Tandem Motorized Bicycle Project

Discussion in 'Rack Mounted Engines' started by Tom, Mar 30, 2009.

  1. Tom

    Tom Active Member

    Ever since the Theft of my Green Machine, I have had the itch to build something new.

    I have always wanted to try a rack-mount engine, and had that tandem bike sitting around collecting dust.

    The only problem is that it was so rickety to even ride without a motor, I couldn't imagine motorizing that tandem. I went ahead and stripped the frame down. I am going to put on a bunch of new components including:

    - New wheels/tires/hubs
    - New brakes
    - New gearing with a derailer in the rear

    I would also like to:

    - Sand the frame/fork/bars down and paint them (any color suggestions? Maybe green in memory of the green machine?)
    - Add some accessories like a kick-stand (my last bike never had one), mirrors, lighting, new grips/seats, etc.

    Once I get the bike up and operating again, it will be time to add a motor. It must be a 4-stroker (cleaner and quieter), and it should have ample power to scoot two people along at 15mph. I guess that as long as I have high enough gearing, I should be able to do this. I am going to start by looking at GEBEs.

    Finally, I want to do some sort of advanced security system. Anyone know if a sort of bike alarm exists? My last kryptonite lock failed to detour the previous theif(s).

    Attached Files:

  2. DetonatorTuning

    DetonatorTuning Active Member


    good to see you moving on a new ride.

    you might consider using left side drive cranks from front to rear BB's then a thescooterguy mount just ahead and above the right side of the rear BB with a freewheel crank on that side, going on back to the rear cassette.

    if you freewheel the left side of the rear BB too you would have both independant no drag pedaling and motor drive.

    then if you wanted to, you could add a horizontal frame member between the 2 seat posts to add panneirs (sp) and have room for a real cargo outfit out back.

    PM thescooterguy about the SUPER idea he has for a bike security system.


    oops, sorry i didn't read your whole post to see that you wanted to use it as a tandem, my idea won't work well in that layout. sorry..................
    Last edited: Mar 30, 2009
  3. Zev0

    Zev0 Member

    Tom, WavyGravy has a schwinn tandem with a Robin/Subaru GEBE set up on it. He's been known to hit 30mph with the little 35 cc engine.
  4. augidog

    augidog Banned


    contact me for gebe "help" if that's the direction you take. yup, wavy's tandem/RS35 has more than proven itself...

    there is a functional motion-detector (loud!) available for bicycles, but the name & source evades me at the moment.

    you want a "greenfield stabilizer" kickstand. looks like you have plenty of room to carry/run real lighting, too...i sure hope you consider a 12V-SLA setup...simple, reliable, EFFECTIVE.
    Last edited: Mar 30, 2009
  5. Tom

    Tom Active Member

    Zev0- I took a look at Wavy's tandem while I was up in Ocean Park last August. Unfortunately, at the time, it wasn't running. It was a much nicer tandem bike to begin with than mine. That sure is one sweet ride.

    Augie- I am leaning towards the 35cc 4-stroke from GEBE, however, the motor is going to be the last piece to the puzzle. I'll have plenty of time to research the different options as I put the actual bicycle together.

    I would definitely want to do the mega-lighting system with a 12v battery. I will be looking at your thread and some of the other stuff on the forum while setting that up.

    The security system will be one of the last things I do, but I just want to make sure I don't lose the bike. Maybe some sort of lojack system? I would love to be able to locate it and beat the **** out of anyone who tries to mess with it.

    Some additional things that I want which I just thought of: A speedometer (easy), but also a tachometer. I would really like to be able to see how many RPMs i am actually running.

    Right now I am just getting new components, trying to get it to be a stable human-powered bicycle, and then I will start tinkering with concept of motorization.
  6. srdavo

    srdavo Active Member

  7. Tom

    Tom Active Member

    Wow! That thing is sweet! I just ordered one and a bunch of other cool stuff from that site. Way cheap!

    Tinytach seems like a viable solution for my tachometer needs.
  8. augidog

    augidog Banned

  9. SimpleSimon

    SimpleSimon Active Member

    Onthe lojack idea, it seems to me that it is viable and utterly concealable. I've thought about getting a prepaid basic cell phone, pulling the works out of the case, and slipping it all into a package that sldes inside a frame tube and uses the frame itself as the antenna. Get that "track your teenager" software on your comp, feed it the cell number, and use the built-in GPS of the phone to have it tell you where it is in the event of a theft. Honestly, I'm not sure this is workable, but I can't see why it wouldn't be.

    I've also been looking at a sliding pin lock system that is key activated, and uses a solenoid to push/pull the pin - much like an electric door lock on a car. Heck, set it up so that default is locked, and it unlocks only when the key is inserted and turned to activate the electrical system on the bike. Be straightforward enough to set that up so as to also close a kill circuit for the engine.

    The pin lock can be inside the top tube just aft the forks, set up so that the forks lock at a set position (say, max turn). Ain't nobody getting away on such a bike except by carrying it.
  10. Tom

    Tom Active Member

    brilliant ideas! You just made me think of another: You could rig something up wired to the speedo sensor. If the front wheel makes a full revolution when the bike is locked up and the alarm is activated, there will obviously be some foul play going on.

    Augie- Thanks for the tacho link. I'm excited about having something like that.
  11. DetonatorTuning

    DetonatorTuning Active Member

    Tom, Augie put me onto that tach too, been using it for over a yr. with no problems at all. good enough refresh rate for a MB and you can't beat the price.

  12. wavygravy

    wavygravy Guest

    toms tandem!

    hey tom the tandem platform is way cool! i origionaly got the bike to haul the wife around on but it soon became one of my favorites for open hwy. rideing as it tracks so straight & smooth, its a litte wide in the turns at first but you soon lean to handle the beast & is no trouble at all, the posabilitys of cargo hauling are endless. i thought about building a set of large saddle cargo bags/racks built on seat post, remove rear seat-install cargo system!! the little robin pushes our 580 lbs down the road without a hitch or blurb & you wont be disappointed! as you know the first concideration is the better wheels combo, mine origionally had the 7 speed cassette which was way cool as you could peddal assist more up to 30 plus mph! & hills were a breeze but the stock wheel turned into a taco & i decided to go simple for now & did the shimano cb 110 12 gauge coaster upgrade, which is ok for now but i want to end up with a cartridge berring wheel ,no ball berring tension adjustments & the wheel runs truer for belt allignment & less belt wear. the clincher brakes work very well in addition to rear coaster you can really stop this frieght train affectionately known as- das limo!! its also very fun to give people there first ride on a motoredbike & listening to all the yippies , yahoos, makes for a real happytime!! :grin5:

    Attached Files:

  13. Happy Valley

    Happy Valley Active Member

    Wavy, who's that down in front and where'd he get that giant tandem? :grin5:
  14. Tom

    Tom Active Member

    hahahaha, I am excited about getting the thing running.

    Just got a nice parts bike yesterday, want to start tinkering with everything today. The wheels are something that are a huge factor since 2x the weight goes on each wheel as normal.
  15. wavygravy

    wavygravy Guest

    the guy down front is peewee! so far the shimano cb 110 12 gauge wheels are holding up with proper tension & a whole lotta grease! keep us posted tom! i just finished doin a happy time build, yes me! and it rocks its the 50 cc version ive never felt one the zinged so scary fast lol!!
  16. eastwoodo4

    eastwoodo4 Member

    tandom mb r awsome.
  17. Tom

    Tom Active Member

    Got the frame and other parts painted and some stuff put back together. Just need to install the derailuer, seat, and brake levers and its going to be good to ride!

    Attached Files:

  18. eastwoodo4

    eastwoodo4 Member

    u got me wanting to get a tandom bicycle.
  19. uncle_punk13

    uncle_punk13 Guest

    Awesome dude!!! Keep on rockin with this baby, it's way cool...!
  20. vegaspaddy

    vegaspaddy Member

    hi tom,

    its been a week where that tandom of yours:whistling: