full suspension 20" MTB build

Discussion in 'Photos & Bicycle Builds' started by def215, Jul 22, 2012.

  1. def215

    def215 Member

    hi everyone,

    ive been on this forum for a while but i havent posted here since i built electrics more than anything. but now that ive just built a gasser, i want to share what ive done:

    i started with this 20" mountain bike which i dont really ride.
    here is my power plant that im using. its a Cag 47cc motor.

    so the building started:
    i made the sprocket by hand since i couldnt find a 100 tooth #25 sprocket anywhere online at scooter or bike parts store.
    here is the finished sprocket. not bad for being a piece of scrap steel and cut out with a dremel.

    i had to make a motor mount. it couldnt fit in the frame, so i had to mount it on a rack.
    some gold paint since i didnt like millscale of the angle iron i made the mount of.
    the sprocket and motor together on the bike to check for chain alignment.

    all together ready for a ride.

    i took it out today for its maiden voyage and its pretty quick.its only geared for 30 mph, due to the fact that i like to have more acceleration than anything. but i got it up to 27 mph because i need to play with the carb a bit. ill try to get a video of it in action in the next week.

  2. wheelbender6

    wheelbender6 Well-Known Member

    Very nice work. Looks like a blast to ride.
  3. def215

    def215 Member

    thanks wheelbender!

    this build really was parts that i had laying around, so i really made due with what i had and i built it so i would have someone to ride with when ever someone asks to ride with me on my electric bike :idea:. it turned out to be not so bad as i thought it would be. at the moment, im working on upgrading my electric bike so i can keep up with this one :annoyed:
  4. Fabian

    Fabian Well-Known Member

    Looks like a novel way to achieve the goal of motorizing a full suspension bicycle.

    I like the linkage mechanism.
  5. Fabian

    Fabian Well-Known Member

    That's some impressive work cutting out the 100 tooth sprocket :likelots:
  6. def215

    def215 Member

    thanks fabian!

    the mount works well so far. i know its not pretty and isnt as nice as some of the motored bike builds are on here. i think i only have about 5 miles on it since this weekend was the very first time i took it out. ill have to ride it some more to see how it holds up.

    the sprocket was an interesting project in itself. it took me a while to actually cut it out and i initially had issues with it because the sprocket pitch wasnt exactly 1/4 in for the #25 chain. it was scrap steel, so it only cost me about 15 hours to make.:-/
  7. Silverfiche

    Silverfiche New Member

    That's a really innovative idea on how to mount for the suspension. Hand cutting a 100 tooth sprocket wow that took patience. Good work. As far as pretty, grind the welds a bit and give it a matching paint job, maybe, and it would be dam pretty but it looks rugged cool as is.
  8. def215

    def215 Member

    my main goal was to get it to work. the 100 tooth sprocket was really to test myself to see if i could actually do it.:grin5: so far ive ran 2 gallons of gas through this thing and its been holding up so far. hopefully it will hold together for many more miles to come.:cool:

    also, i got video of my top speed run on my helmet cam that i did yesterday:

    i hit a top speed of 31.1mph on my iphones gps. so im happy with it, since i was expecting only 30mph out of it. but i have a suspicion i have it slightly undergeared since i feel like im hitting the limiter in that video.:thinking:
    Last edited by a moderator: Dec 15, 2015
  9. professor

    professor Active Member

    Great job Def. I like it.
  10. BonusParts

    BonusParts New Member

    clever mount for that suspension type.
  11. richyrich

    richyrich New Member

    thank you thank you thank you!!!!!!!!!! i have the extact same bike laying around but thought i would not be able to use it. thank you. is there any problems with the design after been using it for awhile??
  12. def215

    def215 Member

    after my 2nd gallon of gas through it, i noticed the chain would derail under hard acceleration. that was because i put that one turnbuckle on the chain side too close to the pivot on the mount causing it to flex real bad. so i moved the turnbuckle towards the back so my mount doesnt flex as bad anymore. and as far as mileage goes, i dont think i barely have 50 miles on it, because i only put 2 1/2 gallons through it so far. i also noticed that this thing has really bad mileage, about 20 mpg. but it could be me enjoying it too much because i noticed myself going full throttle a lot of the time.:devilish:
  13. richyrich

    richyrich New Member

    OK well I'm gonna put a 127cc go cart motor on my 24 inch verion with 32 tooth sprocket. What do u think?
    Last edited: Sep 10, 2012