For those that don't know, the Slate is marketed as an "any road" bike. It's designed around the smaller 650b (27.5" in old money) wheel standard that was popular amongst randonneurs (and now 650b is everywhere on adventure bikes thanks to the Slate). The trick with a 650b wheel is that with a large (42mm) tyre, it has roughly the same outside diameter as a standard road wheel (700c) with a 23mm tyre. Despite this, I found that on the road I tend to ride it in the next higher gear compared to my road bike. Cannondale's rationale for the smaller wheel size was to keep the wheelbase and chain stay in the range of a normal road bike, giving it the zippy acceleration of a road geometry. It certainly has met that particular mark.
The other defining feature is the Lefty suspension fork. It's a single sided fork that offers 30mm of suspension. Initially I was sceptical of the idea of suspension, particularly with fatter tyres, but, after a while (and many corrugations),I really felt the benefit and, despite it being just a push of a button, I now rarely even bother to lock it out, even when climbing.
Rounding out the spec is a lovely aluminium frame dressed in a full Ultegra hydraulic disc groupset with the exception of Cannondale's own magnificent Hollowgram cranks. The other notable item is the excellent Fabric Scoop saddle. I have it on two other bikes. It really is the best saddle I have even used (and I've sat on it for 24 hours and many other silly length rides).
It came with Schwalbe's G-One tyres which I set up tubeless (on both the original and the replacement wheels post recall!). They really are excellent tyres - fast rolling on the road but surprising grippy off it despite the low profile tread.
With everything setup I headed out for my first ride, a mixed terrain ride of a little over 100km. The first thing that struck me was how comfy it was. Yes, fat tyres help but the skinny seatpost and flattened seat stays were doing their job. It also handled well. The additional trail of the Slate is something you get used - it adds stability on the rough stuff but it can have a tendency to flop over through a sharp corner. The disc brakes were a revelation. Wow! On gravel in the wet I had the power to stop and the control to scrub off speed! I was bombing descents and diving down the gravel like never before. It's difficult to seperate whether it was because I was on a Slate or because I was on a disc bike with tubeless tyres. Either way, it was a heap of fun.
I was also a little unsure if I had the right size. It was an XL with a longer reach than I am used to but its a bike you tend to sit in not on and it came with a shorter stem than I usually ride so it actually fitted well. The geometry for the range is a little odd but I'll come to that later! One thing that did stand out is how long the Shimano Ultegra hydro levers are. They must be a full centimetre longer than the cable version.
After many mixed terrain days out, I really have no complaints about how it rides. The one observation I would make is that building the bike around 650b limits the tyre choice - knobbly tyres in the 40mm range are pretty rare with even the Road Plus "standard" too fat for the frame. Saying that, I never found the G-Ones to be a limiting factor and any terrain beyond their capabilities - this is a mixed terrain bike after all - is probably better suited to a mountain bike anyway!
My main gripe would be the gearing. Who thought it would be a good idea to spec a bike intended to be ridden off road with a 52/36 crank mated to an 11-28 cassette (with associated short cage derailleur)? I replaced the rear derailleur with a long cage to accommodate an 11-32 cassette pretty much straight away but ideally I'd like to replace the chainrings with a 50/34 or even better a 48/32, if Cannondale release such an option for their crankset. The Slate isn't the only culprit. The GT Grade, a similar bike, has the same gearing combination.