Back in black
Cannondale has reintroduced the Synapse with disc brakes. Is this now the ultimate do-it-all road bike?
We first saw Cannondale’s new Synapse platform back in issue 10, when we got hold of Peter Sagan’s very own bike, complete with sweat streaks, energy gel residues and Belgian dirt. Things have moved on since then. In its attempt to provide Sagan with the perfect race weapon for the cobbles of northern Europe, Cannondale has updated one of the most capable doit-all bikes on the planet, offering a heady combination of speed and comfort, and now it has added disc brakes into the mix.
Cannondale’s senior project engineer, Chris Dodman, was a key figure in the creation of this new range-topping Black Inc version of the Synapse, and he has a lot to say on its development, so we’ll let him tell the story:
‘Functionality is at the heart of the bike, and so that’s why we made 11 different sizes, with three different fork rakes, to ensure that each bike’s characteristics would be consistent throughout. We developed the split seat tube as it’s the best combination for stiffness and weight. A wide seat tube at the bottom bracket shell is optimal for lateral stability, but that adds extra weight and also does not flex [vertically] much. Using two smaller cylindrical tubes means we can move the material further outboard where it’s needed for lateral stability, plus removing the centre axis [of the seat tube] provides greater [vertical] flexibility. Think of it like skiing down a hill. You are much more stable if your legs are apart, plus you can more efficiently absorb bumps.
‘The smaller-diameter seatpost also flexes more, and because the seat tube is narrower they work together and both flex more. The geometry means there is more slope on the top tube, plus the seat clamp is integrated into the frame, resulting in a more exposed seatpost. This is key in letting it flex to add comfort. Being aero was never a focus, but we’ve since found this works well aerodynamically.
‘Discs, of course, increase the frame weight but only by around 100g, which is a small gain given what they bring in terms of performance. To facilitate discs, the fork has undergone a lot of development. Lateral stiffness needs to be very good for the disc brake to perform optimally, and we have developed a forward facing dropout. This has two benefits. One is that it transfers the [braking] load back into the dropout, and the other is that it ensures the wheel stays located centrally.
‘We did a lot of tests with the [pro] team and mechanics for wheel changes. It’s a huge concern for them, and an ongoing problem that we face with disc brakes in the pro peloton. We timed the wheel removal with the Synapse and found it was actually quicker by a few seconds than a regular fork and calliper brake. That is the main reason we did not develop a thru-axle design. We tested this also and it increased the wheel change time by four or five times. Also a thru-axle needs to use larger bearings in the hub, which means more weight and more seal drag. We’ve tried everything and talked with a lot of people. The mechanics pointed out that
a thru-axle is simply something else in your hand when you’re trying to change a wheel and that’s the kind of thing no one really thinks about. It’s very easy to just go with new technology because it’s there, but it’s not always necessary. We looked to our engineers for solutions and what we have come up with gives us exactly the performance we want.
‘We also worked hard on the cable routing, especially in the fork. I wanted the hydraulic brake hose to be routed internally, and for it to go in the straightest line possible from the lever into the fork crown. It’s the hardest place to put a hole for a cable entry point, due to the huge forces this area sees, but that’s where I wanted it so that’s where we put it.
‘We also developed our own crank, the Hollowgram SISL2, and particularly the onepiece spider. It’s 200% stiffer than bolting on chainrings. We researched the design and ten radial spokes are used frequently in high performance car wheels as this is the best combination for weight and stiffness. So it look's nice and brings real shifting benefits.
‘In the Cannondale workplace, we’ve had employees setting their fastest ever Strava segments on the Synapse Disc, over a Supersix Evo. The Synapse Disc has set a high bar for us to beat, and the Evo platform is the obvious place to develop next. But we will aim to beat it in different ways, because ultimately we don’t want the two bikes to compete with each other. We would still like people to feel like they needed both.’
That’s what the man who built it has to say, so all that remains is for us to throw a leg over it for a full test to see if it really lives up to its potential. Look out for our review in a couple of issues’ time.
‘Discs increase the frame weight but only by around 100g, which is a small gain given what they bring to the bike in terms of performance’