Back again with some comments on the upper link bearing mount.

On the left, the actual mount, to scale. On the right, the nearest correct way to do it - an elastic retainer ring holding the bearing in its recess.



This is a suggested (IMHO good) correction for the existing frames, to scale, using a standard pair of 6703 bearings that fit in the recesses for the bolt heads. Needs a new pair of bolts as drawn - I have a mechanic workshop in the neighborhood, and will check if they can do this and for how much. Probably cheaper if I can order a certain number of pairs. A minor issue is the tolerance of the carbon width (approx. 3mm) between the two bearings, and whether the inner race of the new bearing will rub against the carbon. I've ordered a pair of 6703s to experiment with.

It is worth showing the link assembly issues with pictures rather than just words to get the message better across, so I've drawn some (not to scale, dimensions exaggerated, showing the principles).

This is the 831 assembly of the upper link to one of the rear triangle eyelets, as far as I could make it out. Grey is the aluminum link, black the carbon triangle, blue the ball bearing and pink the screw. The screw presses the inner race of the bearing against the link, so the screw and inner race are one piece with the link. There is some clearance between the screw head and the triangle so that the parts can rotate with respect to each other.





This assembly would be alright if the two eyelets of the triangle (only one shown) were perfectly rigid relative to each other, but that is not the case. So, what prevents the outer bearing from sliding out of the triangle eyelet (to the left) is in practice only the press force of the outer bearing race in the eyelet, as Maffly stated.

Inevitably, when the triangle is submitted to lateral forces, the bearing will end up sliding to this position, where the eyelet contacts the screw head, and rubs against it as the triangle and link rotate relative to each other. After a while, clearance may build up between the outer race and the eyelet, whereby the bearing will move freely in and out... The rubbing with the screw head will cause wear and potentially loosen the screw...





The situation wouldn't be improved if the bearing were pressed from the outside. The bearings should be in the link, not the triangle, as per the SC assembly shown below.





Yellow is a tube for taking up some of the axial force exerted on the bearings by the screw. Here, the bearings are mounted in the link and rely on the rigidity of the link between the two eyelets. The bearings cannot slide out.

Dammit, the 831 link and triangle need to be redesigned!!

A not too drastic redesign would be to provide something for keeping the bearing in the eyelet, such as a retainer ring.

What about the assembly of the lower link to the triangle? I haven't looked close at that yet.