Sunweb’s sprinter Michael Matthews was on a new disc brake bike from team sponsor Giant for the road start of the Tour de France this week. It’s not the first disc brake Giant the we’ve seen Sunweb race, having detailed Bert De Backer’s Defy Disc in this year’s Spring Classics. This pre-production Giant Propel Disc not only suggests that a disc brake specific aero bike is on the way from the Taiwanese bike maker, but all new aero tube shaping could suggest that a full overhaul of the Propel line is imminent as well, with the carbon rim brake bike last updated in 2013 and an alloy version in 2015. Take a closer look at the bike, including the team’s thoughts on discs and fit…
The new Giant Propel Dic strikes a similar profile overall to the current Propel, but a closer look shows all new tubing shapes that for the most part are wider throughout. The downtube for example maintains a more constant depth from the headtube back to the even bigger bottom bracket and gets a chopped off aero Kamm profile for its full length.
Wider tubing also equates to wider tires, with plenty of space around Matthews’ unmarked 25mm Vittoria Corsa tubular tires.
The disc brake aero bike also gets an all-new fork shape, with a more straight and flat-sided set of legs, and an angular extension transitioning back into the downtube. As we can see here and in the photo at the top, the fork gets flattened and angular aero fork tips that extend below the axle.
The disc specific fork also gets a neatly integrated flat mount disc brake adapter that lines up with the fork blade while still offering 140 or 160mm rotor compatibility. We can also see pretty seamless internal routing for the front hydraulic line that enters the steerer tube inside of the stem and exits midway down on the inside of the fork leg.
Curiously like Kittel & Quick-Step, Matthews & Sunweb have ignore the UCI consensus for bigger rotors and have again opted for Shimano’s newest Dura-Ace R9000 series IceTech Freeza rotors in 140mm for both front & rear. While this Propel Disc was setup with a quick-release lever of the front 12mm thru-axle, the rear of the bike goes with a simple 5mm hex bolt interface.
The press fit bottom bracket stays the full massive width of the downtube with an angular transition from the Kamm tail shaping up front. The rear wheel tucks in nicely to the frame cutout, but there are still several mm left for a larger tire if needed. The frame still includes Giant’s Ride Sense speed & cadence sensor integrated into the non-driveside chainstay. And we can also see that Sunweb is one of the first teams to be racing on Shimano’s new R9000 Dura-Ace dual-sided power meter crankset. (It has the unique non-driveside axle cap here, and visible sensors in other photos.)
Of course the huge Giant steam and matching aero profiled carbon handlebar were eye catchers as well.
Matthew’s already long stem looks even longer due to the extended top and rearward covers that manage to completely hide all of the cables internally, including both Di2 shift wires and hydraulic brake lines. The stem uses a fairly standard removable faceplate to clamp the shaped bar, which means it is easy to interchange stem lengths, but has no means to adjust the bar angle.
Opening up the top cover’s four bolts allows access to all of the internal routing, with the rear brake and Di2 shift wiring entering the toptube just behind the stem. In fact the small segments on the rear sides of the steam are actually flaps (you can see the upper hinge element) that pivot up as the bar is turned to keep from binding on the rear brake hose. Presumably the same setup will work with mechanical shift cables and the cable actuated brake on a rim brake version.
Like the current Propel, this new bike uses an integrated seat mast with an alloy seat topper, and the extended lower clamping bolt makes for a tidy mount for that race number.
The seat cluster is a bit revised with a webbed section between the flattened toptube and aero seattube in what has been shown to reduce air turbulence. The end of the dropped seatstays also have a revised shape that is a bit more angular and flat-topped than the current Propel.
The UCI approved sticker number names the bike as the Giant “Propel Advance SL Disc MY18” with six sizes from XS-XL approved to race as of May 18th.
The last look at the front of Matthews’ Propel Disc has a fairly rigged together out front-style computer mount working off of extended faceplate bolts like the FormMount that we recently reviewed.
Giant has been tight-lipped on the official rollout of the new Propel Advance SL Disc, but the UCI approval from back in May also included a Propel Advance Pro Disc version as well, so expect to see at least that coming soon. Interestingly the UCI list does not have a new rim brake Propel listed, so Giant may be going disc-only with their aero bike from here forward.
As for the Sunweb team, for the most part they seem to be totally onboard with the move to disc brakes for improved stopping performance. Giant has worked with the to develop the new bikes, and they say they’ve been able to maintain the exact same racing geometry, fit, and handling with the added benefit of being able to race on wider tires as race surfaces dictate.