External, fork preload adjusters.

JS73 · June 8th, 2010, 04:08 PM

Talking to some 250 racers this weekend at Roebling Road I found out about Slingshot Racing.

They make a set of billet aluminum preload adjusters for the 250 that replace the stock caps. Adjustments range from 5mm to 20mm.

I just ordered a set since I am getting ready to do some suspension work on the bike. They look pretty slick.

Link: http://www.slingshotracing.net/catal...-ad-p-191.html

austexjg · June 8th, 2010, 04:14 PM

I have been eyeing those for a while - look forward to photos and review.

randomwalk101 · June 8th, 2010, 05:25 PM

Nice piece. Looking forward to your review.

edbro · June 8th, 2010, 06:33 PM

Nice! Guess now you can do a DIY and give us your impressions!

kkim · June 8th, 2010, 07:06 PM

why would one need preload adjusters?

JS73 · June 8th, 2010, 07:31 PM

Quote:

Originally Posted by kkim

why would one need preload adjusters?

Is that a trick question, Kelly? lol. Want to be able to experiment with the forks at the track. Yes, I could do it by changing spacers, but don't want to take the thing apart every time I want a small change if I can avoid it.

Also if I make a preload adjustment to the shock, this will affect the front, which might need adjusting to compensate for the change at the rear.

kkim · June 8th, 2010, 08:27 PM

sorry, no trick question. I guess I meant, what problem do you hope the preload adjusters will help combat/fix?

randomwalk101 · June 8th, 2010, 08:58 PM

For me, cuz it's purrrdieee

Posted via Mobile Device

JS73 · June 8th, 2010, 09:02 PM

Quote:

Originally Posted by kkim

sorry, no trick question. I guess I meant, what problem do you hope the preload adjusters will help combat/fix?

Oh, no problem at all. With the adjustable rear shock that will soon go in the bike, those fork caps can come in handy at the track.

I am interested in learning about suspension setting/adjustments. If there is a way to at least adjust one setting in the forks without having to disassemble anything, I'll take it.

gixerhp · June 8th, 2010, 10:19 PM

Quote:

Originally Posted by JS73

Oh, no problem at all. With the adjustable rear shock that will soon go in the bike, those fork caps can come in handy at the track.

I am interested in learning about suspension setting/adjustments. If there is a way to at least adjust one setting in the forks without having to disassemble anything, I'll take it.

With having 2 bikes with Ohlins forks, im spoiled, for track applications, these adjusters are great!
The suspension, here on my girlfriends is very soft, but im going to leave it alone for now. But in the future i will be adding these!

All of my bikes have allways had extensive suspension work done to them, as well as having geometry work done by the GMD Computrack shop here locally!
There is so much more confidence you can have with your bike with good suspension work!

sixstring · June 9th, 2010, 08:13 AM

I just bouht a set of these. Just shipped yesterday. Should have them in a week.

Snake · June 9th, 2010, 09:46 AM

Quote:

Originally Posted by kkim

why would one need preload adjusters?

For the same reason you have a preload adjuster on the back of your bike.

kkim · June 9th, 2010, 12:16 PM

Quote:

Originally Posted by Snake

For the same reason you have a preload adjuster on the back of your bike.

which is?

randomwalk101 · June 9th, 2010, 01:13 PM

Quote:

Originally Posted by kkim

which is?

make it looks pretty

sofo · June 9th, 2010, 01:27 PM

Ok these are a cool idea. I'd like the ability to tune the preload front and rear between track days and days riding distance with loaded panniers and a backpack.

kkim · June 9th, 2010, 01:41 PM

so, does a preload adjuster only allow for adjusting the static fork sag due to differing weights of riders/load or does it actually stiffen up the front end through it's travel, effectively "upping" the front fork springs ability to resist load throughout the entire fork stroke?

ie: will the forks feel stiffer throughout its entire travel?

JS73 · June 9th, 2010, 03:21 PM

Quote:

Originally Posted by kkim

so, does a preload adjuster only allow for adjusting the static fork sag due to differing weights of riders/load or does it actually stiffen up the front end through it's travel, effectively "upping" the front fork springs ability to resist load throughout the entire fork stroke?

ie: will the forks feel stiffer throughout its entire travel?

I see what you are getting at Kelly. Preload does not affect spring stiffness. Its used to adjust sag, this affects ride height also. From what I have read, ideally you want to be somewhere close in the middle of the suspension travel when measuring rider/total sag to avoid bottoming or topping out.

Sag adjustments are individual for each rider as it depends on rider weight.

kkim · June 9th, 2010, 03:29 PM

Quote:

Originally Posted by JS73

I see what you are getting at Kelly. Preload does not affect spring stiffness. Its used to adjust sag, this affects ride height also. From what I have read, ideally you want to be somewhere close in the middle of the suspension travel when measuring rider/total sag to avoid bottoming or topping out.

IIRC, bike w/ rider sag should be somewhere near 1/3-1/4 of the total suspension travel for the front with a static (bike only) sag of about 1/2-1" depending on the application.

so taking your explanation one step further, when we adjust the preload on our rear shock, why does the bike feel so harsh over bumps if preload does not affect spring rate?

JS73 · June 9th, 2010, 03:36 PM

Quote:

Originally Posted by kkim

IIRC, bike w/ rider sag should be somewhere near 1/3-1/4 of the total suspension travel for the front with a static (bike only) sag of about 1/2-1" depending on the application.

so taking your explanation one step further, when we adjust the preload on our rear shock, why does the bike feel so harsh over bumps if preload does not affect spring rate?

Because the spring the spring gets compressed when you add preload. Its like putting pre-weight on the spring before adding the rider. This makes the spring do additional work to resist that force giving the impression of being stiffer.

kkim · June 9th, 2010, 03:38 PM

isn't that upping the spring rate, then?

how does a spring give the "impression" of being stiffer w/o actually being stiffer?

JS73 · June 9th, 2010, 03:55 PM

Quote:

Originally Posted by kkim

isn't that upping the spring rate, then?

how does a spring give the "impression" of being stiffer w/o actually being stiffer?

If I have a spring with a k factor of 100lbs/in, for example, with no preload and a 200lbs load the spring would compress 2 inches. However if we add 1 inch of preload, we have increased the amount of force required to get the spring to begin to compress by 100 lbs.

So, we put the 200lbs load back and the spring will only compress 1 inch. The spring however, is still compressed a total of 2 inches and it's still doing the necessary work to hold 200lbs, no more no less.

Spring stiffness is determined by the materials used and the manufacturing process.

CRXTrek · June 9th, 2010, 03:58 PM

Quote:

Originally Posted by kkim

isn't that upping the spring rate, then?

how does a spring give the "impression" of being stiffer w/o actually being stiffer?

If it's a progressive rate spring i think preload takes out the softer rate coil to reach the firmer coils.
If the spring would've fully compressed with say 300 lbs. it still would still regardless of the preload.

kkim · June 9th, 2010, 04:01 PM

so, with the preloaded spring, the stroke/travel through the fork will feel the same as a spring with no preload?

I guess what I'm after is, will the fork's travel feel the same or feel harder/stiffer?

I know you can't change the inherent spring properties, but can you change the "effective" rate by preloading?

JS73 · June 9th, 2010, 04:14 PM

Quote:

Originally Posted by kkim

so, with the preloaded spring, the stroke/travel through the fork will feel the same as a spring with no preload?

I guess what I'm after is, will the fork's travel feel the same or feel harder/stiffer?

I know you can't change the inherent spring properties, but can you change the "effective" rate by preloading?

The overall travel of the suspension will be the same, it just that part of that travel was taken by the preload. However the "effective" travel that the rider feels and sees will be less, thus giving the harsher/stiffer feel.

That's why it's important that the sag be set correctly to avoid "hitting the stops" of your suspension if you go too far either way with the preload.

kkim · June 9th, 2010, 04:18 PM

Quote:

Originally Posted by JS73

However the "effective" travel that the rider feels and sees will be less, thus giving the harsher/stiffer feel.

so the forks will feel like it's been stiffened up?

JS73 · June 9th, 2010, 04:19 PM

Quote:

Originally Posted by kkim

so the forks will feel like it's been stiffened up?

Yes.

kkim · June 9th, 2010, 04:25 PM

Quote:

Originally Posted by JS73

Yes.

whew... thanks. It's like pulling teeth to get these answers.

So, fork preload adjustments would be a benefit to riders complaining of the front end diving under braking or of the front forks being too soft, correct?

JS73 · June 9th, 2010, 04:39 PM

Quote:

Originally Posted by kkim

whew... thanks. It's like pulling teeth to get these answers.

So, fork preload adjustments would be a benefit to riders complaining of the front end diving under braking or of the front forks being too soft, correct?

I know you know the answers, but it's a good discussion.

You were just asking the right questions to keep me rambling

Yes, it would benefit them, however changing preload affects ride height. So if you increase it at the front, you'll have to move the forks up on the tripple to maintain the original height and F/R weight balance of the bike.

See, there you did it again

sofo · June 9th, 2010, 04:43 PM

Preload on forks / rear shocks like the stock 250R "packs" the spring as described here which makes it stiffer, affecting both determined sag and fork stiffness.

In a perfect world this would allow for correct sag setup and proportional stiffness for fork action and diving characteristics, but isn't a perfect formula but can get close enough for the type of riding I do.

JS73 · June 9th, 2010, 04:53 PM

Quote:

Originally Posted by sofo

Preload on forks / rear shocks like the stock 250R "packs" the spring as described here which makes it stiffer, affecting both determined sag and fork stiffness.

In a perfect world this would allow for correct sag setup and proportional stiffness for fork action and diving characteristics, but isn't a perfect formula but can get close enough for the type of riding I do.

Correct, it depends on the type of riding. But for the track it is of great benefit to have the bike sprung for your weight.

kkim · June 9th, 2010, 04:54 PM

Joel,

Actually, I thought I knew the answers, but in another thread on how to stiffen up the front end, when I mentioned increasing the preload, I was told it wouldn't do a thing and the way to correct for the front end dive would be to replace the springs with the correct rate ones... whatever they might be.

Mine was a cheap trick with washers vs $100 for springs. Glad to finally know the forks I preloaded on the dirtbike is actually stiffer than when I started. Couldn't figure out how the front end on that bike got stiffer if preloading didn't stiffen up the feel.

Good luck with racing... now that's where a minute difference in suspension setup can mean the difference between being first or doing a soil/tarmac sample.

Alex · June 9th, 2010, 05:02 PM

Relevant link on Sport Rider's site:

http://www.sportrider.com/tech/146_9510_tech/index.html

With pretty graphs!

JS73 · June 9th, 2010, 05:08 PM

Quote:

Originally Posted by kkim

Joel,

Actually, I thought I knew the answers, but in another thread on how to stiffen up the front end, when I mentioned increasing the preload, I was told it wouldn't do a thing and the way to correct for the front end dive would be to replace the springs with the correct rate ones... whatever they might be.

Mine was a cheap trick with washers vs $100 for springs. Glad to finally know the forks I preloaded on the dirtbike is actually stiffer than when I started. Couldn't figure out how the front end on that bike got stiffer if preloading didn't stiffen up the feel.

Good luck with racing... now that's where a minute difference in suspension setup can mean the difference between being first or doing a soil/tarmac sample.

Yes, it will give a stiffer feel but all you're doing is "packing" the spring like sofo said. The correct way is to spring the bike to your weight and use preload for sag. Then again, if your not pushing the limits of the bike you can most likely get away with it.

Thanks, I plan on doing my first race in the Sept WERA round at JGP.

JS73 · June 9th, 2010, 05:13 PM

Quote:

Originally Posted by Alex

Relevant link on Sport Rider's site:

http://www.sportrider.com/tech/146_9510_tech/index.html

With pretty graphs!

Thanks for the link, Alex.

Betlog · June 20th, 2010, 08:25 PM

Anyone install these yet? Just curious as to how easy (or difficult) they are to install...

June 8th, 2010, 04:08 PM	#1
JS73 ninjette.org guru Name: Joel Location: Orlando, FL Join Date: Dec 2008 Motorcycle(s): 08 Ninja 250 Posts: 256	External, fork preload adjusters. Talking to some 250 racers this weekend at Roebling Road I found out about Slingshot Racing. They make a set of billet aluminum preload adjusters for the 250 that replace the stock caps. Adjustments range from 5mm to 20mm. I just ordered a set since I am getting ready to do some suspension work on the bike. They look pretty slick. Link: http://www.slingshotracing.net/catal...-ad-p-191.html

June 9th, 2010, 05:02 PM	#32
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	Relevant link on Sport Rider's site: http://www.sportrider.com/tech/146_9510_tech/index.html With pretty graphs! __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

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June 8th, 2010, 04:14 PM	#2
austexjg ninjette.org sage Name: J.G. Location: Austin Join Date: Oct 2009 Motorcycle(s): '09 zx6r Green/Black, (ex-)Diablo Black '09 Ninja 250r Posts: 959	I have been eyeing those for a while - look forward to photos and review.

June 8th, 2010, 05:25 PM	#3
randomwalk101 self wrencher Name: john Location: houston Join Date: Dec 2008 Motorcycle(s): 08 250r and 07 600r Posts: A lot.	Nice piece. Looking forward to your review.

June 8th, 2010, 06:33 PM	#4
edbro ninjette.org member Name: Ed Location: NJ Join Date: Dec 2009 Motorcycle(s): 2009 250r Posts: 157	Nice! Guess now you can do a DIY and give us your impressions!

June 8th, 2010, 07:06 PM	#5
kkim Join Date: Nov 2008 Posts: Too much.	why would one need preload adjusters?

June 8th, 2010, 08:27 PM	#7
kkim Join Date: Nov 2008 Posts: Too much.	sorry, no trick question. I guess I meant, what problem do you hope the preload adjusters will help combat/fix?

June 8th, 2010, 08:58 PM	#8
randomwalk101 self wrencher Name: john Location: houston Join Date: Dec 2008 Motorcycle(s): 08 250r and 07 600r Posts: A lot.	For me, cuz it's purrrdieee Posted via Mobile Device

June 9th, 2010, 08:13 AM	#11
sixstring ninjette.org member Name: Jerry Location: Ontario, Canada Join Date: Jun 2009 Motorcycle(s): 09 EX250 LE Posts: 117	I just bouht a set of these. Just shipped yesterday. Should have them in a week.

June 9th, 2010, 01:27 PM	#15
sofo ninjette.org guru Name: Andrew Location: Vancouver, BC Join Date: Jul 2009 Motorcycle(s): 2009 Kawasaki Ninja 250R Posts: 410	Ok these are a cool idea. I'd like the ability to tune the preload front and rear between track days and days riding distance with loaded panniers and a backpack.

June 9th, 2010, 01:41 PM	#16
kkim Join Date: Nov 2008 Posts: Too much.	so, does a preload adjuster only allow for adjusting the static fork sag due to differing weights of riders/load or does it actually stiffen up the front end through it's travel, effectively "upping" the front fork springs ability to resist load throughout the entire fork stroke? ie: will the forks feel stiffer throughout its entire travel?

June 9th, 2010, 03:38 PM	#20
kkim Join Date: Nov 2008 Posts: Too much.	isn't that upping the spring rate, then? how does a spring give the "impression" of being stiffer w/o actually being stiffer?

June 9th, 2010, 04:01 PM	#23
kkim Join Date: Nov 2008 Posts: Too much.	so, with the preloaded spring, the stroke/travel through the fork will feel the same as a spring with no preload? I guess what I'm after is, will the fork's travel feel the same or feel harder/stiffer? I know you can't change the inherent spring properties, but can you change the "effective" rate by preloading?

June 9th, 2010, 04:43 PM	#29
sofo ninjette.org guru Name: Andrew Location: Vancouver, BC Join Date: Jul 2009 Motorcycle(s): 2009 Kawasaki Ninja 250R Posts: 410	Preload on forks / rear shocks like the stock 250R "packs" the spring as described here which makes it stiffer, affecting both determined sag and fork stiffness. In a perfect world this would allow for correct sag setup and proportional stiffness for fork action and diving characteristics, but isn't a perfect formula but can get close enough for the type of riding I do.

June 9th, 2010, 04:54 PM	#31
kkim Join Date: Nov 2008 Posts: Too much.	Joel, Actually, I thought I knew the answers, but in another thread on how to stiffen up the front end, when I mentioned increasing the preload, I was told it wouldn't do a thing and the way to correct for the front end dive would be to replace the springs with the correct rate ones... whatever they might be. Mine was a cheap trick with washers vs $100 for springs. Glad to finally know the forks I preloaded on the dirtbike is actually stiffer than when I started. Couldn't figure out how the front end on that bike got stiffer if preloading didn't stiffen up the feel. Good luck with racing... now that's where a minute difference in suspension setup can mean the difference between being first or doing a soil/tarmac sample.

June 20th, 2010, 08:25 PM	#35
Betlog ninjette.org guru Name: Dude!! Location: Southern California Join Date: Dec 2009 Motorcycle(s): 2009 250r Posts: 443	Anyone install these yet? Just curious as to how easy (or difficult) they are to install...