Wednesday, September 24, 2014

Retro Direct - Retro Cool

Back before derailleurs became the popular method for having variable gears on a bicycle, a number of different systems were tried with varying degrees of success. Of these various multi-speed systems, one of the more interesting would be the "Retro-Direct" system in which a rider has one gear when pedaling forward, but a different gear (usually the lower gear) when pedaling backwards.

The Hirondelle retro-direct shown here is probably the
definitive version of the system.
First patented in 1869 by Barberon & Meunier, the retro-direct system was further developed and refined by other companies at the turn of the 20th century, including Magnat & Debon, and Hirondelle. Some retro-direct systems used two chains, with chainwheels and sprockets on both sides of the bicycle, but one of the simplest and most reliable versions, introduced by Hirondelle, used a single chain that wrapped around a pair of freewheel cogs and an idler pulley in an almost "figure-8" arrangement. A double-chainwheel version, with an early design front derailleur, was also available and gave riders four speeds -- one such bike was pictured in Jan Heine's Golden Age of Handbuilt Bicycles. Hirondelle would continue to make 2- and 4-speed retro-direct bicycles well into the 1930s, even as derailleurs and internal-geared hubs were becoming almost ubiquitous. The simple reliability of the system kept it alive among some riders.

As seen in this little animated file, when pedaling
forward, the smaller cog is engaged, while the larger
one "free-wheels"backwards. When backpedaling,
the smaller cog "free-wheels" while the
larger one is engaged for a lower gear.
In the first decade of the 20th century, the Touring Club de France organized a series of technical trials to encourage improvements and developments in touring bicycles. In the 1902 trials, riders rode a course through the Pyrenees that included two climbs up the Tourmalet mountain pass. The retro-direct Hirondelles performed very well, though the gold medal in that year's event was awarded to a double-chain 4-speed bicycle built by Terrot. In the 1905 trials, which included passes through the Alps, an improved and simplified single-chain Hirondelle won the gold medal.

The simplicity and reliability of the retro-direct system comes from the fact that without derailleurs and shift levers, the only "shifting" a person needs to do is to reverse pedaling. Some have even believed the system to be beneficial because it would develop more and different muscles than forward-pedaling alone. That would seem to make sense, though I don't know of any studies to prove it. In contrast, from what I've read, it can be very difficult to generate the same kind of efficiency when pedaling backwards. Bicycle Quarterly's Jan Heine has tested a few retro-direct bicycles and found it difficult to back-pedal at any more than 45 rpm. I've read other impressions around the internet from people who have built their own retro-direct systems, and they seem to confirm that pedaling backwards is generally an awkward endeavor, and even more so when trying to do it out of the saddle. By the way, I have also read that a possible unexpected problem can present itself with an R-D drivetrain -- that pedaling backwards for an extended period can unscrew pedals from the cranks! A healthy application of loctite may be in order.

A 1920s Hirondelle, with double chainrings and
a unique front derailleur. (from
Nevertheless, a quick Google search for "retro-direct" will turn up numerous examples (many with how-to instructions) of home-built R-D bicycles. It's clear that such a system still has quite a following, if for no other reason than curiosity, or the "do-it-yourself" interest in building something "different." Though a typical retro-direct system engages the lower gear when backpedaling, a few of these modern home-built creations experiment with the opposite arrangement -- having the higher gear engaged when backpedaling. This may make sense if one considers that it's difficult to spin at a faster rpm (as one would do in a lower gear) when pedaling backwards. Some of these DIY bikes also incorporate a double-chainring crank and a front derailleur to get four speeds -- though it's worth noting that front derailleurs can only shift when pedaling forwards (it's also interesting to note that the front derailleur used on the 4-speed Hirondelle could be shifted in either direction!).

The only dedicated R-D hub on the market today.
Made by Curtis Odom.
While many examples of home-built retro-direct bicycles can be found out there, most (or more likely, all) of them use hubs that have been cobbled-together or adapted to accept two single-speed freewheels -- which is one of the fundamental necessities that makes such a system work. This can be done with a British/ISO-threaded bottom bracket cup threaded between the two freewheels. Unfortunately, that arrangement doesn't bode well for long-term reliability, as the freewheels are not well-supported.

Luckily for those interested in this alternative drivetrain, someone else who has caught the retro-direct bug is component maker Curtis Odom, whose vintage-inspired hubs are well-engineered things of beauty. Curtis was first commissioned to build a retro-direct hub for Hojmark Cycles in Germany, though he has since made several others. In fact, Curtis Odom is almost certainly the only person out there today who makes a dedicated retro-direct hub. Unlike the DIY versions out there, Odom's hub has a much longer threaded section which fully supports the two independent freewheels. Not only that, but just as with modern cassette hubs, the right side of the axle is well-supported by outboard bearings. Odom's R-D hub kit is available with an arm to hold the return pulley in position, which is a smart touch that makes it reliable when retro-fitted to bicycles that don't have a brazed-on attachment point for the pulley (as in any bike not custom-built for a retro-direct setup). See Curtis Odom's website HERE.

A modern, and beautiful, retro-direct bicycle -- built by Hojmark Cycles, with hubs by Curtis Odom. Note that the return pulley is attached to an elegant little brazed-on mount on the chain stay.

Retro-direct is an interesting curiosity of an alternative drivetrain. I don't think it's a system that is exactly poised for a comeback, but clearly there are plenty of people interested in it, and plenty of do-it-yourselfers who are keeping the idea alive. It's not something I see myself building, but certainly, any bike at a club ride with an R-D drivetrain would be the topic of much conversation and would be a blast to try out.


  1. I would love to see and ride a retro-direct bike, if for no other reason to experience it.

    However, what Jan Heine says makes sense: It's hard to pedal backwards efficiently or for any meaningful period of time. About the only times I pedal backward are when I stop for a red light on my fixed-gear bike (I lift the rear wheel and back-pedal to bring my pedals to the position I find most comfortable for starting) or on my coaster brake (on my "beater").

    The retro-gear would be an interesting curiosity nonetheless.

    1. I'd like to try it out too, though I don't see myself trying to build one. Though it's probably not the same without load, just trying to backpedal on a normal freewheel for more than a couple revolutions feels pretty awkward.