Recog­nis­ably a BMW, but a rather rare sight to­day. Alan Cath­cart tells the tale of a very early flat twin

Recog­nis­ably a BMW, but a rather rare sight to­day. Alan Cath­cart tells the tale of a very early flat twin

Real Classic - - What Lies Within - Pho­tos by Kel Edge

The early days of BMW AG ex­actly a cen­tury ago saw it born of a strug­gle for survival, af­ter the 1918 Treaty of Ver­sailles which ended World War 1 banned the man­u­fac­ture of air­craft in Ger­many. BMW (as in Bay­erische Mo­toren Werke AG) had been founded two years ear­lier in a re­or­ga­ni­za­tion of Rapp Mo­toren­werke, a Mu­nich-based air­craft en­gine man­u­fac­turer, so to stay alive it was forced to turn to mak­ing in­dus­trial en­gines, agri­cul­tural ma­chin­ery, tool­boxes, of­fice fur­ni­ture, and then fi­nally, in 1923 – mo­tor­cy­cles.

BMW’s suc­cess­ful strug­gle to sur­vive was largely funded by Italo-Aus­trian banker Camillo Castiglioni (no re­la­tion to the cur­rent owner of MV Agusta), who was ac­claimed as the wealth­i­est man and most in­flu­en­tial fi­nancier in Cen­tral Europe dur­ing WW1, and who un­til 1929 was Pres­i­dent of BMW AG. In 1921 BMW had be­gun man­u­fac­ture of its M2B15 flat-twin mo­tor, orig­i­nally de­signed by its chief en­gi­neer Max Friz as a por­ta­ble in­dus­trial en­gine. It was also used in mo­tor­cy­cles such as the Victoria and the He­lios, which gave

BMW the in­spi­ra­tion to build its own bikes. So in 1923 the R32, the first mo­tor­cy­cle to be badged as a BMW, was launched. It fea­tured a 486cc wet-sump side-valve en­gine with hor­i­zon­tally op­posed cylin­ders and shaft fi­nal drive, a flat twin lay­out which would for­ever be associated with the mar­que.

The R32 was the pro­to­type for all fu­ture Boxer-en­gined BMW mo­tor­cy­cles, and em­ployed a tubu­lar steel rigid frame, like its suc­ces­sor mod­els the R42 and R52. These also fea­tured 500cc side-valve mo­tors like their an­ces­tor, but BMW also de­vel­oped the higher per­for­mance ohv R47 and R57 500cc duo. 1928 saw the ap­pear­ance of BMW’s first 750cc mod­els, the side-valve R62 and ohv R63. The lat­ter re­mained the sporti­est BMW built un­til the end of the 1920s, with an out­put of 24bhp and a top speed of over 75mph, while like its hum­bler sis­ter still main­tain­ing the tubu­lar steel frame, with leaf-spring front sus­pen­sion.

Un­hap­pily, this frame de­sign was in­creas­ingly caus­ing re­li­a­bil­ity prob­lems across BMW’s en­tire model range, par­tic­u­larly when a side­car was fit­ted. This was be­com­ing in­creas­ingly pop­u­lar, es­pe­cially on the R62, both for fam­ily use, but es­pe­cially by the Wehrma­cht (the Ger­man army), even in the days be­fore Hitler came to power in Jan­uary 1933. The in­creased power and es­pe­cially torque of each new gen­er­a­tion of BMW en­gines, cou­pled with the ex­tra weight of the side­car’s pay­load – which in mil­i­tary use fre­quently saw two armed sol­diers be­ing car­ried aboard the mo­tor­cy­cle, and of­ten a third on the side­car, com­plete with the weight of their ri­fles and some­times a ma­chine-gun and ammo – led to the frame frac­tur­ing, usu­ally around the steer­ing head, where the welds just weren’t up to the job of sup­port­ing all that ex­tra weight. The girder forks also had a propen­sity for col­laps­ing, so some­thing def­i­nitely needed to be done.

At the Ber­lin Show in Novem­ber 1928 BMW dis­played an en­tirely new method of con­struct­ing its mo­tor­cy­cles’ frames, the ori­gins of which lay in its ac­qui­si­tion the pre­vi­ous year of the Dixi car com­pany, then mak­ing Austin Sevens un­der li­cence from the Bri­tish man­u­fac­turer. Dixi’s fac­tory in Eise­nach – later, af­ter end­ing up in the DDR post-WW2, to host pro­duc­tion of Wart­burg cars pow­ered by a three-cylin­der two-stroke en­gine de­rived from the Bri­tish Scott-3 mo­tor­cy­cle’s pow­er­plant – also pro­duced rail­way equip­ment and track, which ne­ces­si­tated the in­stal­la­tion of mas­sive 1000-tonne hy­draulic presses.

So not only did BMW con­tinue mak­ing the Austin Seven – re­badged as a BMW Dixi, which thus con­sti­tuted its en­try into the car

mar­ket – but it also evolved a com­pletely new range of pressed-steel chas­sis made at Eise­nach for its mo­tor­cy­cles, both twins and sin­gles. It would con­tinue us­ing these right up un­til 1942, when it re­verted to cir­cu­lar and oval-sec­tion steel tub­ing for its mo­tor­cy­cle frames.

These new much more ro­bust pressed steel chas­sis equipped the two new 750cc mod­els launched at the Ber­lin Show, pro­duc­tion of which be­gan in Septem­ber 1929 at a re­tail cost 5% higher than the steel tube-framed R62/R63 mod­els they re­placed car­ry­ing the same en­gines, al­beit with a 10kg weight penalty for the more durable con­struc­tion of their dou­ble-cra­dle rigid frames. One of these was the 735cc R16 ohv twin re­plac­ing the R63, 1106 units of which would be built in the next five years, along­side its side­valve sis­ter, the 30% less ex­pen­sive 745cc R1, which su­per­seded the R62.

Pro­gres­sively im­proved year on year, in an early demon­stra­tion of what would be­come BMW’s tra­di­tional de­vel­op­ment strat­egy, the R11 was built in five dif­fer­ent series up to 1934. Ex­actly 7500 ex­am­ples of this rel­a­tively aus­tere but work­man­like model were man­u­fac­tured for both civil­ian and mil­i­tary use be­fore it was re­placed in 1935 by the R12. This used the same 745cc side­valve mo­tor, and as such it rep­re­sented BMW’s first vol­ume pro­duc­tion model. The work­force at BMW’s Mu­nich fac­tory rose to 3000 by the early 1930s once R11 pro­duc­tion was in full swing, cou­pled with a fur­ther 1500 at Eise­nach, al­beit also build­ing Dixi cars and rail­way equip­ment.

BMW’s rel­a­tively vi­bra­tionfree flat-twin en­gine was al­ready noted for its smooth­ness and re­fine­ment. Cou­pled with its three-speed shaft-drive trans­mis­sion and new, more rugged frame and front sus­pen­sion, this made the side­valve R11 one of the most pop­u­lar large ca­pac­ity mo­tor­cy­cles of its time in Ger­many, es­pe­cially with its vaguely Art Deco styling with a black paint scheme and white pin­strip­ing. Notwith­stand­ing its re­duced horse­power com­pared to its ohv sis­ter – the R11 pro­duced 18-20bhp de­pend­ing on the year, against the ohv R16’s 25-33bhp – the more hum­ble of the two mod­els sold best. It was no doubt aided by that lower price in de­liv­er­ing sub­stan­tially in­creased torque ver­sus its ohv sis­ter model, as well as the re­duced man­u­fac­tur­ing costs of a sim­pler side­valve mo­tor and eas­ier ser­vic­ing thanks to the re­duced com­pli­ca­tion of its valveg­ear.

Be­sides the frame, BMW also used steel press­ings for its new bike’s trail­ing-link fork. The F66 chas­sis for the R11 con­sisted of two large press­ings, one for each side of the frame, riv­eted to­gether at the steer­ing head to form a twin-loop dou­ble-cra­dle chas­sis, with strength­en­ing cross mem­bers mounted across the top of the en­gine. Sub­stan­tial gus­set­ing fur­ther re­in­forced the steer­ing head, and pro­vided a place for BMW to po­si­tion its al­ready fa­mous blue and white roundel badge. The sep­a­rate 14-litre fuel tank was po­si­tioned within the frame and

pro­tected by the large gus­sets, so it was well shielded in the event of a fall in any of the ar­du­ous cross-coun­try tri­als and races the bike was en­tered in, of­ten with a side­car at­tached, let alone in mil­i­tary use.

Fit­ted with what would be­come BMW’s fa­mil­iar trans­verse kick­starter that had been in­tro­duced on its Boxer twins for 1928, the R11 also fea­tured many neat touches. These in­cluded the tool­box con­tained within the gear­box cas­ing, just be­low the kick­start mech­a­nism, and the cast al­loy foot­boards front and rear – the lat­ter in case a pas­sen­ger seat was sub­sti­tuted for the lug­gage rack fit­ted as stan­dard. BMW was also a pi­o­neer in the use of a cen­tral stand as on the R11, rather than the less con­ve­nient rear stand which had to be clipped onto the mud­guard be­fore de­par­ture. 19-inch wheels were fit­ted front and rear – again, an avant-garde de­ci­sion by the stan­dards of the day, rather than the more com­mon­place larger di­am­e­ter but nar­rower rims.

The R11’s trail­ing-link fork was also com­posed of steel press­ings, with a tubu­lar steel loop run­ning from the axles, up and over the sub­stan­tial and quite deeply valanced steel front mud­guard, to op­er­ate the sixleaf lam­i­nated spring which con­sti­tuted the front sus­pen­sion. There was ini­tially no damp­ing, be­fore the fit­ting of an ad­justable fric­tion damper to the fork for 1932. Brak­ing was pro­vided by a 200mm sin­gle lead­ing­shoe front drum, but rather than a rear brake lo­cated in the wheel, BMW cu­ri­ously mounted one act­ing on the trans­mis­sion fi­nal drive shaft, ini­tially with 37mm shoes in a three-rib hous­ing be­fore these were in­creased in size for 1930 to 55mm, in a four­rib cas­ing.

Weigh­ing 183kg dry, with an un­usu­ally for­ward-look­ing 53/47% frontal weight bias, in spite of its in­creased cu­bic ca­pac­ity the ro­bust and solid-look­ing R11 was how­ever some­what of a slug­gard, with a top speed which never ex­ceeded 62mph dur­ing its five years of pro­duc­tion, against its costlier ohv R16 sis­ter’s even­tual 78mph in 1932 guise on­wards.

The Typ M56 flat-twin side­valve en­gine pow­er­ing the R11 mea­sured a very mod­ern square 78 x 78mm for 745cc, and was a car­ry­over from the pre­vi­ous tube-frame R62 model, with cast iron cylin­ders mounted on a light-al­loy crank­case, and the 2.5-litre

oil sup­ply car­ried in the sump, rather than in a sep­a­rate oil tank as was then al­most ubiq­ui­tous else­where. Run­ning a lowly 5.5:1 com­pres­sion ra­tio and orig­i­nally fired by a Bosch mag­neto (light­ing was an op­tional ex­tra) it pro­duced just 18bhp at 3400rpm, al­beit with plenty of low-down torque. That torque was a key rea­son for the R11’s pop­u­lar­ity, es­pe­cially in side­car use, cou­pled with a 3-speed gear­box with hand-shift on the right and shaft fi­nal drive via a sin­gle­plate clutch.

Ini­tially, the R11 was fit­ted with BMW’s own triple-jet 24mm car­bu­ret­tor serv­ing both cylin­ders, although for 1932 and the third­series model this was re­placed by a bought-in same-size Ber­lin-made SUM CK3/500 carb, which aided cold start­ing by hav­ing pre­heated sec­ondary air drawn through a tube from the ex­haust man­i­fold. In due course, in 1934 the fi­nal ver­sion of the bike fi­nally fea­tured twin carbs, a pair of 25mm Amals made un­der li­cence from the UK by Fis­cher in Frankfurt. This also had the hand gearshift lever mounted closer in to the fuel tank, op­er­at­ing within a pad at­tached to the top of the frame.

The R11’s length­ways crankshaft orig­i­nally fea­tured twin-row big-end roller bear­ings, but for 1933 this was re­placed by sin­glerow caged rollers. The fol­low­ing year the fi­nal fifth-series ver­sion of the M56 en­gine saw the camshaft now driven off the front of the crankshaft by a qui­eter roller tim­ing chain in­stead of gears, and it also fea­tured bat­tery and coil ig­ni­tion for the first time on a BMW mo­tor­cy­cle. Cou­pled with the twin Amal carbs this in­creased power to 20bhp at 4000rpm (there was still a less pow­er­ful sin­gle-carb ver­sion made for the Wehrma­cht), and a few R11 Series 6 mo­tor­cy­cles were also built with a four-speed trans­mis­sion, as a pre­cur­sor to the R12 which re­placed it for 1936 – still with a pressed-steel frame, but with the added ben­e­fit of the first tele­scopic fork with hy­draulic damp­ing.

With 7500 ex­am­ples built over its five-year pro­duc­tion span – a sig­nif­i­cant num­ber for any man­u­fac­turer back then – the BMW R11 isn’t that much of a rar­ity nowa­days, but it is an im­por­tant land­mark in the de­vel­op­ment of Ger­many’s largest man­u­fac­turer. It even has a re­cent claim to movie star­dom, with an ap­pear­ance in Wes An­der­son’s 2014 film

The Grand Bu­dapest Ho­tel set in the 1930s, as the bike rid­den by Willem Dafoe’s hood­lum char­ac­ter J.P. Jo­pling. A fine ex­am­ple of the first series 1929 model is to be found in the Sammy Miller Mu­seum on Bri­tain’s South Coast bear­ing frame no. P1450 and en­gine no. 65542 – early num­bers de­not­ing that it comes from the very first year of pro­duc­tion.

The chance to take it for an af­ter­noon spin pro­vided a win­dow on the world of the early-30s, when ro­bust­ness and dura­bil­ity were keen at­tributes of BMW’s line-up that were ap­pre­ci­ated in ex­port mar­kets like Italy and France, as well as in Ger­many – and the UK, where this bike was de­liv­ered new, as at­tested by its MPH speedo by VDO.

To start the R11 you must fol­low a pro­ce­dure in­tro­duced only the pre­vi­ous year by BMW, which later be­came com­mon­place on all their mod­els. Put it on its easy-on/ easy-off cen­tre­stand, then stand on the left side of the bike, tickle the sin­gle carb un­til it’s prop­erly flooded, re­tard the ig­ni­tion via the left twist­grip, pull out the kick­starter at­tached to the rear of the gear­box from its place tucked away un­der the seat above the large Ex­ide bat­tery, then kick with your right foot while work­ing the right twist­grip’s throt­tle to catch it as it fires into life. With its lowly 5.5:1 com­pres­sion the R11 is easy to start, with a pleas­ant but sub­dued though still dis­tinc­tive crack from the ex­haust, which could only be from a flat-twin BMW with its 180° crank.

Climb aboard the com­fort­able Ra­gusa rub­ber seat, which has enough travel in its springs to ob­vi­ate the lack of any rear sus­pen­sion, look for the cast-al­loy foot­boards nestling be­neath the well-finned cylin­ders, grasp the wide han­dle­bar which gives heaps of lever­age for hus­tling the BMW through city streets and wind­ing coun­try lanes, grab the light-ac­tion clutch lever on the left, and en­gage bot­tom gear by pulling the gearchange lever up and back with your right hand. How­ever hard I tried I couldn’t avoid graunch­ing the gear as it went in, but be­ing su­per low – prob­a­bly to take ac­count of car­ry­ing three sol­diers and a tommy-gun! – it was soon time to change up to sec­ond by push­ing the lever down and away from me, and that was much smoother, ditto the shift to third (top) gear. The R11’s side­valve en­gine is so torquey that it was very happy to stay in top gear even for slow 15-20mph bends, re­quir­ing no clutch slip to mo­tor cleanly away from a slow speed, up to the com­fort­able 50mph cruis­ing speed.

I’d ex­pected this vin­tage BMW to have a rel­a­tively mod­ern feel, but in­stead the rid­ing po­si­tion was a lit­tle cu­ri­ous, with the seat down low and han­dle­bar quite high. Although the long foot­boards let me put my feet where I wanted to, there wasn’t quite enough space for me to use the for­ward sec­tion, else the toes of my boots would have been burned by the heat off the cylin­ders as I wedged them in. Not sure how Wehrma­cht

feet could fit in there – sorry about the spit’n’pol­ish toe­caps on your boots, Fritz!

You want to avoid bumps in the road sur­face wher­ever pos­si­ble, with no rear sus­pen­sion and a prac­ti­cally rigid front end as well. Those lam­i­nated leaf springs didn’t have a lot of give in them, so the BMW front end would hop in the air if you hit a se­ri­ous bump. The 200mm front brake worked pretty well, which was for­tu­nate since the rear trans­mis­sion brake was quite in­ef­fec­tive – no won­der they in­creased the width of the shoes af­ter this first-year model.

The de­but of the R11 model ex­actly 90 years ago this year came at a time when the on­set of the Great De­pres­sion in the USA had pro­duced a se­vere shock­wave in Ger­many. Un­em­ploy­ment grew rapidly, reach­ing 4 mil­lion by 1930, and it’s some­thing of a mir­a­cle that as many as 7500 ex­am­ples of this model were man­u­fac­tured – and sold – dur­ing a pe­riod of mas­sive re­ces­sion in its home mar­ket, up to and in­clud­ing the end of its pro­duc­tion in 1934, dur­ing a time when Ger­many’s post-war Weimar Re­pub­lic was crum­bling. But the fleets of such BMWs in mil­i­tary guise equipped with side­cars be­came an ever more reg­u­lar fea­ture of Hitler’s rule – such as the 400 R11 side­car out­fits car­ry­ing 1200 Wehrma­cht sol­diers be­tween them, which pa­raded past the Führer in Ber­lin on April 20, 1936 to cel­e­brate his 47th birth­day. Within four years they would be used on the bat­tle­fields of Europe, many of them never to re­turn. Sammy Miller’s sur­vivor has spent all its life in Bri­tain, as a demon­stra­tion of Ger­man series pro­duc­tion ex­cel­lence at the most dif­fi­cult time eco­nom­i­cally in the mod­ern era – well, up un­til 2008, at least…

Imag­ine, if you can, rid­ing one of these on UK roads in 1929. Con­ti­nen­tal ma­chin­ery was con­sid­er­ably dif­fer­ent to most of the home of­fer­ings A glimpse inside to show the work­ings

Above: Power is de­liv­ered by a side­valve flat twin, while rider com­fort is pro­vided by awe­some cast al­loy foot­boards and a sprung sad­dleRight: Lots of bikes get de­scribed as ‘mo­tor­cy­cle art’. Well… we reckon that this is cer­tainly that! Inside the en­gine. Sim­ple enough, and neatly ef­fec­tive

It might be true to sug­gest that op­er­at­ing the BMW’s hand shift did not come en­tirely nat­u­rally… The 1930 Ital­ian BMW en­duro team, with two ohv R63 750s on the left and a soli­tary R11 side­valve to the right

That front end again, show­ing the trail­ing link de­sign and the 200mm front brake worked ‘pretty well’ Above: Shaft drive (of course), hand shift for the three speed gear­box driven by a big twin. All wrapped in a pressed steel frameLeft: Pos­si­bly the most re­mark­able fea­ture of all lives at the front, where the wheel’s sus­pen­sion is pro­vided by a lam­i­nated leaf spring con­trol­ling the trail­ing link

Right: The rear wheel it­self doesn’t carry a brake. In­stead, there’s a trans­mis­sion brake liv­ing inside the finned cas­ing where the drive shaft at­taches The fuel tank con­tains both the fuel filler (com­plete with an in­ter­nal fil­ter) and the speedo, and is it­self con­tained inside the top frame rails

Some con­cen­tra­tion is re­quired un­til fa­mil­iar­ity be­gins to grow. Chilled an­kles would never be a prob­lem here…

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