Tag Archives: duralumin

Mercier Meca Dural Restoration Progress

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2016-12-11-015

Restoring vintage bicycles, especially those from the “golden era” which lasted from the 30’s through the 50’s, sounds vaguely romantic and thrilling.  Which it can be.  But the truth is that it can also be a very solemn and tedious process, full of stops and starts.

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This late forties or early fifties Mercier Mecal Dural is one of those projects that can test your resolve.  The bike, whose frame is made from aluminum “duralumin” tubing, was not 100% original, yet the frame itself was in beautiful condition.  Over the course of its life, someone had tried to mount 700c wheels from the 1970’s on this late 40’s/early 50’s bike designed for 650b rims, and had spray-painted over the rust and corrosion on the bike’s original steel fork.  Some parts were missing, such as the original chain guard as well as the bike’s bolt-on attachments for the shifter and chain guard.  And, the Meca Dural head badge was gone.

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Undeterred, I set out to research the history of this method of frame building, as well as to find as many other examples of these frames as possible.  Fortunately, I was successful on both counts.  Several others before me have successfully restored these bicycles, and there is a decent amount of information available on the web and in print which gives a history and background for this interesting frame construction.  However, I still haven’t been able to locate any information on the serial number scheme used by Mercier.  This frame’s SN is 16822.

1953 Mavic rim 650b

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My first task was to find a 650b wheelset from the same era.  I harvested the wheelset from another project, which dates to 1953 and features Mavic aluminum rims laced to Fratelli Brivio hubs.  One of the initial challenges involved rebuilding and restoring the wheelset itself.  While the front hub was easily brought back to its free-spinning glory, the rear hub proved difficult.  I was not able to remove the unbranded 4 speed freewheel from the hub, lacking the particular removal tool.  I modified a Suntour two prong remover, applied copious and various kinds of lubricants to the threads, used both my vise and my giant-sized long-armed wrench, to no avail.  I didn’t want to take this freewheel apart – it is working fine and will probably last another 60 years.  So, that meant cleaning and rebuilding the hub with the freewheel attached.  All went well until I discovered that the original axle was slightly bent. When I was ready for the hub’s final adjustment, I found that the axle could not turn in the hub, due to the zero distance between the hub shell and the cone.  This particular hub has no dust cover, so I couldn’t strong-arm the opening by widening the dustcaps themselves.  That meant trying to find another perfectly straight 9.5mm axle of a similar length and with similar threads.  Amazingly I had ONE such axle in my parts bin – it was only slightly shorter than the original axle.  Whew!  On to the next problem.

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CLB 700 brakes with 650b rims

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CLB 700 brakes with 700c rims

Once I had the wheels rebuilt it became clear that the CLB 700 sidepull calipers were probably not original to the bike.  Their 70cm reach is not quite long enough to engage the 650b rims.  Darn it!  The extra reach needed is only about 2mm.  When there is enough material on the brake calipers to allow for it, you can take a round file and sand the opening lower at the bottom of the caliper arm to allow for a slight improvement in brake reach.  But, these calipers do not have enough material on the lower brake arms to make me comfortable with this approach.  Instead, I will now locate long reach side pulls from this era.  One more setback.

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Tight clearance – chain ring and chain stays

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Stronglight 49D crankset with Louis Verot chainring

Then it came time to rebuild the bottom bracket and install the beautiful, lightweight Stronglight 49D crankset, with its 46T Louis Verot chainring.  Everything went well until I observed the clearance of the chainring to the frame.  I had previously noted what I thought was a crimping mark on the sleeves which serve as the chainstay fender bridge.  When I looked closer, I realized that the “crimping mark” was actually a gouge caused by the chainring contacting the frame at the chainstays, probably under vigorous pedaling.  Investigating further, I found that the chainring itself had a wobble, which is not unusual for this type of crankset with a tiny bolt circle diameter.  A larger diameter can resist stresses from the rider, but the downside is that a larger diameter BCD cannot accept tiny chainrings needed for climbing.

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One of the things I learned in my research about these duralumin frames is that the bottom bracket shell is set up to provide for chain line adjustment.  The shell is a simple aluminum cylinder, held in place with bolts.  In order to address the issue of the crankset contacting the chainstay sleeve under vigorous pedaling, I first measured the torque setting on the bottom bracket bolts, referencing the highest setting at 100 inch pounds as being the most accurate.  After removing the bolts, I twisted the BB shell using the locking on the non drive side of the bottom bracket.  I adjusted the BB shell over about 2mm to provide for additional necessary clearance for the crankset, by taking a mallet and gently tapping the BB.  I would not have known about this option had I not seen numerous examples of other duralumin framesets showing the BB shell in various positions.  Unfortunately one problem with these frames is that the aluminum chain stay sleeves can fail.  I wanted to give this frame a good shot a lasting through the decades, so by adjusting the BB shell, further damage to the chainstay sleeves will be avoided.

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Huret derailleur

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Beautiful Dural Azur stem with arrow design

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Hammered rear light

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Lefol hammered fenders

The next steps involve installing the Huret derailluer and shifter, polishing and cleaning the beautiful components, and setting up the brakeset and cables, and installing the tires, as well as cleaning and lubricating the leather saddle.  Stay tuned for more torture, and related thrills!

Clear Coating a Vintage Steel Fork, Part II

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2016-11-20-015

I have now clear coated the vintage steel fork which was part of the 1940s/50s Mercier Meca Dural I have been working on for the past year.  The bicycle was mostly original, with its beautiful aluminum frame in fantastic condition.  Unfortunately, the fork was terribly pitted, made worse by the application of an amateur spray paint job.

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This Mercier Meca Dural bicycle was built in the late 40’s or early 50’s.  The main tubes are made from “duralumin” – the same stuff blimps were made from. The forks on these bicycles were always steel, and in this case the fork had probably been originally painted gray or was chromed, to match the color of the unpainted aluminum on the main tubes.  Because the main tubes cannot rust, there was no need to paint them.

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But, the original fork was compromised – it was pitted with corrosion and rust. I needed to decide how to restore it or replace it.  After many hours of paint removal, sanding, and polishing, the fork looks much better. I became concerned about removing too much material from the fork blades, so I finally tossed in the towel.   On the bright side (pun intended), I guess you might say this fork has patina in spades.  I ended up deciding that I wanted to clear coat the fork (for now) rather than chroming it or sending it out for a professional paint job.  That would enable me to continue restoring the bicycle, which I am anxious to complete.

I decided to use Proctaclear by Everbrite for the paint, and MAAS metal polish for the final finish work prior to painting.  Both products worked very well.

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The steps I used, after removing the original paint and then sanding with finer and finer sandpaper to create a smooth surface are as follows:

  1. I polished the fork blades and crown with MAAS metal polish – this took hours!  However, I really like this polish and will continue using it for steel parts.  It’s not as good as NevrDull on aluminum fenders, but can make even funky metal parts look very nice.
  2. After polishing, I cleaned the fork blades with alcohol and a soft cloth – I didn’t have to use an acid neutralizing baking soda bath, because as advised by the Protectaclear instructions, MAAS polish does not contain acid.  However, some restorers do this process anyway, regardless of the polish used.
  3. I did a final wipe down on the fork blades with a tack cloth – to remove any debris from the surface.
  4. I cleaned the paint brushes and prepared my work area so that I could avoid fouling the brushes on an unclean surface.  I put the fork upright in my work stand so that the paint would flow downward. My paint brushes were new, so I only needed to wash them in warm water to remove their protective coating – however, see below.
  5. I poured a tiny bit of Proctectaclear into a clean glass jar – this stuff goes a long ways.  The small container I purchased could probably cover 2 bicycles in full.2016-11-15-007
  6. I painted the fork blades with smooth, even strokes.  The paint went on easily, and as the instructions advise, the paint will naturally smooth itself out on the surface so that you won’t see any brush marks.  This was an accurate description, and the painting itself took no time at all.  However…see below!
  7. As I was painting, tiny surface anomalies began to appear in the painted surface.  At first I thought the paint was reacting to something on the fork blades, but then I realized that my paint brush was depositing little particles onto the blades.  The new brushes still had some leftover protective glue which I thought I had washed off.  I then stopped painting, cleaned the brush extensively, then wiped the brush with tack cloth, and that solved the problem. I had to carefully remove the tiny particles with my fingernail (gloved) and then smooth the paint out again.
  8. After a couple of hours, I applied a 2nd coat, as provided for in the instructions.
  9. The paint cures hard in 4 – 5 days.  It is very soft prior to this, and even scuffed a bit when I laid the fork down on a wood surface about 24 hours after the final paint coat.

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The painted fork looks pretty much exactly like the raw steel fork. It really is a clear coat. I will know soon just how robust the paint is, but for now I am excited to begin building up the frame and completing the restoration.

The whole process to restore this fork took well over 25 hours.  Rather than following the typical 80/20 rule for paint jobs (80% preparation time, 20% painting time), this job was more like 99%/1%.  The painting portion of the work was almost a let down, because it was really so easy compared to all the other work involved in preparing the fork.  I’ll plan to do a long-term update once the Mercier Meca Dural is restored and back out on the road.

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Unrestored 1940s/50s Mercier Mecal Dural

 

Removing Paint from a Bicycle Frame the Safe(r) Way

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Mercier fork

The 1940’s/50’s Meca Dural bicycle that I am currently restoring had an unfortunate encounter with an amateur spray painter.  While this bike’s frame is made from duralumin, a form of aluminum alloy which needs no paint because it cannot rust, the bike’s fork was steel.  When I purchased the bike, I knew it had a number of issues, the horrifically painted steel fork being one of them.

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As you can see from the photos, the spray paint appeared to be hiding rusting and pitting on the fork blades.  While I normally send all paint jobs out to the professionals, feeling that frame painters deserve their due, I decided that I wanted to prep this fork for painting myself so that I could assess the usability of the fork.

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Before venturing out into this unknown territory I did some research to determine what materials and tools I would need for the job.  I ordered emery cloth and wet-dry sandpaper in varying grades, some brass brushes (which will not scratch steel), and a few other items such as tack clothes and dish scrubbers.  All based on advice from Randy at mytenspeeds.com who has done some very nice paint work on his collection of bicycles. I knew that I did not want to use harsh, environmentally unfriendly chemicals for this job.

I fired up my new (non-wimpy) Dremel to use for the hard to access areas near the fork crown, but for the fork blades themselves I wanted to do all the work by hand, the old fashioned way. Unfortunately, whoever painted the fork did so while it was covered with rust.  When I began to remove the paint, I was disappointed to see just how bad the fork blades looked.

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The blades are pitted near the fork crown.  I wondered whether I should try to remove enough material to eliminate this pitting, worrying that I might take too much off and weaken the fork blades.  Then I remembered that fork blades are very thick and sturdy, given the job they must do, so I decided to keep going after observing the very nice brazing done on the dropouts and fork crown.  The fork is well constructed, and deserved my efforts, I felt.

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Cleanly brazed dropouts

While I was working, I was reminded of the bicycle frame that I built, and the effort required to sand the frame and remove excess brazing material.  This is a very similar process.  Using vigorous and speedy strokes with the emery cloth and sandpaper was the key to bringing the fork back to life.  Wearing a mask is a good idea, since you will be creating a lot of dust in the process.

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You can see the progression in these photos.  This process took about 4 hours, and yet  I still need to continue sanding with finer grade sandpaper to complete the work and have the frame ready for paint.  One thing to know:  it is most efficient to sand very quickly, mimicking the action of a power tool.  While my hands are now sore, I am happy with the results, and look forward to the finish work needed before I send this fork off to be painted.