Cairn Cycle’s updated e-gravel machine brings more assisted adventure

Rider feedback and tech improvements key to the E-Adventure V2 ebike

The new Cairn E-Adventure 1.0 Version two road ebike

While Cairn Cycle’s original E-Adventure bike was popular with its customers, and we were impressed with the original when we tried it back in 2018, for its latest iteration the company has gone back to its customers to find out what they would change or improve about the bike.

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As well as changes to its geometry, other key improvements include an update to the motor, changes to cable routing and controller position, and wheel options and compatibility for a dropper to cater to more adventurous riders.

Six improvements to the V2 Cairn E-Adventure

  1. Improved cable positioning
  2. Re-positioned controller for easier operation
  3. Increased standover height
  4. Improved comfort and compliance
  5. Updated motor system
  6. Two versions: 650b and 700c

Cairn Cycles E-Adventure V2 frame and geometry

The first area that sees a refresh is the bike’s cabling, which cleans up the front end and provides provision for both a dropper post and e-system powered lighting.

The cable guide positions have been moved, but a full internal routing design has been avoided – fast becoming the trend of 2021 model bikes – because Cairn discovered owners of its bikes like to modify and personalise them. Simplicity was the key here, for easy maintenance and component switching.

Cable routing on the Cairn E-Adventure V2 road ebike
Cable routing has been simplified and routing for lighting and dropper post compatibility added.
Warren Rossiter / Immediate media

The frame design has also been tweaked. Shortening the seat tube and lowering the top tube to seat tube joint has increased standover height and improved compliance by giving more exposed seatpost.

The rear seatstays have also been changed by removing the seatstay bridge to aid rear-end compliance. But don’t fear, mudguard fans, the bridge has been replaced with a light single-sided bolt-on plate for a removable ‘guard fitting.

The rear seat stay bridge on the Cairn E-Adventure V2 has been replace with a single sided bolt on mudguard mount
The rear seatstay bridge has been replaced with a single-sided bolt-on mudguard mount.
Warren Rossiter / Immediate media

While the off-road biased geometry and handling, which earned the original lots of praise, remains, the changes bring more comfort and compliance, which Cairn claims will make the E-Adventure an even better assisted all-road machine.

The V1’s generous tyre clearance remains too, with a claimed 45c for the 700c bike and 2.25in in 650b guise.

The Cairn E-Adventure V2 road ebike has generous tyre clearance
Tyre clearance is generous, with space for 45c tyres on the 700 build and 2.25in on the 650b version. The 700c bike comes fitted with 38c tyres.
Warren Rossiter / Immediate media

Cairn E-Adventure V2 geometry chart

 S M L XL
Seat angle (degrees) 73.5 73 73 73
Head angle (degrees) 71 71 72 72
Seat tube (cm) 47 50 53 55
Top tube (cm) 53.3 55.8 57.4 58.8
Head tube (cm) 13 15 17 18.5
Fork offset (cm) 4.8 4.8 4.8 4.8
Trail (cm) 7 7 6.35 6.35
Fork length (cm) 39.8 39.8 39.8 39.8
Bottom bracket drop (cm) 7 7 7 7
Wheelbase (mm) 1,010 1,031 1,037 1,052
Standover (cm) 77 79 82 83.5
Stack (cm) 55.1 57 59.3 60.7
Reach (cm) 37 38.4 39.3 40.3
Front centre (cm) 59.1 61.1 61.7 63.2
Rear centre (cm) 43 43 43 43

Cairn Cycles E-Adventure V2 motor

Cairn has stayed committed to the lightweight German Fazua motor system, but has moved the position of the controller from the original bike’s down tube position to a flush fitting in the top tube.

This always seemed to us to be a better place for it because it means you can easily and quickly switch between modes, whereas the position of the V1’s controller was hard to reach at the best of times.

Cairn E-Adventure V2
Fazua’s bottom bracket and down tube mounted system is one of the lightest on the market.
Warren Rossiter / Immediate media

Fazua’s latest update to the motor, ‘Black Pepper’, brings much more control to the rider too, and it’s possible to tailor the power delivery of the system. Cairn has used this to create its own tuning that comes pre-set on the V2.

Black Pepper also brings compatibility with third-party head units such as Garmin’s Edge computers to display ebike metrics on screen and even provide dual-sided power meter data from the Fazua’s bottom bracket motor system.

E-Adventure V2
Anything-style cages on the front fork are designed to carry the 1kg expansion batteries.
Warren Rossiter / Immediate media

Cairn now offers a Fazua range extension battery in the form of the Cairn battery keg (and a special bottle cage), which weighs in at just 1kg, so you can easily carry extra power reserves on long-haul rides.

Cairn Cycles E-Adventure V2 wheel and tyre options

Cairn E-Adventure V2
Cairn worked closely with Hunt on ebike-specific wheelsets for the Adventure V2.
Warren Rossiter / Immediate media

One thing that Cairn learned from the original owners was that there were two distinct types of rider; those who use the bike on both tarmac and trail and want a fast-paced 700c bike, and those who want to have more off-road adventures with larger tyres for a more robust ride and more comfort when things get rocky. Many also wanted a dropper post for when the trails point downwards.

Cairn worked closely with Hunt (both are part of The Rider Firm collective) on designing e-gravel-specific wheels based on Hunt’s well regarded 700c 4 Seasons and 650b Adventure Sports.

These 25mm internal width rims are laced to new ebike specific hubs. The four pawl, 36-point engagement rear hub is strengthened over the standard hubs by using a steel axle rather than alloy. This is to handle the increased torque put through the drivetrain from the ebike motor at full power.

The new 700c wheel is called the Hunt X Cairn E-Gravel disc and is specific to the Cairn Adventure 700. A new ebike-specific version of the Adventure Sport 650b wheel comes with the same strengthened steel axle rear hub.

The 700c bike’s Hunt X Cairn E-Gravel disc wheels are fitted with Vittoria Terreno Dry 38c tyres. The textured centre section and shoulder knobbled tread should offer a good balance between on-road speed and off-road grip.

The 650b bike’s Hunt Adventure Sport rims are built on the same Hunt E-Gravel hubs but run Vittoria’s Mezcal tyres in a 27.5 x 2.25in front, 2.1in rear combination.

Cairn Cycles E-Adventure V2 kit

Cairn E-Adventure V2
Praxis provides the ebike-specific chainset but Cairn has switched to Shimano GRX for the rest of the drivetrain and braking.
Warren Rossiter / Immediate media

Cairn has also switched the bike over to Shimano’s GRX group. The reason, it says, was due to Shimano’s introduction of Servo Wave into the brake system on GRX (something previously only found on mountain bikes), giving superb control and brake action from the hoods – and when we tested Shimano GRX Di2 we found the Servo Wave tech to be simply brilliant.

The 700c bike is finished with a Ritchey bar and stem, a carbon seatpost and a combination of Fabric saddle and bar tape taking care of the contact points. It’s priced at £2,989.

The 650b bike gains a Trans-X 80mm dropper post with a drop bar-specific cable actuated remote designed to be easily operated from both the drops and the hoods. Like the 700c model, the 650b is also priced at £2,989.

Cairn Cycles E-Adventure V2 specifications

Cairn Cycles E-Adventure V2 700c specifications

  • Frame: 6061-T6 alloy with top tube integrated Fazua touch remote
  • Fork: Full carbon with Anything mounts on both legs
  • Wheels: Hunt Gravel X Wide rim, Hunt E-Gravel hub, Pillar triple-butted spokes
  • Tyres: Vittoria Terrano Dry 700 x 38c
  • Handlebar: Ritchey Butano Comp / S – 42cm, M/L – 44cm, XL – 46cm
  • Stem: Ritchey 4-Axis-44 7-degree / S – 70mm, M – 80mm, L – 90mm, XL – 100mm
  • Bar tape: Fabric Knurl black
  • Crankset: Praxis Fazua Alloy w/42t Spider / S – 165mm, M/L – 170mm, XL – 172.5mm
  • Cassette: Shimano CS-M7000 11-speed 11-42t
  • Chain: KMC e11 Sport with EPT coating
  • Shifters: Shimano GRX ST-RX600 right and left for single ring
  • Rear mech: Shimano GRX RD-RX812
  • Brakes: Shimano GRX BR-RX400
  • Rotors: Shimano SM-RT64 160mm
  • Saddle: Fabric Scoop Elite Shallow
  • Seatpost: Cairn Carbon, 27.2mm, 350mm
  • Thru-axles: Cairn Alloy with removable bottle opener handle
  • Other: Removable rear mudguard bridge
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Cairn Cycles E-Adventure V2 650b specifications

  • Frame: 6061-T6 alloy with top tube integrated Fazua touch remote
  • Fork: Full Carbon with Anything mounts on both legs
  • Wheels: Hunt Adventure Sport disc rim, Hunt E-Gravel hub, Pillar triple-butted spoke
  • Tyre: Vittoria Mezcal 27.5 x 2.25in front, 2.1in rear
  • Handlebar: Cairn Adventure 20-degree flare, 65mm reach, 105mm drop  / S – 44cm, M – 46cm, L – 48cm, XL – 50cm
  • Stem: Cairn Adventure 6061-T6 / S – 60mm, M – 70mm, L – 80mm, XL – 90mm
  • Bar tape: Cairn Anti Slip Gravel
  • Crankset: Praxis Fazua Alloy with 42t Spider / S – 165mm, M/L – 170mm, XL – 172.5mm
  • Cassette: Sunrace CSMS7 11-speed 11-42t
  • Chain: KMC X11
  • Shifters: Shimano GRX ST-RX600 right and left for single ring
  • Rear mech: Shimano GRX RD-RX812
  • Brakes: Shimano GRX BR-RX400
  • Rotors: Shimano SM-RT30, 160mm
  • Saddle: Cairn E-Adventure, 143mm
  • Seatpost: Trans X 80mm drop with dropbar compatible lever
  • Thru-axles: Cairn Alloy with removable bottle opener handle
  • Other: Removable rear mudguard bridge