new Propel while also offering some aero benefit. However, that line is blurrier than it’s ever been, and given the option, I’d personally go with the Propel. Giant surely must be looking to figure out how to further differentiate the two (if they haven’t already), and the most obvious way to do so would be to make the TCR even lighter to appeal to the diehard weight weenies. 

The TCR Advanced SL is also fantastic, but does it still need to exist?

You can look to Specialized’s road range for comparison. It wasn’t long ago that you bought a Venge if you wanted to go aero, or a Tarmac if you wanted to go light. But the latest Tarmac is supposedly so aero that there’s no need need for the Venge, and there’s now the ultralight Aethos for those that prioritize low weight and ride quality. It wouldn’t be hard to see Giant moving in a similar direction, and part of me wonders if the TCR could even be spun off as an ultra-premium model under the growing Cadex premium brand umbrella. 

The Propel and TCR are both outstanding, but I nevertheless see little point in Giant keeping both of them around in their current forms.

It’s a winner

There’s a smorgasbord of great choices right now when it comes to aero road bikes. If you’re after the ultimate of aero gains, you’ll unfortunately either have to head into a wind tunnel or do some instrumented on-road testing to find out which offers the most performance for your particular body. 

However, if you’re the type of roadie that wants to go fast without giving up much in the way of other performance aspects in the process, man, does this Propel seem like a great way to go. And the fact it manages to achieve everything it does without resorting to any truly unusual fitments is a major bonus in my book.

Feel free to chime in below with your thoughts if you’re lucky enough to own one of these, but if there’s a major flaw with this bike, I can’t find it.

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