Frame question

GoldenMotor.com

dtv5403

New Member
May 4, 2015
322
1
0
USA
If one needed to widen one's rear dropouts to accept a wider hub, how would one tell if it had been done correctly, and that both sides of the rear triangle had been spread apart evenly and the same distance from the center?
 
Dec 11, 2014
628
14
18
Tucson
Wrap a string around one rear drop out, loop it around the head tube back to the other drop out, making sure they are laying against the drop outs identically. Then take measurements from the string to the seat tube on both sides, also attach levels to each drop out so they extend above and below by at least a foot then measure that it is true in that direction. If your local bike shop has one Park Tool makes a frame alignment gauge that you press against one side then set the contact point to the rear drop out then flip to the other side. Honestly you can be as or more accurate and thorough with string, levels, rulers, and a plump bob.
 

dtv5403

New Member
May 4, 2015
322
1
0
USA
So here's what I did. I finally found some string I had laying in a box. My frame has holes in the rear dropouts, they aren't for fenders but they're there so whatever lol. My frame is also a double top bar frame, the kind you could mount a tank between the bars. So I ran the string through the hole in one dropout, between the double top bars and through the hole in the other dropout. I then took my tape measure and ran it from where the seat tube meets the bottom bracket to where the string came out of each hole. On both sides I got exactly 18.5". I suppose I could have measured without the string, but I think the string gave me an easier point to measure to. Anyway, I'm assuming since the distance was the same, the dropouts are spread evenly apart?
 

curtisfox

Well-Known Member
Dec 29, 2008
6,041
3,935
113
minesota
Sure should be, also if you need a frame spreader you can by a small block chev exhaust spreader cheep on the bay.......................Curt
 

dtv5403

New Member
May 4, 2015
322
1
0
USA
Measuring to see that the frame is properly aligned after widening the space between the dropouts.
 

racie35

Active Member
Nov 17, 2012
1,702
5
38
usa
Yes but why the long measurement ? Sounds like you're doing it wrong. Need help?
 

dtv5403

New Member
May 4, 2015
322
1
0
USA
Wrap a string around one rear drop out, loop it around the head tube back to the other drop out, making sure they are laying against the drop outs identically. Then take measurements from the string to the seat tube on both sides, also attach levels to each drop out so they extend above and below by at least a foot then measure that it is true in that direction. If your local bike shop has one Park Tool makes a frame alignment gauge that you press against one side then set the contact point to the rear drop out then flip to the other side. Honestly you can be as or more accurate and thorough with string, levels, rulers, and a plump bob.
I didn't quite understand this the first time I read it. During a Google search, I came upon a Sheldon brown article where the exact same method is described and pictured. I then understood it and realized it was the same method you described. And upon measuring, I found the distance from the seat tube to the string to be equal on both sides, about 1.375". Thank you for your help, although I did not understand it at first, it was correct and I figured it out eventually lol.