Saturday, April 24, 2021

Building a Cheap and Cheerful Singlespeed

It's time to build something a little different.  The white Schwinn Traveler that I repainted was in pretty rough shape, and I want to rebuild it without spending a lot of money.  Its front derailleur was the wrong clamp size, and used a rubber shim to secure it to the seat tube.  The rear derailleur was corroded and in bad shape (I think this bike was left outside for years).  Instead of trying to find replacements, let's just do away with them both. 

To make a singlespeed conversion you first need a singlespeed freewheel.  In the past I used inexpensive Dicta freewheels, but new bike parts are getting rather expensive now.  I happen to have an old 5 speed Normandy freewheel with a worn out 14 tooth sprocket.  Using a pair of chain whips I was able to unscrew both the 14 tooth and 17 tooth sprockets from the freewheel body. After sliding off the remaining sprockets, I reassembled this freewheel with three spacers behind the 20 tooth sprocket.  Since this sprocket is splined, I screwed the 17 tooth sprocket back on to hold everything in place:

This setup is a little bit heavier than a proper singlespeed freewheel, but the goal here is cheap.

Next it's time to look at the front part of the drivetrain. After removing the 52 tooth chainring there is an issue with the chainring bolts:


You can buy shorter chainring nuts and bolts to fit a single chainring.  However, that costs money so that's not an option for this build.  Instead I can grind the nuts down to make them shorter.  An even easier option is installing 10mm or 3/8" washers in place of the large chainring.  These washers will take up the slack and allow me to fully tighten the bolts.

I ended up having to grind a flat side on each washer so they could fit properly on the crank spider, but that only took me a few minutes.  With all the washers in place, the chainring could be securely installed:

The chain needed to be shortened, so I loosely installed the rear wheel and looped the chain around both sprockets in order to find the right length. Since this frame has horizontal dropouts, there was a lot of room to adjust the chain length:


Getting the chain to run straight between the front chainring and the rear freewheel is the main concern when you convert a bike to singlespeed.  To accomplish that, I simply moved the 40 tooth chainring back to its original location on the inside of the crank spider.  This provided a nice straight chainline:


After reassembling the rest of the bike I spent a slightly painful amount money on new handlebar tape.  The drivetrain isn't the prettiest, but this bike rides quite nicely.

Repainting a Bike Frame

 I bought a Schwinn Traveler that has seen better days:

At first I sort of liked the dirty rusty paint, it looks like an old messenger bike that has been ridden for thousands of miles.  However, I live in the salt belt so it just reminds me of every old beater car I see on the road.  Time to deal with it.  I used a product called Naval Jelly to dissolve the rust and prevent it from returning:

After brushing it on the entire frame I left it overnight to do its thing.  Next I hammered out the headset cups with a tool I made from a length of metal electrical conduit:


Now it's time for the tedious part.  I sanded the existing paint (or at least whatever is left of it) with sandpaper and a medium grit sanding sponge.  The idea was to blend the chipped edges of the paint into the bare metal so that the edge lines wouldn't show through the new paint.  I also tried to avoid hitting the decals since I wanted to keep them.  After sanding, I cleaned the frame with denatured alcohol:

 Next I taped over decals with masking tape:


I should mention that I am not a professional painter, and I also didn't have the time or motivation to make this paint job look perfect. I just wanted the bike to look presentable from 20 feet away. Anyway, time for primer:

I sprayed three thin primer coats using a can of rustoleum automotive primer.  After that dried I used some string to hang the frame in my garage:

Spray paint cans are difficult to get a good finish with.  They tend to spray too much paint at a time, which causes drips and runs.  Also, the paint coming out of the can is very thin, so you will have to spray lots and lots of very light coats.  Instead I have a small air compressor and an inexpensive spray gun.  I mixed some rustoleum gloss white and almond colored paint together to try to color match the existing paint:

I also added enough mineral spirits to thin the paint.  The proportions were about half white paint, one quarter almond, and one quarter mineral spirits.  I set the compressor's air regulator to 60 psi and got to work:

The spray gun is much more forgiving than spray cans. I was able to lay the paint on pretty thick without worrying about drips.  After a few coats I peeled off the masking tape.  Much to my disappointment the new paint didn't match very well:

I touched up the areas around the decals by hand with a small brush.  The end result is much better looking than the rust.  It's not perfect, but I'm more than happy with it.