Adjusting fork static sag.

[gumpt1oo]

Not trying to tell you guys how to suck eggs, thought it may be useful to anyone new to bikes.
Static sag is the amount the forks compress under the weight of the bike and rider.
To check this, raise the front wheel off the ground so that the forks are fully extended.
I then put a piece of tape around the fork leg as a reference point, and a cable tie around the fork leg tight to the dust seal.

I then measure the distance between the cable tie and the tape and record it. ( 66mm)

Now sit on the bike, with both feet off the floor, then measure the distance between the tie and tape again. (22mm)

So the static sag is 66mm -22mm = 44mm

I like the front to be a little stiffer, but the Bonneville and Scrambler do not have any pre-load adjusters on the forks. So I bought some 36mm diameter x 2.7mm thick stainless steel washers that fit inside the fork tubes.

Removed the fork nuts and fitted 2 washers (5.4mm) to each fork tube and refitted the nuts. Then repeated the measuring process.

With the washers fitted the measurement is 31mm, giving a static sag of 66mm - 31mm = 35mm.
This gives a firmer ride with less fork dive under braking.

A very cheap and easy adjustment to make.

 

[DaveM]

Great threads as per normal Steve thanks

 

[Rocky]

All such great tips are welcome here. Good job

 

[Bikerdriver]

Yes you `re right, that´s an improved measurement to increase the tension of the springs.

 

[devo]

The only static sag I have at the moment belongs in the hotspot.
Seriously tho Steve, is there a calculation to determine the number of washers reqd or is it a trial and error thing.
I ask this because 5.4mm of washers took out 9mm of sag.

 

[otherwise]

When a bike doesn't have adjustment built in Steve demonstrated you can work around the problem.
Steve is almost as good as Gromit when it comes to technical matters so thanks again Steve.


The net is full of helpful vids like this if you have adjustment screws from factory.
http://www.youtube.com/watch?v=mK3flKxf41U

Steve this may be a good time for you to reintroduce the Thruxton fork adjuster conversion thread that you did a couple of years ago.

 

[gumpt1oo]

The only static sag I have at the moment belongs in the hotspot.
Seriously tho Steve, is there a calculation to determine the number of washers reqd or is it a trial and error thing.
I ask this because 5.4mm of washers took out 9mm of sag.

I just used trial and error to end up with 35mm static sag. That is the measurement I have on my T100 using Thruxton pre-load caps as Kevin mentioned. The Thruxton pre-load caps cost me £80 the washers cost me £1.50!
Here's a link to the pre-load mod I did on my T100.
https://www.triumphtalk.com/showthread.php/2997-Bonneville-fork-mods

 

[devo]

cheers guys

 

[The Seeker]

This is a cheap and easy way to firm up the front end. Many Trophy owners have been using PVC pipe cut to 1/2 to 3/4 inches and inserted into the forks as "spacers".

If you attempt to add a PVC spacer that's any longer than 3/4th of an inch though....you can't get the top fork nuts to thread back down (or at least it's not too safe to try).