Simplex Tour de France Rear Derailleur Adjustment

It’s been quite a few years since I last posted about how to set up a Simplex Tour de France rear derailleur.  These mechanisms were found on bikes dating from the late 1940’s to the early 1960’s, but are not in any way intuitive to fine tune.

The routing of the chain through the pulleys was so puzzling that Simplex had to include a chart in their technical instructions to indicate how this was to be done.  In fact, when I had first started my vintage bike restoration endeavors many years ago I had taken a vintage Peugeot to a reputable bike shop for some repair help with a rear wheel.  When the bike was returned to me, the chain had been incorrectly routed through the Simplex rear derailleur.  That shows just how perplexing this rear derailleur can be.

1953 French mystery mixte with Oscar Egg lugs

Recently, I have been working on my mystery French mixte with its Oscar Egg lugs.  The bike was equipped with tubulars which have proven to be a challenge to keep maintained, as I haven’t ridden this bike on a regular basis, even though they do offer a beautiful and comfortable ride. The glue holding the tires to the rims is no longer robust.  So, upon deciding to temporarily replace the tubular wheelset with a clincher set from the same early 1950’s era, I needed to perform a few tweaks to the Simplex TDF rear derailleur in order to get this bike set up so that I can ride it with more regularity.

My replacement clincher wheels are 700c 1950’s Super Champion rims laced to Normandy hubs.  I wanted to lower the gearing from the the original configuration, but had read that these rear derailleurs can only manage about 24-25 teeth maximum on the freewheel.  I found a 5 speed freewheel with French threads with a largest 25 tooth cog, and then adjusted the internal threaded shaft on the Simplex TDF rear derailleur to tune out the highest fifth gear, as this derailleur can only accommodate 4 gears.  (The bikes’ original drilled Regina freewheel’s largest cog is 21T).  This is accomplished by loosening and removing the nut on top of the knurled washer, and turning the threaded shaft as needed to position it correctly so that the chain lines up with the smallest and largest cogs as the pull chain is moved through its range of motion.  It takes a bit of trial and error.  The knurled nut is meant to be used to turn the shaft, but if that proves difficult, there are flats on the shaft which engage with a 12mm wrench.

Once the alignment to the cogs was correct, I proceeded to adjust the derailleur using the two spring tension adjustments available in this 1950’s rear derailluer:  chain tension, and pulley tension.  The chain tension is controlled by the spring on the arm, and the pulley tension is controlled by the tension on the pulley spring, using the notched mechanism, shown above.  Moving the pulley spring’s position clockwise increases the pulley tension.

Before going further into the weeds, it’s always a good idea to look at a component’s schematics.  Here is the front page of the TDF instruction guide included with these models.  I also consulted the excellent advice from Peter Underwood at the Classic Lightweights website.  After some contemplation, I decided to overhaul a NOS Simplex TDF that I had in inventory, which needed cleaning and re-greasing, hoping this would illuminate this derailleur model’s nuances.

Upon removing the outer nut with a 17mm wrench, I proceeded to removed the pulley cage, which takes an 11m wrench.  The outer steel flexible cover over the shaft reveals an internal spring.  This model had lots of extra washers, which I ended up not replacing (more later!).  After cleaning and lubricating all the parts, came the difficult task of getting the pulley cage back on to the shaft, with its attendant spring.  After some trial and error, I realized there is always a trick to getting derailleur spring back where it should be.

After taking time to review the schematics, I realized that I needed to move the threaded shaft as close as possible to the notched piece, so as to push the moveable part of the shaft down as far as possible.  While holding the spring and cover tightly in place, I was finally able to thread the pulley cage back on, sans a few washers!

And finally, I was successful at re-assembly.  This NOS derailleur now has free-running pulleys with all parts lubricated and is ready to roll.

Meanwhile, I had tried various adjustment scenarios, changing the chain tension and the pulley tension.  The above is a video I made discussing the various adjustments possible for this derailleur.  I initially set the chain tension to push the derailleur back so that I could use the 25T freewheel I had selected.  But, you will see from this video, that by doing so, my shifting performance has suffered.

So I decided to reduce the chain tension by adjusting the nut at the back of the mounting bolt (which has the chain tension spring threaded around it).  This is done by removing the spring from the arm, releasing the bolt, moving the spring back or forward (in this case, forward to reduce tension), and re-tightening the nut.

You can see from the above video that my shifting has improved dramatically.  However, upon taking the bike on a test ride, the torque on the drive train while riding caused the derailleur pulley to contact the 25T cog, making the bike unrideable in that gear.  So, back to the drawing board!  I’ll either switch the freewheel back down to a 24T model, or fiddle with the tension adjustments yet again (NOT!), and most likley swap out the front chain ring for something a bit smaller to help make this bike more rideable for a Portland commute.

1947 Camille Daudon – Frame Details

My 1947 Camille Daudon bicycle, custom built for Irene Faberge Gunst, is currently in a state of disassembly, so this seems a perfect time to share some details of the frame’s construction.

While I have some information about this bike from the previous owner, I wasn’t sure about the steel tubing.  Because the previous owner had re-chromed the frame, all the original decals and transfers were lost.  So, I was delighted to see this VITUS logo on the steerer tube when I removed the fork.  This logo probably means that all the frame tubes are Vitus – a quality steel tubing made by the French company Atelier de la Rive.

The work done to create this frame is far beyond anything you would ever see today, except from a custom builder.  The creases in the chainstays, to provide clearance for the crankset and the wheels are beautifully executed.  And, the sloping downtube connection to the seat-tube is one of my favorite designs for mixte bikes that use a single, rather than double, sloping top tube.  This type of robust brazing firms up the frame, and gives the mixte bike better handling characteristics.  Peter Wiegle has continued this concept on the mixte frames he has built.

Pinned chainstays

Another interesting feature are the pins used to secure the chain stays, as can be seen by peering inside the bottom bracket shell.  Pinning the tubes was a method used by a number of builders of this era, and is even continued today by Mercian, whose process involves using a brick oven to heat the tubes for brazing.  I don’t know whether Camille Daudon used this heating process, as the only tubes which are pinned in this frame are the chainstays.

The finish work on the stays is beyond anything I normally see – simply extraordinary.

This frame has only a few braze-ons -the shifter mount, pump pegs, and shifter and brake cable routing.  Most notably, there are no braze-ons for a dynamo nor for a chain guard.  Since this bike was designed for commuting and city riding in San Francisco, that seems odd to me.

1947 Camille Daudon mixte, prior to re-chroming

Prior to being re-chromed, the frame looked as above.  As you can see, the chrome was seriously compromised.  Chroming a bicycle frame is a harsh process that may not yield the results you are looking for.  It is very labor intensive, and will remove some brazing material from the frame.  It is essential that the frame be thoroughly cleaned and the old plating removed before re-chroming.

The previous owner thought that he had prepared the frame correctly for the chroming process, but unfortunately a small section of the drive side seat stay developed a hole during the re-chroming, due to incorrect preparation.  This is an area of frame construction where failures can develop.  However, in this case it looks like the combination of incorrect preparation, along with the harshness of the re-chroming process itself, caused this hole to develop. While it is a small flaw, it’s something to take note of.

I haven’t decided yet whether I will try to re-create the Daudon logos which were original to the frame, as shown in the above photo.  I love seeing such a large head tube on a smaller frame such as this, which should provide for a comfortable riding experience.

Best of all about this disassembly process was seeing the codes engraved on the fork and rear dropouts – “471” which makes me think that this was the very first bicycle off the line from Daudon’s shop in 1947.  A nice, and interesting,  thought.

Frame dimensions:

Seat tube:  50 cm

Top Tube -effective:  52.5 cm

Wheelbase:  102.5 cm

Frame Weight:  5 pounds, 15 ounces

Material: Vitus steel tubing

1950’s Simplex Pull Chain Front Derailleur

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I was cleaning out one of my parts bins and discovered this unusual Simplex pull-chain front derailleur.  I can’t remember the bicycle this came from, so I didn’t have any clue as to its date of manufacture.  But, I assumed this piece dated from the 1950’s to 1960’s.

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I pulled out my copies of The Dancing Chain and The Data Book, hoping that I could spot some info about this front derailleur.  But, nothing was there.  Then I did an internet search and found that a 1938 version of this front derailleur is on sale on eBay.  Additionally, there are some photos on flicker featuring an earlier version of this model.  I also found what appears to be this exact model on the Velobase website – a Simplex Juy 56 front derailleur.

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This Simplex front derailleur features an adjustable cage for adapting to 1/8″ or 3/32′ chain sizes, effected by the two screws on top of the derailleur cage.  I disassembled the derailleur for cleaning, and was able to observe the specifics of how it operates.

When the pull chain is engaged by a shifter cable, the whole mechanism slides on the two cylinders which attach to the cage.  One of the cylinders contains the spring system, and the other is meant to provide stability to the cage as it slides, so is rigid.

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The derailleur mounts to a seat tube bracket with two bolts, shown on the left side in the photo above.  If a frame lacks such mounts, then brackets can be attached to the derailleur so that it will mount to any seat tube.

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The eBay model for sale today is purportedly a 1938 “NOS” version with a $475 asking price.  We’ll see about that.  Meanwhile, I am going to keep this front derailleur in my collection, in case something comes along that warrants its application.