BMW K100 cast wheel on chair ?

Discussion in 'Hacks' started by Shaggy63, Feb 18, 2013.

  1. Shaggy63

    Shaggy63 n00b

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    Hi All,

    does anybody know about the use of a BMW K100 wheel on a sidecar ? everything I remember from my younger days said you shouldn't use a cast wheel on the chair as it is not designed to withstand the side forces a sidecar generates and will break at some point. I'm not sure if this refers to all cast motorcycle wheels or only older 'jap' wagon wheel style wheels.

    I have recently seen a picture of a Ural fitted with a K 100 front wheel on the sidecar and a 2 wheel drive K75 with a K rear wheel fitted to the chair but I just wondered if anyone knows if they will work in the long run.

    I have a spare K 100 RS swingarm, diff and rear wheel and was going to incorporate this into my next sidecar build but will it stand the forces involved ?

    Any ideas ?

    Thanks
    Shaggy
    #1
  2. Rockman

    Rockman Been here awhile

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    I've had a K100 front wheel on mine for a while now. Bikes done about 30,000 km with this set up no probs.



    [​IMG]
    #2
  3. jaydmc

    jaydmc Long timer

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    I see no problem, The Chinese even copied this BMW wheel and run it not only on thier bikes but also on thier sidecars.
    Jay G
    DMC sidecars
    866-638-1793
    #3
  4. Hellracer.nl

    Hellracer.nl What the hack???

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    @ Rockman; Can you post some details on how the wheel is mounted? Did you use the original axle? I'm planning to use a K100 front wheel and axle on my second leaner hack.
    #4
  5. MotoJ

    MotoJ Mobtown Hacker

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    I've collected parts for a /2 earles front end conversion on my R80/7 sidecar rig. I plan to use a snowflake cast front wheel.

    I had this cast wheel discussion with a friend of mine who insisted the cast wheel would be a death sentence. Research led me to a BMW recall that is still being honored regarding the BMW cast snowflake wheels. Apparently the early ones would indeed crack and eventually shatter. They redesigned the wheel and beefed it up and I did not find any instances where they broke just from riding stress.

    Since I started looking into the issue I have met a handful of Beemer hack pilots using snowflake or K bike cast wheels and no-one has had a problem. Your K100 wheel should be fine in any position. Do make sure your bearings are in good shape and seated right, because if the races spin you'll ruin the wheel hub. The bearings will take a beating.
    #5
  6. Rockman

    Rockman Been here awhile

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    I'm not sure if its the original front axle or not (probably). Its 20 mm dia and welded into a box section swing arm. I'll get a pic or 2 over the weekend and post them for you.

    Incidentally, I seem to remember the "cast" wheels that caused problems were the Comstar wheels used by Honda in the 80's. These were a built up construction and not up to side forces.
    #6
  7. Rockman

    Rockman Been here awhile

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    Heres an innovative use of a K100 rear swingarm mounted on the front as a leading link. Something to ponder.

    The wheels shown are Renault with adaptors. I eventually took the Renault wheel & the adaptor off the front and fitted a K100 rear wheel instead. The Renault wheel was offset about 40 mm from the centreline of the bike and pulled left quite hard. The K100 rear lined up well with the centreline and steered fairly straight.
    [​IMG]
    #7
  8. Wazzz

    Wazzz Adventurer

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    Hello Rockman
    Do you have anymore photos of the front end?
    #8
  9. Hellracer.nl

    Hellracer.nl What the hack???

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    Are you sure that those are Renault wheels? They look suspiciously much like Citroen wheels..

    Here is what I used for mounting a K100 front wheel on my leaner sidecar:
    Original front axle on swing arm( unwelded here):
    [​IMG]

    Welded together and wheel mounted:
    [​IMG]

    Other side:
    [​IMG]

    And completely finished:
    [​IMG]
    #9
  10. Rockman

    Rockman Been here awhile

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    G'day Waz(zz), no mate sorry thats the only one I seem to have kept. Imagine a K100 rear swingarm turned around to
    face forward, complete with the final drive and mounted on a leading link type setup. Used a K100 rear shock. I didnt take it apart at any stage, but I suspect the input pinion had been removed from the final drive, leaving just the main gear as a wheel carrier. This would reduce drag. Downside is that you only have 1 front disk.
    #10
  11. Rockman

    Rockman Been here awhile

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    #11