Mid-Life Cycling

Mid-Life Cycling

31 January 2012

The Rise And Fall Of Rapid Rise

I forget who told me that there's no idea so bad that nobody will try to revive it.

Here's a case in point:  low-normal rear, and top-normal front, derailleurs. 

On the bikes most of you ride, pushing the right lever forward shifts you to a higher rear gear (top-normal), and pulling the lever brings you to a lower gear.  Conversely, pulling on the left lever shifts your chain to the larger front sprocket, and pushing it drops your chain to the smaller, or lower gear (low-normal).  The derailleurs I'm talking about do the exact opposite. 

It seems that every generation or so, someone tries to revive the idea.  Why, I don't know.


This is an early example of the genre:  the Simplex Champion de France, circa 1935.  Believe it or not, it was a technological marvel for its time, even though it couldn't handle much more than a 22 tooth rear cog and a difference of 8 between the largest and smallest cog. 

It is, I think, rather elegant:  In particular, the cage shape makes me think of a part of a piano rather than a bicycle.  However, the shifts of single-pulley derailleurs are inherently imprecise; low-normal operation only exacerbates the problem.

As one might expect, World War II halted derailleur development and all but stopped their manufacture altogether.  The 1950's would see new innovations and experiments, including the pull-chain mechanism (which Shimano briefly revived on its mountain bike derailleurs during the late 1990's) and, most important, a derailleur with a parallelogram mechanism rather than a single arm or cam.  However, Simplex and other companies also revived low-normal rear derailleurs.

To be fair, the first modern rear derailleur (and, some would say, the first that shifted well)--the Sun Tour Gran Prix of 1964--also was low-normal.  But within two years, Sun Tour abandoned that operating principle, realizing that the slant-parallelogram design (which is found on every derailleur of any quality made in the last quarter-century or so) did more to improve shifting than any other idea or innovation.

However, Sun Tour continued to make front derailleurs that were "top normal" well into the 1970's.  I had one such derailleur.  It shifted well enough until the spring started to lose its tension.  With a low-normal front derailleur, you can sometimes adjust the cable tension to make up for the lack of spring tension.  That's not an option with high-normal front derailleurs.

It's also not an option with low-normal rear derailluers.  I briefly rode one on my mountain bike about fifteen years ago:  a Shimano XTR.  Luckily for me, the shop from which I bought it allowed me to trade it in for a more conventional XT rear.  The owner of the shop reasoned that the amount of wear I put on the XTR made it depreciate enough to warrant an XT as a replacement.

I'd say that was an example of addition by subtraction:  I was happy with the XT, as I was with an earlier version of the same derailleur.  On the other hand, I never liked the low-normal XTR, which was one of the most expensive derailleurs made at the time.  It never had the firm, postive feel I like when shifting:  Even when the gear engaged smoothly and silently after a shift, it always felt as if the chain would slip or jump off the gear at any moment. 

Other cyclists with whom I rode--who included hard-core mountain bikers as well as roadies like me who went off-road for a change of pace--felt the same way about that derailleur. And, in looking back at some old magazines and books, it seems that every time low-normal derailleurs come out, the high-mileage and hard-driving riders don't like them.  Even less-experienced riders who thought they were the newest and latest thing soon soured on them.

I see that Shimano has given up on low-normal (or, in their lingo, "rapid rise") rear derailleurs, at least for now.  I wonder whether they, or any other company, will revive them.  Maybe they will in a decade or so, when there's a cohort of cyclists who didn't use rapid-rise and who don't heed this gem of wisdom from Ecclesiastes:  There is nothing new under the sun.

4 comments:

  1. The top-normal Suntour front dérailleur on my wife's bike still works great after nearly 40 years. Suntour built them to last. If that spring wears out, we have a spare to last for the next 40 years.

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  2. Steve--I can see more of a rationale for top-normal front derailleurs than I can for low-normal rears. Actually, I rather liked the shift of the Compe V I had, especially on hills. If I'd known where to get a spring and how to install it, I would have kept on riding that derailleur. On the other hand, I purely and simply didn't like the shift of the rapid-rise XTR rear, or of the other rapid-rise rear derailleurs I've tried.

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  3. I used to ride with a high-normal front derailleur, until it wore out and all I could get was a low-normal. I have still never got used to having to move the two levers in opposite directions (25 years later). You never got confused - levers forward for faster, levers backwards for slower - if you wanted a really big change you could even do both levers together. I've still got the old worn-out unit somewhere - maybe I'll try to refurbish it.

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  4. as a pedicab (bike taxi) in a hilly city, I insist on low-normal/rapid rise rear derailleur.
    it allows me to downshift under torque while pulling up to 1,000lbs uphill. on a more traditional rear derailleur, i would have to reduce my power input in order to downshift, destroying any momentum i could have kept with the rapid rise.

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