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.


  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.

  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.

  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.

  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.

  5. "Hardcore" mountain bikers even ganged up against discbrakes calling them useless... You generally can't judge the merits of any technology on the natural friction caused by the simple fact that people will tend to cling on technologies they are already familiar with.

    That said obviously newer is not always better. For example implementing dual control levers on MTBs was decisively misguided, as bikers tend to rest fingers on the brakes during technical sections and that would eventually move the lever just enough for the chain to jump cogs. That's not to say no biker flourished on the trails riding dual control levers. But that's besides the point.

    Low normal rear mechs actually addressed two inherent problems of the way rear mechs operate:

    1: bump shifting: trails are hard no the vertical Gs... Those have a tendency to mess with your mech as bumping your rear wheel will sometimes send your mech flying down against it's spring and shifting into a lower gear momentarily. I've had a couple of tumbles because of that running old LX top normals in my day racing cross country. Low normals are resistant to this because to travel down during a bump they have to work against the cable (witch is not possible) and therefore are virtually immune to bump shifts.

    2: cog ramps: Up-shifting simply pulls the chain out of the cog and drops in onto the smaller one. But down-shifting smashes the chain against the larger gear and expects the chain to grab onto an up-ramp and climb onto it. Low normals use the spring to do the smashing, witch provides even and controlled pressure on your cogs. This is far safer and far more efficient than you mashing the lever.

    Apart from those very important problems solved, there are other reasons low normal is the bomb:

    FAST upshifts: Coming out of the trail and mashing the release lever will get you through 9 cogs in a heartbeat! There is literally NO time needed to get thorough you entire cassette if you need to, and it happens in a controlled manner without the fear of pulling anything out of alignment, or smashing your mech against the low-stop (witch many a-time has pulled the rear mech out of tune on bikes with not many rides since last replacing shift cables).

    When up-shifting you use your thumb against pretty much nothing, so the feel is lighter.

    PRECISE up-shifts when you REALLY need them: Anyone saying he hasn't messed up an up-shift when climbing a steep uphill, out of breath gunning for the finish line is either lying, forgetful, or not a racer (ok I exaggerate for effect :P ). You will sometimes pull a little two hard and almost change two cogs instead of one and get that horrible clung of the chain falling back down a cog. That can put you off balance and cost you time. Low normal let's you leave the difficult job of being precise when you actually need it: climbing uphill.

    I understand it being difficult for many to get used to low normal (I curse and moan and kick when I get to use my freeride rig witch has an standard top normal mech! ) But once you actually get used to the low normal it's hard to go back.

    I never got the feeling flimsy part you mentioned. I have an OLD 2004 XT and apart from picking up an ever so slight slack on the hanger bolt pin after 11 years, 2000Km and a few medals it's still absolutely rock solid and precise. I obviously had to change the pulleys once but that's it.

    So the point is: anyone doesn't like low normal: I absolutely get you, it's not everyone's cup of tea. After all to each he's own and what works for you is the best.

    But It's definitely NOT a useless fad, and it's definitely not inferior to top normal.

  6. Stelios--I said that my top-normal front derailleur was fine until the spring wore out. The mechanism itself was sill good; I just couldn't find a replacement spring and didn't know (at the time) how to replace it.

    I don't think I said anything about the durability of low-normal rear derailleurs. Having so little experience of riding them, I can't speak of their longevity.

    You may like such derailleurs--as the previous commenter does--because you ride under conditions in which I haven't ridden much, or at all. Perhaps if I'd been a more dedicated off-road rider--or pedaled a pedicab for a living--I might appreciate low-normal derailleurs more.