khp
-
Posts
956 -
Joined
-
Last visited
-
Days Won
1
Posts posted by khp
-
-
I'm wondering if anyone here has experience with this. The edges of a set of Pirelli SuperCorsa's that I had run on my Ducati 748 track day bike started to turn blue. Both the front and rear tires had this blue haze on them. I've been told to just run them up to temperature gently and the discoloration will scrub off without any detrimental effect on tire performance and I've also been turned away at tech at a track day because the bluing was indicative of some of the rubber compound's petrolium based components being overheated and boiling off. I did change them for the track day but, I would still like a staright answer about the cause and effect. I was running 30 PSi in both tires at the time and the bike's suspension was stock.
Glenn,
I've been running Pirelli Diablo Supercorsa's for the last couple of seasons. The bluing is quite normal for the Supercorsa's and all other tires I've abused hard enough on the track - and yes, it's the additives that are getting heated up and start to "leak".
As for the tech inspection to turn you away due to the bluing makes me wonder if they've got rocks in their heads - as long as you've got a decent thread depth, the tires should be good.
Since this is in no way unique to the Pirelli's, maybe Steve can weigh in here?
Kai
-
How would someone get their gauge calibrated when they do not have access to our standard? I honestly don't have an answer to that. Lets see who chimes in and give a good way to calibrate a gauge in the field. Ideas?
Excuse me while I geek out...
Creating your own calibrated gauge shouldn't be that difficult - all it takes is a bit of ingenuity and knowledge of the ideal gas law: Pressure * Volume = n * R * Temperature.
Take a tubular tank where you can connect your gauge in one end and be able to compress the air using a piston. First, vent the tank to atmospheric pressure. Then, Compress the air volume to 1/2 using the piston - and you have 2 bar (+/- the difference in atmospheric pressure, which isn't that much). Sure the compression will heat up the air a bit, but that's really marginal (Temperature is in Kelvin, so we're at ~300K to start out). There are 14.5 psi to 1 Bar. You should be able to make smaller volume compressions to have 2-3-4 points where you can calibrate your gauge to.
So 1/2 volume = 2 Bar = 29 psi, 1/3 volume = 3 Bar = 43.5 psi. 14.5/20 volume = 20 psi.
The rest is left as an exercise for the gentle reader
Kai
-
if you're meant to roll on the throttle smoothly, evenly and consistently through out the remainder of the turn, what happens when TC cuts the power??
i take it you still have enough power going to the back wheel to provide acceleration, just not as much as before it cuts
its probably a stupid question, but its the offseason, so the perfect time for stupid questions
Now why would the Traction Control (TC) cut the power to the rear wheel at all? - unless grossly mis-adjusted, the TC should only cut power in order to avoid the rear wheel from loosing (further) traction. So if the TC is cutting into the power, the rider has already fed too much power for the rear wheel to handle (at the particular lean angle). That would imply that you're not generating that roll-on that transfers about 10% of the weight back to the rear wheel, but much more.
Would that be proper throttle control? I'd say no.
Kai
-
To advise, there have been dates for Denmark added on 14th/15th July 2011. I have no details on which circuit yet I'm afraid, but please keep an eye on the schedule to find more details over the coming weeks.
Awesome - I'm already looking forward to this. Keep the details coming :-)
Kai
-
You seem to be a faster rider. I would discuss any specific issues with your local track-side tire rep, as he is better equipped with the local track info and his product's specifications to help your specific issues.
I appreciate your belief in my abilities, but I wouldn't even qualify at the tail end of a rookie race here in Denmark. I'm just an engineer and a trackday junkie at the same time (dangerous).
As for my local track-side tire rep, there is none (can't even find the name of the distributor on www.dunlop.dk!). I've certainly never seen one at the track days in Denmark/Sweden (makes sense, I'd say), and I don't recall seeing any at the Cup races last year either.
Kai
-
Kai, I'm going to chime in on one point of this, regarding riding technique.
I wasn't aware that I was asking a riding technique question
... But the soft tire question brings back an observation I had this summer with a Supercorsa SC0 rear (they don't come softer than that): I noticed that if I did not soften up the compression damping on the rear, I would be chewing up the soft tire pretty quickly. Sure enough, when reducing the compression damping, the tire started to heal up pretty quickly - although the rear would oscillate quite a bit when accelerating hard out of corners (with elevation/camber changes thrown in).
I guess the reason is that the "hardness" of the tire must be followed by a similar suspension setup (ie soft-soft or hard-hard), in order to avoid forcing the tire or suspension, to be overloaded because the other part is too "hard".
Steve - any comments here?
Kai
-
(snipped for brevity)
For a track day rider going 15 seconds off the winning pace, his feedback for grip is invalid. At those lap times one cannot determine the level of grip, thus the feedback is not as usable.
When factory riders, setting track records, can only notice about 0.5 seconds difference from one compound to the next, there is no way a rider going 5 seconds slower can tell the difference from one compound to the next.
After we look at this we also have to note that harder tires do tend to last longer, yes this is true. but in a race situation (like you see on TV) the tires only need to last that race. Choices for track day riders would be based on other factors than the procedure above.
Also softer tires sometimes will tear in colder conditions, so a harder tire in colder conditions might be a better choice for track days or even racing depending on the conditions and the compound. This may seem backwards from logical thinking, harder tires when cold, but it is workable.
The main point here is there are no hard rules for compounds. Its whichever compound works. Track day riders can usually use any compound. The faster you go, the more the compound can make a difference.
Two questions:
For the track day rider, going at the infamous 15 seconds off the winning pace, you say his feedback for grip is invalid. Do you mean that it's overall invalid, or just invalid as a reference for the gals and guys on the winning pace? - Surely the feedback or sensation that the rider gets is important to the rider her/him-self?
Secondly, since the track day rider can usually use any compound, would it not make sense for said hapless track day rider to buy rear tires in the "Endurance" compound from a longevity/cost point of view?
It's really hard to know "whichever compound works" if you haven't tried them, and last time I checked, the truck with Dunlop sponsored tires haven't stopped at my doorstep yet
Thanks, Kai
-
I can't wait, I get a day off for nothing. I think it might be the first positive contribution the royal family have made to my life to date.
Didn't you get a day off when mother was married too?
Yeah, I remember. I was actually at Jersey at the time.
Kai (showing my age here). As a penance, I'll go and ask Steve a real question.
-
If I have a criticism/observation of the Sportsmart, is that it has a different profile, and I'd describe it as a rounder profile from the more track orientated tyre like the GP Racer. This means that the tyre isn't as quick to turn and feels a little like a rolling into the turn rather than quickly flicking into the turns. This is more than likely because of it's orientation for road usage I would suggest.
Does that mean that the GP Racer are 'flimsy' and feel like they're searching for the right lean angle when turned in?
I'm asking because I'm wondering if it's like the Metzeler Sportec M1 vs the M3's. I used to run M1's on my 2003 R1 and loved it, but when I got the M3's I was surprised because especially the front tire is much more pointed, which makes them quicker to turn, but they give the sensation that they're constantly changing the lean ever so slightly. Not comforting at all, although they have plenty of grip at my speeds.
Kai
-
Have any of you guys ridden the NO B/S bike? That is a real treat, highly recommended
. No, not me, Cobie. Like ozfirebalde, I don't know if the UK school has one. Bullet, Andy?
Didn't see one when I was doing Level 3 & 4 at Silverstone in July 2009
Kai
-
is it possible to downshift more than one gear with only 1 blip?
or do you need to blip (and clutch) for each gear you downshift?
thanks
Yes, it is possible. Takes a little more practice, than a single shift, though. As an example, you go from 6th to 2nd gear at the end of the 'flight straight' at the Scandinavian Raceway Anderstorp, and going down 2 gears at the time is not unusual there.
Kai
-
For those who are running Pirelli tires, the Diablo Racer forum may be of value.
Kai (hoping that I won't attract the unforgiving wrath of Steve and Cobie for this)
-
No info personally, let me know if you do get a response.
CF
No responses so far, but I think I have located some local (ie: Danish) potential sources of Starlane Athon logfiles
- people that I've actually met and 'raced' (read: met a trackdays) with previously.Googling on Starlane GPS laptimers brought up a user name of one Dylan Code. Do you know if he have one?
Kai
-
Hopefully DUNLOP-RTS can help here.....
I've been doing my research on the new Qualifier tyres and there appear to be 2 kinds - Q2 and Qualifier II. Each seems to have a different tread pattern, see links below :-
http://www.dunlopmot...sportmaxQ2.html
http://www.dunlop-ti...ualifier_II.jsp
Can you explain what the difference is please?
Hi richinio,
I'm not Steve, but he has previously explained that there are different tyres available in different parts of the world.
But judging from the contents of the links, the tyre in the first link (Sportmax Q2) is a US tyre, while the second tyre (Qualifier II) is available in UK/Europe.
Hope this helps,
Kai
-
I think traction control can be helpful to a low/intermediate level rider, because it would make sense to me that a more inexperienced rider is more likely to make the sort of error (and have less experience with how to handle it) that traction control can help with.
Apparently, guys like Matt Mladin and Niel Hodgson don't think that TC has made racing easier for them - but then again, they're getting paid to find those tenths and hundreds that we loose every other second ;-)
Andy Ibbott told about him almost binning the S1000RR first time he was on track with it, because the ABS system wouldn't let him brake anywhere near the limits of traction on dry pavement, but in rain mode, coming up to a corner.
Kai
-
First: Link, please?
Sorry, here's the link.
Thanks. I've seen it "live" and while it looks very convincing, it seems like it's taking a lot of space up, even when disassembled for transport.
Besides the ultra-cheap manual "machines" (like this), there's this one by GP503 in Germany (sorry, webpage is only available in german), with a nylon "head" that touches the wheel.
Kai
-
Sorta Off-topic, but here goes:
I have a Starlane Stealth GPS-2 laptimer, and I'm trying to unravel the contents of the DatiRx.bin and gps.gps files (so far Starlane won't tell me) - I'm mostly there with getting Longitude, Latitude, Speed, Bearing, lap/intermediate times and several other things figured out.
If anyone else out there on the forum has a Starlane laptimer and are willing to email me a set of DatiRx.bin/gps.gps files please shoot me a PM.
I'm especially interested in getting hold of data from a Athon GPS-RW/PRO system where the tacho is hooked up, so I can get the RPM /gear datafields sorted out.
My hope is to be able to do an alternative visualization program, over the DigiraceMMX that Starlane delivers.
Thanks,
Kai
-
Another question related to tires- getting them changed. It seems a couple of options exist that I've seen:
- have the place where you buy the tires from change them. No tools or stands needed but it's probably the most expensive option
- have a trackside vendor do it for you. Less expensive.
- Put your bike on stands, take the wheels of and go and have someone do it.
- Get one of the tire changing fixture gadgets and do it all yourself. Some initial investment required, but then you (and all your friends) can change whenever you need.
I saw a demo of one of those "no-mar" tire changers by a vendor at Moto GP and it seemed like a nice way to go. Any reasons not to start doing this yourself?
First: Link, please?
The only reason I can come up with is that you either don't want to get your hands dirty with it (yes, brake dust and the chain is dirty) or you don't change tires very often.
The club I am a member of bought a second-hand professional electro/pneumatic tire-changing machine 7 years ago, and we've been using it since then (it needs repairs/replacements from the use). Using it requires minimal training (1-time demo/instruction) and once you have the knack of it, it is easy and fairly quick to do. I have recently bought a manual machine for doing it at track days.
I am waiting to buy a balancing stand for the spring season so I can change tires when I want it
Kai, itching to go to the workshop and do stuff after watching too many OnTheThrottle.TV videos lately.
-
I've see students hit a wall until we told them to "pin it" (half jokingly of course).
Gotta try it on one of these marvellous bikes one day.
What did say the parts deposit was on the bike was?
Kai
-
Another is some bikes have had a bit of a snatch, and that can normally be tuned out, if it has carbs using a kit, or if fuel injected a different map. On some bikes the cush driver didn't fit correctly, and can be helped there too.
For us less mechanically verbose... What is a "snatch?"
I presume that Cobie is talking about that some bikes have a very rough on/off-throttle action (some call it "jerky"), which makes smooth nice throttle action when going on/off the gas a near impossibility.
Many of the first-generation fuel-injection bikes were like this, and some "2nd generation" FI bikes have a CV valve to get the smooth off/on-throttle behaviour [like my 2003 R1].
Kai
-
Silverstone is a fair travel for me but I will do it!
The thing I wondered is, I could be doing with coaching on my low speed stuff, chicaines, tight turns etc so which of the 3 configuration's would be best?
mainly chicaines because the ones at Oulton are killing my lap times!
Also does anyone know if your allowed to camp at silverstone?
Bobby,
The Stowe circuit looks (from the Silverstone circuit maps) like the best option for you.
The South circuit version that I rode in 2009 was pretty open, and from the new map it looks even more open now (they've removed the section with Becketts and the chicane between Club and Farm).
Bullet and The Office can probably also provide some good info here.
Kai
-
My dad still can't stand hearing me talk about riding, I hide the race photos when he comes over.
To me, this sounds like that you have to hide or hold back a part of the real, authentic you when he's around - not the ideal recipe for a great relationship.
Although my parents aren't over-joying for me riding, they are pretty relaxed about it. As my mum pointed out, continuing to oppose that I was riding was very unlikely to make me change my mind about it.
Kai
-
There are at least two ways a tire can heat up: heating up from the deformation (internal heating) and heating from the tire spinning (if you don't believe this, go and find any video of Gary McCoy riding the RedBull Yamaha GP500's from around 2002-2003 - he would spin the rear tire so much it would literally lay down a blue smoke!).
Steve is the expert here, but my understanding is that the primary heating action is from the tire deformation - not the abrasion against the surface.
Kai
-
Kai (I'll be stepping outside while I rant over tires not being the same across the world).
Its hard to compare tires from one continent to another. Some tires are manufactured and supplied to certain regions.
where are you racing/riding? what tracks?
Hi Steve,
I'm primarily riding in Sweden, on the tracks Sturup Raceway, Ring Knutstorp, and Anderstorp (a former GP/F1 circuit). For the past two seasons, I've been going to the Eurospeedway Lausitzring during Easter for a Spring training camp. I may go to Most in the Czech Republic for the training camp (organizer has decided to go for Most this time).
Most of our tracks are pretty small and technical - Anderstorp is the antithesis to that statement (4025m, average speed of 140kph+).
Regards, Kai
... 
- people that I've actually met and 'raced' (read: met a trackdays) with previously.
Noise Levels...
in School Questions/General Discussion
Posted
Hi Steve,
Welcome aboard the forum. I had exactly the same question 2 years ago before attending on Silverstone South. I shot off an email to Silverstone's Enquiries email, and this is what they replied:
My Yoshimura full-exhaust system was significantly above the limit, even with a dB-killer inserted so I ended up putting the standard exhaust back on and I haven't looked back since then (too many noise problems these days).
Best regards,
Kai