The discussion regarding confidence in tyres in the Cascades thread really got me thinking about how we use our tyres on the street and the differing experiences we seem to get from them. To set some perspective of my motorcycling use:
And so on to tyres… Some thoughts and comments:
- I ride a 2006 GSX-R750. Currently has about 30,000km on the clock. My bike is well maintained and VERY well looked after and cared for.
- I currently have Pirelli Diablo Rosso Corsas on the bike. Not Super Corsas. Not Diablo Corsas (I or II or whatever they have now). Before that I had Michelin Pilot Power 2CT’s on it.
- Probably around 85% or more of my riding is two up. My wife started riding pillion when we were dating: around 40 years ago. During this time I have always had at least somewhat sporty bikes (and one has to recognise how that definition has changed over the decades!). When we started dating I had a Suzuki T350-II 2- stroke, then a Suzuki GT550 triple, then a Honda CB900F, then a Honda 1100F. We used to do somewhat decent distances even in those years: longest trip was a 1500km trip in two days from Johannesburg to Cape Town in South Africa.
- In modern times I have only had two real sport bikes: 2004 GSX-R750 and our current bike. Granted that technology changes quickly: by a lot of current standards our 2006 Gixxer is antiquated.
- We do somewhat respectable touring two up on our bike. Longest trip was a ride to Ashland in Oregon (to the Shakespeare festival) with a brief dip into California: did around 3,500km in 9 days.
- We try to do at least one decent local ride per year. In recent times we have also done foreign trips on rented bikes: Italy on a Ducati Multistrada in 2013 and South Africa on a BMW F700GS in 2015 (could not find a decent sportbike to rent).
- Blasting at light speed in a straight line does not hold much attraction for me: I live for twisty roads. I am a smooth rider: riding two up teaches you that. I really like smooth braking into corners with smooth downshifts that should be all but undetectable for the passenger. I love flowing through corners. I love smooth but not manic acceleration out of corners. THIS IS LIKELY A STRONG INFLUENCE/CLUE TO MY PERCEPTION OF TYRES.
- We are not group riding people. Yes, we have done some over the years. But we much prefer doing our own thing at our own pace. Most recent ride was with Shovelhead and someone whose name I cannot recall down to Mount Baker last year.
- The “40 years” comment in item 3 is a clue: we are no teenagers. Having ridden together for 40 years has very definite benefits: I almost do not feel my wife on the back of the bike. Of course you cannot be as quick two up as alone. While we have never gone on a group ride where people have gone stupid fast, I have always felt that I could comfortably keep pace with the group: had we been on our own we would likely have gone more quickly through the twisty bits. The only time that I have ever really felt that I could not keep up was behind two locals close to Mt. St. Helens on our Oregon trip. They graciously offered to show us the road to where we wanted to be but they made it clear they were out riding to blast down this section of road. They knew the road like the back of their hands, we had never seen it before. They were solo on their bikes; we were two up. I knew we had no way of keeping pace with them so we rode at a pace we were comfortable with. Even so we did not fall behind too badly….
- I distinctly recall not liking the feel of the Michelins. I had no qualms about the absolute levels of grip. Turn-in seemed to be extremely sharp: almost felt like I used to “fall into” corners. However: likely because of this, these tyres always felt “twitchy” to me. Almost as if the tyres were uncommonly “triangular” and you were falling off the apex of the triangle as you entered corners. It also tended to feel as if the bike wanted to weave from side to side as you came to a stop and the speed dropped below say 20km/h.
- Contrary to this twitchiness, the Pirellis have always felt rock solid to me from day one. They track truely, they feel very stable indeed and I have not experienced anything that gives me concern re grip. They are not as quick on the turn in. I suppose they may be slower in a tight, quick left-right-left kind of “flick”, but this is not something I encounter so this is hypothetical. Personally I prefer the feel of the Pirellis to the Michelins.
- How do I use tyres? Well, it all depends.
- The following are pictures of my Michelins after a Mission track day. Nothing unusual there I do not think.
- The following is a picture of the rear Michelin after the quick ride as described in item 9. This was after quite an extended period of quick riding in relatively high temperatures. I do not think I want to do much more to my tyres on an unknown public road two up
- The following is what my rear Pirelli looks like right now. Noted hat for one reason or another we have been doing more highway riding and not a great deal of twisties with these tyres.
And no: that is NOT rust on my chain: my bike's chain came with the links a goldenish colour!
What I found interesting is that you can sort of identify a number of “zones” in this picture:
- There is the flat piece in the middle: too much highway riding! #1
- Then there is an area around the shoulder that shows quite consistent use. This I would classify as the area we use normally/frequently/regularly. #2
- Next is an area with a bit of use but not a lot: #3
- Then there is an area with very little use: on these tyres I have clearly not gone there very often for whatever reason. I know that last time and place I did that: the 270° turn when coming from the Tsawassen ferry road onto Hwy 99 north toward the Massey tunnel this past Saturday. This was when we were coming home from a ride on the island. #4
- Lastly there is the unused area. #5
The effect that riding two up has is difficult to quantify. I have not analysed the physics involved but I do not believe it affects the required lean angle for going around a certain radius corner at a certain speed. My gut says that all that happens is that both the vertical and horisontal accelleration components stay exactly the same but the forces in both planes increase proportional to the weight. Note that on my bike the C of G of the passenger is pretty much directly above the rear axle, so one can quite safely assume that pretty much all the added weight is on the rear tyre.
- As mentioned before I believe the smoothness that two up riding has instilled in me over the years certainly plays a part in how I perceive the perfromance of tyres. It is quite possible that if I were to ride “harder” I might have felt very differently about tyres.
If the above assumption is correct then I find it doubly strange that I have not experienced the “small slides” others have referred to with Pirellis. Maybe my butt has grown totally insensitive over the years and I just do not feel slippage? Unlikely I think… Maybe the bigger contact patch due to the added weight reduces the potential for sliding? But then again: riding two up I run much higher tyre pressures that I have seen mentioned in the Cascades thread: I run the rear tyre at the recommended 42psi for two up riding compared to the 34 – 36 others mentioned in the Cascades thread.
As an aside: I also do not move around the bike much and when two up I really do not move at all: for the same speed around the same corner this would obviously increase my lean anle compared to someone who does move around.
Bottom line: I believe I use tyres reasonably hard, particularly given the fact that we ride two up. In spite of this and contrary to competent comments to the contrary, I find Pirelli Diablo Rosso Corsas extremly grippy.
Different bikes that just handle differently? Riding style? I am just way slower than I think I am (aren’t we all?). But then again: leaning the bike to the edge of the tyre (especially with extra weight) surely should expose inadequacies regardless of anything else?
I am so confused…