's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

Determining Frame Geometry(4 posts)

Determining Frame GeometryWannabe
May 10, 2002 12:02 PM
I have an older Bianchi USA Alfana from around '91 or '92 that I would like to figure out the frame geometry of. The tubing is Tange Prestige and came with 105 group double.

How would I figure out the various angles and tube lengths? As in, how do I measure them?

I want to continue to ride this bike but I would like to change how I sit on the bike to more closely mimic my new bike (not a lot I can do, I know) and I want to get an idea as to what I'll be starting with...

Any other suggestions as to making changes to this bike would also be appreciated. Am in the process of upgrading wheelset...


re:measure what mattersdzrider
May 10, 2002 1:09 PM
I don't know how to find frame angles with a protractor, but I can tell you how to mimic your new bike. Measure distances between the points where you contact the bike. It works best with the same saddle on both.

Put the cranks parallel to the seat tube and measure from the top of the saddle at the post to the top of the pedal spindle.

Measure from the front of the saddle to the handle bars.

Put the pedals parallel to the ground. Use a plumb line and measure horizontally from the front of the saddle to front pedal spindle. Write the numbers down and try to duplicate them on the second bike. It's not quite as simple as you'd think, but I've been able to get very close. Have fun!
I have that exact same ride...jtolleson
May 11, 2002 4:25 PM
as my retro bike. It is a boat anchor but is it sweet or what?
It has never failed me...Wannabe
May 11, 2002 6:49 PM
It's like an old pair of slippers. I have not moved the seat a mm in over 10 years... It's my trainer/inclement weather bike, that I want to make some upgrades to! :) It just deserves 8 speeds and a new set of open pros! :)