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Discussion Starter · #1 · (Edited)
Suspension set up is the #1 most over looked mod to make to any bike being Street or dirt. Suspension set up is more important than a modded faster engine. From the factory most street bikes are set up rather soft and have quite a bit of sag so the bike feels cushy and to make the brakes feel amazing. Here's my guide to setting up the sag on you'r 500. If you do this you will notice a night a day difference in the way it handles. The #1 misconception is that when you add preload to the springs forks or rear shock you are making the shock or forks stiffer. That is completely untrue. The spring rate is what controls the stiffness, all you are doing by adding preload is bringing the springs to their rate sooner. Ok so first things first.

To measure the rear sag this takes 2 people. Use 2 fixed points. In my picture I used the chain adjuster to the rib on the grab handle. Measure the distance between the two while the other person pulls the bike onto the side stand letting all the weight off the rear tire. Write that number down. For instance my measurement was 25.5".



Now sit on the bike with you'r normal riding gear in your standard riding position with all your weight on the bike and have the helper measure from the same points. For instance I had 24.5". The difference was 1" or 25.4mm. Ideal sag in the rear should be 30-35mm so I needed to take some preload out of the rear spring with a spanner wrench on the on the preload adjuster. I ended up with 32mm.

Now the front is the same concept. You can take a zip tie and put it around the inner fork tube snug and slide it down to the top of the dust seal/ wiper. I took my fork off and put an o-ring on the tube for future reference. With that 0-ring or zip tie all the way to the dust wiper sit on the bike with all you'r weight and gear in you'r normal riding position. Once again have your helper pull the bike onto the side stand taking the weight off of the front wheel. Measure the distance between the wiper and o-ring or zip tie. That is you'r sag number. For instance I had 49mm of sag. You want to be 30-40mm. So how do we fix that?






To add or subtract spring preload in out forks we need to make or cut the existing preload spacers. Atleast until someone makes new caps that we can adjust on the fly.

step #1 you need all the weight off of the front of the bike. I used tie downs from my garage ceiling.



Next is to take the caps off. Be careful doing so as the preload will throw the cap in the air if you arent paying attention.



Next thing to do is to make new preload spacers. You can use either PVC pipe or make them out of metal. The stock ones are plastic. They need to be 1 3/8 od. The stock length of them are 5 7/8 = 149.26mm. I made new ones out of PVC that are 10mm longer =159.26mm so I added 10mm of spring preload to the forks which put my sag at 33mm. Keep in mind the length of the preload spacers will be different for rider weight. I'm 135lbs. I do not recommend making them over 20mm because you might coil bind the springs and thats no good.




put the spacers back in and tighten up the caps and re measure. You may have to make different length spacers a few times until you hit the correct number. The bike feels stiffer on the bumps which i'm fine with but it does not dive nearly as much and corners great " not that it didnt before" but it's better now . I hope this makes some sense and helps you guys out.

In time Racetech will make different springs and emulators to control the dampening for different rider weight but either way you will end up having to set the sag.
 

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Thanks for posting.
What torque value are you using for the fork caps?
 

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Yep, getting the preload (sag) set up right will make a world of difference.

My CBR250R had about the same front rider sag...jeez and Im only 155lb! Easily fixed, now 32mm. So it sounds like the front is soft as the 250R's was. God knows what some people going 180lb's + have...

Great post!

Dave
 

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Where the front springs single rate or dual rate like the 250R has?

Cheers,

Dave
 

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What grips do you have there? Are they stock - that blue bit look I mean.
 

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Oh... WITH riding gear (leather suit, helmet, boots, gloves) I bet I weigh in at 240lbs +...

But let me get this straight; if my weight pushes the bike down more than 30-35mm, I have to stiffen the rear suspension in order to avoid that the rear sags further down than that number? And the wrench you use for that, where do you get that?
 

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I also posted on suspension set up here:

http://www.cbr500riders.com/forum/w...ront-suspension-adjustments-cbr.html#post2120

With too much sag the suspension has very little travel, and is not operating in the best region of the compression...

Its the same front and rear: 30-35 mm sag. It is measured (as BBR showed above) as the difference between when there is NO load on the bike (ie. lift it up by the grabrails for the rear; bars for the front) and the measurement when you are sitting on the bike geared up. Its really a 3 man job or two man and a front wheel chock. 1 to hold the bike upright, one to measure and you sitting on the bike.

If you weigh 240"lb then you will probably need to move the rear to a higher number, and go get the front shocks seen to. If BBR needed an extra spacer at the front ~10mm at 145lb, I doubt that you can get it okay. You will need stiffer springs. Leaving the front soft and stiffening the rear will probably leave the bike a bit unbalanced.

Getting it set up right will make a world of difference. My local bike suspension specialist will set a bike up perfectly for *you* as best as it can be for about $50, and give you a range of options for improvements. I was lucky and got mine done with minimal work for $100 - no new springs, but he adjusted the front spacers. Rear on stock setting 2 was fine for my 250R.

Dave
 

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great info bbr, thanks.
I bought k speed caps for front and they gave me an inch of adjustment on the fly. Only 33 USD and they created a big difference. But thinking about some stronger oil in them, any ideas about fork oils?
Besides, adjusted the rear shock - it is in setting 5 now out of 9 - and it is better now too and like you said, suspension mods are easy and cheap to do and they create as much positive difference as an aftermarket pipe or ecu can regarding a spirited ride.

http://www.k-speed.net/product.detail_973482_th_5134244
 

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Oh... WITH riding gear (leather suit, helmet, boots, gloves) I bet I weigh in at 240lbs +...

But let me get this straight; if my weight pushes the bike down more than 30-35mm, I have to stiffen the rear suspension in order to avoid that the rear sags further down than that number? And the wrench you use for that, where do you get that?
Yes. That is sag. Must measure it correctly though, as described. The tool kit that can with the bike has a special spanner to adjust it, and its use comes under RTFM ;-)

Dave
 
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Discussion Starter · #14 ·
great info bbr, thanks.
I bought k speed caps for front and they gave me an inch of adjustment on the fly. Only 33 USD and they created a big difference. But thinking about some stronger oil in them, any ideas about fork oils?
Besides, adjusted the rear shock - it is in setting 5 now out of 9 - and it is better now too and like you said, suspension mods are easy and cheap to do and they create as much positive difference as an aftermarket pipe or ecu can regarding a spirited ride.

?????????????????????????????????-??????? FOR CBR500R / F #5134244
I have found silkolene Pro RSF fluid to be the best money can buy. A little pricey but worth it. I do suspension on a daily basis and have found it not to fade nearly as much as any other fluid on the shock dyno. It's more consistant than any other fluid.
 

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Discussion Starter · #15 ·
great info bbr, thanks.
I bought k speed caps for front and they gave me an inch of adjustment on the fly. Only 33 USD and they created a big difference. But thinking about some stronger oil in them, any ideas about fork oils?
Besides, adjusted the rear shock - it is in setting 5 now out of 9 - and it is better now too and like you said, suspension mods are easy and cheap to do and they create as much positive difference as an aftermarket pipe or ecu can regarding a spirited ride.

?????????????????????????????????-??????? FOR CBR500R / F #5134244
How the heck do you order off the site if it's in a different language lol?
 

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Someone please sticky this.
 

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How the heck do you order off the site if it's in a different language lol?
Yeah, I was going to order those, but even with Google Translate, there were certain bits of info they were asking for that I didn't care to give (dob and maybe ssn). So, I bailed.
 
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