Adjusting preload on front suspension

I had guessed at the best length of the spring spacer on my front forks, after deciding the standard spacer was making the front end too harsh. The standard spacer is 110mm long but, as my replacement springs are 20mm longer than the springs I took out, this was preloading the replacement springs quite significantly. So I made up a pair of 90mm spacers. These turned out to allow more sag than I wanted so I decided to add an additional packing for the replacement springs. Also, the 90mm spacers were from a narrower diameter tube than the standard spacer (which has a diameter of 38mm). 

90mm spacer shown loose in stanchion

 I decided to use o-rings to keep them centralized in the fork tube. I bought a Hilka O-ring kit some time ago and it included some that were just right.They made the spacers a snug fit in the stanchions so I have better confidence the forces will be centralized and distributedevenly.

Top 3mm disk being installed over 9mm spacer and lower 3mm disk

I added the additional length to the spacer I made up before with two 3mm thick disks and an extra section of tubing 9mm long. I cut the disks out of sheet aluminium with a drill attachment and a jigsaw: a very noisy business. It took a fair amount of filing to sort them out after the power tools but I was pleased with the result. This means the total spacer length is 86 + 3 + 3 + 9 = 101 mm.

I rode south to the Sammy Miller Museum today and was pleased with the result. The ride is firm but not overly firm. This is a matter of personal preference of course. It feels more controlled than with the 90mm spacer but just that bit more compliant than 110mm.

TriMoto 1200 outside the Sammy Miller Museum