Unfortunately for us bikers, like it or not, two wheels have always been the poor relation in the motoring hierarchy. There is no getting away from the fact that cars sell by the shed load but bikes are generally more of a lifestyle choice or leisure activity than a mode of day to day transport.

But this has its advantages. Due to the fact bikes don't need the necessary practicalities to lug around 2.4 children and the kitchen sink they can be made remarkably entertaining and cheap.

For the cost of a fairly middle of the road family car you can get a bike with a top speed of 186mph that will out-accelerate a Ferrari. When it comes to performance for your pound you simply can't beat two wheels and the level of engineering in bike motors puts their four wheeled cousins to shame.

Nowadays if your 1,000cc sportsbike doesn't make in the region of 170hp at the rear wheel it is considered underpowered - and that is in a vehicle that weighs around 200kg. How many cars deliver around 850hp per tonne? And for less than £13,000! But what happens when you stick this kind of a motor in a lightweight car?

The car that thinks it's a bike
Radical's SR3 RS is one of the few cars that makes the most of a bike motor. Starting with a Suzuki Hayabusa engine, on this car Radical has bumped the 1,340cc DOHC in-line four out to 1,500cc, increasing its power from a genuine 185hp to a claimed 250hp by keeping the same 81mm bore and increasing the stroke 6.5mm to 71.5mm. Even with the standard 1,340cc Radical SR3 RS gets 210hp, the V8 version (based on two 'busa engines) nearly double that While it keeps the six-speed sequential Suzuki gearbox, Radical adds a gear drive system that feeds into a limited-slip differential with interchangeable gear ratios, pneumatic paddle shifts and a reverse gear. Well, you try paddling a car out of a gravel trap!

The chassis of the SR3 is a steel spaceframe (the Hayabusa has an aluminium beam frame) while suspension is fully-adjustable Nik units (the Suzuki has fully adjustable Showa) and the bodywork a combination of fibre glass and carbon fibre. Tipping the scales at 570kg the Radical isn't exactly a heavyweight, however it is still just over twice the weight of the Hayabusa, which Suzuki claims is 260kg. What does this do to its performance?

Acceleration
With two huge 10.5x16-inch drive wheels and Dunlop slick tyres, the Radical gets the jump on the Hayabusa when the flag drops. It may have a chunky 190/50-section rear, but that doesn't stop the front lifting when you dump the clutch so a degree of caution is needed on the bike - something that I spot Radical driver Ian Flux doesn't require as he smokes his tyres for the first few meters.

Once underway the 'busa's 1,480mm wheelbase and less than sharp geometry make it a lot less frisky than a sports bike, meaning you aren't fighting to keep it in a straight line. However, until you hook second there is always the chance of the front rising so you have to be cautious. Once high in the revs in second gear you can just hold the throttle wide and feed it gears.

With the Radical getting to 60mph in 2.7 seconds (our data on the day) compared to the Suzuki's 2.89 seconds the initial part of the run is very close. However, once the 'busa gets into its stride it hits 100mph in 5.32 and 180mph in 20.49 seconds, leaving the Radical trailing behind. In the car world 0-100mph in 7.4 seconds is impressive, but in that time the 'busa is going through 125mph and starting to stretch its legs. Topping out at 126mph due to track gearing the rest of Bruntingthorpe's straight is a case of trying not to over-rev the Radical for Ian, while on the Hayabusa I hit its 183mph top (restricted!) speed in 30.52 seconds, just 1,984 metres from the start line...

Under brakes
Both vehicles run four-piston calipers, with the Radical's gripping 260mm discs and the Hayabusa 320mm. But there is one huge difference. Brake hard on the 'busa and the soft forks bottom out and front tyre squeals. Slam on the anchors in the Radical and you've got four calipers driving the slick tyres into the tarmac. On the Hayabusa all your braking goes through the front 120/70 section tyre which is easily overwhelmed while the car has two 8-inch width tyres at the front and two 10.5-inch width rears to bring it to a halt. It is also a lot harder to flip a car over the headstock! The results are a complete car whitewash. A Hayabusa will stop from 100mph in 5.34 seconds in 130 metres with a maximum deceleration of 0.9G. The Radical stops in 3.4 seconds in about 80 metres, pulling 1G and as much as 2G if the grip levels are up to it. So when it comes to stopping quickly four wheels are certainly better than two.

On a lap
"I was impressed how fast the Hayabusa accelerated." To be fair Radical's tame racer Ian Flux was being more than a little generous - that's about the only thing the Hayabusa has over the Radical on a lap of Bruntingthorpe's handling circuit. Despite containing a monster engine, the Suzuki is basically a fast tourer and as such comes with soft suspension. Yes you can up the pace on it, but get it working and it isn't long until the brakes become a bit spongy and the suspension makes the 'busa wobble through the bends like a fat kid on a trampoline.

On the road the 'busa is excellent, on a track and when there is a Radical with a mad racer piloting it right up your chuff it's a bit out of its depth. I asked Ian if he could stick behind for a few photos - despite easily losing him down the straights - at every corner he was right behind me. Photos done I found out why when I sat in the Radical's passenger seat for a 'quick lap.' At every corner I thought Ian had forgotten to brake and we were about to steam onto the grass then, at the point I was starting to wonder just how strong the SR3's honeycomb front crash structures are, he would stamp on the brake and hurl the car through the corner at a completely incomprehensible speed.

To be honest my car history isn't great (a Citroen 2CV and a Triumph Spitfire) but I've ridden a lot of very fast bikes and while I expected the Radical to corner well, it was another league to what I imagined. As a biker my brain couldn't compute the levels of grip generated by the Radical's downforce. When I tip a bike on its side I'm more than aware I'm cornering with a tyre contact patch the size of a squashed CD, with the Radical it felt like Ian was driving in glue! He may well have been, to be honest my eyes were either shut or stuck to the inside of my visor for most of the lap...

See it for yourself
Blurring the boundaries between bike pace and car grip, the link between the two will be reinforced with demo laps in this car by multiple British Superbike champion John Reynolds at rounds of the British Superbike Championship. So if you fancy seeing John putting the Radical through its paces he'll be at Brands Hatch this weekend and putting in a few laps in at lunchtime on Monday around the pit walk and VIP safety car rides. As previously reported John will also be racing the car in the Radical UK Cup - see Radical's website for dates. Why not turn up and cheer the old boy along!

---

SUZUKI GSX1300R HAYABUSA
Engine: 1,340cc, 4-cyl
Power: 185hp@9,000rpm (tested)
Torque: 111ft lb@7,000rpm (tested)
Top speed: 183mph
Weight: 260kg
MPG: 40 (est)
Price: £10,935

RADICAL SR3 RS
Engine: 1,500cc, liquid-cooled, inline four, DOHC, fuel injection
Power: 250hp@10,500rpm (claimed)
Torque: 160ft lb@10,500rpm (claimed)
Top speed: 155mph (varies according to gearing)
Weight: 570kg
MPG: 20 (approx.)
Price: From £55,000

---

---

Lap video
 

Standing start video