‘Marathon’ bikes – full-suspension machines designed for day-long epics – are big over on the European mainland. That’s probably why German company Ghost offer nine different versions of their 100mm-travel RT platform. The Actinum 5900 sits in the middle of the three-bike aluminium range.
There’s lots to like about this bike, which combines a Shimano Deore XT transmission with a pair of Fox shocks – not least the fact that the rear suspension works well without relying on a constipated shock for pedalling efficiency. If you like your trails technical, though, you’ll find yourself cursing the low bottom bracket.
Ride & handling: Reasonable alternative to the norm for those who ride less-technical trails
Despite claims that the RT’s pivots are positioned in some clever way to prevent pedal input from ruining the ride, we can’t see anything in particular that sets the Ghost’s four-bar system apart from similar supension setups. The proof is in the riding, though.
The rear end is certainly active over small bumps, sucking up tricky technical climbs with an alacrity that means you can just sit there and pedal. With no heavy compression damping to hinder its performance, the shock just gets on with it.
It’s a similar story on the way back down the trail, helped by spot-on weight distribution and a ride position that feels perfectly balanced. If this were the end of the story we could award the RT Actinum 5900 a gold star and all go home, but sadly there’s a fly in the ointment.
A low bottom bracket means it’s all too easy to clout the pedals on trail obstacles, particularly if the shock is set up with a decent amount of sag. Less sag helps, but higher shock pressures rob the bike of some of its small bump response. It’s the very definition of a rock and a hard place – and that’s a shame.
Frame & equipment: There’s nothing not to like about XT, and the suspension is supple and active
Hydroformed top and down tubes form the bike’s backbone and, unusually for an aluminium chassis, there’s barely a straight line to be seen. Like many new bikes, Ghost have equipped the RT Actinum 5900 with a tapered head tube. By increasing the diameter of the lower headset race, the front of the frame is stiffened and strengthened. Reducing the tendency of the head tube to twist also increases bearing life. It’s a win/win situation.
The vertically-mounted Fox shock is driven via a curvy linkage and needle bearing pivots to improve small bump response, while full-length cables run neatly down the underside of the down tube. The whole lot is adorned with acronyms aplenty and torque settings for each pivot bolt.
Ghost’s designers give each frame size its own chainstay length, claiming that this results in a better balanced feel. Mud clearance at the rear is tight, though. In fact, it’s among the worst we’ve seen on a 26in-wheeled full-susser, at least with the 2.25in tyres that it wears as stock. And narrower tyres would make the low bottom bracket even lower.
It’s unusual to see a plain vanilla Fox Float RL shock holding up the rear of a full-susser. Ghost are clearly confident that careful pivot placement – they call it ‘anti-squat technology’ – doesn’t need a helping hand. The shock is matched to a Fox 32F fork with remote lockout. If you’re a dedicated racer, tend to ride the climbs out of the saddle and worry about fork bob, this is worth having. For the rest of us, it’s arguably overkill.
As for the rest of the kit, Shimano’s Deore XT transmission is still the benchmark by which everything else is judged, while Deore hydraulic discs are up there with the best in terms of performance.
This article was originally published in What Mountain Bike magazine.
|Name||RT Actinum 5900 (12)|
|Description||Sizes: 40, 44, 48, 52, 56cm|
|Front Wheel||Shimano Deore hub/Alex XD Pro rim/DT Swiss spokes|
|Tyres||Schwalbe Rocket Ron 26x2.25in|
|Top Tube (in)||23.25|
|Standover Height (in)||30.5|
|Seat Tube (in)||19|
|Bottom Bracket Height (in)||12.5|
|Shifters||Shimano Deore XT|
|Rear Shock||Fox Float RL air|
|Rear Derailleur||Shimano Deore XT|
|Handlebar||Ghost alu riser, 665mm|
|Front Derailleur||Shimano Deore XT|
|Frame Material||Hydroformed alu|
|Fork||Fox 32F RL air, 100mm travel|
|Cranks||Shimano Deore XT, 22/32/44T|
|Cassette||Shimano HG62 10 speed, 11-34T|
|Brakes||Shimano Deore hydraulic discs 180/180mm|
|Rear Wheel||Shimano Deore hub/Alex XD Pro rim/DT Swiss spokes|