TITLE: Rebuilding a bike
DATE: 2018-07-25
AUTHOR: John L. Godlee
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The bike that I normally use around town is in storage for the
summer, and I was missing having a bike. I've also been wanting to
refurbish an old bike for a long time, to learn skills and
understand the mechanics and compatibility issues with building
bikes. I found this BSA Tour De France on Gumtree for £30 and it
immediately got my attention:
I decided to make the bike into a single speed, as I've already got
a decent geared bike, so I set about stripping it down, removing
the rear derailleur and the down-tube friction shifter.
Lots of people suggest using a single speed conversion kit to
change the gear setup, but these rely on the rear wheel having a
cassette on the backwheel, rather than a freehub. Sheldon Brown has
a good guide on identifying whether you have a freewheel or a
cassette. Basically, cassettes come apart and you can slide off and
rearrange the cogs or replace them with spacers, while freewheels
have a group of cogs all connected together that screw onto the
hub. A lot of older bikes with their original wheels have
freewheels, as mine did, meaning that a single speed conversion kit
won't work. Some people recommend just screwing on a single speed
freewheel, like the sort you would put onto a BMX, but this would
mess up the chain line as the wheel on a multispeed bike will be
dished to allow space on the driveside to fit a multispeed
freewheel, and a single speed freewheel is much smaller. You can
redish the wheel, but this was beyond my expertise, so I just kept
the 5 speed freewheel that was already on the wheel. Maybe later
I'll learn about re-dishing the wheel, as single speed freewheels
aren't that expensive. Having all the cogs also made it super easy
to pick the cog which had the best chainline to the front cog.
[single speed conversion kit]:
https://www.planetx.co.uk/i/q/SKOOSSKK/on-one-singlespeed-converter-
kit
[Sheldon Brown]:
http://www.sheldonbrown.com/free-k7.html
[single speed freewheel]:
https://www.sjscycles.co.uk/freewheels/16-ird-defiant-332-inch-singl
e-freewheel/
To keep tension on the chain and to ensure that the chain stays on
the correct rear cog, I bought a chain tensioner. This is a bit
like a stripped down rear derailleur. THe type I bought is spring
loaded and screws into the rear mech hanger. Specifically I bought
the 4 Jeri SS Chain Tensioner. I could have removed the rear mech
hanger completely and used the horizontal dropouts on the frame to
set the frame tension, but I find using a chain tensioner much
easier and reduces maintenance.
[4 Jeri SS Chain Tensioner]:
https://www.bikeparts.com/BPC148137/4-jeri-ss-chain-tensioner-black
I replaced the seatpost with longer one, making sure to check the
diameter of the bottom of the seatpost to fit into the frame AND
the top of the seatpost to make sure it fits into the seat clamp.
Maybe in retrospect it would just have been easier to buy a
seatpost that came with a clamp, but I was trying to save on
materials as much as possible.
The last thing I did was replace the bar tape, as it had become all
worn down. I watched a tutorial from Park Tool on how to properly
wrap the tape:
[tutorial from Park Tool]:
https://www.youtube.com/watch?v=5MzIiv7pewE
Update - 2018_09_09
I finally got this bike out of storage after the summer break. I
counted the gear ratio, it's got 46 on the front and 16 on the
rear, which is nearly a 3:1 ratio, which is actually quite normal
for single speed bikes, though possibly more suited to a fixed gear
than a freewheel like mine.
