Anyone Narrow A Rear Wheel Hub?

Discussion in 'Performance Mods' started by 5-7HEAVEN, Mar 18, 2012.

  1. 5-7HEAVEN

    5-7HEAVEN Member

    What I'm trying to do is fit an 8-speed cassette hub with disc brake into a cruiser frame.

    Cut the hub in half, narrow it, weld it back together and fit it into the narrow cruiser frame. Run the disc brake on the left and the engine/bicycle drive sprockets on the right. The disc brake adaptor will either be bolted onto the dropout or welded to the frame.

    This is for a 6hp Robin engine on a Roadmaster cruiser frame. No muti-speeds, maybe a single engine sprocket/bicycle sprocket chained to an SBP setup at the bottom bracket.

    Yes, I know that the pedalling ratio will be 'way off. Pedalling is just for starting off, if necessary.

    Would it be better to pry/widen the steel frame?

    Any thoughts?
    Last edited: Mar 18, 2012

  2. V 35

    V 35 Member

    Oh Yeah, your idea sounds far fetched, at best, I mean no disrespect, and admire your thought process.

    Spreading the rear stays is easy, when you say narrow, do you mean an old 3 speed type bike ? [ That's * narrow * ! ]

    Use 2 builder's squares to measure width of hub [ assembled ]
    or a ruler, if hub is unlaced. Measure stays, now you know how
    much spread you need. For minor spreading, use a sizzors jack
    on rear dropouts. You can splay out aprox. 1" cold, for more splay, you should strip the paint, and anneal the tubing, heat before bend. If you indeed have a 3 speed frame, and are desireing a big wheel, kerf stays, splay, weld kerfs shut.

    I'm sure if you do some calculating, you won't need to narrow hub. I'm guessing a cold bend would do it.
    Last edited: Mar 19, 2012
  3. motorpsycho

    motorpsycho Active Member

    I'd go with the above suggestion.
    Just widen the rear of the frame by spreading it apart.
    narrowing a hub would be a ton of work and it would have to be welded back together PEREFECTLY to keep it true.
  4. 5-7HEAVEN

    5-7HEAVEN Member

    LOL, I just had to throw out that idea. It didn't seem too complicated. A machine shop coulda prolly done it precisely and sleeved for more strength. The axles, spokes and bearings would've held, I believe. The sleeve would've strengthened the hub.

    Sometimes ya gotta think outa the box. Don't downplay anyone with unusual ideas. That's what makes everyone unique.

    However, it's MUCH cheaper and quicker to stretch the stays. That's probably been done countless times over a hundred years or so. Triangulation is key, I presume.

    Thanks for your tips. The other forum's members gave me the same advice.
    Last edited: Mar 20, 2012
  5. BigBlue

    BigBlue Active Member