Everyone talks of lowering the bikes. Got that....dog bone or some such.

I want to raise my F-4i slightly at the rear to keep the proper sag and to improve the feel of my turn in. I weigh about 180 with gear. The bike came to me just awful feeling, excessive turn at low speed and it wanted to fall right over...at higher speeds I had to exert big force on the inside bar to keep from over turning....Yes, it had crummy old tires, quite squared off.
I fixed that, mostly, with air pressure adjustment and I also raised the fork legs (lowered the front end) by 5 mm. That made it much better.

Then I went to the rear and found the spring pre load set full hard. I could feel that in the ride, too...stiff as hell and almost no sag. So I went two clicks softer with spring preload. Now I have the right sag and compression/rebound settings are close, but the crappy 'over turn' handling is back...it wants to fall over to the inside on slow corners.

My front sag is right, now, and the fork dampening settings are close...feel good. I don't want to raise the fork legs anymore if I can avoid it, they are already raised 5 mm, remember? Iwant to adjust the rear ride height again, but not with spring pre-load, which is right for me now..

So the question is how much do I shim the rear shock to raise the rear? (shooting for about 5-10mm with me on the bike as a start) Most rear suspensions are not 'direct' in that a 10mm washer or shim will not raise the rear exactly 10mm.. Usually a few mm of shimming at the shock mount will raise the ride height like 2 or 3 times that...Can anyone tell me what the ratio is for an F4i? How much should I shim to get about 10mm of ride height change for the rear?

I don't want to lower it any more, but I don't like having to push the bars through every corner.

I could probably 'sneak up on it' by adding tiny shims over and over, but I think it will be tedious removing the shock mount, so I'd like to get close with the first try..
Thanks, if anyone knows

Don Hanson

 

I just recently did this. Remember its about a 3 to 1 ratio. So for every mm you shim the shock you get 3 mm of over all height. For my race bike I raised it by 9mm which from what I can tell was as much as you could go and maybe a bit into the danger zone. The reason I say that is you have to be careful that the nut has enough of the bolt to hold tight. On the F4i there are two nuts I got rid of the top one and just used the bottom one.

I'm not sure shimming the rear will give you the feeling you want, as raising the rear is going to make the bike turn in more aggressively, unless your on the track or regularly dragging knee you may find it tips in pretty hard. As well I would strongly recommend adding a steering damper as my bike at speed now likes to throw the steering around.

Hope this helps, feel free to message me if you want details on how and what I did to raise the rear.

Cheers,
Sean

 

How did you make out?

S

 

I haven't done anything other than some preliminary inspection and some more messing with all my suspension settings. I haven't had everything apart yet. I have a gearbox re-work staring me in the face, so I am going to have everything off the bike...I will work something then. I don't see a way to shim this shock set up...just looking without everything off. It looks like I will have to change the link somehow, or find a shock with height adjustment other than the spring pre-load. I might be able to shim the spring itself....I want to see how much extension there is in the shock that is there now before I add to that, somehow.
thank you for the approximate ratio, though. That will come in handy when I get to it...this weekend maybe.
Don Hanson

 

If it stock it should easily shim up to 8mm unless something has been changed on it. I simply used washers and put them on the under side of the bolt that goes through the frame cross member.

In the next couple of weeks I will be doing it to the F4i, if you want I can do a write up and take pictures.