Shifting Gears--Literally

When I first became a dedicated cyclist--around the time that the '70's North American Bike Boom was peaking--all derailleur-equipped bicycles had gear clusters (freewheels) that screwed onto the rear hub.  

Cinelli Bivalent Hub, circa 1961

That is, all of the derailleur-equipped bicycles I saw.  I'd read and heard about the Cinelli Bivalent hub, which was produced for a few years during the 1960's.  Other than that, I believed, there was only one sprocket system for derailleur-equipped bike, and your only concern was whether the hub had British, French or Italian freewheel threads. 

And, as far as I knew, the first departures--apart from the Bivalent--from such a system came around 1980, when Maillard introduced its Helicomatic system and Shimano came out with what was then called the Freehub.

Shimano 600 Freehub system, circa 1981

Shimano's system was essentially the same any of today's hub-and-cassette systems, save for those of Campagnolo, which have a different spline pattern.  The only major difference between those early Freehubs and today's Shimano and SRAM ensembles is that the on old Freehubs, which had six cogs, five cogs slid onto splines and the smallest one screwed on, acting as the lockring.  On current hubs, all of the cogs are joined as a cassette that mounts on the splines and is held in place by a separate lockring.

Helicomatic.  From a 1984 Peugeot brochure

When I first saw the Helicomatic, I actually thought it was a better idea than the Freehub.  I still do, and I think it's a better concept than any of today's hubs with cassette bodies.  The problem with the Helicomatic--as with another "revolutionary" French component of the time, the Huret Duopar derailleur--is that while it was a great concept, it wasn't well-executed.  Maillard offered lower- and higher- priced models of Helicomatic, and they suffered from the same problems:  soft helical spines (the "bayonet" mount) that often gouged or stripped, rather weak axles that frequently broke and, on the racing model, smaller-than-normal ball bearings that caused the cones and races to wear quickly and, in a few cases, "explode."

But the Bivalent, Helicomatic and Freehub were not the first systems to depart from the screw-on freewheel cluster.  Just recently, I became aware of another, which also employed its own unique rear derailleur.

In the early 1930s, Alex Shuttleworth and William Hill paptented the TriVelox system.  It had three rear cogs--which was all most derailleurs of the time could handle.  It also used a 1/8" pitch chain,  in contrast to today's 3/32" derailleur chains.  

But most improtant of all, the TriVelox derailleur--unlike those of today--shifted gears by moving the sprockets rather than the chain.  Apparently, the sprockets were fitted onto splines, much like the Helicomatic or Freehub cassettes. And the derailleur remained fixed while the freewheel block moved sideways on the hub.

Why was such a system developed?  It was a response to, as Michael Sweatman of Disraeligears says so eloquently, "a peculiarly British fixation with chainline".  British cyclists, by and large, shunned derailleurs--as they would until the 1950s--because using them meant running the chain out of line on the extreme gears (small chainring with smallest rear cog or large chainring with largest rear cog).

As Sweatman tells us, they had a point.  Roller chains are meant to run in a straight line.  Thus, while riders in Albion had an exaggerated fear of the friction incurred by running a chain out of line, they were correct in believing that chains wear out more quickly when they're run out of line, let alone bent and flexed when shifted on conventional derailleurs.

Bicyclists of that time had good reason to think about longevity:  Chains were comparatively much more expensive than they are now.  That is why people were more fastidious about keeping their chains cleaned and lubed--and why many bikes came with oil-bath chain cases, something that couldn't be used with a derailleur.

The TriVelox system did what its creators intended.  Walter Greaves rode such a system for 45,000 miles (!) in one year and used only two chains and two sets of sprockets.  In other words, his chains lasted about ten or fifteen times as long as a chain made for a current 10- or 11-cog system.

TriVelox seems to have been in production for about two decades.  It was never a mass-market item, but it had its following, particularly with tandem riders.  One reason why it didn't become more popular is that it was much heavier than conventional derailleur/freewheel/hub combinations.  Another is that the system required a very wide rear axle to accomodate the sliding freewheel system. That, of course, limited its development to three speeds because additional cogs would have required an even bigger axle.

But most important of all, by the 1950s, most dedicated cyclists were realizing that derailleur systems were reliable and practical, and would allow for more than three cogs without widening hubs or axles.

I came across a TriVelox set on eBay.  I'd be very curious to see it--and other predecessors of today's cassette-and-hub systems--up close.