Adjusting My Preload

[Proteus]

I've been playing around with my rear preload adjustment the last couple weeks, I rode my whole first season with it on 1 (I didn't know it was adjustable).

I'm 6'1, about 210 lbs.

I put it on 5 for a week to see what the most extreme setting was like, and I immediately felt like the bike handled and turned better. But going over any bumps was ROUGH and in Chicago there's more potholes than rats (and there's a lot of rats).

I tried it on 3 for a week, which was better for bumps but I started to feel some front-to-back bounciness at highway speeds. I don't know if I'm describing this well but it felt like when I went over anything but smooth pavement that the bike was kind of see-sawing a bit. I thought this might be because 3 was too low now that I had gotten used to 5, so I put it on 4.

I've had it on 4 for a week now, and I still get the same see-saw kind of movement AND the bumps feel just as rough as 5.

2 is the only setting that I haven't tried yet, and I was planning on switching to that this evening.

Does what I'm saying make sense?

[Flying]

Pretty much my experience. Though I'm fairly comfortable at 3 for all conditions. 2 didn't get to the firmness as fast as I wanted it to.

[Somchai]

Steve everything what you're saying makes sense.
The problem with the N250 is the front end, what Kwaki tried to solve by raising the oil level from 108 mm (N250) to 100 mm, but at least the best is to get springs for the fork that fit your weight.
For the calculation you can use the Sonic calculator http://www.sonicsprings.com/catalog/...pring_rate.php

[csmith12]

Your describing the "pogo" effect of the bike's suspension. On a stock bike with a rider of your weight, if you adjust the rear preload to 4-5, the front will feel very soft. And since the rear will not compress as easy, that energy must go somewhere. So your front dives down... and then pops back up when you get back to the throttle. ie.... pogos back and forth. The fix is proper springs in the forks for your weight and riding style.

Sounds like your bike is a bit of a commuter, give 2 a try and see if you like it. May I ask why you were adjusting the preload in the first place? Where you trying to adjust for another problem?

[Proteus]

I'll check out the springs, thanks @Somchai.

@csmith12 I wasn't trying to fix a particular problem, I just felt like I had gotten to a point where I felt like I had a good understanding of how the bike handled and was confident in my control inputs and wanted to see if I could make it better for me. After I got my new tires (BT-45's) I immediately felt that I could do everything better and easier, so I wanted to see what else I could change. It's definitely a commuter - at this point my riding is probably 95% commuting and 5% fun cruising.

[csmith12]

Cool! Rider skill increases and personal feel/preferences can warrant suspension changes from time to time. Gratz!

[Proteus]

Based on that calculator I should be around 0.85 kg/mm and from what I found on here stock is 0.65 kg/mm. New springs aren't in the budget at the moment, but this will be my next upgrade. For now I'm going to try #2 and see how that goes.

The problem is that my riding is about 50-50 highway and surface streets, and the highways are very smooth and surface streets in our fine city often look like a bomb went off.

[Proteus]

Originally Posted by csmith12

Your describing the "pogo" effect of the bike's suspension. On a stock bike with a rider of your weight, if you adjust the rear preload to 4-5, the front will feel very soft. And since the rear will not compress as easy, that energy must go somewhere. So your front dives down... and then pops back up when you get back to the throttle. ie.... pogos back and forth. The fix is proper springs in the forks for your weight and riding style.

It sounds like going from 3 to 4 actually made the pogo effect worse, which sounds like what I've been feeling.

[csmith12]

Gratz!

You have found one of the secrets of riding, ie your sweet spot of lean and speed. Set your bike up for that and 90% of the time you will be happy. Sure, there will be times where you push beyond that where it chatters a bit or times where you're slower and it's a bit harsh, but that is why riders are in charge of their bike's setup. So the rider is happy the majority of the time.

[Proteus]

What does "chatter" refer to? That seems to come up a lot in suspension discussions.

[csmith12]

Vibrations in the front and/or rear. It is unmistakable, you will know it if you have it.

[snot]

https://www.ninjette.org/forums/showthread.php?t=115660

Some more good tips

[Somchai]

@Proteus - you're welcome Steve.
Here's a tipp for a lower budget, just get some 10W fork oil (SHOWA SS08 or equivalent) and lower the air gap of the front forks what would make the fork a little bit stiffer.
You need 24 ml for each side and the oil level will change from 108 mm to 92 mm with the result from above (stiffer).
So you'll have some time until you get the stiffer springs.
And here's what the manual says about the rear shock:
○ The standard adjuster setting for average-build rider of 68 kg (150 Ib) with no passenger and no accessories is 2nd position.
Spring Preload Setting
Standard Position: 2nd position

Good luck

[Proteus]

Originally Posted by Somchai

@Proteus - you're welcome Steve.
Here's a tipp for a lower budget, just get some 10W fork oil (SHOWA SS08 or equivalent) and lower the air gap of the front forks what would make the fork a little bit stiffer.
You need 24 ml for each side and the oil level will change from 108 mm to 92 mm with the result from above (stiffer).
So you'll have some time until you get the stiffer springs.
And here's what the manual says about the rear shock:
○ The standard adjuster setting for average-build rider of 68 kg (150 Ib) with no passenger and no accessories is 2nd position.
Spring Preload Setting
Standard Position: 2nd position

Good luck

Thanks, I will try that when I get some free time and am feeling adventurous.

I think that in the USA setting #1 is for 150lbs as it's compensating for fat Americans.

[InvisiBill]

Remember, preload doesn't affect how much weight the spring can support. That's determined by the spring's rate. Preload/sag affects how it travels within that range.

The same weight will always compress the spring down to the same total length, as a function of its spring rate. Extra preload just compresses the spring ahead of time closer to that compressed size. Since you're starting off partially compressed, it squishes less when in use, so it feels firmer. However, the spring will still always compress down to the same point regardless of initial preload, because physics.

If your weight doesn't match the spring rate, preload can never correct that. It might be able to compensate some, but you really want springs that match your weight. The $90 I spent on RaceTech fork springs was the best upgrade I've done to my bike, and the cheap NewGen shock for the rear was the icing on the cake.

FYI, on the 500, the mathematically-derived bench-setting for preload to get the proper sag for a rider whose weight matches the NewGen's spring is the middle position. I'm sure the Ninjette's suspension isn't exactly identical (though they're very similar), and different people may like more or less preload. But the middle setting should be a good starting point if you're in the right weight range for the spring. RT's calculator says it's good for ~220lb (which matches up pretty well with the 500's numbers), but don't take that as gospel.

[Proteus]

Thanks for the explanation.

I dialed it back to two this evening and it feels better for around town. We'll see how it does on the highway tomorrow.