CaptainHaddock

Hey gang,
seeing as the Cannondale RT2 is fairly popular 'round bout, I thought I'd share what 650b gravel focused tires I've found to fit in the rear (the chain stay being the pinch point) so far, and my thoughts on them.

First off are the Panaracer GravelKing in the 27.5×1.90 / 48-584 size. What I've noticed with these is that on my half-bike the wheel flop up front is atrocious and the hookup in hard braking in the rear is equally problematic. HOWEVER! when mounted to my tandem, the longer wheelbase and near 40/60 weight distribution has really allowed these tires to shine. They track really well, and grab most hard pack quite well.

Next up is the Kenda Flintridge in the 27.5x1.77 / 45-584 size. So these seem to ride the same between the half-bike and the tandem. They are equally fast on the hard, and yet have horrible roll out. BUT! I would never ever worry about them getting snake bit or goat head thorn punctured. Suffice it to say, they are dependable (if seemingly heavy).

Finally (for the moment) are the Continental ShieldWall race king in the 27.5x2.0 / 50-584 size. Just mounted today. All I can say is that they fit. I mean, by the barest whisper, but they fit! We're headed out for a ride this weekend, and I'll update.

CaptainHaddock

As an update on the RaceKings. Wow, just what the doctor ordered! We just back from having spent the last week out in SW Washington, riding some amazing gravel in the Gifford Pinchot forest. Aside from an aborted climb up to Bell's Mtn (first 4 miles averaging 6%, and initial climb @ 12%+ [so kind of a deal breaker for our first serious ride in a few years]), the tires were able to provide both the connection and comfort enough to reassure both captain and stoker. The tires proved to be both supple, and hooked up in just about every situation we faced (I felt confident in descending in semi-loose gravel @ -10 to -18% grades), and we were able to run very low pressures (roughly 35psi front and back) with no worries of snakebites or burping the tyers. They even were fairly good on paved road at low pressures and fast (30+mph) descents.

CaptainHaddock

And yet another update on those racekings. we took her out to the Dallas (Oregon) hinterlands and completed a ride which we had failed at many year prior (6 flats, no more patches, no more co2 cartridges, didn't have a pump) before having kids. Anyway, I started the ride out @ 40 psi front and rear as there I already knew that there were long paved road transit sections at the beginning of the ride. That served us well up until we got about a quarter of the way in and the gravel got rough. I dropped the PSI down to (guesstimate) 35/30 PSI. And that did the trick (or so it seemed) until we hit the rough stuff, when my stoker commented that she felt as if the rear was bouncing / really low. As I didn't have a guage with us, and after a few field tests seemed to imply everything was still ok, we continued on our way. Long story short, we get back to the car (where I've got a digital tire gauge) and it turns out we had dropped down to 25psi. a good 5 PSI (and really 10) lower than what I thought we were at. Anyway, the point of all of this is to say, that a 650b wheel mated to a '09 to '12 RT2 can easily manage a 50mm tire in the rear @ 25 psi. No burping, no snake bites (and to my knowledge, we never grounded out).