When I began riding bikes, 'very big' was 650cc. About 1970 sizes began to grow as Japanese makers began to muscle into the market by offering "MORE". Of course, from time to time, there had always been bigger machines, like BSA's 750cc triple cylinder Rocket 3, but these were expensive enthusiast machines, out of reach, or too fussy for mainstream motorcyclists. When the car-like 750cc 4 cylinder Honda arrived at the end of the sixties, all the rules changed. Most makers began scrambling to build bigger bikes. Triumph soon "matched" with a 750cc Bonneville twin. then Norton replied a year or two later with its 850cc Commando model. Ducati had made innovative 350 and 450cc bikes but now stepped up to the international market with a beautiful 750cc, later increased to 860cc. Laverda had been offering their fast smaller bikes but now they offered a beautiful 750cc twin and later they launched their 225 kph 1000cc triple.  Kawasaki heaved in for Japanese builders with a marvelous 900cc bike in the mid 70s. They then began to enlarge it. Meanwhile, traditionalist and conservative by nature, BMW was dragged into the race, their horizontally opposed twins stretching to 750cc, 800cc, then a beautiful 900c which was soon increased to 1000cc.

During my lengthy ride around Europe in the 1970s on a 650cc Triumph I became convinced the most critical dimension for any bike is not the size or power of its engine but its weight. If a bike lies down on the road, and there's just me to lift it back onto its wheels, then it is imperative the bike's weight should be a manageable lift. The bike should not lie down on the road of course, but Murphy's Law states if it is going to, it will always do it when there is no help at hand. From my point of view then, the significant measure for a motorcycle is 230kgs. I can lift that amount of weight unassisted.

As engine sizes continued to grow and the mass of big bikes passed 230kgs, passed 250kgs, passed 300kgs, passed 400kgs,motorcycling became sillier and sillier. Weight matters. Not only when recovering from a fall. Weight negatively affects the agility of the machine. The more mass, the more centrifugal force tries to drag the bike off line when cornering. The more mass, the greater the breaking effort required to stop the machine. The greater the mass the greater the potential loss of adhesion in wet or muddy conditions. The greater the mass the more quickly things get SERIOUS when they go wrong.

There's a good reason that most manufacturers held 650cc as a kind of 'agreed' upper limit for so long.

My current bike - the  BMW pictured above - is a 750cc triple (3 cylinders). At 223kgs it is on the border of being a manageable solo lift. Like me, it is getting pretty old now and with age it has acquired a certain patina. It has become a good friend. Although I am a conservative rider, every now and then it is fun to open the throttle wide. It can still turn on fireworks, with a marvelous wailing, snarling banshee scream ..... especially when the road is broad and open and not afflicted with intersections and traffic calming obstacles. Although a little top heavy, it is beautifully balanced. It slides easily up onto its center stand and when cornering, it leans alertly and skilfully into turns. It is a treat to slice through a series of familiar mountain bends. Mostly I use it now for touring.

I have copied this photo from the Internet (here http://www.b50.org/index.php?option=com_content&view=article&id=51&Itemid=12 ) since I can't find any of my own photos of this diabolically fabulous product of English industry's contempt for the paying public.
This bike had it all (on occasions when it would start!). It accelerated with alacrity, amid a deafening symphony of mechanical banging and clattering. And it pulsed. A deep sonorous vibration PULSED through it in a steady rising rhythm that somehow blended with the softest of rides. Rider and machine hung together unaware of the gravitational attributes of planetary life because it became weightless. Compared to other machines that had to be coaxed into movement and persuaded out of it, the 'beeza' simply burst into movement and it would stop on a pinhead. There is no acceleration to be experienced quite like the on / off kind.
Yes this bike had a defect though. It was English. It had a malevolent and revengeful nature. On a beautiful day it would start on first kick and then entice you to ride 300 kms. It would let you stop and start again through the day as often as you wished. However when you stopped to fill the tank for the ride home - at that point - it would fold its arms and stare you down, refusing every coaxing effort to start. Even after you had spent hundreds of dollars getting it collected and trailered home, it would still sit in the garage skulking, refusing to start. It could refuse for weeks and weeks. You'd just have to wait it out knowing, one day, for no reason any expert mechanic could give, it would just CHOOSE to start again. And once again you would get sucked in.

It was the sort of thing you can get saddled with. There's no way you can sell a bike that is so bad tempered. What can you say to a drooling enthusiast with a fist full of dollars after he has spent 90 minutes trying to kick the damn thing over? In the end I swapped it for some house plans. I guess an archaeologist will dig it up some day. It should be venerated like the iconic hero it pretended to be, but better looked at through a museum glass than owned. The pleasure it could give touched ultimates, but the despair and humiliation it inflicted were the full equal. And you know - no one else - only the English could ever build such a finely tuned and uncompromising thing. Its such a shame.

What a glorious thing this was. Actually I had 2 Bonnies between 1972 and 1976. A purple one that I sprayed black with hundreds of top coats of 'Clearcoat', so its surface was deep and glass-like; and the one shown here, that carried me all around Europe through 1975 and 1976. The thing I remember about these bikes is that they were wonderful to ride and just as good to own. They always started. You always arrived. You always enjoyed yourself along the way. They were quick. Not in the sense that modern fuel injected, multi cylinder, sling shots are quick, but quick compared to any other form of transport at the time. They accelerated smoothly but hard enough to keep you very interested. Around town the twin cylinder motor had plenty of torque and the gearbox ratios were exactly right. You could creep along in traffic just as easily as blast through a gap that suddenly opened. There was no feeling of ever being in the wrong gear, too high or too low. There was so much torque that riding two up was just as effortless. I "inherited" this blue bike from a former flat mate who'd brought it to Germany from Australia, and then rode it on to England via Scandinavia. I used it to cross through ice and snow and to tour far and wide on warm summer days. I rode this Bonnie across the lowlands of Holland and over the highest passes of the European Alps and  those memories are as fresh today as they were in 1976. I don't think there is any better way to experience autumn, than to be riding an old Triumph Bonneville through the Black Forest region of southern Germany, amid banks of gold and crimson leaves; the air laced with the 'fragrance' of wood fires drifting in plumes of blue grey smoke from kitchen fires. The journey remains so indelibly memorable after 35 years I can still feel the old bike beneath me when I close my eyes and think of some particular piece of roadway.