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By Brian, September 13, 2008 10:41 am

After my wheel building project that initially seemed to have gone sour, I’ve made some incremental progress on a bicycle I’ve been rebuilding.

It started off as a mountain bike in rough shape that my brother gave me. I cleaned and lubed the whole bike, upgraded the brakes, added fenders, added road tires, and swapped out the cranks. Sadly, none of this resolved a drive train issue where it seems to skip on the smallest rear cogs while under any sort of load.

A little creative thinking later, and I took a three-speed internal geared hub and built it up to a modern 26″ aluminum rim. Immediately upon attaching it to the bicycle I realized I was going to have a few technical issues to contend with.

The first problem was that the derailleur chain was the wrong size. I was very dismayed by this issue since the chain that went with the hub is destroyed by a mass of rust and not worth attempting to recover. A little research revealed that there was a pretty good chance the issue was the chain width – internal gear hubs and single speed bikes use a 1/8″ wide chain which is slightly wider and less flexible.
A quick visit to the local bike shop was very helpful since they had such a chain for $9.99.

I cold-set the rear triangle to the narrower width of the internal hub and sized the chain. Ideally the chainline wants to be to the innermost gear on a 3-gear crank, however the gear ratio that produces leaves little to be desired. Coasting works fine, however back pedaling quickly will throw the chain so it needs to be tensioned. The reason for this is the rear dropouts are vertical, meaning the wheel cannot be pulled back into position to tighten the chain.
To solve this, I filed an axle sized groove into the dropouts so the chain can be tensioned. Unexpectedly this raised another problem – since the chain is going to the middle cog, the chainline is not perfectly straight. Once the chain is tensioned it starts to bind on the cogs since it is less flexible than the narrower chain.

That’s pretty much where I took a break from it so I can devise the best method of resolving this. Somehow I need to reduce the angle of the chainline while maintaining an adequate gear ratio. I may have to re-examine the angles on the rear triangle and do another round of cold-setting the metal.

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By Brian, September 2, 2008 3:20 pm

Sporadically I wander the neighborhood for discarded bicycles before they get scooped up by the metal scavengers or waste disposal engineers. I came across a 3-speed CCM made in late 1977 – or at least the Shimano components date to that time.

Rust has built up on various portions of the bicycle, leaving it’s restoration dubious besides it being too small a frame for me. The reason I had for picking it up in the first place was the three speed Shimano hub on the back wheel. It’s internally geared, sealed and still ratchets fine.

The only problem (or is it…) – the rim is steel and slightly too large to fit a bike designed for 26″ mountain bike wheels. The brilliant plan I have is to learn how to build a bicycle wheel!

Indeed this is what I did this weekend, with eventual success. Following instructions from the late Mr. Sheldon Brown’s website, referencing existing wheels and finally following truing instructions on the late Mr. Ken Kifer’s website. As an aside – it’s very sad that some of the best sites regarding cycling where created by people who are now deceased.

Sadly, while test fitting the wheel to a bicycle I discovered the sprocket teeth are slightly differently spaced than modern multi-speed bike chains. I suspect it has more in common with a track bike.

That basically puts this project on hold. I now need to source appropriate sized chain and cranks to match this cog before proceeding.

The ultimate goal was to convert a mountain bike into an all weather grocery hauler. With the sealed gearing I could eliminate some of the mechanical wear caused by the elements and still have a small range of gears.

Despite the stall to this project, I’m pleased to have learned all about wheel building and truing – this was a gap in my mechanical abilities that should prove valuable in the years to come.

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