Dropout extensions... where to buy?

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by silverbear, Sep 12, 2011.

  1. silverbear

    silverbear The Boy Who Never Grew Up

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    I have come to the conclusion on an oddball build of mine (Tomos/AMF Roadmaster) that I want to go with 26" rims. There isn't room in the frame for that big a wheel in the rear, so I want to extend the axle point back by a few inches. A year or more in the past someone on this forum bought dropout extensions which bolted on to the existing ones and also had a couple more bolts added if I remember right. Does anyone know of a source?
    Any suggestions or photos from someone who has made their own? If I have to make my own then I'd like to have horizontal dropouts with adjustment bolts. I think I'd leave the welding to someone with some skill in this area. If a friend and I do it then I'd want a pro to look over the welds to be sure they are right. Any suggestions on type and thickness of metal? Don't want anything coming apart ever. I can't be the only one who has wanted to do this.
    SB
     
  2. deacon

    deacon minor bike philosopher

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    I bolted some extension in the front fork but never the rear. In my craziness, I used a 6" shelf bracket and cut it in half. I bolted it through the fork on the outside, then welded it just to prevent it from moving. The bolts where the securing point. I went from a twenty inch fork in front to a 26". I had a hub motor in the fork and it held even with my crappy welding.

    In the rear you could theoretically do the same bolt the bar in with a 3/8 bplt then find a spot to hold a `1/4 inch bolt behind it somewhere just to keep it from moving. Use a lock tight on the threads. Two nuts and bolts on each one should be enough. There really can't be any twist action on the bolts it is all going to be up and down where their strength really is. I wouldn't have it welded. I would want to be able to take the bolts off to remove the wheel.

    On second thought you probably need a chain tensioner as well, since you wont be able to adjust the position of the wheel. you can take it on and off, but not slide it around this way. Unless of course you were to bolt the extension onto the axle then run your bolt through the extension instead of a bolt behind the dropout use a serious automotive clamp on the round part of the frame to keep the extension in place.

    Please remember this is from a man who fell off his bike and broke 6 ribs and his collar bone you might not want to take my advice. If you do check it carefully and often.

    It is an interesting problem.
     
    #2 deacon, Sep 12, 2011
    Last edited: Sep 12, 2011
  3. silverbear

    silverbear The Boy Who Never Grew Up

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    Deacon,
    Thanks for your thoughts on this. What I was picturing was bolting the extensions on, but having the extensions open at the rear so the wheel could come on and off, with adjusters to get the chain tension right. In other words, it would be like it was, but further back. The problem is in how best to join the extension to the existing dropout. I"ll post photos of what I have in mind. A good thing now that I think about it, is that the AMF dropouts are of the vertical kind, so a bolt through there and into a hole at the rear of the extension plate would be pretty secure I would think. As you said, a smaller bolt or two elsewhere on the plate and through the AMF dropouts would stop any up/down movement. Maybe welding isn't even necessary. Don't know.
    SB
     
  4. deacon

    deacon minor bike philosopher

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    Or you could make the extensions to wheel the perm mount. Then drill a hole in the extension for the existing dropout and hook the chain to it. Tighten the chain by sliding the extension back in the dropout. then drill the small hole through the tight extension and the frame at the same time. Bolt it down and it would never move again until you wanted it to. Then if you needed to later you could just replace the extension or slot the smaller hole to get a small adjustment.
     
  5. azbill

    azbill Active Member

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  6. silverbear

    silverbear The Boy Who Never Grew Up

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    Thanks, Bill. The guy is doing a nice job of it. I think I'll go with steel rather than aluminum, but it's good to see what others are doing and how they're going about it.
    SB
     
  7. Bicycle Motor Fun

    Bicycle Motor Fun New Member

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    I've been thinking about making my own rear wheel drop outs too, like I had on my old bikes as a kid. This way, I would eliminate the chain tensioner on the engine drive chain and the derailier would take care of the original pedal drive chain. Karl
     
  8. timboellner

    timboellner Member

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    Hey SB,

    I found a post where a guy name poorboys bikes made his own drop-out extensions that look nice and are bolt-ons. He doesn't sell them and it looks like he might not be around here anymore. I don't know.

    I'm sure they are one a kind but,this may give you a good idea what to do when designing something specific for your bike.

    Post#4 has the picture you'll be needing

    http://motorbicycling.com/f26/heres-what-ive-been-workin-25048.html

    I'll keep a look out for more in my bookmarked bike parts supplier lists.

    Take er easy buddy... Hope to see you again someday in the not too distant future.
    TiM
     
  9. silverbear

    silverbear The Boy Who Never Grew Up

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    Bicycle Motor Fun,

    Having no drive chain tensioner sounds good to me, too. Welcome to the forum, Karl...
    SB
     
  10. silverbear

    silverbear The Boy Who Never Grew Up

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    Hey Tim,
    Thanks for the thread... just what the doctor ordered. I may go ahead and cut out a couple before I head for Maryland. The I can get Dan to help me with welding them on (along with bolting).
    Think you can make it to Thurmont for Colorfest? I don't know the date, but think it is mid October. If not then, let's get a ride together with Tinsmith when we can before the snow comes. See you soon, I hope.
    SB
     
  11. timboellner

    timboellner Member

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    I'll surely try!
     
  12. poorboys bikes

    poorboys bikes Custom Bike Builder

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    Thanks for remembering me guys, I saw this thread, but forgot my password cuz its been a while since I tinkered. I just traced the dropout on cardboard, & the factory holes of course. Then cut them outta 2" flat bar on a band saw. MAKE SURE you cut them both at the same time or yer wheel will be sittin sideways:) The possibilities are endless for your rear wheel placement, mine is sitting about 1" back from stock & 1/2" up so the bike sits lower.
     
  13. silverbear

    silverbear The Boy Who Never Grew Up

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    Not sure where I got the idea that there was something commercially available. I'm doing the same basic thing and have the materials together. but have not yet cut the extensions out. I'll post some photos when the time comes.
    SB
     
  14. The_Aleman

    The_Aleman New Member

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    Will this help, Silverbear? Frame Building Parts | Parts | Surly Bikes

    I know some higher-end frame companies sell individual dropouts, because my family's laser shop used to make S&M's dropouts. S&M once sold them alone without a frame as a replacement/upgrade part. Those were serious business too, .250" 4130!
     
  15. silverbear

    silverbear The Boy Who Never Grew Up

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    Looks like a good resource for someone. I'm at a point now where I have the materials together, a plan and a welder... so will go with what is already in process. I've bookmarked the website. Good to know such parts are available. Thanks!
    SB
     

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