How to adjust non-stock rear suspension preload?

[felixcontour]

I'm a bit embarrassed to ask this, but what exactly do I adjust the rear preload to? I searched on it a bit, and most advice was to refer to the manual, which I don't have.

I know the basics - it's using a special wrench to "ratchet" the collar into various positions to change the tension on the spring. I just don't know what values (measurements) in terms of sag I'm looking for.

If you saw my other post on the exhaust, you'll notice my bike is sitting on aftermarket rear shocks of unknown pedigree. I believe they are 11.5" or 11", so it's a fair drop over stock. They look high quality, but that's neither here nor there.

So, if I'm off the bike, I'll take a measurement, and when I'm on the bike, I'll take a measurement. What's the value difference in the measurement I'm looking for here?

 

[jd750ace]

Your stock travel is around 3.15 inches or just about 80 MM. if you set it to compress around 30MM from full extended when you are sitting on the bike, it will be in the ballpark. That is assuming that the springs are anywhere close to the right rate for your weight, and the available travel is close to stock. Assumptions are far from science, but it will give you something to aim at for starters.

 

[felixcontour]

Thanks! Exactly what I wanted to know. I'll start with that and see if I have enough travel.

 

[grizld1]

That's part of what you need to know. To measure rear laden static sag, measure distance from the axle vertically to a point on the frame. Take the first measurement with the bike on a lift with the rear wheel hanging free. For the second measurement, have a helper hold the bike vertical while you climb on and get in riding position, and have a second helper measure distance from axle to the same point as used before. Subtract the second measurement from the first and you have it. Unlike measurement of front sag, there's no need to correct for seal drag; there isn't that much, due to the small diameter of the shock shafts (as compared to fork tubes). For details on sag adjustment from the founder of Race Tech, Google "Paul Thede plush ride" .

 

[5twins]

Have you guys looked at the shocks he's running? They appear to be those cheapos from Mike's with the rock hard springs. There will most likely be no sag to measure, lol.

 

[grizld1]

Oops--I missed that, 5t. Felix, that's not the only problem if you're concerned about handling. Cheap shocks=poor damping, and if you want clean steering, the back needs to come up, not down.

 

[felixcontour]

Alright, thanks for the input. I might have to live with these rear shocks temporarily. I'll adjust preload as best as I can and save up for better ones.

I do think the rake looks nice as it sits. For what that's worth. I don't want to go much higher than stock (12.5", right?) if I can help it.

What's the best rear shock bang-for-the-buck?

 

[XSLeo]

Call MMM at 650 central. Talk to him about his Progressive shocks. After a bit of talking about you, your bike and riding style He can assemble a set with the right springs.
Leo