R51/75 History Now Complete!

The life and history of my 1950 BMW R51/75

Until recently, I only new half of the story of my R51/75.  But through a random twist of fate, and thanks to this very blog, I no longer have to imagine the early history of my motorcycle, I know it in fairly good detail.

My bike started life in Munich.  The project of Hans Bretzner (an Austrian born and German educated car designer) and a Mr. Brenner (race engine mechanic for famed German sidecar champion Walter Schneider).  The project was conceived of and begun in 1948 when Bretzner was only 18 years old.  The bike was ultimately completed in 1950.  It was constructed of new, original spare parts left over from the war.

In attempting to license the bike for road use, a 7 digit serial number was conceived, a combination of Hans's birthdate and his grandmothers house number. This proved problematic with the authorities later on as only 6 digit serial numbers were in use on BMW's at the time.  Ultimately the bike was licensed for street use in Germany and reportedly clocked 124 mph on the autobahn with the open megaphone exhaust.

Some time in the early fifties, Hans immigrated to the United States to work as a designer at GM in Detroit.  He sent for the bike in 1955, prior to which it was gone through at the BMW Works and fitted with full width hubs.

Around 1958, Hans took a job as a designer with Mitsubishi in Tokyo.  Realizing he could not take the bike with him, he reluctantly sold it to Mr. Billie Hummel.  Mr. Hummel and his wife enjoyed riding the powerful bike two up.  He proudly displayed the bike at the Detroit Auto Show, where it was well received.

In the early 60's, the bike was sold by Mr. Hummel to Dutch Becker in California.

Under Becker's stewardship the bike received new valves, specially made from Alfa Romeo racing  valves.  The work reportedly done by Taylor and Ryan Engine Rebuilding in Whittier, CA.

In the 60's, the bike traded hands from Becker to Tom Bell, who owned a gas station in Hollywood on Beverly, near La Brea.  Tom is undoubtedly the "hippie kid" who subsequently sold the bike to Duane Ausherman (some time around 1972).  Duane had run across Tom while at a motorcycle event in Visalia, CA.  Duane, then owner of BMW of Marin in the Bay Area, recognized the bike as something quite special.

One of Duane's mechanics, by the name of Art Pels, campaigned the bike at an AFM sponsored "Run what ya' brung" road race event at the Presidio in San Francisco.

The bike was purchased by Rod Miller, who in the early 1980's undertook a sympathetic restoration.  Work was limited to cosmetics and the motor was never torn down as it was always a strong runner.  Brian Hilton, mechanic for Ozzie Auer in Chico, CA fashioned new fenders for the bike.  Also added was a sportier Lugauer racing tank.

Miller later sold the bike to Bob Garrett of San Francisco.  By this time, the final drive was in need of attention.  Garrett sought out the help of legendary Bay Area machinist and mechanic Joachim Groeger.  Groeger was able to rework to final drive, but perhaps because of lack of interest or money, the bike was sold to Groeger.

It was at Groeger's shop in 2001 that I first laid eyes on the bike.  It was a wonderful machine with a large, powerful 750 motor tucked into the demure plunger frame.  When I came upon the bike, it had suffered from clutch problems. After years of persistence I struck a deal with Joachim to purchase the bike and together we rebuilt the clutch.

Later I reconditioned the top end, putting new piston rings and valves in.

I am indebted to Eric Hummel, son of second owner Billie Hummel for providing me with the photos of the bike from the late 50's and early 60's as well as filling in the information about the original owner, and builder Mr. Bretzner.

Finally, a tremendous thanks to Billie's wife, who was able to dig up the original sales ad from when her husband sold the bike in the early 60's!