Mid-Life Cycling

Mid-Life Cycling

01 June 2017

Without Cotters, But Not Cotterless?

The French firm Specialites TA is probably best-known for its Pro Vis 5 crankset, often called the "Cyclotouriste" (though TA itself never used that name). Even if you've never ridden one, you've almost surely seen it:




It may well be the most versatile crank ever made:  The outer chainring, which bolts on to the inner bolt circle (the one closest to the center of the crank), were available in  sizes from 40 to 64 teeth.  The middle and inner rings, which bolted to the outer ring, were available in sizes from 26 to 50.  You could bolt one or two rings to the outer ring--or ride just the outer ring as a single.  So it may well be the only crankset that ever was truly designed to be used as a single, double or triple.  (On Vera, my Mercian mixte, I use a Shimano Deore MT-60 triple crank by substituting a BBG bashguard for the outer chainring.)  

Also, it may be the only crank that spawned as many imitations as the classic Campagnolo Record:  Sugino made a crankset that looked like a TA with a satin rather than a polished finish, and an early Shimano Deore crankset had the same bolt pattern, if a different look--as did the Stronglight 49D, the crank I'd probably choose if I wanted one with the 50.4 mm bolt circle and the option of single, double or triple.

Anyway, from the time it was introduced in 1963, the TA Pro 5 Vis became the crankset most commonly used on custom and other high-end touring bikes, particularly tandems, for about a quarter of a century.  Even early mountain bikes sported these cranks because they offered such a wide range of gearing--and, in spite of their appearance, were actually all but unbreakable.

Before Specialites TA introduced the Pro 5 Vis (five-bolt professional), the company produced chainrings used on cranks by other manufacturers.  Founder Georges Navet--who started out with ill-fated front-wheel drive experiments (hence the name:  TA stands for traction avant) wanted to produce a crankset to rival the best ones made by Campagnolo and Stronglight.  




Although Stronglight had been making cotterless cranks--fitted to the familiar square-taper  bottom bracket axle, which they originated--since the 1930s, some were still skeptical about the design.  Track racers were still using cottered cranks into the 1960s and some tourists still feared being stranded somewhere because the local garage or machine shop didn't have the right tools.  Other cyclists simply didn't want to change.




So, Monsieur Navet came up with a crankset that has the same arm and chainring bolt pattern we see on the Pro 5 Vis.  Unlike the Pro 5 Vis, this crankset--called the Criterium--was not cotterless.  So, in following the logic of cycle componentry from that time, you might say it was a "cottered" crank.  And you would be right--sort of.





If you didn't look closely, you might mistake them for cotterless cranks--which they are, sort of.


Specialites TA Criterium cranks with Spence Wolf-modified Campagnolo Nuovo Record rear derailleur, 1969.  From Velo Vecchio.


OK, you ask...What are they?  Well, the cranks were held to the axle by a bolt with an allen key head on one end, and a nut that threaded on to the other end.  That made the "cotters"--and the cranks easier to remove than those of traditional cottered cranks, and didn't require a special extractor, as cotterless cranks require.

An engineer once told me that the bolt holding the Criterium crank to its axle is technically not a "cotter", but rather a "pinch bolt."  The reason, he said, is that the traditional cotter has a wedge cut-out that is force-fit (usually by hammering) onto an axle with a flat spot.  The force--or stress, if you will--is what holds the crank to the axle.  On the other hand, the bolt in the Competition bore no such stress, and it merely holds the arm in place on the nearly pear-shaped axle end. 

The "not-cottered-but-not-cotterless" design had its advantages, in addition to not requiring special tools.  For one, the bolts were less prone to breaking or stripping than traditional cotter pins.  For another, it allowed 4mm of lateral movement in either direction on the axle.  That allowed the crank to be positioned for the best possible chainline.


One further advantage was that the design allowed the cranks to be made from aluminum.  A few companies made aluminum cottered cranks, but nearly all of them broke outright or ended up so gouged that the cotter pins could no longer hold them on to the bottom bracket axle.  But, because the Criterium's pinch bolt did not need hammer-blow forces to attach them, and because the shape of the axle and the way the bolts fitted into the crank provided an inherently more secure attachment, there was little to no danger of breaking or gouging the cranks.

What that meant was that the Criterium was, at the time it was introduced, the lightest crankset on the market.  It weighed even less than the alloy cranksets from Stronglight and Campagnolo because the Criterium's design allowed it to be made with skinny arms, like cottered cranks, and thinner around the axle interface.  it almost goes without saying that the Criterium was lighter, by far, than any other crankset because most--besides the aluminum cotterless sets made by Campy, Stronglight and a few other companies--were made of steel.


Cinelli Super Corsa with the drivetrain shown in the above photograph.  Also from Velo Vecchio.


The Criteriums were, like most Specialites TA products, meticulously made and beautifully finished.  Spence Wolf, the owner of Cupertino Bike Shop (one of the first in the US to devote itself to high-end bikes), equipped a few of the Cinellis and some of the Alex Singer bikes he sold with these cranks when the customer wanted wide-range gearing.  He would pair the Criteriums with a Campagnolo Record rear derailleur he modified with a long pulley cage he made for it.




But Specialites TA didn't make Criteriums for very long.  They introduced the Pro 5 Vis only a couple of years after the Criterium and, by that time, most dedicated, high-mileage cyclists--even track racers and tourists venturing into remote areas--were convinced that cotterless cranks were indeed a superior design.  To use a cliche, the rest is history.

Note:  I have seen only one of these cranks in person, on a bike I tuned up when I was working at the Highland Park Cyclery.  The bike had no markings on it, but the customer said it was "built in France".  I don't think it was a constructeur bike, but it looked fairly high-end.

8 comments:

  1. I know many a cotter pin had been installed/removed by the pound'em in/pound'em out method but swinging a hammer that close to thin wall tubing always gave me the willies. Last winter when work was a little slow I designed and machined myself a cotter pin press. It works great and no hammer required.

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  2. I had successfully buried memories of the horrors of cotter pins, now I am shuddering again. The jiggle jiggle which developed in the crank leading to the need to replace the pin. loose as the crank seemed the pin could feel welded in place and bike be destroyed before it came out! Then you had to file the angled plane just the right amount and accurately to make it fit properly and rust away in place.

    How I dreamed of being able to afford a cotterless crankset...

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  3. Phillip--I always had the same feeling about hammering cotter pins. Thin frame tubing is not the only concern; it was also easy to score a bottom bracket cup or axle in the process. And, of course, the cotter pin, more often than not, did not survive the experience.

    I'd be interested to see the press you made. I know that Park Tools was making one; I think they still are. The French bike tool maker VAR also manufactured one; I believe the German company Eldi did as well. Those presses were very expensive, so almost all of that were sold were purchased by bike shops.

    Coline--I remember that sensation all too well. It seemed that there were two kinds of cotter pins: the ones that were always coming loose and the ones that froze in place. The latter, I am sure, deterred many people from cleaning and lubing their bottom brackets.

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    1. I'll try to post a photo if I can figure out how to do it(internet moron). I'll consult with my IT advisor,my 17 year old son. If that fails the one I made is pretty much a shameless copy of the one found here.

      http://www.bikesmithdesign.com/CotterPress/

      It sells for $59.00 bucks plus SH. That wouldn't have broke the bank but I like making stuff myself. I have a sketch floating around somewhere with all the dimensions, if I find it I'll post that too.

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  4. Interesting and informative article, TA cranks were always synonymous with a touring bike in my mind.
    Thanks for the article

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  5. Hello Ward--I believe that many of us feel the same way. Even though I'm not using a Pro 5 Vis or Criterium, whenever anyone says "touring bike", I still picture something euipped with one of those cranks.

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  6. If not using the press, I imagine you all backed up the other side of the cranks with a bar to the floor to isolate the force from the crank bearings. That one trick also made it easier to remove the cotter.

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  7. Breezer--I remember doing something like that. The trick was always to get the cotter off without damaging the bearings!

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