Bridgestone badges its new Battlax S20 as a 'premium sports tyre' aimed at sports riders who ride on all types of roads, through all conditions. There are plenty of tyres capable of that but the S20's remit's made wider by the fact Bridgestone rate the S20 as a great choice for those who partake in the occasional trackday.
As occasional trackday locations go, Portimao is out of the top drawer. The undulating circuit is technical yet flowing. It's a firm favourite on the World Superbike calendar and features every type of corner except a chicane. Hurrah. It's truly a great place to put a sports tyre through its paces.
Bridgestone's road tyre line-up is straight forward compared to some. The stickiest, sportiest tyre is the R10, an only-just-road-legal tyre designed with the track in mind. Then comes the BT-003 RS, the RS standards for Racing Street. Still sticky and aimed at track and fast-road riding.
Then comes the new S20, it replaces the BT-016 Pro, which itself replaced the BT-016. The S20 sits below the BT-003 RS in terms of outright performance but it's the first time the phrase 'wet conditons' is used in the firm's sports tyre line-up. One rung below the S20 sits the BT-023, Bridgestone's popular Sports Touring tyre.
Bridgestone got a bit of a pasting for the BT-016, it was the tyre the 2011 ZX-10R came on, a bike I've run for a year and I replaced them at the first opportunity. After riding the bike at Losail, Qatar on its world launch on Bridgestone's BT-003 RS tyres, the BT-016 didn't feel like a good match to the ZX-10R when I took the bike to Bedford Autodrome. A good road tyre, they felt out of their depth on track. Bridgestone revised the BT-016 with the BT-016 Pro, a better tyre but perhaps still hamstrung by the original 016's mild reception.
Compared to the BT-016 Pro the new S20 features a slightly revised profile which increases the tyre's contact patch at all angles of lean. More rubber on the ground equals more grip. The tread pattern has changed, running right to the edge of the tyre, helping the S20 disperse water but also taking rigidity out of the tyre, adding feel in the dry. The S20's rubber compound has changed too; designed to warm-up faster but also offer longer mileage. Don't ask me how that's done: we weren't there to test mileage but we'll fit a srt and test their durability out on UK roads.
So in short it's designed to be sportier than the BT-016 without sacrificing mileage capability. So what's it like on track?
We had 5 sessions: for the first two I went out on the 2011 ZX-10R. I've put 4,000 miles on the 10R this year and went on the bike's launch so I know it well. We started on cold tyres, running 30psi. With just two sighting laps of Portimao before we got going, I had an exploratory third lap, getting to know the circuit, building trust in the S20 front tyre and building speed.
With all day to ride on the tyres, lap records weren't going to be tumbling in the first session, but the tyre definitely warmed up fast. Sure, Portimao was warm, the track is grippy, but even larking around and playing with the traction control on the opening couple of laps it took some ham-fistedness (of which I'm quite capable) to get the rear tyre moving.
After the first session I remembered my experience at the Ron Haslam school, riding a CBR600R on BT-023 tyres. The BT-023 are billed at a Sports-Touring tyre, but I didn't know this and gave them as much of a hammering as I could. They mostly stuck firm.
So with that in mind, in the final half of the second session, at home with the bike, getting to grips with the track I felt confident to really push the tyres. Winding everything up; I carried more front brake into corners, leaned on the front mid-corner when running in deep and scraped the - already raised - pegs plenty of times while looking to squeeze out a bit more lean.
An all-rounder sports tyre is by its very nature a compromise, but some of the features compromised are things like turn-in and mid-corner feel. There's little worse than tipping in and realising you're going to struggle to make the apex, but the profile of the S20 is sharp enough to help keep the turn-in nice and tight, without being too sharp they're unstable in a straight line.
They're super stable on the brakes. Coming down from 179-indicated-mph at the end of the start finish straight, you're braking hard just before the track heads downhill, it's a good test of your confidence in the tyre underneath you. While I didn't feel like you could take the piss like you can with an out-and-out road-legal racing tyre, you can still anchor on well into the danger zone and scrub off speed without the front tyre protesting or worse, letting go.
Even though gods like Jeremy McWilliams turn traction control off, I'm so used to it on the 10R I kept it on. It helps show me how much the tyre can take before braking away and when it does the S20 is smooth and predictable, it doesn't snap out of line with the impending doom associated with a supersticky tyre, but neither does it spin up at the slightest hint of drive. In the last session of the day I rode McWilliams' S1000RR with his setup, including the traction turned off. After a couple of cautious lap - my first on the S1000RR with the traction off - I could really get stuck in and when driving out of corners even though the traction light was flickering, showing the rear wheel was spinning, the bike felt composed and not about to swap ends under power.
For the third session I took a Daytona 675R out, the dripping-with-Ohlins version of the already brilliant 675R. The bike itself was better suited to the technical turns of Portimao, but it was in this session I really clicked with the S20 tyres.
Having tried to shred the rear under power with the safety of traction control on the 10R, it was really clear the S20s aren't about to budge in a hurry, so I had one of my best sessions on any bike on the 675R. Chasing laptimes, I actually forgot about the tyres and what they may or may not be able of and just got stuck in. The 675R was scraping its pegs through most of the infield while its Brembo monobloc calipers were luring me into braking deeper and deeper towards the first turn, which the front S20 was more than a match for. For the whole session it was just me and the bike and that, I suppose, is the sign of a good tyre.
Without doubt better than the BT-016 on track, mainly in terms of confidence to run into a corner carrying speed. If they're half as good on the road and if they deliver on the mileage Bridgestone claim, then they'll be a hit. Afterall, they match the type of riding the majority of us do.
Unfortunately not even I'm lucky enough to spend my life lapping Portimao but for a day on the S20s, I didn't want for more.
Watch an onboard video lap with Jeremy McWilliams on an S1000RR running Bridgestone S20 tyres.