Front Suspension Springs Preload

[DONCZ]

I got all parts to change front springs.
New springs are from RACETECH and they are longer by about 1". Im 220lb and mainly ride solo. I ordered 1kg springs. Do I need to shorten spacer tube? How mutch, what is safe number to start?

 

[dduelin]

I thought RaceTech provides that information based on your weight.

If I had to guess, like you do, I'd build a spring/spacer stack the same length as the OEM one and plan on the extra stiffness in the RT 1.0 kg springs taking up much of the excess sag you now have with OEM. If that length provides too much more than 36 mm rider sag, then increase spacer length proportionally.

If sag becomes 46 mm then make a set of spacers 10 mm longer than the stock 200 mm ones.

 

[TerryS]

The method that RaceTech prescribe is to drop the springs into the assembled forks and measure from the top tube edge (fully extended) down to the top of the spring. Then subtract any length that is taken up by the fork cap and any spring washers. Add 15mm to what is left and you will end up with 15mm preload on the springs which is where RT usually suggest that you start.

https://racetech.com/download/InstructPDF/IP FRSP S Street Fork Springs.pdf

 

[SMSW]

You can use a plumbing tailpiece (1 1/4" pvc tube that goes from the bottom of your bathroom sink to the trap) for the spacer. If you really want to blow the bank on this, get the chrome plated brass tailpiece. The pvc is easier to cut, but the chrome looks nicer (until you slip it inside the fork leg.....).

 

[dduelin]

You can use a plumbing tailpiece (1 1/4" pvc tube that goes from the bottom of your bathroom sink to the trap) for the spacer. If you really want to blow the bank on this, get the chrome plated brass tailpiece. The pvc is easier to cut, but the chrome looks nicer (until you slip it inside the fork leg.....).

A 45 mm fork requires ~ 1 1/2” OD spacers.