Fork static sag question

[azr]

My front end on the 80' 1000G feels 'sensitive', meaning it seems to pick up on every rut in the road moving around a 'bit' more than I like. Front has progressive springs, rear has progressive as with the stiff spring. I measured static sag according to the sonic sight. 140mm full extension, 87mm pushing down/let settle on the front end, 100mm lifting up/let settle on the front end. Calculation equals 46.5mm which is 33% of total sag. Does this number explain why it feels the way it does? By increasing the PVC spacer by 1/4 or so, that will decrease my static sag and improve the feel?

[GregT]

If that sag figure is unladen - ie without the rider - I'd replace the fork springs. If it's with the rider aboard, and you're using 1/3 of the fork travel before you move off, it's still too soft.
IMO you should be looking for about 25mm of sag on something the weight of the 1000G - with the rider aboard.

[azr]

Those numbers are with the rider on the bike. Does this explain why the bike seems to pick up everything on the road? If I remember that last time I put the PVC spacers in they were pretty dang tight to get everything back together, I'll pull them out and see what length they were.

[azr]

Current PVC spacer is 46mm ( 1 3/4 inch), it's going to be pretty darn tight to get a 2 inch spacer in there.

[Sandy]

If the springs are the right weight you shouldn't have to compress the spring that much to get the cap back on. On my 1000 with the Progressive brand springs and spacer combination I use I only push down on the cap about 1/2" so total compression once the cap is installed is around 1" at most. I've also settled on 15W fork oil. Unladden sag last time I checked was probably slightly more than 1", didn't check ladden sag but I do use tiewraps to measure how the suspension is working under different scenarios such as sporty riding and close to but not bottoming under tire howling full braking. My Progressive springs were pretty much a full length spring so my spacer length is very small. If you're running shorter springs with an overly long spacer than could possibly result in the springs getting coil bound on full compression or being very stiff once you get much beyond the initial sag. Are you trying to compensation for the Windjammer? If you are it might be time for a step up or two in initial spring weight so you can reduce your spacer length.

[azr]

I'm using Progressive springs in the G with 15W oil. I've increased the spacer from 45mm to 52mm with a noticeable improvement, it now has a unladden sag of 38mm. Running the bike hard through corners has been pretty good, the issue I've been noticing is at low speeds, it tends to 'track' for a lack of a better word, seems to move around a lot. I was reading one of Dan's threads and on his 80' 1000G, with progressive springs, he put a 90mm spacer in there I've got 20 lbs on him and a Vetter so there's that to consider.

[Sandy]

That's all lot of weight up front. Just curious, did you put a fork brace on that one?
Something here is not making sense unless something else is out of wack.

[posplayr]

Those numbers are with the rider on the bike. Does this explain why the bike seems to pick up everything on the road? If I remember that last time I put the PVC spacers in they were pretty dang tight to get everything back together, I'll pull them out and see what length they were.

When I mentioned how hard it was for me to push down to stuff springs in, Rich as Sonic posted in reply that springs were too weak, I had had preload set mainly to avoid bottoming out (during hard braking using the zip tie method) so I have now purchased a set of 1.0 Kg/mm straight springs from Sonic but have yet to install.

[azr]

That's all lot of weight up front. Just curious, did you put a fork brace on that one?
Something here is not making sense unless something else is out of wack.

Yes the G has the more modern Tarozzi fork brake. What part about the numbers isn't making sense to you?

When I mentioned how hard it was for me to push down to stuff springs in, Rich as Sonic posted in reply that springs were too weak, I had had preload set mainly to avoid bottoming out (during hard braking using the zip tie method) so I have now purchased a set of 1.0 Kg/mm straight springs from Sonic but have yet to install.

I've got Sonic springs in the 78' and do prefer them but as the G isn't for hard riding I'm hoping I can make the Progressives work, there's not reason I should be able to.

[posplayr]

I've got Sonic springs in the 78' and do prefer them but as the G isn't for hard riding I'm hoping I can make the Progressives work, there's not reason I should be able to.

If the sag is too high due to too low of a spring rate, you can increase spring rate by cutting off the flatter coils of the spring. I believe Ed (Nessism) has done this up to about 4" worth (maybe even a little more). It can give you easily a 10% increase in spring rate.

[azr]

If the sag is too high due to too low of a spring rate, you can increase spring rate by cutting off the flatter coils of the spring. I believe Ed (Nessism) has done this up to about 4" worth (maybe even a little more). It can give you easily a 10% increase in spring rate.

Yes I've read that, but these are relatively new progressive springs within the last 3 yrs or so.

[Sandy]

Yes the G has the more modern Tarozzi fork brake. What part about the numbers isn't making sense to you?

I don't know exactly. With what you've said you have and what Dan has, even if the setup isn't bang on you shouldn't be having a driveability issue. It might feel a bit tight or loose and need some fine tuning, but it should track properly. I know you're meticulous when going over a bike but I'm now wondering if you're chasing ghosts in your forks and the actual problem might be somewhere else. Maybe the head bearings, assuming you've changed them, have shifted a bit and need retorquing? I asked about the fork brace because I have the same one on my 1000 and it actually made more difference for low speed tracking and feel than it does at high speed. But you've done that so.......

[azr]

It's got new head bearing, but you're right they did loosen up a bit last year and needed tightening, I'll check them. It's likely as well that I'm being a bit 'too' picky. The bike rides great, corners great, etc..... It's like vacuum synching, you can chase those levels so much trying to get the 'perfect' that you can spend hours doing basically nothing.

[GregT]

If it is still a little unsettled with sag in the right range, time to look at the front tyre and it's pressures. Some brands are more directionally stable than others.
Re the fairing - frame mount or fork mounted ?

[azr]

Frame mounted.