Category Archives: Bicycle restoration

It’s Not Me, It’s the Bike

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These are the words I say to myself when I am riding especially fast.  Or especially slowly, as of late.

This winter I have been using my Panasonic MC 7500 winter bike as my primary commuter, which is a change from past winters, partly driven by this winter’s wet and colder conditions which heralded the onset of a typically Portland rainy season last November.  Very recent winters have been gloriously warm and dry, so my choice of commuting vehicles was vastly expanded and even included scooter rides in the dead of December.  But, not this winter.  Portland is back to typical seasonal weather which can include anything from 35 degrees and raining hard, to light sprinkles in the lower 50’s (like today), and the occasional freezing rain and snow.  The short days also come with twilight seeming to descend in apocalyptic fashion in the middle of the afternoon.

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This bike was actually quite the machine in its day – the top of the line Mountain Bike in Panasonic’s line up in 1987.  It is built with Tange Prestige Cro-Mo double butted tubes, with forged drop outs and chromed chain stays.  The geometry on the smaller frame that I am riding features a slack 70 degree head tube combined with minimal fork rake, which would normally make it less than ideal for commuting, but its long wheelbase (107 cm) makes up for the higher than ideal wheel flop.  Consequently, I can usually avoid putting my foot down as I approach red lights and four way stops.

I bought this Panasonic as a frame and fork, then built it into a city commuter.  It went through various iterations, and now is set up for maximum comfort and utility.

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I was using a Shimano grip shifter and a 6 speed cassette, but after a black ice crash in 2012, the shifter broke apart (because it is made of plastic), so I splurged on a $7 no name friction shifter, made of good old steel.  That meant that I could install a 7 speed freewheel, and increase the bike’s gear range a bit.

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I had been using these UNO city bars, pictured above, but the shape and width did not agree with my anatomy, so I swapped them out for a vintage steel Northroad bar.  This bar is a great improvement in comfort, being narrower and putting my hands and shoulders in a much more neutral position, and increases the bike’s un-coolness factor by a few thousand degrees.

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Steel Northroad bars

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Further agitating bike snobs in Pdx, the Panasonic is sporting a duct tape rear fender repair job, and a ghastly kickstand.

The kickstand is a convenient accessory, and this design is useful for any bike where mounting in back of the bottom bracket is not an option (in this case due to the U-brakes residing there).  The stand is adjustable to any wheel size, and keeps the bike secure, even when I have my bags loaded up with groceries.

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I like using these Jandd Hurricane bags, which are aptly named and can handle just about any kind of weather.  Their vibrant colors augment my winter bike’s 1980’s color scheme, and add a lot to its visibility.  If you haven’t used Jandd bags, you are missing out on the ultimate in practicality and quality.  I have a set of Jandd panniers that are 30 years old, and still look new.

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The Panasonic MC 7500 is a bike that enthusiasts have embraced, but the frame does have its downsides – one of them being that on some builds, holes drilled in the seat stays (necessary to allow heat to escape while brazing), were actually drilled very close to the seat stay attachment.  Fortunately, on my frame, the holes have been drilled near the dropouts.  Unfortunately, the seat stay holes have caused a stress riser to appear on this cyclist’s bike.

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Paul’s chain keeper for my 1×7 drive train, with vintage Peugeot branded crankset.

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Specialized Nimbus Tires. Never a flat in six years, and the exact opposite of supple side walls.

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Possible stress crack

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After sanding to remove the paint, no stress crack visible.

On my own frame, I had concerns about the paint cracks which had developed near to the U-Brake braze-ons on the chain stays.  Whenever you heat the tubes to braze, there is a danger of overheating and weakening them. Since the frame was already cosmetically challenged, I had no qualms about taking my emery cloth and sandpaper to this area to see what lay beneath the cracked paint.  Fortunately, nothing at all.  But now I can monitor this area.  I will paint it with Testor’s clear paint so that I can watch for any future changes.

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SunRims on the wheelset I built for this bike – holding up okay but the sidewalls have been scored by my too hard brake pads.

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Offending hard pad on the U Brake – showing no wear which is a bad sign. Meaning that my rims have suffered instead.

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Repair job on the broken fender attachment.

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Repaired fender bracket.

While I had the bike in the shop stand, I decided to do a full tune-up.  I washed the wheels (a new wheelset which I built last year, and which are working well), picked rim material out of the brake pads, sanded the rear ones, replaced the too hard original Tektro pads which had messed up my new rims, and cleaned and lubricated the SunTour freewheel (more on that, below).  I repaired the broken fender attachment by rummaging through the parts bin to find a reasonable facsimile with which to repair the broken bracket.  I drilled a new hole through the center of the fender, and installed the new bracket.  Hopefully, it will survive and thrive.

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New front Kool Stop pads – replacing the original Tektros which badly scored my new rims.

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But now, to my chagrin, my newly cleaned and lubricated 7 speed Suntour freewheel is making very odd grinding and clunking sounds.  I have always loved Suntour freewheels, and have never had one fail on me.  After doing some research, Sheldon Brown (RIP) came to the rescue.  He described a situation similar to mine, where my newly lubricated freewheel began sounding clunky under load, and noisy while freewheeling.  I believe the problem may be a loose cover plate.  Meanwhile, I have a fun old Atom 5 speed freewheel from the 1970’s with English threads which I am going to install while I troubleshoot the beloved Suntour. The higher geared old Atom freewheel should make me ride even more slowly.  But, as I said before, it’s not me, it’s the bike.

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28 lb machine ready to hit the road.

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.

Meca Dural Duralumin Bicycle Frame Construction

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Meca Dural bottom bracket shell

From the 1930’s through the 1950’s, the French were enamored with aluminum bicycle frames, even though steel was the material of choice for most builders.  A number of examples still exist today, and after disassembling and cleaning this 1940’s/50’s Mercier Meca Dural frame, I can see why.  The bottom bracket shell is a work of art, looking as if it had been machined yesterday, rather than more than 6 decades ago.

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I became curious about the method of joining the aluminum tubes with aluminum lugs, using what I had read were internal steel expanders.  Apparently, at the time there was no method to “glue and screw” the aluminum tubes, a method that was pioneered by ALAN beginning in the early 1970’s.  The only joining methods which were available then were gas welding the tubes – a process used by Nicola Barra; connecting octagonal aluminum tubes into aluminum lugs with connector bolts – a process used by Pierre Caminade; joining the tubes with aluminum lugs and wedged internal expanders – the method used by Meca Dural, and other other hybrid methods involving pinning the lugs, and using a steel rear triangle.

When I passed my magnet over the frame, I picked up no attraction, except for a very faint pull near the lugs.  You will note that the chain stays and seat stays are connected with a combination of bolts and aluminum sleeves, and that the bottom bracket shell is held in place with two large bolts connecting the lug to the chain stays.  The aluminum sleeves do double duty as the brake bridge and chain stay bridge.

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The seat tube/seat stay lug is pinned, as you can see above.  But what about the main tubes – how do the internal expanders work?

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As it turns out, it was fortunate that the Meca Dural headbadge was missing, which allowed me to peer into the head tube lug to examine the expander inside.  My magnet told me that the expander is steel, and the method to accomplish the expansion process seemed to involve a steel tab which was probably manipulated with a special tool.  When you think about it, the same idea is used for quill stems inserted into threaded steerer tubes.  That seems to have worked pretty well, so why should these lugs be any different?

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At first I wasn’t sure of the purpose for the large holes underneath each of the two headbadges.  Upon closer examination, you can see that the head tube and head lugs are actually machined as one piece.  The holes are necessary so that the expanders can be inserted to join the top tube and down tube, necessitating a hole for each tube.  And that is why there are always two headbadges on every Meca Dural frame -to cover these holes.  That’s one mystery solved.

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One thing that seems true of older aluminum frames is their flexibility, relative to steel frames.  My ALAN is a very flexible frame, but not too flexible.  I guess you would say it is flexible in the right kind of way.  To satisfy my curiosity about this frame’s flex characteristics, I squeezed the rear dropouts to test the amount of flex.  Then, in my unscientific experiment I compared the amount of flex on this frame, to all the other bare frames hanging in my shop, all of which are steel, and some of which are Reynolds 531.  I was able to flex the dropouts on the Meca Dural about 7 or 8 mm, using my weaker left hand at full force.  On several mixte frames, I could barely move the drop outs 3 mm, and on a diamond vintage Reynolds 531 frame, I could flex the drop outs about 6 mm at full force.  That’s a significant difference in flex, and it will be interesting to see how this frame rides once I have it restored.

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With just some minor polishing with a wadding cleaner (I use NEVRDULL), the frame shines beautifully.  I need to source some 650b wheels from the period, because at some point someone tried to install 700c wheels on this bike, and that is how the bike was configured when I acquired it.  The spacing at the rear dropouts is 115 mm, so it would be hard to find the vintage hubs to build a wheel set, even though I have a nice vintage set of rims.  Instead, I am on the hunt for a donor vintage bike from the 40’s or 50’s which can give me a decent 650b wheelset, and maybe a few other parts to add to my collection.