Would someone please post a (not too) short explanation of the Sportster rear adjustable suspension? I know it is adjustable with a spanner wrench and that you can adjust the pre-load. But I have yet to see an explanation of what this exactly does, and how to tell if it has too much pre-load or too little? In other words, how does adjusting preload actually effect the ride? And what steps can you take to assure a correct setting?

Thanks!

With the spanner, as you increase number, it increases tension on the spring giving a firmer ride. I weigh 215 and set my suspension at 2. The zero setting is for an average weight of 180, which allowed me to bottom on rough roads and intersection dips. At the 2 setting I am not bottoming. Also if you have a rider, crank it up to 4 or so for the same reason.

It's a shame that the Roadsters only get 3 preload settings as opposed to 5 on the customs. The original shocks were so bad for our roads (and dangerous two-up) that I had to change them straight away. The first time I have had to do that in 25 years of riding!

sportymark,


Know exactly what you mean about the roads in London. Lived in Wimbleton Village back in 1994 while my wife was completing a business assignment. Used to drive into The City. Not a fun drive!!!! If it wasn't the street traffic that screwed you, it was trying to get across the bridges in proper cue, or it was trying to get through some work zone.:headb

If you check out the service manual, it'll tell you exactly how to set the shocks. To do it right, it takes 2 people. One to sit on the bike and balance, and the other to measure the deflection in the shocks when person #1 is balanced on the bike. I think the deflection should be about 3/4". I don't know the exact number, but that is basically how it is done.

I think preload controls ride hieght more than anything else. I'm going to use made-up numbers for the sake of argument (it doesn't really matter what the exact measurements are) so don't take the specifics as gospel.

For arguments sake, lets say that spring is 10 inches long with the lowest preload setting. When you sit on the bike, the spring will compress 2 inches, bringing the length of the spring to 8 inches, and lowering the rear of the bike the same 2 inches. If you bring the preload all the way up, it will compress the spring by 1 inch from the bottom, so the ride height is not yet affected. The spring is now 9 inches long with preload all the way up. When you sit on the bike, the spring compresses an additional 1 inch (a total of 2 inches of compression --- you + preload), bringing the length to the same 8 inches as before. But because there is a preload of 1 inch already on the spring (from the bottom), the ride height is only lowered by 1 inch. In a sense, you're raising the bottom mouting point of the spring while keeping the top still. When you sit on the bike, the spring has the same amount of tension on it regardless of where the preload is. But with the preload higher, you're less likely to bottom out (because the ride hight is raised), and with the preload lower, you have greater negative (upward) travel.

When I had the stock shocks on my '04 1200R, I used the middle setting (I weight about 160 lbs). When I put my girl on the back, I moved it up to the highest setting, but still had issues with bottoming out on big dips (bumps were ok because there was so much negative travel).

The rear shocks should compress about 25% of thier total travel when you sit on the bike. Hope this helps.

With the spanner, as you increase number, it increases tension on the spring giving a firmer ride. I weigh 215 and set my suspension at 2. The zero setting is for an average weight of 180, which allowed me to bottom on rough roads and intersection dips. At the 2 setting I am not bottoming. Also if you have a rider, crank it up to 4 or so for the same reason.


Amazing what you can learn just from reading through the forums. I had no idea that I could adjust the rear shock load. I went and bought the spanner and bumped it to the 3 setting and the difference is night and day. It feels stiffer, more controlled, and hasn't bottomed yet.

Felt pretty good two-up as well.

Thanks for the tips, gang!

As long as the bumps are not killing the back and kidneys then you probably have the setting right. I have progressives with stronger springs and the ride is brutal at the top setting. Can't imagine why anyone would want a hardtail. They have to hurt on bumps. Rottenralph

ive got the 412 11" heavy duty shocks on my bike.
went 2up riding at the weekend and had the setting on no.4, nice ride.
forgot to change it back before work this morning, and i actually liked it.:wonderlan
might try the hardest setting tomorrow for comparison.
maybe a hardtail project could be comming up in the future?? :D

cheers
crackers

I also have the 412's and set them on the highest setting, great ride!!!! :D

I have the cheapest Ohlins and I am 150% happy with them. ;)

I have the stock custom shocks and they are racked up as far as they will go and never bottom out, the ride is fine but I switch these with struts now and again which is a totally different feel. Will be going to a hardtail frame next year.


Can't imagine why anyone would want a hardtail.

They look cool :chop

G'day ALL

read these links..saves me tryin to explain.



http://www.directparts.com/static/goose/supension_tuning.htm


http://www.cartestsoftware.com/fz1/suspensionadjustment.html

http://www.yft.org/tex_vfr/tech/setup1.htm

Thanks! That was a huge help.

stevo
I guess with age I also got a bit thick headed........what does the poem mean????? :confused:

look at the avatar



Skippy was the name of a TV show and also the name of the Kangaroo tha starred on it.......
Sonny was the name of the young boy that looked after Skippy..


Ya should be able to work the rest out

:smackh :smackh :smackh :smackh :smackh let me go cry in shame.....