The original Topstone Carbon gravel bike introduced their KingPin rear suspension platform in 2019. What’s new here is the addition of a new Lefty Oliver Gen2 fork, and the switch to 650B wheels and tires for most models. Now it’s a real full suspension gravel bike.
Our Topstone launch story covers the frame’s suspension tech and design in full detail, but here’s the quick version: The Topstone Carbon uses flattened carbon fiber chainstays with tuned, engineered flex.
The seatstays are thin, and meet the seat tube with a bearing-equipped pivot to allow for greater system flex without stressing a key junction point.
The seat tube, too, is flattened, particularly at the bottom. Combined, the three rear tubes all flex to provide about 15mm of total “travel” to the saddle. It’s hard to see, but it works. And it carries over unchanged for 2020/2021 models. What’s new is the suspension on the front…
Cannondale Lefty Oliver Gen2 gravel suspension fork
Lefty Oliver Gen2 is built on the Lefty Ocho chassis, but tuned and scaled for gravel bikes. There’s a new All-Over damper tune, and new ISO High-Ride air spring that you can tune with volume spacers.
It uses the Delta Cage Needle Bearing system from Ocho, which is comparatively friction free compared to traditional sliding stanchions. There’s just 30mm of travel in stock trim, but can be expanded to 40mm travel by changing a piston’s lock ring position.
The Damper was tuned to give it more control over pedal oscillations, handled by “generous” low speed compression damping.
The rebound circuit is isolated from compression, and it’s called Bleed Stack, and it means that adjusting compression or rebound won’t affect the other. It also has 60% more rebound adjustment range.
It gets a new, tool-free disc brake mount that removes with the twist of a lever. To remove the wheel, just release the lever on the front of the fork and pull the brake caliper off the back. Then just remove the axle (tooled) like normal and slide the wheel off.
Reverse the process to put the wheel and brake back on. It’s super simple, and super quick, and it remained rock solid throughout our test.
Other Lefty Oliver v2 specs:
- 1340g carbon version
- 1610g alloy version
- Standard tapered steerer tube
- Lockout switch with blowoff valve
- Lefty 50 hub, same as used on Slate
- Flat mount 10mm rear brake caliper
- 650Bx47 or 700x45mm
- $1,500 MSRP (carbon), available in either wheel size option for use on any gravel bike with a standard tapered headtube.
Notice the generous 700×45 tire clearance figure…that’s considerably larger than you can run on the rear of the bike. More on that in a minute. If you want to use 700c tires, you have to change the air piston because it’s limited to 30mm travel, but it needs to sit in a higher position to keep the tire from hitting the crown during bottom out.
Axle to crown heights are:
- 650B 30mm – 405mm
- 650B 40mm – 415mm
- 700c 30mm – 419mm (requires new air piston service kit)
2021 Topstone Carbon Lefty Geometry
Smaller wheels make a big difference
The original model’s 700×37 tire spec sat on wide Cannondale rims that pushed the tires’ measured width out to 40mm+. Which made for a tight fit with file-treaded, semi-slick gravel tires. Put anything with knobs on there and it could rub the frame.
This is largely due to the fact that they need wide, flat chainstays to get the frame flex necessary to hit their compliance goals. And the cranks can’t go anywhere without messing up the Q-factor, so tire clearance ends up on the chopping block.
The new 650B wheel size gives it more room between tire and frame. We’ll have a before/after comparison in our ride review (coming soon). The Topstone Carbon will still be sold with 700c rigid fork options, but you’ll probably want to use a maximum of 37mm tires.
How does the Topstone compare to the Slate?
We reviewed the Slate a few years back, which was their first “gravel” bike with a Lefty fork. The Topstone is taller and shorter than the Slate, with what’s become more traditional gravel geometry. The Slate was good (good enough for Alison Tetrick to win Dirty Kanza on one), but the Topstone feels like a real gravel bike.
Fortunately, the 405mm A-to-C has been a legacy standard for them for many years now, so if you have a Lefty-equipped Slate, you can upgrade to this new Oliver fork by simply using their headset adapter to reduce the upper cup to 1-⅛”.
Now it’s a proper full suspension gravel bike
The result, on paper, should be a better gravel bike that feels balanced. One of our complaints with the original was that the front end felt comparatively stiff, while the rear end soaked up bumps. It was a bit backwards, and just felt unbalanced.
And 700×40’s were kinda pushing it. But with these changes, they’ve addressed our two biggest concerns. With the Lefty, it feels more like the bike it was always meant to be. So, thoughts? We have some, and we’ll have a review posted here shortly. In the meantime, here’s what’s available:
2021 Cannondale Topstone Carbon Lefty models & pricing
All models come ready for a dropper seatpost and 2x drivetrains, but all stock builds use a standard post and 1x groups. The top model, shown above, uses a wider range SRAM Eagle cassette (with eTap wireless shifting), and the others use a smaller 11-42 Shimano SLX 11-speed cassette with GRX mechanical shifting.
Topstone Carbon Lefty 1 – $7,500
Topstone Carbon Lefty 3 – $3,750 (two color options)
Women’s Topstone Carbon Lefty 3 – Europe Only
The women’s model gets the same build as the regular Lefty 3, save for shorter crank arms and a different saddle.