Transition Relay Carbon

The Transition Relay Carbon is a premium lightweight electric mountain bike for riders who want enduro-length travel and a real shove on the climbs, without the bulk or the dominant motor feel of a full-power eMTB. Picture a trail-centre loop where the assistance keeps you with quicker friends on the way up, then a descent where you still want to pick a line and move the bike. Two builds share the carbon frame. The Relay Carbon Eagle 90 is the 160mm air-sprung trail bike, with dual 29-inch wheels from SM upwards. The Relay PNW Carbon Eagle 90 is the 170mm coil-sprung build for days when the steep, rough descents are the reason you went out.

This is the current UK model, on the Relay Carbon platform produced from 2023 to 2026. The Eagle 90 specification carries no official model year, so a year printed on a listing doesn't mean a different frame.

Assistance that still leaves you a bike to ride

The chassis is carbon, with Transition's GiddyUp suspension and Speed Balanced Geometry. On the regular build the head angle is 64 degrees, the wheelbase is long and the effective seat angle is steep, so the bike stays calm at speed and puts you in a useful place to pedal. The PNW head angle is a fraction slacker, and reach is slightly shorter in the same size label. You're looking at a stable long-travel bike, not a nervous short-travel one.

It is at its best with committed intermediate and expert mountain bikers. Less experienced riders can use it, but the price, the speed and the setup choices make more sense once your trail skills are already there.

The Relay uses a Fazua Ride 60 mid-drive, with 60 Nm, 250 W continuous output and 450 W in Boost. Fazua designs the motor to decouple once you are above the assistance limit, so on easier spins it gets out of the way more than a full-power motor tends to. Jamie Darlow rode a size LG Relay Carbon GX AXS for MBR, the earlier wireless 160mm build. He found that chassis lively and easy to move between lines, and it passed more feedback through than a plush, isolating eMTB. You will notice that on a long rough ride. Tyre pressure and shock setup are the first things to adjust if it wears on you. The PNW coil, longer travel, ZEB fork and smaller rear wheel are the factory package when those descents are steep and keep coming.

The lower shock flip chip is how one frame accepts either rear-wheel size. LOW is for a 29-inch rear wheel and HIGH is for a 27.5-inch rear wheel. The rear end is 12mm x 148mm with SRAM UDH, so the Eagle Transmission derailleur mounts without a conventional hanger. Moving between the 160mm dual-29 setup and the 170mm mixed-wheel setup needs the matching rear wheel, a 205mm x 60mm or 205mm x 65mm shock, a 160mm or 170mm fork, the right chip position and often a chain-length change. The frame can be converted, but it costs more than a simple wheel swap.

XS isn't a scaled-down version of the larger bikes. Both builds give that size dual 27.5-inch wheels, the HIGH chip, a 37mm fork offset and 160mm cranks. Larger sizes use 165mm cranks and a 44mm fork offset. Vivid and Float X2 shock bodies only clear this carbon frame in the LOW, 29-inch position, so a large aftermarket shock isn't automatically a fit with a 27.5-inch rear wheel. Dual-crown forks aren't approved. There are no ISCG tabs, so a normal frame-mounted chain guide isn't a direct fit, though a Relay-compatible bash spider can add impact protection. The PNW includes that spider. The regular Eagle 90 uses a direct-mount 32t ring instead.

Eagle 90 or the PNW Eagle 90

Relay Carbon Eagle 90 is the build for a mixed week: a trail-centre climb, some natural singletrack, and descents that are technical without being the entire day. Travel is 160mm at both ends, with a RockShox Lyrik Select+ and a Super Deluxe Select+ air shock, 205mm x 60mm. SRAM Maven Bronze brakes run 200mm rotors front and rear, and the tyres are a Maxxis Assegai 2.5-inch front with a Minion DHR II 2.4-inch rear, on DT Swiss E 1900 wheels. Gears are mechanical SRAM Eagle 90 Transmission, 1x12, with a 10-52t cassette and a 32t chainring, so you still have a climbing gear when assistance is low or the battery is out. The official UK RRP is £8,599. Claimed weight for a size MD is 19.55 kg with the battery and 17.28 kg without it, which you notice when the bike has to go on a rack or up a stairwell.

PNW Carbon Eagle 90 is the descending build. Travel is 170mm, the fork is a RockShox ZEB Ultimate, and the shock is a Vivid Coil Ultimate at 205mm x 65mm. From SM to XXL you get a mixed wheelset, 29-inch front and 27.5-inch rear, plus a 220mm front rotor on SRAM Maven Silver brakes. XS stays with 200mm rotors and dual 27.5-inch wheels. Schwalbe Magic Mary and Big Betty Super Trail Soft tyres, both 2.4 inches, and a factory bash spider around the 32t e-ring, are there for repeated rock and root strikes. Claimed weight for a size MD is 20.21 kg with the battery and 18.00 kg without it. Ride this build when steep, rough descents are a regular part of the week. For mellower loops, the Eagle 90 is the more willing bike.

Charging, wet rides and workshop time

Every charge starts with the battery out of the frame. Transition and Fazua put a full charge at about 3.5 hours on the supplied 3 A charger, so the tool-free Fazua Energy 430 can come indoors while the bike stays in a garage, a shed or a shared hallway. There's no port for charging the complete bike, and Transition doesn't currently offer a dedicated Relay range extender. At 430 Wh the pack is modest next to full-power eMTBs. How far it takes you depends on the mode, the gradient, how much you pedal and the temperature. Boost suits a short, awkward step in the climb, and it spends the pack quickly if you leave it on. Drop the assistance, or use Fazua's adjustable support, when the day is long.

Remove the pack and the Relay is still an electric bike, because the Ride 60 stays fitted. You can pedal without assistance, which helps on a tarmac link or any journey where a lighter bike is easier to lift. It won't ride like a bike that was never electric.

Dry the battery and the charging contacts after a wet ride. Fazua rates the system IP54, enough for rain and spray, not a pressure washer pointed at the connectors. Leave some room around the tyres too. A 2.6-inch maximum is the published limit, not a target, and sticky UK mud will fill a tight rear end long before a dry-day measurement says you have space.

Servicing is the usual pivots, suspension and chain, plus firmware checks and e-bike diagnostics. Eagle 90 is cable-operated, so there's no shifter battery, and replacement links, guards and cage parts can make a crashed derailleur cheaper to repair. Change the chainring size or the flip-chip position and the chain setup needs checking again. Internal cables are reached through the battery opening, which is worth knowing before a housing change.

Bottle space depends on the size. MD, LG, XL and XXL take a normal bottle. XS and SM take a 450ml Fidlock bottle, and may need a Fidlock Twist Base Adapter depending on the shock. There is also a gear accessory mount under the top tube.

Deore, GX and AXS bikes on this frame

Deore, GX, GX AXS, XO AXS and PNW GX offers use this same carbon platform. They are earlier component builds, not a previous frame generation. Relay Carbon Deore was the more affordable 160mm option, with Shimano Deore equipment and a simpler suspension package. Relay Carbon GX was the previous mechanical build on the 160mm chassis, with a historical UK RRP of £8,599. GX AXS was a wireless build with Fox suspension. Relay Carbon XO AXS was the previous premium wireless 160mm build, historically £9,999. Relay PNW Carbon GX was the earlier mechanical version of the 170mm mixed-wheel setup, historically £8,999.

None of those matches the Eagle 90 specification. A GX-labelled bike can still be a sound buy when the suspension, brakes, drivetrain and wheels on that offer are what you actually want. The kit listed with the offer is what you are buying.

Most mixed weeks belong on the Eagle 90: climbs you can share with a quicker group, descents you can still play on, and a battery that unclips for a charge at home. The PNW is the better companion when those descents are steep, rough and frequent enough to use the coil, the ZEB and the larger front rotor. You get the hills covered, and you still get to ride the bike yourself.