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Dr_greg
| | Posted on Friday, September 02, 2005 - 04:05 pm: | 
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As the starter of this topic, I'd like to thank everyone for the discussion; it's been most informative.
1. I will probably tweak my suspension settings a bit.
2. My tires ARE worn; might try a different brand of tire (although I've generally liked the M-1 Sportecs).
3. Like M1, I don't think the ZTL is to blame, although I haven't tried to track the force path through the front end (I'm a mechanical engineer, and have some familiarity with statics/dynamics).
4. It is possible to "compensate" for the effect by altering your riding style, but it is difficult to do this SMOOTHLY as you apply and release the front brake, and we all know that when you're hauling a-- you want to be as smooth as possible.
I'm grateful nobody criticized me for bringing up this characteristic. I love my little XB9R and I just want to make it better!
One thing I will say: you can "brake first---then turn", "slow in---fast out", etc., etc. until you're blue in the face...but then maybe just once due to rider error you find yourself entering a corner too fast and you apply the front brake...it sure is nice to have a "fault-tolerant" bike that still holds its line.
Anyway, 'nuff said. Thanks, guys, for all your suggestions. Ride safely. |
M1combat
| | Posted on Friday, September 02, 2005 - 04:34 pm: |
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Greg - If you'd like a tire that behaves like a new sportec for a longer period of time maybe try the Metzeler Z6? I have never tested the very edge of a Z6 so I don't know if they offer enough grip when you're leaned over a long way, but they would take longer to wear far enough to cause problems I think...
Just FYI - I think this topic is far from over  ...
I would very much appreciate someone making a free body diagram of the forces in the front end of the XB at a 40 degree lean with the front brakes applied, and maybe one with both brakes applied.
I suspect that the issue is the short trail/small caster angle combined with the difference between front and rear profile of the tires when you apply the front brakes. I really see no reason to use the front brakes only when entering a turn or the early part of the mid-corner section. When you do that, you get a pretty drastic change in wheel base at the least, let alone loading up the front tire and un-loading the rear.
A question for you Greg... I've worn down four or five Metzeler Sportec fronts (and a slew of rears) and the front typically ends up being fairly triangle shaped, whereas the rear does not. If you were leaned over on a tire that had been worn in at a certain lean angle, then applied the front brake, causing the bike to pitch forwards, don't you think that the extra pressure on the outer portion of the "side of the triangle" would cause the steering head to be turned into the turn a bit? This would cause standing and running wide.
I say get new tires.
How many miles do you have on your front right now? I usually replace my Sportecs every 3000-3500 miles, less if I feel like it. |
Justice
| | Posted on Friday, September 02, 2005 - 04:48 pm: |
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Changed to Michelin Pilot Powers on my XB9R. I also changed to the Shawn Higbee suspension settings. The tendency to stand up has not surfaced since (3000 mi).
I'm running 36psi front, 38 rear. |
Midknyte
| | Posted on Friday, September 02, 2005 - 04:49 pm: |
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4. It is possible to "compensate" for the effect by altering your riding style, but it is difficult to do this SMOOTHLY as you apply and release the front brake, and we all know that when you're hauling a-- you want to be as smooth as possible.
Just as you want [need] to brake or scrub off speed before entering the turn, you also want to shift your weight (or hang off) as you approach the turn as well.
You should be doing everything to set up for the turn well before you begin it so that the suspension is settled before you enter the turn.
If you find that you are unable to do this, you should consider yourself riding too fast for conditions and/or not looking far enough ahead.
The 9/12R is a bike that rewards proper form, almost to the point that it requires it...
* Do feel free to correct the above. Is based as well as possible on experience and [my] readings. |
M1combat
| | Posted on Friday, September 02, 2005 - 05:10 pm: |
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I think what you said sounds true to me at least... With the D207's, the XB enters into the realm of requiring proper form as you said. |
Diablomichael
| | Posted on Friday, September 02, 2005 - 05:43 pm: |
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same post different thread
I posted the same question back when I first joined this board. Riding around the issues is not the answer. I was given tips on riding from the board. Keep in mind I have road raced for going on 10 years.
The truth is this
Everybody likes it a little different . Michelin tires will help among others . Dunlop's seem to be part of the trouble for many . I would recommend starting with the suspension suggestion posted on Sprtrider.com. Very little adjustments will make big changes. I soon will re-adjust my suspension as I find the stock suspension way to soft. I will switch to the buell spring kit as soon as the race bike 1450 motor is done. The main thing to remember is you don't have to change much to get big results. If you feel like you have to adjust your riding style or are giving up anything in the corners the bike is set up wrong.
Michael Snell
Street Bike 2003 9R
Race Bike 2004 12R |
Surveyor
| | Posted on Friday, September 02, 2005 - 05:53 pm: |
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If you re read the posts on this topic and eliminate the gimme's
a) make sure your tyres are properly inflated
b) make sure your tyres are not worn out
c) make sure your tyres are suitable for your type of riding
d) radial brake conversions are too expensive for most applications
Then you are left with two options;
x) Adjust your riding style to suit the characteristics of the bike
y) Raise your rear or lower your front ride height (you may need to fit a steering damper)
Hope that summarises the opinions expressed without over simplifying the problem/solution. |
Dr_greg
| | Posted on Friday, September 02, 2005 - 06:07 pm: |
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Just checked my service log, and I've got 5,500 miles on the M-1 Sportecs.
Time for a change!
On the Mille once at the end of a 500-mile day I was checking the tire and I saw the cord showing...oops!
Gotta quit being such a tightwad! |
M1combat
| | Posted on Friday, September 02, 2005 - 07:47 pm: |
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So really it was your tight-assedness that nearly killed you...
 |
Henrik
| | Posted on Friday, September 02, 2005 - 11:33 pm: |
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Re. suspension settings: I saw a graph once depicting traction vs. suspension feel. Basically optimal traction is at suspension settings just a fraction softer than optimal feel.
I looked through a few sites looking for the graph - no luck. All my books are boxed up, but I'll post the graph when I find it.
Henrik |
Xbolt12
| | Posted on Sunday, September 04, 2005 - 12:43 am: |
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Set the suspension correctly-owners manual explains, and by all means chuck the 207's they ARE the culprit.
M1's will raise the back about 7mm and quicken the steering to an amazing degree. However, I have found the Diablo Corsa's have no tendency to cause stand-up, are extremely stable, easy turn-in, wear as well as the others, grip extremely well, and allow trail braking without any side-effects.
Other tires may also work as well, these are just the tires I have direct experience with on the xb12r... |
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