Fork spring spacer info - adjusting preload

[RinconVTR]

I will be adjusting my front fork preload soon and wanted to confirm the current spacer size and how much preload is currently there. From the spring free length, the only preload amount is the height of the fork cap. That's it folks.

Because the spring is progressive and a high number of coils are for a soft initial travel, more spacer length will eat up the soft/tightly wound coils and provide a firmer front end. (I've done this on every Honda motorcycle I've ever owned...and strangely...only the Honda's)

Stock spacer out of my bike is 5-7/8" tall.

OD (thin wall tube...ID not worth measuring) This is the max OD for any replacement.

A replacement tube should have an ID of around 1-1/8", but it can be less and not cause any problem.

 

[dduelin]

I used 1" PVC when I did mine to get the fork sag correct for my weight. A nice fork upgrade that isn't very expensive is to install Fork Caps for the Honda CB1100. Honda P/N 51450-MGC-003. They are adjustable for preload so the exact spacer length becomes less critical. They are longer than the stock caps by 18 mm IIRC so shorter spacers may be required to get the sag in the range the adjusters can work. I use metric dims as round numbers were easier to do the math - the stock ones are 150 mm long by 34 mm OD. I think I'm running 143 mm spacers now with the CB1100 caps in the middle of adjustment range.

 

[Beemerphile]

There is a reason why most suspension tuners replace dual rate and progressive springs with a single rate spring. It makes tuning the suspension much more straight-forward and there are other (better) ways to obtain progressive resistance.

 

[dduelin]

There is a reason why most suspension tuners replace dual rate and progressive springs with a single rate spring. It makes tuning the suspension much more straight-forward and there are other (better) ways to obtain progressive resistance.

Many, but not all.

 

[Beemerphile]

Many, but not all.

Most = many but not all

 

[dduelin]

I hope you feel better soon Lee.

 

[RinconVTR]

There is a reason why most suspension tuners replace dual rate and progressive springs with a single rate spring. It makes tuning the suspension much more straight-forward and there are other (better) ways to obtain progressive resistance.

Agreed. Progressive springs are mostly for street-ability-comfort.

 

[MZ5]

I use the CB1100 caps on my forks, too. On the one hand it's kind of silly, because I have no need of adjusting front preload on a regular basis, but on the other it seemed cool, wasn't very expensive, and does indeed make precise spacer length less critical.

 

[RinconVTR]

Well in the end for me, I'm back to the original spring spacer (cant believe it!) but I raised the forks 3/4" and then 1/2".

3/4" raised (front lowered) was fun but too twitchy during very fast commuting with a lot of turbulence.

1/2" feels about perfect and I might settle at 3/8".