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Old March 18th, 2018, 08:15 PM   #1
corksil
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Raising the front forks in the clamps?

Seeing as I switched to clip-ons, I suddenly had the option to raise the front forks in the triple clamps. I decided to do it, and found threads about how 24mm is the optimal height.

After riding for 100 miles or so, I have mixed feelings. On one hand, the bike feels a little easier to ride at slow speed and turn the bars lock-to-lock at parking lot speed.

On the other hand, I really feel all of my weight located further forward on my wrists. It's a little uncomfortable.

What's the deal with this adjustment? Raising the forks would increase the rake and make the forks closer to vertical.

Why do people do this and what's the real benefit?

Probably a stupid question but I'd like to learn.

Thanks guys!
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Old March 19th, 2018, 04:54 AM   #2
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Its a way to adjust your bikes trail. Raising the tubes in the triple clamps reduces the amount of trail. This makes steering more responsive, makes the bike want to fall more into the corners, increases the tendency to headshake. I find myself making the opposite adjustment as my bike with me on it would otherwise tend to fall into corners. Im on the track though so hanging off and leaning more than the street.
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Old March 19th, 2018, 07:49 AM   #3
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Trail is self-centering action of front-end. It's like caster front wheels on shopping-cart, it'll automatically aim wheel in direction of travel. The more trail you have, the stronger the self-centering torque on steering.



By lowering front-end, you make fork-rake steeper and reduce trail. Stock 250 has about 84mm trail, which I think is very short and makes the bike responsive as is. I don't think making it even more responsive has measureable benefits. It won't get me faster lap-times at track, but makes causes stability issues as Dave pointed out.

My CBR600RR has 95mm trail in comparison and doesn't feel as responsive at low-speeds. However, at 100mph, it's much more stable than Ninjette.
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Old April 2nd, 2018, 02:15 PM   #4
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This is just a FYI story.
I was coaching a rider, on a Ninja250, recently, he claimed he was at the limit of traction as far as the front end was concerned. I encouraged him to push harder and in doing so he lost the front end and low sided. He asked me to go over his suspension and set it up as mine was. I did this for him and in the next session he knocked 2 seconds off his lap time, this was the first time out after his crash on a track we had been running for 2 days. I set fork protrussion at 25mm measured at the gap in the tripple.
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Old April 3rd, 2018, 01:45 PM   #5
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So did you lower or raise fork-tubes in triple-clamps on his bike?
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Old April 5th, 2018, 10:47 AM   #6
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Quote:
Originally Posted by bruce71198 View Post
This is just a FYI story.
I was coaching a rider, on a Ninja250, recently, he claimed he was at the limit of traction as far as the front end was concerned. I encouraged him to push harder and in doing so he lost the front end and low sided. He asked me to go over his suspension and set it up as mine was. I did this for him and in the next session he knocked 2 seconds off his lap time, this was the first time out after his crash on a track we had been running for 2 days. I set fork protrussion at 25mm measured at the gap in the tripple.
Bruce, @bruce71198

What is your shock length, eye-to-eye?

Fork height: 25mm above triple

Tires? Size?
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Old April 5th, 2018, 11:19 AM   #7
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Quote:
Originally Posted by DannoXYZ View Post
So did you lower or raise fork-tubes in triple-clamps on his bike?
I moved his up in the triple clamp
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Old April 5th, 2018, 11:21 AM   #8
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Quote:
Originally Posted by mgentz View Post
Bruce, @bruce71198

What is your shock length, eye-to-eye?

Fork height: 25mm above triple

Tires? Size?
My shock is out getting freshened up, ill post the length when i get it back.
110-140 Pirelli tires.
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Old April 5th, 2018, 11:47 AM   #9
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I was given the below from Ed Sorbo (Lindemann Engineering):

Stock shock length: 320mm
Recommended length: 324mm

Stock fork height: 12mm above triple
Recommended height: tube flush with triple

Tires:Pirelli Diablo Rosso II
Front: 110/70
Rear: 140/70

I currently have a 120 front and feel like their is not enough weight up front. I will be going back to a 110 front.
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Old April 5th, 2018, 01:04 PM   #10
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Quote:
Originally Posted by bruce71198 View Post
I moved his up in the triple clamp
Is the increase in front-end grip from putting more weight on front wheel? A whole 2-sec/lap improvement is HUGE with just that one change!!
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Old April 5th, 2018, 07:57 PM   #11
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so are you saying you have 25mm tube showing?
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Old April 10th, 2018, 05:24 PM   #12
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Quote:
Originally Posted by DannoXYZ View Post
Is the increase in front-end grip from putting more weight on front wheel? A whole 2-sec/lap improvement is HUGE with just that one change!!
2 things, it reduces trail or as some call it, the chopper affect making it turn quicker, and it tilts more weight onto the front tire. Reducing the trail also makes it a little more twitchy in a straight line. @ seconds is huge with one small adjustment but it gave him the feel and feedback to increase his corner speed.
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Old April 10th, 2018, 05:24 PM   #13
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Quote:
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so are you saying you have 25mm tube showing?
Yes, at the split in the upper triple.
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Old April 12th, 2018, 02:55 PM   #14
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Quote:
Originally Posted by mgentz View Post
I was given the below from Ed Sorbo (Lindemann Engineering):

Stock shock length: 320mm
Recommended length: 324mm

Stock fork height: 12mm above triple
Recommended height: tube flush with triple

Tires:Pirelli Diablo Rosso II
Front: 110/70
Rear: 140/70

I currently have a 120 front and feel like their is not enough weight up front. I will be going back to a 110 front.
The 300's rear shock is at 328 eye to eye and the 250 is at 325, 140 rear tire on the 250 as apposed to a 120 on the 300
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Old April 12th, 2018, 03:07 PM   #15
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So....stock length is 325mm On the 250? Is that what you you set yours too?
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Old April 12th, 2018, 03:30 PM   #16
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I found a variety of spots, including the below stating that the stock length is 320mm.

https://www.solomotoparts.com/Ohlins...ja-250R-09-11/

However, I then found this article that would suggest the length is only 315mm.

https://faq.ninja250.org/wiki/Instal...k_on_a_Classic

I tossed my stock shock, otherwise I would have measured it. Does anyone have one they could measure? If Ed truly has me at 9mm longer than stock, I could see why my forks are so low...

Last futzed with by mgentz; April 12th, 2018 at 06:19 PM.
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Old April 15th, 2018, 08:26 PM   #17
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Quote:
Originally Posted by mgentz View Post
I found a variety of spots, including the below stating that the stock length is 320mm.

https://www.solomotoparts.com/Ohlins...ja-250R-09-11/

However, I then found this article that would suggest the length is only 315mm.

https://faq.ninja250.org/wiki/Instal...k_on_a_Classic

I tossed my stock shock, otherwise I would have measured it. Does anyone have one they could measure? If Ed truly has me at 9mm longer than stock, I could see why my forks are so low...
I have no idea what the stock one is, haven't seen one in years, I gave you what I have ours set at.
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Old April 16th, 2018, 03:56 AM   #18
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Cool. Stock is 320mm. Had it confirmed by another member here. Thank you for all the help and information.
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Old April 20th, 2018, 10:36 AM   #19
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as you can see the front is pretty low on the brakes. This is my son last weekend at CMP I coulndt catch him!
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Old April 20th, 2018, 10:45 AM   #20
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crazy. I adjusted mine to 325mm rear and 12mm showing up front. I'll see how she feels and go from there. I will be switching to a 110 front as well.

Maybe I'll see you guys at Road America in a month! Still not sure how to introduce myself though.. "Hey I know you from the Internet" sounds stalker crazy.
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