[motoyoyo]

EZ and Nail have made a 12mm offset a-arm to test, so I decided to make one for myself to test as well so we can compare notes on the same setup. I have installed mine and have put almost 300 miles on it so far. Overall I would say it is successful but with mixed impressions so far. Unlike the 10mm offset which feels great immediately, the 12mm requires a lot more attention to suspension setup and even riding technique.

Let me start off by listing my original specs before any offset mods took place. My bike is equipped with a GS 365mm torque arm and a 5-1/2" wide rear wheel. The following is a typical setup for a good handling BCR spec'd with Ohlins shocks.

Rider Weight - 230 lbs
Ohlins Rear Spring - 17.0 kg/cm
Ohlins Front Spring - 6.2 kg/cm
Rear Laden Sag - 32mm
Rear Shock Length - 323mm
Front Laden Sag - 34mm

With the 10mm offset a-arm installed, the only change I made was to lower the rear Ohlins clevis to 318mm overall length. This is basically the stock position the Ohlins come set at when you buy them. I did not change any other suspension settings and the bike performed really well right from the start. After a few thousand miles I did not feel the need to change the settings.

When I mounted the 12mm offset a-arm, I again attempted to ride the bike without making any changes in the suspension. Right away, I felt the bike needed more laden sag up front, and adjusted it to around 35mm rider sag. I rode the bike for a good 100miles and felt the front end was very harsh and did not seem to settle into turns too well. I came to the conclusion that the front spring was too stiff due to the geometry changes and not allowing enough suspension travel.

Before the next ride, I swapped the 6.2 kg/cm spring for the original 5.7 kg/cm spring and adjusted the laden sag to around 34-35mm. I also added some rear preload to bring the rear laden sag to around 30mm. I took the bike out for another 100 mile test run and found it to be much better than the previous test run. The suspension felt well balanced front and rear and it was very quick yet still stable.

I did feel that a more aggressive riding position was helpful in making the bike fall into turns as easily as the 10mm offset. A little more forward body positioning with arms bent gave the bike some pretty dang quick turning response. After another 100 mile ride I am still slowly gaining more confidence in the handling but can not say for sure yet if I would recommend the 12mm offset. I never felt any instability issues but it definitely takes a bit more concentration to feel comfortable on faster turns. It carves the tighter stuff like mad, but as far as an overall setup for all kinds of riding, it is still too early for me to say for sure.

I can still say without hesitation that the 10mm offset is an amazing ride that anyone will appreciate. The 12mm offset can be fun for an aggressive rider with the ability to work on suspension settings, but it is probably not necessary for having all the fun you could ever want, and still turn way quicker than any stock offset R1100S. I have one more a-arm to mod and I may try an 11mm offset just for kicks but I will take my time testing the 12mm a bit more first.

When I get a chance I will also try to get some measurements of the actual rake and trail on the current 12mm setup. Off hand, the rake looks steeper than I had perdicted it would be. Before making any more conclusions it would be helpful to know just exactly what rake numbers we are dealing with. I can say with a fair amount of certainty that any offset position more than 12mm would probably be too much for this bike and I won't even consider going in that direction.

I will be very curious to hear what conclusions EZ and Nail come to when they try out their 12mm offset a-arm. Also, EZ is more than qualified to make a-arms for anyone interested. I can easily recommend the 10mm offset, but if anyone is considering another offset I can not vouch for anything else as yet.