Stone Cold Race Tires

[Hotfoot]

Hello Dunlop Answer Man,

 

Last weekend I did a fair amount of riding on stone-cold race tires (coaching with CSS, no tire warmers, 45-50 degree windy day), and it got me wondering: why is it so hard to tip-in the bike on those cold, stiff tires, and why does it want to stand right back up afterwards? I don’t notice that on Q2s, which handle well right from the start, and then warm up quickly. I’m sure it has to do with the stiffness or profile of the race tires, but what is ACTUALLY happening, that makes the bike want to pop back upright? I noticed that in the first two turns I actually had to hold the bike in the turn – if I released the pressure on the bars the bike would stand right up and go straight.

 

After the first couple of turns, I could turn the bike in and release the bar pressure, but the bike felt like it was moving around a LOT (almost like a wobbling oscillation); at first I thought it was the tires sliding around and then I starting wondering if I was just feeling the tire flex then spring back repeatedly (contact patch getting bigger, smaller, bigger, smaller), instead of flexing and staying planted.

 

Conditions were: about 45 degrees, and windy, Las Vegas outer course track, I think the tires were the 211s, no tire warmers; also the suspension was cold and was set up for a heavier rider.

 

The tires took forever to warm up (every session) and until they did they felt very squirrelly, so I was riding cautiously – but if that weird wandering-around feeling was actually just the tire being a bit springy or bouncy (versus SLIDING AROUND) maybe I was being more cautious than really necessary.

 

What do you think is physically happening on those cold race tires?

[DUNLOP-RTS]

Hello Dunlop Answer Man,

 

Last weekend I did a fair amount of riding on stone-cold race tires (coaching with CSS, no tire warmers, 45-50 degree windy day), and it got me wondering: why is it so hard to tip-in the bike on those cold, stiff tires, and why does it want to stand right back up afterwards? I don't notice that on Q2s, which handle well right from the start, and then warm up quickly. I'm sure it has to do with the stiffness or profile of the race tires, but what is ACTUALLY happening, that makes the bike want to pop back upright? I noticed that in the first two turns I actually had to hold the bike in the turn – if I released the pressure on the bars the bike would stand right up and go straight.

 

After the first couple of turns, I could turn the bike in and release the bar pressure, but the bike felt like it was moving around a LOT (almost like a wobbling oscillation); at first I thought it was the tires sliding around and then I starting wondering if I was just feeling the tire flex then spring back repeatedly (contact patch getting bigger, smaller, bigger, smaller), instead of flexing and staying planted.

 

Conditions were: about 45 degrees, and windy, Las Vegas outer course track, I think the tires were the 211s, no tire warmers; also the suspension was cold and was set up for a heavier rider.

 

The tires took forever to warm up (every session) and until they did they felt very squirrelly, so I was riding cautiously – but if that weird wandering-around feeling was actually just the tire being a bit springy or bouncy (versus SLIDING AROUND) maybe I was being more cautious than really necessary.

 

What do you think is physically happening on those code race tires?

 

Hotfoot,

 

Lets look at this:

COLD TRACK

COLD DAY

WRONG SUSPENSION SETUP

COLD TIRES

WINDY

UNKNOWN TIRES (you "think" they were D211, but which? D211GP, D211GP-A. Which size??? )

UNKNOWN LAPS/WEAR ON TIRES

 

Any one of these would account for the feeling you noticed.

 

Pointing the finger at the race tire as the culprit, and giving the Q2 a pass, is the wrong direction.

 

Race tires are fine, even in cold conditions they are as good or better than street tires. The Q2 does not heat up any quicker.

 

The biggest issue I see in the list above is the COLD and WINDY day. Sometimes you must deal with the conditions.

 

I hope this helps.

[Hotfoot]

Sorry, I must not have phrased my question properly. Of course the conditions were poor, and I was absolutely not trying to be critical of the tires. I just want to have a better understanding of what they are actually, physically doing, so I have a better understanding of why they feel so much different than street tires. Why is the bike hard to turn, at first, when the tire is really cold?

 

I also am curious if the weird swaying motion I was feeling in the turns could have been just the springiness of the rubber - it felt like little slides but if it wasn't, maybe I could have ridden more aggressively and gotten the tires warmed up quicker. The tires were the N-Tec slicks, on the S1000RR coach bikes.

[fossilfuel]

Hotfoot,

I don't think your issue was tire...I ran at NOLA in February in the low 40's on NTEC slicks on a green track with no issues, in January at Jennings GP in the low 40's with no issues. I think it was suspension. It could be that your forks react more to the extreme in temperature because of fork oil level and or viscosity and rebound or compression settings.

 

It probably wouldn't hurt to re-evaluate your fork level and oil viscosity, Rebound and damping.

 

Check and see who is more long winded, me or Steve? LOL!

[Cobie Fair]

Hotfoot,

I don't think your issue was tire...I ran at NOLA in February in the low 40's on NTEC slicks on a green track with no issues, in January at Jennings GP in the low 40's with no issues. I think it was suspension. It could be that your forks react more to the extreme in temperature because of fork oil level and or viscosity and rebound or compression settings.

 

It probably wouldn't hurt to re-evaluate your fork level and oil viscosity, Rebound and damping.

 

Check and see who is more long winded, me or Steve? LOL!

 

I don't know Fossil, it was butt cold that day and windy. It snowed later in the day, coaches have no tire warmers and are constantly on/off the track, in most cases never actually being able to warm the tires fully. There is nothing wrong with the tires, that was not the question, just trying to have a more complete understanding of what was happening with the tire. Hotfoot's an engineer, likes to understand things (as do I!)

[DUNLOP-RTS]

Sorry, I must not have phrased my question properly. Of course the conditions were poor, and I was absolutely not trying to be critical of the tires. I just want to have a better understanding of what they are actually, physically doing, so I have a better understanding of why they feel so much different than street tires. Why is the bike hard to turn, at first, when the tire is really cold?

 

I also am curious if the weird swaying motion I was feeling in the turns could have been just the springiness of the rubber - it felt like little slides but if it wasn't, maybe I could have ridden more aggressively and gotten the tires warmed up quicker. The tires were the N-Tec slicks, on the S1000RR coach bikes.

 

 

I have a piece of data for you on this subject. Hotfoot, you really made me dig for this one (good for you because its a valid issue)

 

After talking with tech guys from the factory and the test grounds in Huntsville, we have some answers for you on this subject.

 

The Q2 has a softer JLB construcction than the N-Tec race tires. Thus giving the Q2 a smoother "feel". The N-Tec race tire has a stiffer carcus and thus the tire responds much more information to the rider, sometimes this may also translate into the tire feeling like its harsher, stiffer or sliding/skipping when cold. Its not the compound that is the issue, its the construction differences that gives the feeling your are describing. Keep in mind this is harsh and uncommon condition for most racetrack riding, thus we don't hear of this much.

 

IF you feel better with the Q2 then certainly go with that in those conditions, but if you are going to run the race N-Tec, consider trying less pressure, maybe 2-4 PSI less(20-17 psi cold), this lower pressure will likely feel softer to the rider. Feedback if you feel this was a good solution to the feeling you experienced. I would be interested in your feedback if it made a difference or not. Also is it possible to try both the Q2 and N-Tec back to back session in the same conditions?

[Hotfoot]

 

I have a piece of data for you on this subject. Hotfoot, you really made me dig for this one (good for you because its a valid issue)

 

After talking with tech guys from the factory and the test grounds in Huntsville, we have some answers for you on this subject.

 

The Q2 has a softer JLB construcction than the N-Tec race tires. Thus giving the Q2 a smoother "feel". The N-Tec race tire has a stiffer carcus and thus the tire responds much more information to the rider, sometimes this may also translate into the tire feeling like its harsher, stiffer or sliding/skipping when cold. Its not the compound that is the issue, its the construction differences that gives the feeling your are describing. Keep in mind this is harsh and uncommon condition for most racetrack riding, thus we don't hear of this much.

 

IF you feel better with the Q2 then certainly go with that in those conditions, but if you are going to run the race N-Tec, consider trying less pressure, maybe 2-4 PSI less(20-17 psi cold), this lower pressure will likely feel softer to the rider. Feedback if you feel this was a good solution to the feeling you experienced. I would be interested in your feedback if it made a difference or not. Also is it possible to try both the Q2 and N-Tec back to back session in the same conditions?

 

GREAT, thank you VERY much for taking the time to research this. I know the conditions were atypical compared to normal use of these tires, so I really appreciate you looking into it. What you describe above makes ALL KINDS of sense - presumably the N-Tec needs that stiff carcass to withstand the high driving and cornering forces of race pace, and they do indeed feel totally planted even when leaned over and hard on the gas - but I can see how that would translate to a harsh-feeling ride when really cold, especially combined with suspension that is also cold.

 

I DID actually had the opportunity to compare the Q2 and N-Tec back to back - my husband runs the N-Tecs on his bike and I prefer Q2s for track days. We did a track day at Streets of Willow yesterday and morning conditions were similar to the above posts - 43 degrees and 25mph wind.

 

So here is my observation:

First session of the day on N-Tecs with NO warmers, the tire feels resistant to turning the bike (wants to stand the bike back up) for about two-three turns. Then for the remainder of first lap it feel sort of squirrelly, as described above. Once up to pace and warmed up, though, the tires feel like they have incredible grip and especially feel very secure in the drive out of the corners, and that weird slippy feeling disappears.

 

First session out on Q2s, no warmers, they feel a little springy in the first 2-3 corners, and give me the impression that they could sidelip a bit if pushed too hard, but they steer smoothly and predictably, and I did not feel any noticable resistance to leaning the bike over. By the time I had completed half a lap I felt I felt like I could safely up the pace.

 

As far as pushing the tires as far as I dared when cold, I noticed the Q2 (if I deliberately rode too fast or leaned over too far into the corner when it was cold) would do a smooth little sideways slide that was easy to correct and did not scare me, but did let me know that the tires were still cold and I was pushing them too much. I had to do it within the first three turns to get it to happen, after that they felt very grippy and seemed like they were ready to go as fast as I wanted. On the N-Tecs, when cold, both tires FELT like they were doing constant little slides in the turns, for a good part of the first lap, which made the bike feel wobbly, which made me REALLY cautious - but they never actually WENT anywhere. All that feedback made me afraid to push them harder - but after reading your post, I wonder if I had more grip than I thought.

 

I have not yet had the chance to try lowering the pressures, I will DEFINITELY do that, that is a really workable and helpful solution and I'm really interested to see how much difference it makes. Thanks for the help - I know the N-Tecs are made for racers and race conditions, are designed to be ridden at a fast pace and generally would be used with tire warmers ... but when coaching I need to be able to ride confidently on the N-Tecs in all conditions with no warmers and I think your info will really help me with that.

[DUNLOP-RTS]

As far as pushing the tires as far as I dared when cold, I noticed the Q2 (if I deliberately rode too fast or leaned over too far into the corner when it was cold) would do a smooth little sideways slide that was easy to correct and did not scare me, but did let me know that the tires were still cold and I was pushing them too much. I had to do it within the first three turns to get it to happen, after that they felt very grippy and seemed like they were ready to go as fast as I wanted. On the N-Tecs, when cold, both tires FELT like they were doing constant little slides in the turns, for a good part of the first lap, which made the bike feel wobbly, which made me REALLY cautious - but they never actually WENT anywhere. All that feedback made me afraid to push them harder - but after reading your post, I wonder if I had more grip than I thought.

 

 

I hope this helps.

 

Often riders switching from another brand onto Dunlop will note that the tire feeds back much more information, some say its "harsh", some say "stiff". What they are relating is the differences in going from a lighter construction tire to a stiffer tire.

 

Lighter construction tires tend to isolate the rider from what is happening on the track surface. This is not bad, its just something that needs to be noted. Some riders love this feeling, and on a street bike on the street it gives a smoother rider. But for racing conditions, with faster riders, they want to feel the road better and more precisely, thus the N-Tec fits the bill and gives the rider what they need for that application.

 

If you are happy with the Q2, great, stick with it. You may find as you progress in lap times and quest for more grip, you will want to go with the N=Tec construction.

 

Here is a chart that helps understand the progression..