b-group crash video and tire question

ok , i went down in the chicane at t-bolt sunday . last session ,cold tires but we just got on the track and taking it easy wtf happened i can only relate it to the above and possibly to much tire pressure . i am running q2's with about 6 trackdays on them . the front washed right out and i went right down . what tire pressure is ideal ? dunlop says 32-32 cold that seems to high , i was at 28rear 29front cold . check out video http://www.youtube.com/watch?v=IS4T1PEnpFQ
 

PatFitz9

Member
I don't know the numbers for Dunlop, but why do you think you know more than the manufacturer?

And I can't tell from the video, but I highly doubt your 3psi difference caused you to crash. Too often riders try to blame the tires, suspension, etc when usually you did something to cause the crash. It's not the answer you want to hear, but I'm guessing your inputs caused the crash. You could have some clapped out bike, messed up suspension, borderline flat tires, and that doesn't guarantee a crash. Turning the bars too hard, too much throttle, too much lean angle... These factors are a lot more likely to cause a crash.
 

noobinacan

Member
first time on left side of the tire..and just cold tire.
and cold pavement too, cause sun's going down and pavement starting to cool off.
after 6 track days, front's getting old anyways.
 
PatFitz9;222178 wrote: I don't know the numbers for Dunlop, but why do you think you know more than the manufacturer?

And I can't tell from the video, but I highly doubt your 3psi difference caused you to crash. Too often riders try to blame the tires, suspension, etc when usually you did something to cause the crash. It's not the answer you want to hear, but I'm guessing your inputs caused the crash. You could have some clapped out bike, messed up suspension, borderline flat tires, and that doesn't guarantee a crash. Turning the bars too hard, too much throttle, too much lean angle... These factors are a lot more likely to cause a crash.
a while back i was reading a thread on tire pressures and there were a lot of guys disagreeing with dunlop , i am sure it was something i did but i just don't know what . my suspension was set up by evan yarnell at solid performance ,when it happened everything (my inputs) seemed fine . i'm just searching for something ,it just seemed to go out way to easy .
 

Smithereens

Control Rider
N2
Since I was right behind you I gave you my two cents at the track......the video shows a lack of grip.....I didn't look for it on the video but were you on the brakes when it happened or was it just the result of your turn in. It was getting colder but you weren't hot going into the chicane. We all knew we had to be careful in that left and I'm just wondering if you might have done a little brake check input that asked the tire to do too much.
 
Smithereens;222207 wrote: Since I was right behind you I gave you my two cents at the track......the video shows a lack of grip.....I didn't look for it on the video but were you on the brakes when it happened or was it just the result of your turn in. It was getting colder but you weren't hot going into the chicane. We all knew we had to be careful in that left and I'm just wondering if you might have done a little brake check input that asked the tire to do too much.
nah i kinda just kept the throttle pretty steady from right turn in to the left ,it may have been what you mentioned at the track that since i wasn't going fast that maybe i just relaxed to much in the body positioning . at the time i thought i was doing the right things .. thanks for a good day riding with you and john ,its gonna be a long off season.
 

dbarufaldi

Member
eaglebike600;222208 wrote: nah i kinda just kept the throttle pretty steady from right turn in to the left ,it may have been what you mentioned at the track that since i wasn't going fast that maybe i just relaxed to much in the body positioning . at the time i thought i was doing the right things .. thanks for a good day riding with you and john ,its gonna be a long off season.
I crashed in that very spot, in very, very similar conditions. I think it was May, I was on brand new Q2's, it was cold, tires were cold, and the bike went down at very, very slow speeds (like 20-25mph) as soon as I tipped into that left. Here are my observations:

- Some tires are better in the very cold than others. I found the Q2s to be much less grippy until they come up to temp. After dumping my bike that time, I made it a point to put some heat in the tires by hard accel/braking in the paddock just before going out. Also warmed up the brakes.

- With the above caveat, I think the Q2s are awesome in the dry and once warmed up. More grip than a street tire has any business having, IMO, and tons of wear. That tire can take you to upper I without issue, and even well into A if you are willing to ride on a tire near it's limits.

- I don't think 6 days on the front is, by itself, an indicator that the tire was wasted. I got 9 out of my front and rear, and the front had plenty left in it. Your style, bike geometry, weight, etc all factor in, of course.

- For your warm up laps, try keeping the revs lower - short shift a bit more. It will help dull the effects of sloppy throttle inputs, a must for when tires are cold. Also better for the bike, if all parts of the engine are not up to operating temp(temp gauge just tells you temp at the location of the sensor).

- I can't quite tell, but it looks like you are either gripping the bars too tightly, or putting too much weight and force on the bars - hard to say from the video, but it looks that way...and with grip compromised by the cold, every factor counts. I've heard the following when talking about the correct amount of force for the grips: "Imagine the grips are two canaries - don't kill the canaries, and don't let them fly away, either". When I think of this, my grip immediately lightens up, and I ride smoother.

All that said, I don't see any big issues with how you were riding. A bit hot for a beginner out-lap in the cold, on Q2's, perhaps. OTherwise, looked pretty good.


Dan B

Oh - and your pressures were perfect, so not an issue there.
 

JRA

New Member
After dumping my bike that time, I made it a point to put some heat in the tires by hard accel/braking in the paddock just before going out. Also warmed up the brakes.
I understand why you want to do this but please don't. This won't help you at all but it could hurt you or someone else. All the tracks have wording in our contracts that prohibit any type erratic riding in the paddock, and specifically mention weaving, sudden starting and stopping, brake pad bedding, etc.

If you want to have heat in your tires prior to entering the race track get some tire warmers and use them.

Thanks.
 

stkr

New Member
Erik - Do you have fork extenders installed?

If not, then your forks are slid way too far up in the triple clamps, unless this is some new setup. You say it's because your clip-ons are mounted "below" the upper clamp, but that's the way they're supposed to be. Not mounted above. (see picture). Mine has duct tape with a reference mark, but you can still see the black upper.

If your forks are that far up, this is going to reduce your "trail" dimension, and make the bike extremely twitchy. Yes, it will turn in easier, but it will be unstable at higher speed. If you're unsure of where they should be, then please let one of the trackside suspension vendor do a baseline setup on your bike to make sure it's good-to-go.
 

madriders86

New Member
^ Yeah that's kinda what I was getting at...unless the bike had the clipons on top like that to begin with and he just relocated them below the upper triple...
 

eE jeremy

New Member
Looks like you applied a lot of bar pressure to initiate that turn, try to be smoother and slower on the inputs, use more body position to initiate a turn rather than bar input. Add in that mistake, plus cold worn out tires...
 

dbarufaldi

Member
JRA;222225 wrote: I understand why you want to do this but please don't. This won't help you at all but it could hurt you or someone else. All the tracks have wording in our contracts that prohibit any type erratic riding in the paddock, and specifically mention weaving, sudden starting and stopping, brake pad bedding, etc.

If you want to have heat in your tires prior to entering the race track get some tire warmers and use them.

Thanks.
John,

Appreciate the feedback. I did this in the far areas of the paddock, where no one is present, but if the tracks find this objectionable, I will take it under advisement. FYI - it was a NESBA control rider who suggested doing this warm-up, after the crash I mentioned.

In terms of helping, there is considerable difference in tire temp between when I first roll the bike out of my pit, and when I am done start/stopping. Have not used anything more sophisticated than the ungloved palm of my hand, but the temp variance is very noticeable, especially in the front. I was contemplating one of those inexpensive infrared temp gauges to put some real numbers behind the observation, but if the behavior in the paddock is frowned upon, I guess it's moot.

Dan B
 
stkr;222235 wrote: Erik - Do you have fork extenders installed?

If not, then your forks are slid way too far up in the triple clamps, unless this is some new setup. You say it's because your clip-ons are mounted "below" the upper clamp, but that's the way they're supposed to be. Not mounted above. (see picture). Mine has duct tape with a reference mark, but you can still see the black upper.

If your forks are that far up, this is going to reduce your "trail" dimension, and make the bike extremely twitchy. Yes, it will turn in easier, but it will be unstable at higher speed. If you're unsure of where they should be, then please let one of the trackside suspension vendor do a baseline setup on your bike to make sure it's good-to-go.
i am on an old f2 with f3 forks and they did mount on top . i also spent the money with evan at solid performance to set the suspension up last winter. he rebuilt the f3 forks for the track and had me get a penske rear race shock . suspension should be right
 

Hambone

New Member
You in good company with that crash. That turn gets a lot of people. It got me on cold tires. I also agree with the suggestion that your suspension might need a little work. I thought that it looked a little strange. I hope you weren't hurt though.

Also, I would caution you against all the tire warming stuff in the paddock. All you need to do is to try a hard stop to warm the brakes and tires and then lose the front and him somebody. Either get some warmers or just take it easy for a few turns. As you get more experience you will actually feel the bike trying to squirm around a little bit and you will know to back off a tick. But until then, just pay close attention to your tire wear, track conditions and your brain conditions (make sure you aren't getting tired). That can be a tricky little section if you do it a little wrong.
 

Matt

New Member
there's nothing wrong with the bike, setup anything.

cool day, cooling track, cold tire, first left, it got ya. don't sweat it, that kinda crap happens. I had a bad tire warmer bite me my last time out. luckily I was able to put the bike back together to go racing.

don't sweat this one during the off season. get some warmers so you can have confidence in T1 on lap 1.
 

erick1670

Member
me when I go in to that corner for the first or second lap depending on weather, I tend to not flick the bike too hard side to side... until I feel my tire has heat to go hard there
 
Matt;222401 wrote: there's nothing wrong with the bike, setup anything.

cool day, cooling track, cold tire, first left, it got ya. don't sweat it, that kinda crap happens. I had a bad tire warmer bite me my last time out. luckily I was able to put the bike back together to go racing.

don't sweat this one during the off season. get some warmers so you can have confidence in T1 on lap 1.
i think i only missed about 10 minutes of the session ,only had to straighten left bar out !
 
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