Air fork Conversion

[RichDesmond]

...preload will make a difference as well, (doesn't change the spring rate, but seems to change how much force it takes to get the spring to start compressing)...

Good point, and it's the other reason (the first being bottoming) that a too soft spring will actually be less comfortable than one of the proper rate. With a soft spring and a lot of preload, when the forks top out (which happens more often than you might think) it takes a lot of force to overcome all that preload and get the forks moving again, and that's felt through the bars as harshness. Stiffer springs with less preload make that transition much more smoothly and comfortably.

[Ecklund]

Another point to remember, though, is that "spring rate" is not all there is to suspension.

"Damping" is another point to consider. Some guys will put in 15w or 20w fork oil to "firm up" the suspension when using stock springs. That really does nothing to hold the bike up, it just slows down reactions. When braking hard, the bike will still dive, but will do it much slower. Only spring rate will keep it from diving as much.

Using a lighter oil, like 10w, along with the proper rate springs will go a long way to adding control while maintaining comfort.

.

Agreed.

This combo worked well for me. A set of fork springs that are 'correct' rate for me, emulators and 10 weight oil - as opposed to 15 wt.

Good suspension control at all speeds yet reacts well to smaller road irregularities.

[Steve]

I read an article once that was written by the suspension tech on a major race team. He was asked about some specifics about the damping on the race bike, and his answer was "I use the lightest damping possible that will still control the wheel and keep it on the ground." He wanted the wheel to move freely, but not bounce unctontrolled.

When I got my Wing, the previous owner had already installed Progressive springs in the forks, along with the recommended 15w oil. I noticed that at the end of an all-day ride, my wrists were hurting. I analyzed the riding position and found that it was not that much different than my previous bike, but I noticed the pain when I encountered small bumps, like expansion joints on the freeway. Simply switching the fork oil to 10w allowed the wheel to move freely, without the hydraulic lock-up that was jolting my wrists.

.

[RichDesmond]

I read an article once that was written by the suspension tech on a major race team. He was asked about some specifics about the damping on the race bike, and his answer was "I use the lightest damping possible that will still control the wheel and keep it on the ground." He wanted the wheel to move freely, but not bounce unctontrolled.

When I got my Wing, the previous owner had already installed Progressive springs in the forks, along with the recommended 15w oil. I noticed that at the end of an all-day ride, my wrists were hurting. I analyzed the riding position and found that it was not that much different than my previous bike, but I noticed the pain when I encountered small bumps, like expansion joints on the freeway. Simply switching the fork oil to 10w allowed the wheel to move freely, without the hydraulic lock-up that was jolting my wrists.

.

People are often surprised by how compliant a well-sorted race setup is, and by how little the spring and damping rates change from street use.
For example, on a street SV650 I use 0.85 springs. That's for a mix of commuting, touring and sport riding. The race bike uses 0.90s. Granted, the race bike is 45lbs lighter, but even adjusted for that we're still looking at less than a 10% difference. If I was going for a totally comfort-oriented setup I'd put in 0.80s. So the difference in spring rate between "plush touring" and "race bike hard" is just ~15%. The damping range is a little wider, but not much.

[Sci85]

Well, after consulting with Rich, I think I'm going to go with a set of the .85 springs and 10wt oil. I will post a full report if I get a warm day in to take it out.

Thanks everyone for the feedback. It's been a real help.

[derwood]

cartridge emulators practically eliminate the "hydraulic lock-up" on compression that is experienced with damper rod forks. It is caused buy trying to force oil through a fixed orifice at an increasingly rapid rate. The oil will not compress.
Once emulators are installed you can adjust /affect compression damping with the emulator spring and rebound damping with oil viscosity.

time consuming, but interesting and rewarding, but you have to write everything down, and not lose it.