R7 rarity

[bikerfish1100]

posted on another site, this is a stunning and amazingly unique machine.
http://www.sport-touring.net/forums/...c,36127.0.html

[jlaban]

That sure is something to see, thanks for the post.

John

[20774]

Peter Nettesheim had some additional pictures of this bike over on the VBMWMO forum. One of them that was pretty cool showed what was under the cover...opening it revealed the electrics.

[gstom]

That is one of the most knock dead gorgeous bikes I have ever seen. Thanks for posting!

[37071]

That is much more than a tarted up R12. Thank you for the pictures

[darrylri]

It was the first motorcycle in the world (normally the Americans claim these kind of titles) with a telescoping front fork. That feature found its way into production in the R12/R17. BMW had it so covered with patents, that if it would not have been for WWII, no other manufacturer would have had that feature for quite some time.

Not so. The Nimbus type C of 1934 was the first production motorcycle with a telescopic fork. What was different here was that it was also hydraulically damped.

And while it's true that BMW took out a lot of patents on the idea, they themselves completely revised the internal workings at least twice in the next several years. The R12 forks have compression damping only; while the R5 and then the R51 fork designs have rebound damping only.

The tank shifter for the 4-speed tranny had an "automotive" style H-pattern, also a first (and probably last) on a motorcycle.

Also not true. Z??ndapp of Nuremburg was making a 4 speed H pattern hand shift bike in their 1934 K500. (What's interesting to note is that the Z??ndapp gear boxes have 1st and 2nd on the outside and 3rd and 4th on the inside, while the R12/R17 bikes have it the other way round. Another interesting thing about the Z??ndapp gearbox is that it actually has no gears.) They expanded their line to include 600cc sidevalve and OHV models and even a flat four 800cc sidevalve, all using the same arrangement for shifting.

[dbrick]

Another interesting thing about the Z??ndapp gearbox is that it actually has no gears.

I'll bite: how are different gear ratios achieved without using gears? I can imagine a factory-like system of a series of belts (or chains), and pressure-actuated differentially-sized sheaves, but somehow I doubt that in a motorcycle gearbox.

[darrylri]

I'll bite: how are different gear ratios achieved without using gears? I can imagine a factory-like system of a series of belts (or chains), and pressure-actuated differentially-sized sheaves, but somehow I doubt that in a motorcycle gearbox.

No, you've hit the nail on the head: Z??ndapp had a set of sprockets on the input and output shafts and ran single row chains around them. It was "constant mesh" so to speak, and a set of shift forks and sliding dogs made the connection for power to flow.

Perhaps sprockets and chains wear faster than hardened gears, but they also don't need the elaborate shimming that BMW transmissions are (in)famous for. Since they run completely enclosed and in an oil bath, wear is greatly reduced. And replacing a chain is not a difficult effort.

[bmwdean]

For rarities, you gotta love the opposed fours with shaft drive -- Zundapp, Wooler, Brough, and (well, not so rare) 1975 Honda GL1000.



http://jeffdean2.home.att.net/brough.htm

[dbrick]

And don't forget the BFG, powered by Citroen.

[darrylri]

That Brough is sort of a Squariel, but sideways!

[bmwdean]

David,

I didn't know about the BFG-Citro?½n.

You learn something new every day.



Thanks!

[dbrick]

You're welcome, Jeff. It's an interesting bike - very reminiscent of BMW - and air-cooled to boot. I've seen two in museums in France, and there are several BFG clubs in Europe. Production was only a few hundred, I think, and ceased in the late 80s.

[bmwdean]

Here's all I have learned:

The BFG-Citro?½n of 1982 was powered by a boxer, stacked four-cylinder 1,299cc Citro?½n automobile engine and shaft final drive. About 450 of them were built in 1981 and 1982. One-quarter of them were purchased by the French police.

The motorcycle's acronym derives from its three designers, Louis Boccardo, Dominique Favario, and Thierry Grange. The motorcycle was designed in response to a 1978 contest initiated by the French Department of Industry.

[dbrick]

Your research is more accurate than my memory!