Frame question

Discussion in 'Motorized Bicycle General Discussion' started by dtv5403, Jul 2, 2015.

  1. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    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?
     
  2. LandSpeedRecord

    Joined:
    Dec 11, 2014
    Messages:
    604
    Likes Received:
    0
    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.
     
  3. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    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?
     
  4. curtisfox

    curtisfox Well-Known Member

    Joined:
    Dec 29, 2008
    Messages:
    4,126
    Likes Received:
    52
    Sure should be, also if you need a frame spreader you can by a small block chev exhaust spreader cheep on the bay.......................Curt
     
  5. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    Ok cool, that works for me :D Now that's one less thing to worry about.
     
  6. racie35

    racie35 Active Member

    Joined:
    Nov 17, 2012
    Messages:
    1,700
    Likes Received:
    0
    Dtv...are you measuring length or width?
     
  7. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    Measuring to see that the frame is properly aligned after widening the space between the dropouts.
     
  8. racie35

    racie35 Active Member

    Joined:
    Nov 17, 2012
    Messages:
    1,700
    Likes Received:
    0
    Yes but why the long measurement ? Sounds like you're doing it wrong. Need help?
     
  9. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    How would you do it?
     
  10. racie35

    racie35 Active Member

    Joined:
    Nov 17, 2012
    Messages:
    1,700
    Likes Received:
    0
    I'll walk you through a sure way if you wanna call
     
  11. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    Can you just post it here so everyone can have the info?
     
  12. racie35

    racie35 Active Member

    Joined:
    Nov 17, 2012
    Messages:
    1,700
    Likes Received:
    0
    Only if I felt like typing it all out and I dont
     
  13. dtv5403

    dtv5403 New Member

    Joined:
    May 4, 2015
    Messages:
    322
    Likes Received:
    0
    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.
     

Share This Page