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Wheel offset for an R12?
- schrader7032
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Wheel offset for an R12?
I don't know if this applies to the R12, but here's the website for a recent article on /2 wheel building. Down towards the bottom is a discussion about offset.
http://agwalker.com/wheelbuilding.html
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- Darryl.Richman
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Wheel offset for an R12?
- schrader7032
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Wheel offset for an R12?
For my own education, what's the purpose of the offset? Is it to put the hub in a position that "works" for the rim and also "works" for the frame? Obviously, the hub should be somewhere between the two outside edges of the rim. But I guess it could be moved closer to one or the other in order to mate with the final drive all the while keeping the two edges of the rim more or less centered between the frame, or at least in the position to track with the front wheel. Is that about it? Is there any way to compute what the offset should be based upon the known dimensions of the frame?
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- Darryl.Richman
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Wheel offset for an R12?
There's a two page document that shows all of the set up information for the R12, but it doesn't include this value. Likewise, neither do the various "Betriebsanleitung" manuals I've perused. There are some drawings indicating the centerline of the bike (for sidecar setup), but curiously, the war bike drawing contradicts the civilian drawing about where the centerline really is.
Finally, the reason I'm so interested in this is that I'm having the frame straightened by The Frame Man in Sacramento, and they wanted me to build a wheel so they could use it to align the frame!
A supplier I use and rely on in Germany has told me that it's not critical, and a few mm either way won't be noticable. He suggests that I lace up the wheel counting the number of turns on the spoke threads to get to a "natural" position. That might be true, too, but I'd like to hear about it from more than one source, before I make a mistake with spokes and nipples I paid to have painted...
- schrader7032
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Wheel offset for an R12?
http://www.vintagebmw.org/current/news- ... tech13.htm
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- schrader7032
- Posts: 9058
- Joined: Fri Oct 27, 2006 3:00 am
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Wheel offset for an R12?
I ran across this on the /2 forum...maybe he could do a measurement for comparison??
http://www.bungeebob.com/R12Photos.html
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.
- Darryl.Richman
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Wheel offset for an R12?
Considering the conditions of roads when these bikes were current, the low top speeds they attained, and the apparent lack of detail in the manuals regarding rebuilding them, I have to suppose that the numbers aren't that critical to the bike's performance. Still, after the time and money I've sunk into this, I'd like to make the best of it I can.
- Bruce Frey
- Posts: 536
- Joined: Fri Oct 27, 2006 3:00 am
R12 wheel
I would ask Vech, Huggett and the Archives.
There has been discussion in the Kradrider group whether the rims should be centered in the frame or not, but I can't imagine German engineers designing them to be off center.
Best regards,
Bruce
- Darryl.Richman
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Wheel offset for an R12?
27 January 2004 - I contacted the BMW Historical Archives in Germany to see how much higher the hub should be relative to the rim. They found an original dimensioned wheel drawing and the distance is 7mm. Tonight I disassembled the rear wheel. Some of the spokes came loose. Others were rusted solid and had to be cut off.
Wheel offset for an R12?
Before I disassembled the old ones, I measured the offset of the hub from the wheel. Needless to say, the wheels had different offsets. The really crooked wheel varied by nearly 4 mm depending on where I measured, but even on average, it was 6 mm different from the straight(er) wheel.
So, I wonder if anyone out there knows what the correct offset really is?