Falco shock spring rate (yellow spring Sachs)

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#1 Post by **mangocrazy** » Sat Jul 12, 2014 8:53 pm

I was just wondering what the esteemed members of this forum think regarding the spring rate on the shock they have fitted to their Falcos. Until fairly recently I only had one Falco (a Flamingo red and Anthracite jobbie), and that has an aftermarket Ohlins shock that has been revalved to suit the standard Falco linkages. Initially I had used the same spring rate as OE (allegedly 800 lbs/in or 14.3 kg/mm). I found that way too hard and for the last 4 or 5 years have used a 700 lbs/in or 12.5 kg/mm spring - a reduction of 12.5% from OE.

As a large part of my riding is two-up (Mrs Mango gets very upset if I don't include her in my ride-out plans), I had found that the above setup worked very well. Sufficiently plush, but by no means soft or undersprung. A couple of weeks back I went off on a solo hoon around the Scottish Highlands with a bunch of mates (some of you may have seen the odd pic on the Facebook Aprilia Performance pages), and found that the spring rate was decidedly borderline on some of the more badly-surfaced roads. One really bad series of bumps in precisely the wrong place resulted in a tank-slapper - something I've never experienced before on the Falco.

It recovered itself very quickly, but it did make me wonder whether I should further soften the spring rate and perhaps get the high speed compression damping further reduced. To add credence to this I went out today on the blue Falco, which has a different setup to t'other one.

The blue Falco has what started life as a yellow spring Sachs shock, with the appropriate RSV Mille linkages. John at Revs Racing reduced the high speed compression damping (a major bugbear of mine) and changed the spring to one with a 500lbs/in (8.9 kg/mm) rate, a reduction of just under 8% from OE (540 lbs/in or 9.6 kg/mm). He refused to go any lower as he felt it was too much of a reduction.

On the first real solo ride-out I had on the blue Falco, to Jay's excellent Trentside bash, I felt that the spring rate was still too firm - kicking me out of the seat over bumps I felt should have been absorbed. So I contacted a local Sheffield spring firm (springoil.co.uk) and got them to make me a spring with a rate of 8.25kg/mm (462 lbs/in) - a reduction of approximately 15% over standard.

I finally got it fitted today and went out for a blat over some of the adjoining Peak district roads, and I have to say it feels just about spot on. Dodgy and rutted surfaces are absorbed, although you're still aware of them, but the bike feels planted and well in control over the faster stuff. It also feels much more balanced with the front end (progressive Wilbers springs and Race-Tech Gold valves in the forks). I weigh around 11 stone in jeans and T-shirt, I hasten to add.

What are other people's experience with shock spring rates?

HisNibbs · #2 Post by **HisNibbs** » Sat Jul 12, 2014 9:42 pm

Running Mille R Ohlins and linkages. I weigh in just under 12 stone. Always thought it feels just right with one of my daughters on the back, so totaling about 18 stone but a bit firm solo. Sill it provides a more compliant ride than either of the BMs. Suppose it's to be expected from a bike with a dual seat! If it was right solo then it'd be a liability two up with a bit of luggage.

#3 Post by **mangocrazy** » Sat Jul 12, 2014 9:54 pm

Yes, take your point Keith. Spring rate is always a compromise. That's why I've got remote hydraulic preload adjusters on both Falcos, so I can find a decent setting when two-up. Playing around with C-spanners all the time is definitely a no-no.

I try and get spring rate so that it's correct solo with zero preload, which gives me a decent range of adjustment for passengers, luggage etc.

HisNibbs · #4 Post by **HisNibbs** » Sun Jul 13, 2014 10:35 am

Pre load adjustment is only going to go so far by maintaining the starting point. Throw in a bump and taking changes in damping out of the equation, the spring compression is going to be nearly double with nearly double the weight on board. So as I do some two up and some one up and loaded with camping gear, I've lived with the compromise. If I recollect last year, when I had my shock rebuilt I did persuade John to fit a lighter spring but I think he didn't drop the rate by much.[/i]

#5 Post by **mangocrazy** » Sun Jul 13, 2014 11:44 am

You're right Keith - you can only do so much with preload adjustment. Unless you're a solo-only rider or do all your riding two-up, it's always going to be a compromise.