I am trying to source a correct set of spoked wheels for my '76 R90S and need help. In all of the photos I am seeing of original R90S and /6 for that matter, the rear rim looks like the below photo from my '78 R80/7. However, every time someone offers me a set, the rear rim does not have the hump with the arrow pointing to it, it is just a larger flat spot as shown in the second photo. Can someone tell me definitively which rear R90s came with from the factory? I believe that they are interchangeable, but I want the period correct one. If the one I have on my R80/7 is the same that came on the R90S, what bike/years did the humpless one come on? If it could have come with either, is there any advantage of one over the other? The humped one seems better structurally but perhaps is heavier. From my '78 R80/7 stamped 9/77: What everyone tries to sell me as correct:
Hi Fronton It's ashame that you dont live in OZ i have what your looking for, actually a few of them (front and back wheels /hubs etc). If you get stuck and cant find one over your side of the pond send a PM.
Took a look at my two 90Ss and one's got the hump and the other doesn't. The one that has the hump, I've owned since 95 and don't think the wheel was ever replaced, but who knows? It could have been. Until you brought it up, I'd never noticed this before.
Thanks, sounds like it could have come with either. Perhaps only the '74 had no hump since BMW changed the front wheel for '75+, perhaps they tweaked the back wheel as well, just not the dimensions that mattered.
My 76 R75/6 has the hump and I know it is original. I am the second owner and I knew the first very well, and have known the bike since new.
Could be wrong, but I seem to recall that there was an issue with the spline coupling rivets flogging out on the /5, and the first of the /6. The factory solution was to provide more "meat" around the rivets - hence the hump. My '75 90/6 (owned since new) has the hump. GOB
From what I've heard, September was the month the new model year began. If your R90S was indeed built in August 74, it should be one of the last of that years production. Did it come with aluminum turn signals? Kick starter? /5 style handlebar switches?
My early R90s (94th ever built) has all of the early features; non-humped wheel hubs, aluminum turn signals, tape pinstriping, /5 style handlebar controls, and the fairing has the 2 holes under the headlight opening. I'm sure I'm forgetting some other quirks.
No kick starter, black plastic turn signals, new style switchgear, drilled disks, ribbed seat, curved mirror stalks etc. Full 1975 model Lokking up the chassis number gives August 1974 as date of manufacture
