Announcement

Collapse
No announcement yet.

BBSHD - Luna Eclipse offset adapter idea

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    BBSHD - Luna Eclipse offset adapter idea

    I moved the Luna BBSHD motor kit and parts over to another bike

    Everything was great except the Luna Eclipse 42 tooth chain ring was hitting the chain stay
    It needs about 6mm reverse/positive offset to make it clear

    Shimming the motor out away from the BB is not an option with my 120mm BB and 120mm BBSHD
    Shimming the chain ring out 6 mm with spacers will not work
    The chain ring would be hanging out in the air without any center support

    The chain ring is only a couple weeks old and I really want to be able to use it again
    In the mean time, I am using a Luna mini 30 tooth chain ring
    It's a great chain ring, but not enough offset and not enough top end with an 11 tooth cassette gear.

    So I came up with an idea to make an adapter to add 6 mm positive offset to the motor-chain ring
    6 mm lets the chain ring just barely clear my frame

    I made a mock up adapter out of plastic to test the concept
    It looks to me like this idea will work if made from 7075 aluminum.
    I would have to find a machine shop with a lathe because I only have a small hobby lathe

    Or maybe Luna thinks this is worth a look?

    Here's the mock up and how it works

    The video has a full explanation and shows detail of how it looks on the bike

    Last edited by EL34; 05-13-2019, 12:45 PM.

    #2
    Ok, here is the adapter, fresh off the lathe

    I have to get some longer 5 mm bolts today and then I can test it with the 42 tooth Luna eclipse chain ring

    Comment


      #3
      I had a similar issue. Eclipse had too much offset. Mighty Mini fit.

      I modified one Eclipse to fit by removing material from the ring, then putting sprocket back on. Made the eclipse have less offset. Worked fine.

      Now I just use Luna's 130 BCD adapter, which has less offset, stock. No mods required.
      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

      Comment


        #4
        Originally posted by JPLabs View Post
        I had a similar issue. Eclipse had too much offset. Mighty Mini fit.

        I modified one Eclipse to fit by removing material from the ring, then putting sprocket back on. Made the eclipse have less offset. Worked fine.

        Now I just use Luna's 130 BCD adapter, which has less offset, stock. No mods required.
        How much offset does that 130 BCD give you?
        What size ring are you using?

        I ended up having to remove almost 7mm of offset from my eclipse using that apadter

        Luna says that eclipses has 24.8 mm offset
        So 24.88 - 7mm = around 17.8 mm offset to clear my frame with a 42 tooth ring

        I really would like to use a 36 tooth, but it looks too small to fit over the motor hub metal area

        Comment


          #5
          I run 42 and 44T.

          It has 9mm offset, a bit more than the Mini. See here: Luna Alloy 44T, 42T: https://electricbike.com/forum/forum...g-offset-guide
          Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

          Comment


            #6
            Originally posted by JPLabs View Post
            I run 42 and 44T.

            It has 9mm offset, a bit more than the Mini. See here: Luna Alloy 44T, 42T: https://electricbike.com/forum/forum...g-offset-guide
            I ended up with about 16mm of offset and the chain line is not too bad

            Comment


              #7
              I got to get out and test the 42 Tooth Eclipse ring with the adapter shown above.

              Did 28 miles with 2000 feet of climbing.
              Everything went smoothly.

              The new 11-40 cassette had enough low end on the steepest stuff I did.
              The 11 tooth had enough top end for my fat bike.

              I tested the top speed into a strong headwind on a flat section
              It hit almost 36 mph which is more than enough speed for me.
              So I consider this project a success.

              Comment

              Working...
              X