BMP Friction Drive Kit converted to V-Belt Drive

Discussion in 'Photos & Bicycle Builds' started by lowracer, Oct 22, 2010.

  1. lowracer

    lowracer Member

    I finally got my project to the point where I am happy.
    Don't get me wrong, I love the simplicity & easy installation of the friction drivetrain, but since I already went the extra mile attaching a DIY rim to rim pulley system, I had to try this out & bought the BMP kit specifically for its 1/2" clutch drum shaft thru the 2 outer bearings. My 1.5" V-Pulley mounts onto the 1/2" BMP shaft perfectly & has a set-screw to keep everything tight. I just had to remove the 1.25" friction drive roller (2 set-screws). My top speed using the Robin EH035 w/friction drive setup was ~33 mph. With the V-Belt drive, top speed today was ~36 mph. I really like the BMP Kit & the company behind it. Jim @ BMP provided me with strong communication throughout my build. Here are my latest pics of the way I will probably leave things until I give in to my need for speed & go out & buy a higher displacement 2-stroke?

    Attached Files:

    Last edited: Oct 23, 2010

  2. aero07

    aero07 Member

    I really like your setup.
    Could I have a little more info
    on how you did the rim, where you got parts
    I would like to try it myself.
    Thanks, Aero07
  3. lowracer

    lowracer Member

    I have many bike parts lurking in my garage from the many years I have been an avid cyclist. The rim to rim pulley is simply an extra wheel I had that I removed the spokes/hub/nipples leaving just the hoop. First measure your fork for clearance & the width of your rim to rim before starting such a project. I cleaned both the bicycle front wheel & the pulley hoop with sandpaper & alcohol before using JB Weld to glue them together & a few days to dry laying them flat on the hoop side. Then I drilled 4 small holes thru both wheels but under the area that the tube would be in to bolt it all together in case the JB Weld decides to break free. This means you can only use Disc or Drum brakes (no more rim brake unless your bolt thru very aero deep v rims thru the V area). The rim hoop becomes a perfectly sized pulley along with a 1.5" V-Belt pulley w/ 1/2" bore available at for a few bucks to get the gear ratio for these little engines into the correct 18-19:1 ratio. The rest is easy if you use a BMP kit to support the engine & keep everything nice & sturdy. The quick release skewer allows tension adjustment for the V-Belt. Definitely use a notched AX type VBelt (on eBay $15) to better wrap around the smaller 1.5" engine VPulley. V-Belts last a real long time before needing replacement & can handle loads way in excess of what these small engines can dish out.
    Last edited: Oct 23, 2010
  4. Esteban

    Esteban Active Member

    Ingenuity is essential with some of these rigs. LOOKS GOOD !
  5. lowracer

    lowracer Member

    Just when I go & write that I am happy with it now, I go & add a belt tensioner today to help the belt track perfectly centered inside of the rim
    I have now added three new pics showing the tensioner added.
    Last edited: Oct 23, 2010
  6. BMP

    BMP Motored Bikes Sponsor

    Great setup lowracer! Glad to see the kit being customized to the belt drive system.
    Best of luck with your excellent build, James
  7. lowracer

    lowracer Member

    BMP Conversion (Friction to VBelt) New Pics

    Shortened the stem & lowered the handlebars. Changed the seat & dropped it real low...Getting a few more MPH riding low

    Attached Files:

    Last edited: Oct 29, 2010
  8. lowracer

    lowracer Member

    I was getting some chattering & mechanical noise from my clutch drum area that was due to some play in the drum shaft/bearing area. I decided to see if I could get all the play out to quiet things down.
    1- I loosened the Phillips head screw that retains the shaft collar.
    2- I added another washer behind the included kit washer with a hole large enough to fit over the 1.2" driveshaft.
    3- I loosened the shaft collar & tightened the Phillips head screw tight.
    This made the assembly not spin very well (too tight).
    4- I backed the Phillips head screw out incrementally to allow everything to just start to spin freely.
    5- Then I tightened up the shaft collar & finished tightening up the Phillips head screw.
    All is perfect now & quiet as a mouse.What a difference it makes motoring thru my local neighborhood without all that extra noise.
    Last edited by a moderator: Dec 16, 2015
  9. Will Snow

    Will Snow Member

    I like your creative approach, good for you.

    I too have been doing this for many years (1981) and have tried many setups. I have a BMP friction drive and like the product and the person also. I also have the Golden Eagle, something like you created . I have several others but none as personally built as yours.

    Thank you for sharing this. I don't get on this forum much any more, slowing down I guess. But when I do, it is your kind of project that I enjoy seeing. Good luck with it.

    Best Regards

    Will Snow
  10. lowracer

    lowracer Member

  11. Stoney

    Stoney Member

    Thank you