Bicycle

I have so much pleasure riding my own handmade bicycle that I want to share the way I did it.

Design a bike that fits your body

Framebuilding isn't knew and some books are explaining the process. Among them, the patereck which can be find free of charge here, is the one I used.

It explains all the rules needed to match the size of your frame to the size of your body. To facilitate the process, I have written all the measures you need inside a little python script called patereck.py available in this repo:

#### parameters to choose:
##### rider
A = 82 # inseam height
cubit = 46 # from elbow to nails, hand opened
TM = 67 # torso measurment
AM = 66 # arm measurment

##### bike
B = 27 # bottom braket height in cm
C = 4 # crotch clearance (4cm for touting 6cm for racing)
E = radians(73.2) # seat tube angle
HTA = radians(72) # head tube angle:70:resilient and confort (touring) 75: stiff (race)
FR = 4.5 # fork rake: + for touring - for race
R = 33.4 # wheel radius

once you run it using python patereck.py you'll find all the measurements you need:

Down Tube : 51
Seat Tube : 53.273750437
Top Tube : 54.3
========== checks ===========
Stem from torso: 3.52608695652
Stem form cubit: 9.2
Trail (5 to 7):  6.12073784511
Front center (around 58)
chainstay (40 for race to 47 for touring
check clearance

there are two ways to compute the stem and I guess I misunderstood one because both don't give me the same result. I chose the one derived from the cubit.

Once you've got these measurments, download RattleCad which is a free, open source version of BikeCad. It is far from being perfect but it does the work for the frame ajustments and mitering:

The mitering is particularly usefull as if you take care of printing these images without resizing, you'll just have to cut them and round them on your tube to cut them properly.