Good tools for measuring frame geometry
12-02-11 | 10:10 AM
#26
Icantre Member
Joined: Jun 2011
Posts: 384
Likes: 0
From: the Bayou City perpetually under construction
Bikes: 2001 DBR Axis TT, 1998 Trek 5500 OCLV, 1993 Trek 1100, 1971 Raleigh Grand Prix, 1972 Gitane Attic Beater
sum of angles of a triangle = 180 degrees
sum of angles of a quadrilateral = 360 degrees
sum of angles of a quadrilateral = 360 degrees
12-02-11 | 02:36 PM
#27
Decrepit Member
Joined: Aug 2005
Posts: 10,488
Likes: 92
From: Santa Rosa, California
Bikes: Waterford 953 RS-22, several Paramounts
I made up some hardwood slides that fit over an 80x20 alloy extrusion with axles. I am not crazy with the tires on the ground, I would go bare rims if the bike was together.
Referencing off the axle centers will give the best info though in my mind and is how a framebuilder would replicate a bike.
The little digital angle finder is a nice one it appears, small enough, most are not, I had to use a 1/2/3 block to offset mine for the head tube.
IF the axle plane or base plane is level then the angle measures will be good. the fork can be arrived at without taking it apart, but I appreciate the element accuracy.
I think noting bottom bracket drop is important.
One thing not to do is assume that the top tube is level, it more than not isn't.
For measuring top tube ctc length I place some masking tape on the joints and draw the intersections out.
Referencing off the axle centers will give the best info though in my mind and is how a framebuilder would replicate a bike.
The little digital angle finder is a nice one it appears, small enough, most are not, I had to use a 1/2/3 block to offset mine for the head tube.
IF the axle plane or base plane is level then the angle measures will be good. the fork can be arrived at without taking it apart, but I appreciate the element accuracy.
I think noting bottom bracket drop is important.
One thing not to do is assume that the top tube is level, it more than not isn't.
For measuring top tube ctc length I place some masking tape on the joints and draw the intersections out.
I fabricated some brackets for the front and rear dropouts that get the axle centers the same height above whatever flat surface you're using, and high enough so that the BB shell clears the surface, assuming the BB drop isn't more than ~100mm.
12-03-11 | 09:38 PM
#28
Senior Member
Joined: Feb 2008
Posts: 1,115
Likes: 17
This is pretty handy:
https://www.amazon.com/Wixey-WR300-Di...1686591&sr=8-4
This might work pretty well, too:
https://www.harborfreight.com/multipu...nder-1028.html
https://www.amazon.com/Wixey-WR300-Di...1686591&sr=8-4
This might work pretty well, too:
https://www.harborfreight.com/multipu...nder-1028.html
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