Fixes Repairs & Comments

The Problem – Bad Wheel Alignment

Unfortunately my rear wheel, although in-line with the front wheel, was tilted to the right.  This had to do with the fact that my dropouts had sagged slightly to the side when the glue was drying.  I initially tried to bend them back to vertical.  This didn’t work terribly well….  so

The Fix – Bad Wheel Alignment

I used a 1/4 inch round metal file and slowly filed the dropouts.  Filing vertically upwards on the dropout tips the top of the wheel left or right and filing backwards moves the front of the wheel left or right (depending on the side you file, pretty simple)  This allowed me to put the wheel back into alignment.

The Problem – Cracks

Luckily this has not been a problem with my frame.  But I saw this on instructables.com and I thought the lessons might be useful.

Below we can see a crack that formed when clamping the seatpost directly to the bamboo seat tube.  The main lesson here is that bamboo is only strong in certain ways.   Think about a bamboo pole in a grove somewhere, if the force is non-natural (horizontal compression) your bamboo will likely give out on you.

The Fix – Cracks

I think the kid here did the right thing more or less.  First he drilled a hole (ideally at the base of the crack) to alleviate pressure.  Then he used his resin and hemp fiber to reinforce the whole crack (not shown here).  My guess is that it worked for him.   Although under this circumstance he could have cut the top of the pole down more and put in a metal seat tube collar.

The good news it seems is that most cracks can be repaired with some resin and fiber.  I have read one or two instances where calfee patched a frame this way, so you have to assume that it works.   You might consider injecting some thicken epoxy inside of the tube also, if possible.  This surely would alleviate most of the stress on the area.

Another fix option was used by a reader “Kobike” to fix a blemished pole.  The carbon patch is likely the best possible fix.  Check out other pictures from Kobike  http://picasaweb.google.hu/bamboobikeboy/BamboobikeS2?feat=directlink#.  Looks like a beautiful bike.

Potential Issue

Although immaculately built I have one concern for Kobike’s build.  All the hemp fibers appear to be lined up in one direction.

Although its not a death sentence of an sort, with a unidirectional matrix (as shown above) there is nothing to keep the epoxy holding individual fibers from tearing apart.

The Fix

Use multiple layers with fibers oriented in different directions to maximize the strength of your joints.