Gemellology (the scientific study of twins)

You've no doubt noticed that the era of the twin may very well be coming to a close in World and AMA Superbike racing. Here, the Yoshimura Suzuki GSX-R1000s are handing the RC51 and Ducati twins their butts on a platter more often than not. Overseas, WSBK has turned into the Ducati Cup, with no official Honda or Aprilia entries. This may be the end of the line for sporting-twins fans, as the class has traditionally been heavily dependent on its Superbike relationship. Not having that link decreases the likelihood that a manufacturer will continue to develop or even offer a twin to the sportbiking public.

For the time being, things are rosy in twins-land. The Aprilia Mille has been updated for 2003 with a close-ratio gearbox, four-pad Brembo front calipers and a more aerodynamic tailsection. We're intimately familiar with Ducati's incredible Pierre Terblanche-penned 999 ("Style or Substance," April '03). And Honda's similarly amazing RC51, which returns unchanged for '03, handily won our twins shootout last year ("Twin Peak," Oct. '02) as well as making a strong showing in our modified BOTY showdown ("Higher Learning," Dec. '02).

Now before all you Suzuki TL1000R owners get your rotary dampers in a twist and fire up your computers to e-mail us about how great the TL is, and how it's an injustice that we are ignoring it, know this: The TL, still a current model, was the proverbial knife in the last twins shootout we included it in ("With Both Barrels Blazing," October '00), and it would fare no better against these updated models. That's srmail@primedia.com, attention Kent Kunitsugu....

On to the nitty-gritty, then, as the Italian twins attempt to better the performance turned in by last year's champ, the RC51.

Hot times, summer in the city
Here's where we'll let you in on a little tip. If you're looking for a bike to ride down to the corner store to pick up your vittles, look elsewhere. None of our trio is overly pleasant in the city, but not just because they're twins. Of the three, it's the Aprilia that gets used the most for commuting. It has the most upright riding position, a comfortable seat, decent mirrors, a nice gauge package, and the engine runs cleanly at the low rpms needed around town. Low-speed handling is light and easy, and the new-for-'03 four-pad Brembos are strong, but just a bit grabby at low speeds. All three bikes have close-ratio gearboxes (the Aprilia's is new for this year) and the Aprilia deals with its tall first easiest. One thing we didn't like about the new tranny is its reluctance to go into neutral. The clutch drags just enough at a stop, especially when the engine is cold, that you need to be rolling to find neutral.

If someone has snagged the Mille, it's the RC51 key that will disappear next. The Honda's engine runs quiet, clean and smooth around town, even with the tall first gear-though you'll only be using the next two for anything below 60 mph. The brakes are excellent, with power and feel similar to the four-pad Brembos of the Italian bikes. Handling is a bit ponderous at low speeds, with the compact riding position and low, narrow-spaced clip-ons not giving you very much leverage. The RC51's mirrors are easily the best of this bunch, with wide stalks and a clear view if you aren't lugging the engine.

The Ducati would be a fine city ride if it weren't for two major faults. In the good column of the good/bad list are the adjustable and not-backbreaking-like-the-previous-generation ergonomics, the free-revving 998cc mill that deals nicely with the ultra-tall and close gears and low-speed handling that falls between the Honda and Mille. In the bad column are the mirrors, which are so horrid you have to lift your arms up to see behind you, and engine and exhaust heat that is so annoying on the back of your thighs that you'll want to stop and hop off if you're stuck in traffic on a hot day.

But like we said, you don't really buy these bikes for trolling around the city. Nor do you really want them for...

Ridin' on the freeway of loveIs there a pattern developing here? Once again, the Aprilia is a staff favorite for taking a trip of any decent length. It has the most comfortable seat of the bunch, few vibes aside from a low-frequency tingle in the footpegs, and the ergos are nicely relaxed (though the pegs could be just a touch lower). Overall gearing is not quite so tall as the RC51 or 999, with the Mille revving at 4500 rpm at 75 mph and running smoothly in top cog at speeds as low as 50 mph. And the Mille's softish suspension does the best job of absorbing those annoying expansion joints.

It's pretty much a toss-up between the Honda and Ducati for droning. The RC51's seat is a plank, and will give you a hot spot on each cheek for your time. The Ducati's seat, if not harder, at least has some shape to spread the pain. Wind protection is superior on the Honda (with the RC51's pilot even more out of the wind than the Mille's), but the Ducati's suspension is slightly plusher than the Honda's. Both show less than 4000 rpm at 75 mph and have little vibration at that rpm. Any slower, however, and both will shudder and vibrate as the engines lug.

Let's do the twist
This is what you want these bikes for: riding in the twisties. Get there, and it makes all the city plodding and freeway hauling worthwhile. There's nothing quite like the sound and feel of twin cylinders throbbing between your...er...you get the idea.

Say all you want about the 999's looks, but one thing's for sure: This thing flat hauls butt down a curvy road, be it a tight and bumpy goat path or an ultra-fast almost-freeway. We raved about the 998's engine last year, and in the 999-with its free-breathing airbox and exhaust system-it's even better. More than enough power is present from as low as 3000 rpm, and that power is delivered smoothly and effortlessly, with almost perfect fuel injection. The only engine-related faults our testers could admit to was vibration at higher rpms, and that, even with the throttle's long throw, its light return spring means you have to be careful on bumpy surfaces not to jar it for an unexpected burst of steam.

The brakes on all three bikes work exceptionally well. The Aprilia's four-pad Brembo calipers (left) are a touch grabby. The Ducati's similar calipers (middle) make the wildest buzzing noise, and the Honda's two-pad Nissin calipers (right) are incredibly powerful. Each bike sports a Showa front fork.

The Ducati's suspension and chassis are equally impressive, with a solid and predictable feel. The 999 feels (and is) narrow between your legs, and the more upright riding position-we moved the seat to the most forward setting of three-compared to the 998 is easier to deal with. Still, steering is a bit on the heavy side, and the bike wants to fall into some corners, especially when compared to the Aprilia. We experimented with the headstock in its more aggressive of the two positions, but found that to be too much of a change, though in the right direction.

Some of the Duc's fall-in tendency is surely courtesy of the 999's 190-section rear Pilot Sport, which is pinched onto a 5.5-inch rim, rather than the recommended 180/5.5-inch or 190/6-inch combinations. It's hard to believe that a bike designed to such exacting specifications and attention to detail would have such an obvious mismatch in tire selection, but-as we found out later at the racetrack-it certainly suits the bike in this case.

The 999's Showa boingers are the best of this trio for street use, falling between the soft Aprilia and racetrack-stiff RC51. The range of adjustability is wide enough that most riders will find a satisfactory setup, which just adds to the bike's ergonomic adjustability. Put it all together as a package-a potent motor, a solid chassis with great suspension and the tiny feel to the bike-and you'll be grinning ear-to-ear blasting down your favorite canyon. In fact, the 999 builds speed so deceivingly that you'll find yourself rushing up to corners much faster than you normally would. In a way, however, that's fine, because it gives you more opportunities to use the excellent four-pad Brembos, which make the most delicious bzzzzzzzttt sound with every stop.

While the Ducati is clearly the functional favorite for intense curve duty, the Honda is not that far off-and, in fact, the machine of choice for a couple of our testers if price and actual ownership were an issue. Unchanged this year save for graphics (and even for that you'll have to look close), the SP-2 has quite a different feel than the 999. The Honda's riding position is more compact front-to-back, but its wide midsection splays your legs more, and the bike feels a bit lumbering at first. Work at it, though, and the RC51 turns out to be more nimble than the Ducati.

The Honda's brakes-two-pad Nissin calipers-are equal to the four-pad Brembos found on the Ducati and Aprilia, offering excellent power and progressiveness. Its suspension-harsh under normal city and freeway conditions-works better at speed for heavier riders (well-fed Mikolas especially likes it), but remains a bit stiff in the damping department for lighter pilots.

The Mille's dash (top) hasn't changed since the bike was introduced, and is great aside from the sun's glare in the flat panel and the red tach numbers on the black background. The tach on our 999 (middle) jumped around a lot at high revs, but is otherwise easily read, and the LCD panel displays lots of information. As always, the RC51's LCD tach (bottom) is hard to read at a glance. All three bikes have shift lights. The Aprilia and Ducati have lap timers and clocks, the Honda has neither.

Overall, it's pretty much a wash between the Honda and Ducati as far as chassis and handling are concerned. In the engine bay, however, the story is different. Whereas the 999 puts out a huge torque spread and gives its rider a choice of gears and revs, the Honda forces you to spin the V-twin mill and keep the revs within 2000 rpm of redline. The gearbox helps and hinders in this respect-the tall overall gearing makes tighter, slower turns a definite first-gear affair, but the close spacing of the higher gears makes the job much easier in faster turns. Again, if you're willing to work at it, the RC is every bit as quick as the Ducati. The difference is this: When you get to the bottom or top of the hill, you'll have worked up a sweat; your buddy on the 999 will be grinning and wondering what all the fuss is about.

The Aprilia, tops for city and freeway, is even more work when the road gets twisty. On an easy ride, the Aprilia's chassis, with it's more upright riding position and wide clip-ons, boosts confidence and flicks side-to-side easier than the RC51 or 999. Up the pace, however, and the soft suspension that is so nice everywhere else has the Mille's chassis pitching about, and it gets to be a handful.

It's the same story in the Mille's engine bay-at a moderate pace, the 60-degree engine feels peppy enough, but in the company of others, and the call for steam upped to match, the Aprilia is suddenly hurting for power, with two very noticeable flat spots. The motor is peppy enough down low-part of what makes the Aprilia so nice around town-and runs smoothly. That initial rush tapers off at approximately 6000 rpm, and aside from a bump at 8000, the engine just doesn't seem to get going, lacking the liveliness of the Ducati mill and the top-end rush of the Honda.

Takin' it to the Streets
It seems hardly fair to confine these twins to the Streets of Willow, with its 16 turns crammed into 1.9 miles, but hey, where's the fun in playing nice? Stripping each bike of its stock buns and mounting up some matching Bridgestones to even the field (see sidebar, page 56), we had some 100-degree fun-and a big surprise-at the track.

We'll spill the beans on the surprise right now: The Ducati, after showing the others its taillight a few days earlier in the canyon portion of the test, was a letdown at the track. Simply put, the Honda, with a one-second-quicker lap time, comes into its own with race tires on a track, and the Ducati becomes slightly unraveled.

The RC51's top-end powerband, a burden on the street, is less so on the racetrack, as the close-ratio gearbox lets you take full advantage of the rush packed up near redline. It doesn't hurt that the Honda's gearing is pretty much perfect for the Streets of Willow's layout, with first gear just right for the tightest turns. The solid chassis feels the most planted of the three bikes, and though the RC requires a fair effort to get turned, midcorner line adjustments are easy, and the Honda willingly goes where you want. Suspension that was stiff on the street feels like top-shelf componentry on the track, soaking up the increasingly bumpy track surface easily and keeping the bike well planted, especially in faster turns.

Helping the strong chassis are the Honda's ergos, which-even though the seat/tank interface is a bit wide compared to the others-are much better suited to the track than the street. The brakes, again, are as good as the Aprilia's and Ducati's four-pad Brembos, offering easy modulation and amazing stopping power, but not quite the progressiveness of the 999's binders.

As a package, the Honda gives the rider the most confidence in addition to getting around the track fastest, but there are a few nit-picking details that need to be pointed out. After just a few laps, the Honda's water temperature shows a staggering 245 F or more, and we shudder to think what that would mean to the engine's internals over the course of extended riding. And we'll comment again on the RC51's bar-graph tachometer, which is difficult to read at a glance.

Just as the RC51 burned off its 1:28.38 lap on just its third lap, the Ducati also turned its fastest lap-a 1:29.41-right away. The 999's excellent street handling changed considerably once the bike was fitted with a 180-series rear tire to fit its 5.5-inch rear rim, and as we worked to find a compromise, the deterioration of the tire in the hot conditions offset any improvement in handling. Still, once sorted and with a fresh bun, there was no way the Duc was going to match the Honda.

Compared to the RC51, the 999 moves around on its suspension more, and doesn't feel as planted. Arcing into turns, feedback is vague until you reach full lean and the bike seems to take a set. Midcorner traction is not on par with the Aprilia or Honda (which is most likely due to the smaller footprint of the 180 rear tire), and on turn exits the 999 tends to run wide. While these characteristics would at first glance seem to be easily fixed with geometry and suspension changes, each adjustment we made compromised some other aspect of the Ducati's handling, and we couldn't find a happy medium.

Our feeling is that the 999 really needs a six-inch rim and a matching 190-series tire. Ideally, we would have experimented with the wider tire on the narrow rim, but ran out of time once we realized what was actually happening. Would that be enough to turn a quicker lap than the Honda? Doubtful-the RC51's suspension would still give it the nod.

The wide spread of power and flawless fuel injection of the 999 give you a bit more leeway with gear selection than on the Honda, and the Ducati does have an edge coming off the corners, especially the few that catch the Honda between gears. Spin the Italian engine up close to redline, and vibration through the bars, pegs and tank can become quite uncomfortable-this is a tiring bike to ride for more than a few laps at a time, handling issues aside.

And that leaves the Aprilia, with its 1:29.87 lap time, less than a half-second behind the Ducati. The Aprilia's chassis is extremely competent on the track, not even let down much by the soft suspension. In fact, the Aprilia is probably the easiest of the three bikes to ride quickly, as the wide bars give you lots of leverage and the bike transitions from side-to-side with just a light touch. And the Mille brakes into turns much nicer than the 999 or RC51, thanks to its pneumatic slipper clutch-you can bang the necessary downshifts without fear of the rear tire skipping around.

It's the engine that lets the Aprilia down, with the powerband's flat spots quite noticeable in a racetrack setting. Exiting turns that have the Aprilia spinning below the 6000-rpm mark leave you struggling through the lower flat spot, but attempting to ride a shorter gear has the throttle too notchy for a clean transition from off to on. Even at that, the Aprilia just doesn't have the steam of the Ducati or Honda. It's all very frustrating, as the Mille is great fun otherwise, and has arguably the most potential of our trio.

Wrap it up
Reviewing the notes and ratings from our three testers reveals some interesting conclusions. The numbers and feedback show the Ducati to be the ultimate street-going twin; its engine and adjustability give it the nod there by a small margin more than the Honda. Obviously, we're willing to sacrifice the creature comforts the Aprilia offers to have the prowess of the 999 or RC51. Turning to the racetrack results, the Honda was the clear favorite-the characteristics that hold it back on the street turn into advantages on the racetrack.

The Aprilia, possibly the most user-friendly sporting twin for everyday use, can hold its own on the racetrack, and could be a capable canyon carver or track bike with some engine work. The Mille splits the price difference between the 999 and RC51, making it an interesting alternative-the performance isn't on the same level as the Honda, but you get exclusivity and save a chunk of coin compared to the Ducati. The purchase of any of the three is easily justified.

Are the Honda's advantages enough to offset the Ducati's streetbike capabilities and keep the twins crown in the Honda camp for the second year in a row? Yes, but only by a small margin, judged by the numbers. Factor in the price difference between the two, and the Honda is even more attractive-you can make a pretty nice bike with the leftovers, upping the exclusivity value substantially. Now that is what this class is about.

Bridgestone Buns
We evened up our trio of twins at the racetrack by fitting each with Bridgestones' BT-001 DOT race tires (www.motorcycle-karttires.com). Offered in three compounds, we used the softest fronts and medium rears for each bike. The Aprilia and Honda, with six-inch rear rims, had 190/55 rears fitted. The 999, with a 5.5-inch hoop, got a 180/55.

We tested the '001s in our last tire test (Feb. 2003) and were again happy with their performance. The front tires held up fine for our track day, as did the 190 rears, offering good traction and feedback as well as lasting the full day in the scorching heat. We can't say the same for the Ducati's 180 rear bun, though that is partially our fault, as the bike simply didn't take well to the smaller-than-stock tire, and we probably should have started with a harder compound. The 999's Bridgestone was torched after less than 30 laps. Luckily, we had a spare hard-compound rear on hand, and experienced no problems with it.

But That's Not All
If you require even more exclusivity from your Italian twin, look no further. Both Aprilia and Ducati offer upscale versions of their top models; here's the scoop.

Ducati 999S
Upping the yummy factor substantially on the 999S, an hlins inverted fork replaces the standard model's Showa unit, and a similar switch is made out back. The 998cc mill puts out 12 more ponies thanks to more aggressive camshafts and different exhaust plumbing. Titanium rods and a deeper oil sump help out, too. Yours for $22,995.

Ducati 999R
This is, you could say, the real 999, as its engine measures a true 999cc with 104 x 58.8mm dimensions. In addition to the suspension upgrades of the S model, the R features all-carbon-fiber bodywork, radial-mount front brakes and forged aluminum wheels. If you don't have one of these $32,000 babies now, you missed this year's offering-sorry.

Aprilia Mille R
We've tested the R-model Aprilia previously ("It's Mille 'R' Time!", Feb. '02), and this year's $17,299 version has radial-mount brakes in addition to the usual R features of hlins suspension and OZ-forged aluminum wheels.

Aprilia Mille Edwards
Along with the Mille-R chassis upgrades, the $19,400 Edwards version adds an Akrapovic exhaust, a 57mm throttle body kit and a carbon airbox.

Opinions
As a quick, off-the-cuff pick, the Ducati is the bike of this trio that I'd want in my garage. It makes the coolest sounds, goes like stink and is just a giggle to ride down my favorite roads. My idea of a sporting twin puts less emphasis on track work-I'd want a 600 or literbike for that-and more on having fun in the twisties.

However, if I was actually going to buy one of these three bikes, there is a huge cost difference that needs to be considered. For the price of the Ducati, I could have a Mille R, or the most badass RC51 in town. How about an RC51 and a used 600 for a track bike? Each is an attractive option, and the decision would also depend on what else I had in the garage.

Knowing how good our modified RC51 from BOTY was last year, what I would most likely do is get the Honda, trick it out just enough to suit me and then take that trip to Hawaii I've been putting off. Aloha!
-Andrew Trevitt

After the street portion of testing, the first thing I thought was "Wow! The Ducati's rider/bike interface is amazing." Unequaled in the sportbike world, the 999 wanted to stretch its legs, yet still gave its rider the ability to dial in his or her own personal tweaks (chassis/suspension and bar/seating position). On my ratings sheets, I gave out just one perfect score, and that was to the 999 and its engine power delivery on the street portion. At a street pace, all the twins proved more than capable, but at the track things would be proven different.

On the racetrack, performance flaws in each bike became evident, but the Honda's dominance was more than impressive-the nervous handling Duc was no match. Considering the Aprilia's 10-plus horsepower deficit and the Ducati's big-ticket cost leaves the RC51 clearly the best twin of the group. The Aprilia has a roomy and comfortable cockpit along with compliant suspension, and the 999 has a great motor and lots of adjustability, but the RC just plain smokes the others hands down. Overall qualities make the Honda best in its class.

All of these bikes make better street than track bikes, and this is why I could own any one of them, for each has its own individual strong points. Long live the twin!
-Steven Mikolas

I'm a big fan of the Ducati's engine, with its supremely responsive power on tap anywhere in the rpm range. I'm sure the desmodromic valve actuation is partially responsible for this, allowing Ducati engineers to get away with cam profiles that wouldn't work on the conventional spring-actuated valves of the other two bikes.

But while the chassis is a definite improvement over the previous generation, it still felt a little long compared to the RC51's comparatively nimble handling feel. And switching the steering-head angle to the more aggressive setting only gave the 999 a tendency to "fall in" at extreme lean angles, while not providing much improvement in steering quickness.

The Aprilia has tons of potential that is being stifled by the EPA-mandated choking of the motor. Even so, I still don't feel as comfortable with the riding position of the Mille when charging hard through corners. The seat feels much higher than the 999 or RC51, even with the ride height lowered to the minimum, giving me the impression I'm riding a supermoto bike with 10 inches of travel.

The RC51 simply feels right to me, and I can put up with the slightly harsh ergos for the outright performance. Plus, the money saved will buy me a lot of accessories.
-Kent Kunitsugu

This article originally appeared in the October, 2003 issue of Sport Rider.

Related Stories:

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• Suggested suspension settings
• Performance numbers
• Weights and measurements
• Aprilia RSV1000 Mille press information
• Ducati 999 press information
• Suzuki SV1000 press information
• Honda RC51 press information