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| | | Road test : 2007/08 Aprilia RXV4.5/5.5 launch-The lion has been tamed (only a little…) |  Written: 05/12/2006 : 11:17. Read 12494 times (7/day). | When Paul Walker from Aprilia called me to see if I was interested in a rendezvous with the brutal V-twin RXV’s I had to say yes. I rode the bikes at the world launch in Sicily earlier in 2006. Already at the end of 2006 the 2007/08 models are ready with improvements. I rode the new models around a castle in the English countryside.
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It was bitterly cold and windy one early morning in November. When I arrived at Eastnor Castle in the West Midlands, England I was already cold from the ride down. I was at the castle to ride the new and improved RXV 450 and 550. The V-twin enduro bikes have been through one season of racing and development since the launch in Italy in January 2006. The main changes are: softer power curve achieved through a new ECU, a new seat with more rounded edges that also gives a slightly lower seat height, new road legal exhaust offered as factory accessory, new front design and new decals.
Aprilia had designed two-three routes for us to sample the new RXV’s on. Eastnor Castle is used as a Land Rover proving ground and 4x4 instruction centre. Today the castle had surrendered to the roaring V-twins from the Noale factory. The journalists were the modern day knights and what a weapon the new RXV is! Not a single obstacle was big enough to topple the RXV’s enduro abilities. The terrain varied from super slippery grass and mud, technically challenging steep ups and downs on trails carved by the spring floods, tight and slippery trails in the woods to high speed gravel sections. -Basically the perfect challenge for any Enduro bike.
I started out on the 450 with the new Akropovic exhaust. It doesn’t look as pretty as the original RXV exhaust, but it makes a big difference when using the throttle. It is road legal and makes less noise than a single at full speed. Off I went on the high speed gravel section first. The power band on the small 450cc V-twin puzzles me a bit still. It is still very much racing and there is a big dip in the curve before all hell comes loose. But with the Akropovic single muffler the throttle response is massively improved. Aprilias enduro race teams asked for this and it has made their job much easier. On full power I almost revved out in fourth gear up the hill and the RXV accelerates hard all the way. Riding as fast as we could go up the hill was exhausting as the revvy little twin demands to stay on high revs to perform at its best on the high speed sections. So you are all the time struggling to push your own weight forwards with the help of your knees clutching the small 7 litre fuel tank whilst standing up. And the RXV pulls like an ox all the way. In that sense the RXV is still a very physically demanding bike to ride. Towards the top of the hill the rear lost grip a few times and tried to whoop our arses several times doing max speed in fourth gear. But it all settles before we have to get ready for the more technical and slippery parts of the route. Suspension set-up is difficult on an enduro bike as we needed to tackle everything from high speed hard surface to the softest grass and wettest mud. I guess we would have needed faster compression on the high speed stuff, whilst that would not have worked on the slow technical stuff. So though fairly soft, the suspension set-up for the day was pretty much what we needed to get through. I really respect those Michelin Comp3’s by the way. They had to tackle everything on this day and did so with relative ease.
Down the slippery muddy section I used 25-30% of the throttle before braking for a tight right hander that led us into a big puddle of water. A couple of the guys decided to take a swim with the RXV at this spot. -Must have been very cold and uncomfortable. After this we headed down some very slippery grass with loads of roots here and there between the trees. At these places all I could do was to nurture the throttle and use the rear brake. Really difficult to go fast at this section so I didn’t risk anything and just got the bike through. The really entertaining parts of the route were a couple of deep dips in the terrain. They can be tackled in several different ways on the RXV. You can sit down and use very little throttle and just climb easily over. You can sit down and accelerate towards the top of the dip and jump over it or you can stand up and go slightly faster so that the front wheel lifts a bit on the top. But if you panic and use the throttle wrongly you will do a nice loop before reaching the top and end up on your arse. A little bit of speed before entering and then just let the momentum, tyres and suspension do the rest was my approach most of the time. After a couple of tight corners we had basically done one round of the first route. It was great fun and nothing too challenging for the RXV.
I did one run on the 550 as well and it’s just more of everything and you hit the torque earlier. No doubt it’s faster up the hill when you can stay on the throttle, but nowhere else. I could easily follow a 550 with the 450 where the technical bits started. When I test enduro bikes like this I am on it straight away. Because I know that fatigue will set in eventually as I’m not an athlete like Chris Iddon for instance. Chris was riding with us the whole day and it was fun following him around later in the day.
The second part of the day we rode more technical, longer and faster trails. These trails were mostly down to the rider to handle, but I do wish that the standard RXV was easier to control on the throttle. The new power band helps a lot, but without the Akropovic silencer it’s too easy to stall the engine without the help of the clutch when you need subtle throttle openings. There is just still something very raw about this engine. I like them a lot and the more I ride one the more I want one. But for competitions I am not 100% convinced yet. I tried to go faster on my second run and boy was I at the mercy of nature a couple of times up that steep and fairly difficult hill. I settled it all down and started again. As soon as I tried to go really fast the same again. It might have been my brain at this point of the day that couldn’t process much more that day, and the fog only got thicker and thicker after the heavy rain we had earlier. So I called it a day and went and had a warm cup of tea.
Aprilia really have something special in the RXV and SXV. It has only been out for a year and a year is not enough for the enduro to win championships. The SXV supermotard on the other hand is just pure brilliance. The engines are very powerful and this is where Aprilia have made some changes on the RXV’s to the better this time. Softer spread of power makes the new RXV easier to ride. But easier does not mean easy. 
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The RXV is just too cool!
Chassis and brakes
Easier to control with new seat and new ECU
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Easier does not mean easy
Pure racing
Can stall on the really subtle stuff, but on the positive it has got a better electric starter than last year.
Words: Tor Sagen/Photography : Tor Sagen & Milagro
Aprilia RXV Technical Specifications (specifications for the 550 engine appear in brackets)
Engine : 77° V twin four stroke. Liquid cooled. Single overhead cam with rocker operated exhaust valves, chain timing drive, 4 valve heads, titanium valves.
Fuel : Lead-free petrol.
Bore x stroke : 76 x 49.5 mm (80 x 55 mm)
Total displacement : 449 cc (549 cc).
Compression ratio : 12.5:1 (12:1).
Fuel system : Integrated engine management system controlling ignition and fuel injection.
Throttle body: 38 mm. (40 mm)
Ignition : Electronic.
Starting : Electric starting.
Alternator : 340 W.
Lubrication : Dry sump with external oil tank. Separate gearbox lubrication.
Gearbox : 5 speed. Enduro gear ratios:
1st 12/31
2nd 13/25
3rd 15/23
4th 19/24
5th 21/22
Clutch : Multi-plate in oil bath, cable operated.
Primary drive : Spur gears. Transmission ratio: 22/56.
Final drive : Chain. Transmission ratio: 15/48.
Frame :
Steel perimeter frame with alloy vertical members.
Front suspension : Ø 45 mm upside down fork, double adjustment.
Rear suspension : Box section aluminium swingarm with cast body.
Hydraulic monoshock with compression and rebound adjustment.
Brakes
Front: Ø 270 mm stainless steel disc with floating caliper.
Rear: Ø 240 mm stainless steel disc with floating caliper.
Wheels : Light alloy.
Front: 1.60 x 21”
Rear: 2.15 x 18”
Tyres :
Front: 90/90 x 21”
Rear: 140/80 x 18”
Dimensions :
Overall length: 2,222 mm
Overall width: 800 mm
Ground clearance: 396 mm
Seat height: 996 mm
Wheelbase: 1,495 mm
Fuel tank : Capacity 7.8 litres (12 litres on Rally version)
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