Advertise on Bikeforums.net



User Tag List

Results 1 to 8 of 8
  1. #1
    Senior Member wtgrantham's Avatar
    Join Date
    Dec 2008
    Posts
    169
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Dropout adjusters

    I have been working on vintage bikes for a couple of years but just realized I don't understand why rear dropouts have adjusting screws. When and why would you adjust the dropout???

  2. #2
    Senior Member Retro Grouch's Avatar
    Join Date
    Feb 2004
    Location
    St Peters, Missouri
    My Bikes
    Rans Enduro Sport, Hase Kettweisel Tandem, Merin Bear Valley beater bike
    Posts
    23,100
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Like the little "wings" on brake pads they just make wheel changes a little quicker.

    They are obviously one of the things you can live without because so many bikes with horizontal dropouts don't have them.

  3. #3
    Senior Member
    Join Date
    Mar 2008
    Posts
    3,927
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    You set the drop out screw to position the axle correctly WRT the RD, after that you leave it alone. Its purpose is to make wheel changes faster. With the screw in place you can simply chuck another wheel in there, tighten the q/r and send the rider on his/hers merry way. If you haven't got one you have to eyeball the alignment pretty closely before you can close the q/r. Doesn't mean much for a casual rider, but can be the difference between winning and losing in a race.

  4. #4
    DOS
    DOS is offline
    Senior Member DOS's Avatar
    Join Date
    Feb 2008
    Location
    Arlington, VA USA
    Posts
    1,188
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    To adjust for chain length. When I went from 6 speed casette with 24 tooth cog to 7 speed with 28 tooth, I had to adjust the position of the wheel a bit forward in the drop out to accomodate the larger casette. With the wheel set farther back with the six spped, the chain was too short for 7 speed. The screws aren't strictly necessary since, once positioned correctly, the skewer will hold the wheel in place, but they make getting wheel positioned correctly when reinstalling a lot easier.
    My Opinions > My Knowledge

  5. #5
    cab horn
    Join Date
    Jun 2004
    Location
    Toronto
    My Bikes
    1987 Bianchi Campione
    Posts
    28,298
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DOS View Post
    To adjust for chain length. When I went from 6 speed casette with 24 tooth cog to 7 speed with 28 tooth, I had to adjust the position of the wheel a bit forward in the drop out to accomodate the larger casette. With the wheel set farther back with the six spped, the chain was too short for 7 speed.
    That's coincidental. If moving it in the dropout back the minor amount of a dropout length makes the chain too short, it was cut too short to begin with.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  6. #6
    Senior Member
    Join Date
    Apr 2009
    Location
    New Rochelle, NY
    My Bikes
    too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
    Posts
    18,066
    Mentioned
    20 Post(s)
    Tagged
    1 Thread(s)
    The horizontal dropout was originally for adjusting chain length, but not for derailleur bikes. They go back to the days before the invention of the derailleur when single speed bikes and internal gear hubs needed a slot for chain adjustment. The forward pointing slot was an improvement over the rear open (track) dropout for road and sped up wheel changes. When derailleurs were added, they were originally mounted with a bolted on hanger that fit the right dropout. (this is a shortened history of the evolution, which included a few side trips and unique designs that didn't last).

    Whether for derailleur or non-derailleur slotted dropouts mean manual centering of the rim between the chainstays with every wheel change. The addition of micro-adjusters eliminates that step ensuring hat the wheel is correctly located every time. Later on horizontal dropouts were first shortened then done away with in favor of the vertical ones in use today for derailleur bikes. One drawback is that this makes changing a frame over to SS use more complicated.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

    WARNING, I'm from New York. Thin skinned people should maintain safe distance.

  7. #7
    velo-orange
    Guest
    All y'alls are right.

    Multiple yeses. Yay!

  8. #8
    DOS
    DOS is offline
    Senior Member DOS's Avatar
    Join Date
    Feb 2008
    Location
    Arlington, VA USA
    Posts
    1,188
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by operator View Post
    That's coincidental. If moving it in the dropout back the minor amount of a dropout length makes the chain too short, it was cut too short to begin with.
    Thats what I thought too so I added two links, but then the chain was clearly too long. So I took one out, but chain seemed just a bit too short. Then I tweaked the dropout screws and everything dialed in nice and tidey.
    My Opinions > My Knowledge

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •