LoBoy Fat Tire Chopper

Discussion in 'Photos & Bicycle Builds' started by graucho, Apr 4, 2011.

  1. graucho

    graucho Active Member

    Been a while since I've posted. I've been busy building electric bikes for the past few years. This one will have a motor, so I decided to come to the place where bicycle motor heads hang out. :bowdown: I'm researching 4 strokes and I haven't came to a decision yet on the set up. I have plenty of room so it will be easy to adapt.

    I took it on it's first roll and it is perfectly straight and smooth. I have a single sided rear axle set up to show off the insane rear tire. It's my first try at a single sided axle so I had to figure in a lot of math and calculations to get it perfectly balanced.

    First Roll.
    http://www.youtube.com/watch?v=Lctcd0rkW8g

    Zero Steering Flop.
    http://www.youtube.com/watch?v=alQKmadQsgc

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    axle11.jpg
    http://i284.photobucket.com/albums/ll13/grauchosbikes/motored bike/axle11.jpg

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    Last edited by a moderator: Apr 4, 2011

  2. srdavo

    srdavo Active Member

    Looking Good!!

    Have you checked out the Harbor Freight 2.5 hp Greyhound??
    Needs about 12:1 gear reduction for bicycle purposes. IMO
     
  3. Wheres my dog

    Wheres my dog Banned

    Now that is one bike with serious rear wheel stopping power!!!
     
  4. ibdennyak

    ibdennyak Guest

    Ooooh, that's nice. Actually your build kind of looks like my mental picture of my current project.....only with......more attention to detail. :grin5: I am using a Lifan 50 pocketbike engine....mainly because the narrowness of the cylinder gives lots of pedal clearance. You don't need the clearance, but that frame would be so sweet with a similar engine. Not only that, if you aren't limited to 50cc, your frame looks to have sufficient heft to take up to a 140....all with the same footprint. They seem to be a very durable engine too, althiugh a bit heavy for a bicycle add on.

    I'm in the process of moving to Washington at the moment, but I have roots in your area. Maybe in my travels, I may have to take the Minnesoota stroll. :grin5: I haven't been there in about 10 years...does that make me a bad person????:jester:
     
  5. motorpsycho

    motorpsycho Active Member

    stopping power??
    there aint any brakes on it yet!!!
    what does the rear wheel have to do with stopping power any-whoo???
     
  6. graucho

    graucho Active Member

    Originally Posted by Wheres my dog
    Now that is one bike with serious rear wheel stopping power!!!

    Actually... these fatties are about 80% of the stopping power as a normal bike. (to the bad side)
    I always have a front brake for the times I really need to stop fast. You get that big tire rolling and
    the centrifugal force wants to keep it rolling. ("manual" disk on the rear) I could change this if I installed "Hydraulic" Disk.
    Since these are slower speed bicycles I save the extra 145 bucks on the hydraulic, since stopping isn't a danger issue with my current manual disk set ups.
     
    Last edited: Apr 6, 2011
  7. graucho

    graucho Active Member

    Thanks for the link srdavo. Is 3600 RPM high enough RPM to engage the clutch and pull the weight. Must be why you need the 12:1 gear reduction? looks like a nice little engine. Thanks.

    Name 2-1/2 HP Horizontal OHV Gas Engine
    SKU 97964
    Brand Greyhound
    Engine Stroke 4
    Overhead Valves Over Head Valves
    Cast Iron Sleeve Cast Iron Sleeve
    Fuel Shut Off Fuel Shut Off
    Mounting Type Horizontal
    Shaft Diameter 5/8"
    Shaft Length 2-1/4
    Decibel Level 90 at 1 meter
    Low Oil Shut Off Low Oil Shut Off
    Material Sheet Metal
    Shipping Volume 1.377
    Item Type Gas Engine
    Certifications/Approvals EPA and CARB
    RPM Rated 3600
    Fuel Tank Capacity .42 gal
    Oil Capacity 13.5 oz
    Start Type Recoil
    Drive Type Direct
    Horsepower 2.5
     
  8. graucho

    graucho Active Member

    Last edited by a moderator: Dec 15, 2015
  9. graucho

    graucho Active Member

    Robotics mentoring is finally finished. Time to get building again.

    Finished my handlebars. Took the dimensions of the schwinn OCC bars and bent a new pair 25% bigger. Scaled for an adult.
    Hand grips will be at 30 inches horizontal. Need to position a little nurling where the clamps are.
    I ground the welds smooth, now ready for putty and primer.



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  10. graucho

    graucho Active Member

    OK, OK, finally after 4 months of Robotics mentoring 38 kids (6 mentors total) 4 tournaments (144th place worldwide of 2400) I had put this bike on hold. Then I needed a months break with nothing mechanical. Not even a 10 minute shower head replacement requested by the wife.

    I've finally turned the shop lights on again and not getting nauseous of the thought of steel and things mechanical. I currently have 2 GEBE set ups for distance riding so I decided on the 58cc 2 stroke for this bike. "PURCHASED HERE" If I trash the engine I will be able to swap it out with another in an hour. I'm not a fan of the HT's but the 4 strokes were too wide for my jackshaft setup with the engine position being so low behind the pedals. (I already have the wide crank) If my calculations are correct I should be able to putt around about 15-30 mph. Also if my exhaust system works out it should be reasonably quiet. Then to keep things looking clean I'm running the throttle cable and brake cable through the frame.

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    I'm running the throttle cable and brake cable through the frame.
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    The handlebars are 30" end to end for a nice stable stance.
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    Finally starting to take shape with the look I visioned from the start.
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  11. motorpsycho

    motorpsycho Active Member

    what good is a custom chopper with a quiet exhaust? (boring in my opinion).
    that would be like putting quiet exhaust on a hot rod car.
    that's a really cool looking bike, but what's with all of the horse heads all over the place?
    sorry if i sound rude, but i'm just curious as to why you chose to put horse heads on a custom chopper....they don't go together.
    you should also consider getting rid of the stock air cleaner and replacing it with something that's more custom. it just looks out of place since the majority of the bike is custom.
    just my opinions...
     
  12. graucho

    graucho Active Member

     
  13. rustycase

    rustycase Banned

    Graucho, your work is GREAT! Inspirational!
    Thanks for posting... hope you give us more !!!
    Best
    rc
     
  14. graucho

    graucho Active Member

    Thanks for the support rc!

    Here are a few shots with the rear tire off while I work on the drive train. I have many emails asking
    how I did it. It's not that complex. A few pillow block bearings, some 1/4" steel and a 1" axle.
    The hard part was the physics behind the frame to keep the center of gravity perfectly centered when
    body weight is applied with the single side rear frame. I have the drive system from engine to jackshaft.
    Now I'm completing it from jackshaft to rear axle. I also have the kickstand mount positioned and ground
    clean. Also have the chain tensioner functioning. (I'll upgrade the tensioner after painting and reassembly)


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  15. graucho

    graucho Active Member

    Almost done with the drivetrain. Waiting for a 3/4"freewheel sprocket for the pedal side of the jackshaft.
    After thatwith a few tweeks I will be taking it for a ride to fire up the engine and test the gear ratios etc etc.


    Here's a few updates.


    Adjustable chain tensioner mount and disk brake mount finished.
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    Rear brake cable route, then through the main frame.
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    The clutch cable and throttle cable will be through the frame. (not finished with the clutch mount)
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    .
    .
     
  16. graucho

    graucho Active Member

    It's been a long time on hold for this build. I put this build on hold in June, due to prototyping robot designs with a
    few past students over the summer to help them with their College year. Hopefully giving them an advantage with "hands on" in their engineering class.

    I got the bike on the road with a lot of high speed frame testing. (Well... hi speed for a hand built bike. 35mph) I temporarily mounted a HT motor on the bike and drove the heck out of it for a week full speed. The bike will end up being 48V 1000 watt electric. I "did" wear a helmet for my weeks tests, but I didn't for my final short test video. Ha! no need to yell at me... I'm crazy, I know. The single sided axle tracked as if I knew what I was doing.This bike has perfect balance for the length, height, weight. Fits a rider between 5'10 to 6'4" Here is a short 3 min. video showing how it rolls. I will be working on it a few days a week now until its finished. It feels good to pull it off the shelf and blow the dust off of it.

    Here's a short 3 minute video of a test run.

    http://www.youtube.com/watch?v=gr6nz9nAZzo&edit=ev&feature=uenh
     
  17. graucho

    graucho Active Member

    LoBoy Fat Tire Chopper Bicycle

    Its been a while since I've made a set pan. As stated in a earlier post I picked up a leather
    stool seat that I want to convert into a bicycle seat. The bike will have a western south of
    the border theme. This one took a little thinking since it's not your standard seat pan.
    Nothing that a few measurements and a little engineering couldn't solve. We all like pics,
    heres' a few.


    Took a few measurements and cut up some steel. Cut a few grooves and
    bent the correct angles to form to the seat.


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    Laying down the initial tack's
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    Continued below.
     
  18. graucho

    graucho Active Member

    LoBoy Fat Tire Chopper Bicycle

    Continuation from above.

    Adding all of the filler pieces and completing all of the welding.

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    Continued below.
     
  19. graucho

    graucho Active Member

    LoBoy Fat Tire Chopper Bicycle

    Continued from above.


    Padding not added yet, stretch the leather over the seat pan.

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  20. chainmaker

    chainmaker Member

    That is a sick looking bike Graucho!! Hats off to you. What are you running in it for power now? Again nice looking bike.
     
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