Hi everyone,
I would like to throw in my opinion.
I think you have to define what is a better fork. I have a BMW R80ST, same as the G/S but with the 650 front end which has a shorter fork tube and a shorter rear shock. When it comes to riding a fully loaded bike like the G/S-ST that short suspension is nice because at 5'10" inches I can get my feet flat on the ground. No tiptoes for me. The new 1200 BMW, no way, a big brute. The trade off is ground clearance but how often do I need that with a good skidplate. The axle on the ST is directly under the fork, on the G/S it is in front of the fork. This affects the trail of the fork. GP road racers use my style, offroad bikes use the forward mounted axle as on the G/S. This is what defines stability in terms of turning and speeds up/slows down the steering(more or less trail). My ST will turn easily and in a very small circle but offroad it is very unstable on loose surfaces. It has broken my collar bone twice off road. You can only do so much to improve stability without sacrificing turning radius and I have pointed out the two main design possibilities. One thing you could do is stiffen the fork with a brace or stronger tubes or a stronger triple clamp. That the more modern forks can do.
The ST is a great bike on the pavement and the GS is great off road if only turning is considered. The rest of the fork absorbs the bumps and here springs really help to get the preload/sag right so the suspension can work within its travel correctly. On my ST I used stock fork oil. I believe the dampening works as well as the antique design will let it with 4 wt oil and it does not bottom or top in use. I use Works Performance 2 piece springs and a Works Performance big body rear shock with a resevoir. I can drag the cylinder heads on a bumpy paved road and hold a perfect line fully loaded with all my travel gear and 8 gallons of gas in my G/SPD tank mounted on the ST. As I said, off road is where the hell is for me. I just did 40K with this setup from the Yukon to Tierra del Fuego and back to the USA. No problems on road. Crashed off road due to my own error, caused by little O2 and sleep in Bolivia. No failures with the suspension, front or rear.
For much of my travels I rode with others, an African twin, a BMW PD single and a KLR. No problem running with these bikes on the road, off road they were more stable so a little faster but honestly they were all on pigs and unless youwant to be the fool we all better slow down and concentrate on riding safely. You dont need a better front end than the stock G/S has. It is good for what it is and well thought out. It works with the bike and frame. A stiffer fork just puts the problems elsewhwhere so maybe a bigger problem in the end. For a single rider and gear the G/S is fine with a good fork brace. Compare the G/S fork to the KLR side by side, which is stronger? Save your money and travel longer and sooner. Pack the bike well. I am looking for a stock G/S front end for my ST if anyone takes one off. I would love to have one. My bike has 180K miles.
Ride well.
BMWST Bill.