Suspension Question 2003? - Honda RC51 Forum : RC51 Motorcycle Forums
 
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post #1 of 9 (permalink) Old 07-28-2011, 10:14 PM Thread Starter
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Suspension Question 2003?

I saw several You Tube suspension how-to's where the expert "deflected" the front and rear suspension. Often the front came down a lot (and bounced).

My front end does not deflect when I try to bounce it standing over the bike on the default suspension settings.

I weigh 205 and now ride on the default suspension settings front and back. It's neutral. (I might beware putting in front preload over default.)

Now before I defaulted all the settings, I stiffened the rear preload one click and the bike was better in the front, better than neutral. Of course I don't really know what any of the other settings were (the bike is new to me). Yes, stupid me.

Of course, I wish I had a clue to head in a direction to get better than neutral. Any thoughts .....Thanks, dreilly
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post #2 of 9 (permalink) Old 07-29-2011, 12:11 AM
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What the fellow was doing was checking the amount of rebound damping that was set.
It's not that he was trying to depress the suspension rather he was trying to gauge the degree of rebound damping.

The suspension should quickly rebound (within approx 1 second), and stop without any further motion.
Too much rebound damping and it takes too long, too little and the suspension rebounds and then starts another downward cycle.

Think of a car with totally worn out shocks. It hit a bump in the road and becomes a hobby horse, rocking back and forth. That's worn out damping.

The pre-load adjusters only vary the amount of additional compression (pre-loading) on the springs. It does not change the spring rate. Only a different spring can do that.

For springs, you look at the difference between the amount of sag (suspension travel) the bikes attains between and unladen (without rider) and laden (with rider) state.
There are various sites that state what the unladen and laden sag should be for front and rear suspension on the bike.

Almost any spring can be adjusted to meet the laden (rider) sag numbers.
What's important is the unladen numbers when the rider is removed.
That's what tells you what direction to go with spring rates (up or down).

A too soft spring will need a bunch of pre-load adjustment to meet the laden sag number.
But when the rider load is removed the unladen sag number will be too little since the spring is still under a bunch of compression from the preload. It's still trying to extend.

A too stiff spring will also meet the laden (rider) sag number, but it won't require as much pre-load adjustment. So it won't be under as much compression as the soft spring.
When the rider load is removed, it might not extend as much due to very little pre-load needed. So then the unladen numbers are too high as the suspension doesn't extend enough.

The perfect spring is one that supports the rider load at the desired sag number, and also extends just enough without rider load to meet the unladen sag number.
The only way to attain this is to change the spring to one with a different spring rate.

Rule of thumb (give a set laden sag number):
If the unladen sag number is too small, you need a higher spring rate.
If the unladen sag number is too great, you need a softer spring rate.

Springs support the bike. Dampers control the bike.
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post #3 of 9 (permalink) Old 07-29-2011, 09:55 AM Thread Starter
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Hi Sailor:
Thanks for the reply. Some one wrote in a Forum that these bikes are suspended for someone 220. Can anyone deflect their front end?And what does it mean for setup?
Still hoping for that better than neutral front adj. (if you have one click stiff rear preload, isn't the bike slightly higher in back and sending a little weight forward?(because the front end changed for the better when I did this.) Dreilly
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post #4 of 9 (permalink) Old 07-29-2011, 09:37 PM
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If you increase rear spring pre-load, it will raise the rear end a bit.
That will decrease the front trail a little, which will make the bike turn quicker.
Sliding the front forks up in the yokes a little will accomplish the same.

Also going to a taller rear tire will tend to do the same to a lesser degree. Say going from a 190/50-17 to a 190/55-17.

However the main advantage of the 190/55-17 over the 190/50-17 is the tire cross-sectional profile.
The 190/55-17 has a more pointed profile than the 190/50-17. This will allow the bike to roll into a turn easier. And I must say it made a world of difference on mine.
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post #5 of 9 (permalink) Old 07-29-2011, 09:46 PM
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See the earlier shortcut to Sportrider's suspension setup page. I weigh as much as you do, and the setting from Sportrider are now the set up on my 2005 RC51 and they are a very good starting point. I would say SP1 are much firmer for the street than SP2's are.
The Sportrider site has settings for at least 4 years of RC51's. Rear preload was almost maxed out to the next to last ramp. Plus your front fork must be in the pulled 8mm through for the right position for some of the bikes. Best setting will be nose down and tail up for faster transitions. With this you may want to invest in a steering damping due to the reduced rake and trail that will quicken up the steering. Headshake will not a issue with a damper.
See the engine work section about suspensions thread. A post by Sub-Sailer has the shortcut to Sportrider suspension settings page!

Last edited by rc51 Red Rider; 07-29-2011 at 09:51 PM. Reason: additional information
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post #6 of 9 (permalink) Old 07-29-2011, 11:02 PM
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Most sport bikes new are sprung for riders 180#~ 200#....I just changed to the 190/55 this last tire change and yes, it does help the bike steer better.

Some folks forget too, when you put on the cow skin or kangaroo hide, your weight goes up considerably. (as far as springs go) I did not see you mention your riding gear.



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post #7 of 9 (permalink) Old 07-29-2011, 11:48 PM Thread Starter
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Hello Sub-Sailor,RedRider,MadBuyer: The thread of the thread is go to 190/55 from 50. I will.
S.S.-Stubbornly: with default except one click stiff r. preload, I can't much tell the difference from all default. It's harder in the back but turning no better. There is an adj. out there. I felt it; I just don't know what it is. I'm not fast and dropping the forks down on the tubes is for fast guys. and I like how solid the bike is- the back doesn't move (at my speeds).
R.R.Steering dampers are for faster guys than I! I've experienced one tank slapper and I slowed down.
Old and slow may be -concomitants???-one is necessary for the other. Dreaming only of rapidity. I'll leave speed to you guys. ATGATT.
I swear for one day my bike turned better just because of susp adj's. Then I defaulted everything and it's lost. Thanks for the help. dreilly, Old and Slow.
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post #8 of 9 (permalink) Old 07-30-2011, 02:33 PM
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Quote:
Originally Posted by dreilly View Post
Hello Sub-Sailor,RedRider,MadBuyer: The thread of the thread is go to 190/55 from 50. I will.
S.S.-Stubbornly: with default except one click stiff r. preload, I can't much tell the difference from all default. It's harder in the back but turning no better. There is an adj. out there. I felt it; I just don't know what it is. I'm not fast and dropping the forks down on the tubes is for fast guys. and I like how solid the bike is- the back doesn't move (at my speeds).
R.R.Steering dampers are for faster guys than I! I've experienced one tank slapper and I slowed down.
Old and slow may be -concomitants???-one is necessary for the other. Dreaming only of rapidity. I'll leave speed to you guys. ATGATT.
I swear for one day my bike turned better just because of susp adj's. Then I defaulted everything and it's lost. Thanks for the help. dreilly, Old and Slow.
I would suggest first trying a 190/55-17 rear tire.
That should really improve the overall roll response.
Some are taken back by the improvement and initially find themselves over turning at the start.
Then you can tweak the suspension beyond that.

There's only so much one can do for OEM suspension settings.
Beyond that requires changing to a premium quality shock, and modifying the fork internals.
For now, try to attain a controlled compliant ride for the street.
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post #9 of 9 (permalink) Old 07-30-2011, 03:20 PM Thread Starter
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Sounds like a good plan SubSailor. Thanks Dan
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