A request for a measurement, please

[WintrSol]

With all the recent talk of ride height and lower seats, a question about my ride comes up. I have Goldwing air shocks, and can set the height just about anywhere, but would like to know what the stock setting would be. If someone could measure from a sprung hard point near the rear to ground, I would appreciate it, if only to get the steering geometry where it should be.

TIA,
Rick

[Cracker Jack]

With the air shock almost certainly having a different spring rate, probably a better measurement would be to measure someone close to your weight on an unmolested stock suspension with them putting their weight on the bike then use that measurement with you on your bike and adjust the pressure to match that measurement.

What you are looking for is to match the height loaded I think.

[Jess from VA]

OE shocks are 13" center to center of bushing mounts.

I would suppose the sag compression under rider's weight (or just the bike alone) would vary, not only based on the rider's weight, but the age and wear of the individual shocks, whether OE (interstate or other), or Progressive 412s, 440s, 444s, or 416s (air shocks).  And by tomorrow, all Valk shocks are pretty ancient, low miles or not.

I'm going to try and ride tomorrow.  I'll try and remember to center the bike up and measure from ground to rear fender tip, with no weight other than the bike (supervalk).  Older 13" 440s.

[98valk]

per Works shocks Goldwing GL1500 oem shocks are 13.75 eye to eye, unstressed.
And Valkyrie is 13.00 as already posted.

[WintrSol]

Shock length doesn't figure in, because mine can be changed to adjust the ride height. I don't need to know exact figures, just ballpark. Spring rate probably does figure in, though, so my nominal weight is about 170#, most days. Unloaded will do, though, as I don't think the little settling it does when I sit is that important. I have found that, if the pressure is too low, handling suffers, a lot. On the Dragon, it felt like it was falling into every turn, until I raised the back some; I just want to know approximately how it should feel if I had stock shocks.

[98valk]

Shock length doesn't figure in, because mine can be changed to adjust the ride height. I don't need to know exact figures, just ballpark. Spring rate probably does figure in, though, so my nominal weight is about 170#, most days. Unloaded will do, though, as I don't think the little settling it does when I sit is that important. I have found that, if the pressure is too low, handling suffers, a lot. On the Dragon, it felt like it was falling into every turn, until I raised the back some; I just want to know approximately how it should feel if I had stock shocks.

shock length does figure in. the bike sits that much higher without a person on it at zero air pressure vs same condition as OEM shocks. higher in the back means the Trail was reduced.
Goldwing GL1500 oem shocks are one air shock and one coil spring shock. honda stated could be ridden zero air pressure. there is no spring inside the air shock.

[Jess from VA]

OK, nearly centered up, my '99 IS with older (but non leaking) 13" 440s measure about 16.5" from ground to rear fender tip center.  Perfect forks with PS springs.  But.... a Goodyear Assurance TripleTred 205 60 at 40 psi in place (closest height to 180 OE bike rear tire).  Because of flat profile, it will be a little taller in leans than bike tires, but pretty close upright.  This is with me off the bike, my arms aren't long enough to do it sitting on the bike.  My shocks don't sag much if at all when I get on (195lbs); HD springs on those interstate shocks.

Really a quarter inch (maybe even a half) either way should not really affect overall handling very much, IMH and non-engineering opinion.  I think good functioning shocks and bushings (whatever they are) are more important than keeping geometry of the bike to pure spec.  But I think a lot of things.  

[WintrSol]

Thanks, Jess, that's what I need, so I can adjust the pressure.

It handles and rides very poorly with less than 30# pressure, so, since shock length only figures in at less than that, it still isn't an issue. I'll check it as soon as it stops raining.

[Itinifni]

I've always set my rear suspension pre-load or sag to approximately 1/3 of the total shock travel when fully laden.

I believe the stock Valk rear shocks have 120mm travel so set for about 40mm of sag. I know you're using different shocks but 30-40mm of sag should be in the ball park.

If you have a lift the best way to do it is raise the bike so the rear wheel is off the ground. Take a measurement eye to eye on the shock (interesting that my 97 std. shocks measure under 13" center to center).

Now load the bike as you'll be riding (passenger, gear etc.), measure the rear shock at the same two points (helps to have a friend do the measurement). If you have less than 40mm of compression let a bit of air out, more than 40mm add a bit.

When I first installed 416s on my GL1100 I took a few measurements and noted the correct PSI settings (one up, with my wife, wife and camping gear). Easy to set the pressure quickly for different situations after that.

The important measurement is shock eye to eye. Very rough estimate of the correct laden shock length would be 11.5", eye center to eye center. That should keep your steering geometry near stock regardless of shock length.

Matt

[WintrSol]

Thanks, but I already know how to adjust preload; what concerns me is steering geometry. If the rear is too low, the front wheel seems to flop into turns, because the rake angle is so high. When I raised the rear after a pretty nervous ride on the Dragon, it felt much better. I want to try setting the steering geometry to near stock, just to compare with where I had it set, to see if it gets better. I had the rear fender at ~15", measured as above; today, I raised it to just over 16", and will compare when it stops raining. If it isn't much improvement, it will go back to 15#, which is about 11psi lower (~39psi vs ~50psi). Of course, it is most important when pulling a heavy camping trailer; with it, I just run it up as far as it will go, connect the trailer, then adjust to match the unloaded height, if possible.

[WintrSol]

I adjusted the pressure to raise the hard point to just over 16", then remembered I had a clinometer app on my tablet computer. I checked the rake angle of the fork tubes, and it came in between 31 and 33 degrees - the tablet doesn't have a good flat side, so that's as good as it gets. At least, I'm very close to the 32.2 degrees in the manual.
Thanks for your help, Jess.

[Jess from VA]

Welcome.