Re-shaping the dropouts..
Posted: January 22, 2012 Filed under: Uncategorized
My tubeset has arrived from Reynolds and I’m ready to draw the frame design. I plan to use 650c wheels as they will allow a little more room for mudguards on this smaller frame size, whilst still being able to take fast 23mm tyres for zipping around town as a fixed wheel bike. The rims can take up to 28mm wide tyres if so desired in “tour mode”.
This bike is for my friend Tamsin, and I hope to show it off in the new builders’ room at Bespoked, the UK hand built bicycle show in March.
Following on from my last post I have to allow some more clearance for the rear quick release nut to pass the derailleur pivot so that the rear wheel could drop out cleanly.
Here are some pictures of how I achieved this:
I marked the dropout with a marker pen so that when I marked the required clearance around the nut and derailleur, my scribed lines would be easier to see.
I then scribed a line to round off the inside corner.
I had to file carefully in the vice to avoid nicking the other surfaces.
I tried to get a smooth curve.
Checking to see if it will pass - the nut I used here is quite large, over 19mm. I thought it would be best to check the fit with the "worst case scenario" size.
The 1st drive side dropout became a template for the non-driveside dropouts, and vice-versa, with flat plate against flat plate. I scribed a line tracing the corner.
the line is marked.
Marking up a batch to be filed.
Before (top) and after (bottom). I'll clean up the stray brass a little and try and remove that broken bolt in the rack mount. Never use a blunt tap.. I bought a much higher quality tap to finish all the other threads properly.
Filing in the vice to the template dropout.
Almost matching now.
Will she pass? Yes!
I filed the inside of the track ends flat and parallel, smoothing out any lumpy brass. I used a round file in the curve.
On a few of the dropouts I cheated and touched in a little brass from inside if there were any small gaps (come on, I am a newbie). This obviously had to be cleaned up with files too.
A flock of filed dropouts.
Still to come: Machining the track end faces, chamfering the edges smoothly, deciding on head tube angle and fork rake to give the best trail figure for both uses and mudguard issues…
Bye for now,