Last night I wrote a book review for Cyclingnews on The Golden Age of Handbuilt Bicycles, by Jan Heine. By and large, I liked this book for the pictures — the craftsmanship on some of these bikes is truly beautiful — and for Heine’s descriptions of the mechanical innovations in these bikes that we’re still reaping the benefits from today.
But there was one bike in that book that I cannot get out of my head.
Meet the Hirondelle Rétro-Directe
Take a look at this:
Notice anything unusual about it? If not, this closeup may help:
So, in answer to the obvious question: yes, the chain is following its intended path. The appropriate followup question, then, is as follows: “Huh?!”
Unfortunately, I read the purpose of this labyrinthine drivetrain before I took a close look at the picture. Even so, I stared at this thing for several minutes before I finally got it into my head how it works. As an experiment, why don’t you see if you can figure it out why the drivetrain follows this path before reading on. Give yourself just a few minutes. Then, after you continue on and find out that you’re wrong, leave a comment saying what your conclusion was.
Want another hint? OK, this drivetrain uses two freehubs, instead of one.
OK, time’s up. Let’s move on.
The Other Way Around
This Hirondelle was built back before there were commercially available rear derailleurs (although it did sport the world’s first commercial front derailleur, making it a technological marvel for a whole separate reason). But people still wanted to go up hills. The Hirondelle’s solution was to give you two gears in the back. Simply pedal normally for the higher gear.
And what do you do when it’s time to climb? Pedal backwards.
When you pedal forward, the freehub for the big cog coasts, and the small cog engages: you’ve got a big gear, suitable for putting the 1920’s version of the hammer down. And when you backpedal, the freehub for the small cog coasts and the big cog engages: up you go, just like an early 20th century mountain goat.
So now, every time I climb a reasonably steep hill, I try to imagine to myself: what would it be like to be spinning in the opposite direction right now? And what if the climb got really steep? What would it be like to stand up and pedal backwards?
Nope, sorry. I just can’t get my head around it. I’m not sure I ever will.
I do wish, though, that someone with this bike had taken it out and ridden it past me before I had learned about how the drivetrain works. Having someone pass me, on a climb, while slowly spinning her cranks backward would have easily been the most surreal moment of my life.