BRIDGESTONE S21 TYRES (190/55 rear)
£240-265 a pair
We first reviewed the S21's as a pair, with the rear tyre being a 190/50. See that review here. This review concentrates on the rear tyre being a 190/55.
After 6 track days the rear was at the end of its life and was starting to spin up on the exits of corners. It became fun after getting used to it, and very predictable, but spinning means the bikes not going forward.
With the front tyre still having quite a bit of life in it, I ordered a new S21 rear, but with a different profile - a 190/55.
Things to watch out for
Fitting a new tyre should be easy, the old wheel comes out, you get the tyre swapped and you put the wheel back in the bike.
With the 929, it didn't happen, it might have done with a standard bike, but on this bike, it wasn't having it...
This has different linkages, different gearing and track fairings. On getting the wheel half in the bike, the tyre was touching the belly pan and the middle of the tyre was touching the swingarm.
A new longer chain was needed to get the wheel further back in the swingarm - lengthening the wheelbase by 20mm! It doesn't sound much, but that took the wheelbase over the factory setting.
On reflection, this process has done my a favour as wet tyre's wouldn't have fitted with the old setup either! Every cloud eh...
The track test!
I couldn't have wished for a better day to test these. The track was 25 degrees all day and as I took the tyre warmer off I didn't get the normal, "I really need to bed this in before giving it the beans" feeling. It felt really sticky. For road, give them at least 40-50 miles before any hard acceleration.
At the end of the sighting lap I'd gone to both edges without any twitches and by lap two I'd forgotten it was new. It worked and gave me all the feedback needed as an inters level rider immediately.
I found myself rolling on more and more throttle through all the bends and past the point of where the 190's were sliding. I'd added an extra click on the steering damper though just incase it went loose at any point.
So, does a 5mm increase in tyre wall height really make a difference? It sounds small, but yes, it's night and day.
The extra side wall height gives a more rounded profile and gives a bigger contact patch whilst on the edge of the tyre. Overall the height difference was 18mm, which meant the ride height also increased by the same amount.
I could have dropped the preload to drop the bike, but as the wheel was now to the back in the swingarm to get everything to clear, I kept the ride high the same. My thinking being that the longer wheelbase would create a more stable bike and dropping the bike 18mm would make it too stable for me.
I like fast handling. Tipping into The Old Hairpin and Coppice it was obvious the new profile was 100% the right decision, and around the whole circuit it was. For the road though, I'd probably stick to the 190/50's.
It got me thinking, I'd gone all day without any slides, I felt like I was pushing up to my limit in and out the bends, are higher performance tyre's such as the R11's going to be a benefit at this stage?
For now, these road tyres are still better than my skill level!
