Giant Propel Advanced SL 0 Disc 2019 review

Even if your bike doesn’t say Giant on the down tube, there’s a chance it was built at one of Giant’s enormous facilities in China and Taiwan.

Giant makes huge numbers of carbon frames not only for itself but for a plethora of other big brand names. This should, in theory, give it an advantage over its rivals – when you’re the one making everyone’s bikes, you can keep all the best stuff for yourself.

By that thinking, there should be a lot of good stuff in Giant’s latest aero road bike, the Propel Disc.

Buy the Giant Propel Advanced SL 0 Disc from Rutland Cycling

Compared to the previous model, the new Propel includes many of the newest trends in the market: fully internal cabling, disc brakes and a totally integrated front end.

Disc brakes may not seem like a particularly aerodynamic option, but Giant claims this is its fastest road bike yet, even given its fairly shallow section (42mm) front wheel.

‘The Propel Disc can outperform our rivals in terms of aerodynamics, but with the shallow front wheel it will be much easier to ride in crosswind situations,’ says Nixon Huang, Giant’s category manager for road.

‘We want to create a bike that you can actually ride fast, not one that just tests fast in a wind-tunnel.’

In addition to a lack of aerodynamic penalties from the disc brakes, the Propel Disc has no big weight penalty either.

At only 7.42kg, it’s nearly 500g lighter than a Specialized Venge ViAS Disc and nearly 800g lighter than Boardman’s top-tier aerodynamic rim brake bike, the Air 9.9.

For me, a big bonus with the inclusion of discs is the adjustability of the brakes compared to aerodynamically concealed rim brakes, which can be fiddly.

Practicality has been a consideration elsewhere too. The cockpit looks like it will be as complicated as a Rubik’s Cube to adjust, but once you remove the aerodynamic cover there’s a standard stem and steerer tube underneath.

Frustratingly, the aero cap means that the stack height can’t be significantly lowered without cutting the steerer tube.

However, I’d still say the set-up is less awkward than with some of the integration of the Propel’s aero-road peers.

Frame stiffness was a priority, and the company claims it has tested the Propel Disc against its main competitors, and its own predecessor, by clamping the rear dropouts in place and applying lateral force to the forks.

By that measure, Giant claims the Propel has a stiffness of 153Nm, compared to 147Nm for the Specialized Venge ViAS and 112Nm for the previous Propel.

I really enjoyed both of those bikes when I tested them, so I was really excited to get aboard the Propel Disc to see if it could deliver on its promise.

The first thing I noticed is that this bike is fast. I could articulate that in a more detailed and nuanced way, but it wouldn’t change the main point – the Giant Propel Advanced SL Disc is a very fast bike indeed.

I really enjoyed both of those bikes when I tested them, so I was really excited to get aboard the Propel Disc to see if it could deliver on its promise.

The first thing I noticed is that this bike is fast. I could articulate that in a more detailed and nuanced way, but it wouldn’t change the main point – the Giant Propel Advanced SL Disc is a very fast bike indeed.

It gets up to speed incredibly rapidly, and then holds that speed easily. I frequently found myself cruising on the flat above 40kmh.

It’s a mystery

That said, cycling isn’t just about speed, otherwise we’d all be riding time-trial bikes. And the Propel offers more than just speed.

For a super-stiff aero bike it’s also remarkably comfortable. I’m slightly at a loss to explain how – with its angular shapes and integrated seatpost it should be like riding a girder – but somehow it seems to soften the road admirably.

Even Giant can’t explain it. Huang says, ‘We got feedback that riders feel pretty comfortable when riding on the Propel Disc, but comfort is not a key feature we wanted to put into this bike.’

I can only surmise the comfort comes from a combination of handlebar flex and the extra compliance provided by supple tubeless tyres, which can be run at lower pressures.

Whatever the reason, there was a certain effortlessness to the Propel.

I felt as if I could cover long distances with no ill effects, and I was inspired to tackle my longest UK ride of the year thus far when I ticked off 140km on the Propel one sunny Sunday morning.

Comfort aside, the stiffness meant the bike was extremely sharp and predictable when cornering or descending.

I really felt as if there were an extra few degrees of lean available in every corner, and even the mildest steering input seemed to make for a decisive yet controlled response.

With the additional confidence of disc brakes, it meant that descents weren’t just fast, but fun.

Splitting the differences

It’s fair to say I really enjoyed riding the Propel Disc, but I’d be lying if I said it’s the bike I’d choose to spend my own money on.

The main issue is that it fails to stand out among the aero competition. There are many very fast and fine-handling bikes out there, and I struggled to discern whether the Propel Disc was superior to its main rivals in any particular area.

And when the asking price is a pound under £9k, I would need to be more convinced that I was getting something special.

That’s the parting impression the Giant Propel Disc leaves me with. Giant may be able to present stats and wind-tunnel data, but on the road I couldn’t separate its performance from the Trek Madone or Venge ViAS.

I can assure you a tighter jersey would make more aerodynamic difference than switching between the three of them.

Of course, the Propel Disc has certain charms, and the future-proofing appeal of disc brakes is one.

For some its aesthetics will certainly appeal – I was stopped on more than one occasion by admiring bystanders – while for others it may seem a little too severe.

Perhaps the biggest criticism would be that where some bikes are leaps forward in technology, the Propel Disc represents a solid but small step. All comaprisons aside, though, the Giant Propel Advanced SL 0 Disc is a very, very fast bike.

Buy the Giant Propel Advanced SL 0 Disc from Rutland Cycling

Spec