I think "advise" would be too strong a word on my part. I don't know of any problems with using a concentric. A handful of bikes have used them for decades. It does move the trail half way in between solo Girdraulic and side car Girdraulic. It also pre loads the springs slightly more than solo. This is not an issue with the short springs, but it increases the pre load on old springs.
I am not sure that the taper roller steering head bearings improve the steering as ball races are still considered top quality. I wanted taper rollers because I would take the racer apart routinely and I came to dislike the extra difficulty of disassembly and assembly. One aspect of the taper roller conversion I did not like was locating the cone on the steering stem. I have looked at many stems and they are not necessarily round as that was not necessary. With the taper roller being held tightly on the steering stem, I would think the new steering stem would be superior to the old.
I should mention that although I do not sell my steering stem with the new geometry, I designed my modified steering stem for eccentrics, so not all new geometry stems are made for concentric bearings. Mine uses the stock spindle with eccentric and can be used with a side car.
David
I am not sure that the taper roller steering head bearings improve the steering as ball races are still considered top quality. I wanted taper rollers because I would take the racer apart routinely and I came to dislike the extra difficulty of disassembly and assembly. One aspect of the taper roller conversion I did not like was locating the cone on the steering stem. I have looked at many stems and they are not necessarily round as that was not necessary. With the taper roller being held tightly on the steering stem, I would think the new steering stem would be superior to the old.
I should mention that although I do not sell my steering stem with the new geometry, I designed my modified steering stem for eccentrics, so not all new geometry stems are made for concentric bearings. Mine uses the stock spindle with eccentric and can be used with a side car.
David