wgsvintage wroteLove those pictures Mark, very inspirational. What a nice bike! I only wish I could see the adjustable parts on the hoop and rocker better.
Bill
Bill--
short answer- it depends upon how flat a progressive rate you like (I prefer the term leverage rate because you are really looking at a changing leverage ratio through the arc of the swing arm and rocker), where the rear axle is located (which is a big consideration with the leverage), the stiffness of the spring you chose, the type of track—bumpy or smooth, and the rear ride height you want – and more I am sure.
But if you are going to put the bike on the track my recommendation is- when looking at the rocker from the right side of the bike- place the shock bolt at any position between 6 to 9 o’clock. This side of the adjustment gives you the flatter rising rate curves because the spring/shock is closer to 90º (perpendicular) to the swing arm. These flatter curves are what most modern track bikes use because they resist squat and works better mid corner. These positions will also raise your ride height so pick a hole accordingly.
Looking at the pictures you can see that most race bikes I have bought have the shock bolt around the 6:00 position—this puts your ride height at maximum and the rising rate at the middle adjustment.
If you want to start with a position John Hackett suggests--- then when put the bolt hole at the 8 o'clock position. I have used this position on one of my track bike -- using the mono ball bolts to make any changes in ride height. I have also used the bottom adjustable Mono ball bolt on my shock but that is a real pain to do. I only change my sprocket by 1 tooth at most on this bike so the axle does move much so the leverage stays about the same and I can keep that position from track to track.
If you are going on the street you may want a bigger curve-- so pick a hole on the the right side of the clock which tilts the shock/spring more forward. Pick a hole that gives you the ride height you like as a baseline and then adjust at the hoop. Mike C reminded me that the street bike came with the bolt hole at the 3 o'clock position-- good for bumpy street roads- but I think it was even too progress for a street bike.
"That's looking very nice, are the forks FG9050's and are the yokes/triple trees 27mm offset??"
Steve-- no these are the '91 FG9030's and the offset is closer to 25 mm.
