new pusher pusher and hinge idea

Discussion in 'Push Trailers' started by jag217, Aug 5, 2009.

  1. jag217

    jag217 New Member

    This is my first attempt at a motorized bike. Thought of doing a bike pusher because I can make it the way I want, not a kit. I've got most of the components: 6.5 hp HF engine. two 1 1/2 multihole square metal tubing for the trailer bed. Got a 10 inch wheel from harbor freight. Need to get: sprocket, centrifugal clutch, axle, axle stop collars, chain.

    Found one of those sit up benches in the dumpster which has a curve in it so that will be the tongue. Went to a local welding shop and had them weld together two door hinges for the "U joint" at the seat post. Pictures attached.

    Question: Given 6.5 hp 3/4" shaft engine. and ten inch wheel. which size sprocket, clutch, chain and pillow block is needed?

    Attached Files:

  2. srdavo

    srdavo Active Member

    Very creative use of door hinges!! I like it!!!!! (Do you, or have you worked in a door factory? I did & have found some unusual uses for hinges.)

    Just a thought... for safety...... where the metal is rolled, (for the hinge pin to slide in & out) the end of that roll is not connected back to the hinge. It might be a good idea to have that gap tack welded. You will be pushing a lot of torque with that 6.5 HF engine..... I'd hate to see the gap in the hinges spread open, at speed.

    Ride safe & keep us posted on your progress.

    again.... nice idea on your design!!
  3. srdavo

    srdavo Active Member

    I just noticed your hinge pins are NRP. (non removable pins) If that metal roll is already connected... disregard my previous safety thoughts.
  4. jag217

    jag217 New Member

    optimal sprocket sizes for 2.5 hp pusher

    hey all

    I'm starting the bicycle pusher trailer project. Have posted pics of the welded two door hinge hitch which i installed yesterday. Also have gym sit up bench curved and square tubing for the tongue. My question for anybody into engines is:

    Given the 2.5 hp Harbor Freight four stroke engine and a desired top speed of 35 mph, which would be the best sizes for:

    a. clutch sprocket
    b. wheel sprocket
    c. wheel size.

    and also, what size sprockets fits which size chain? I've heard of #35, #40 etc. Does the sprocket WIDTH need to be specified?

    I live in a relatively flat area, so won't need THAT much torque, however I would like to get going pretty fast off the street lights. Just a good all around rig with good power and top speed of 35. I thought that since I don't want to be a speed demon, the payoff would be good torqueing power. However, it is only a 2.5 HP motor. I have already figured out from the online calculator and from another poster here, that 37T, 12T and ten inch wheel is a good combination, however he is using HF 6.5hp? Is this overkill? The online calculator does not figure in horsepower into the calculation, only RPM's which both the 6.5 and 2.5 both have 3600. How will the above configuration behave with 2.5 HP?

    Also, where can I order the sprockets, clutch, pillow block etc. Any recommendation on best price? model numbers? suppliers would be welcomed. since ordering online, don't want to be stuck with something.

    Thanks again and happy motoring!

    Attached are photos of hitch and tongue, the project so far.

    Attached Files:

  5. srdavo

    srdavo Active Member

    Hi... I moved your post over here... to kinda keep all your build "eggs" in the same basket. :D
    I am very interested in your project, as I am running the 2.5hp HF engine on my trike.

    with a 10:1 gear reduction, from my engine to a 24" wheel, I am getting 25 mph @ 3600 rpms. (I am tugging on the governor a bit & can get your results may vary! :evilgrin: )

    Take a look at & download jpilot's gear ratio calculator. Very helpful with deciding on wheel/sprocket/pulley sizes.
    Last edited: Aug 6, 2009
  6. pusher gearing

    I've found that 3.5 hp is necessary for good all round performance when geared for top speed of 35 mph. I'd recommend gearing for 25 mph to have reasonable acceleration off the line with 2.5 hp. A ratio that gave 35 mph with 2.5 hp would be useable on flat ground with pedal assist off the line and would give fairly sluggish acceleration from there. That would give you the best fuel economy and a good quiet 20-25 mph cruise, but I think you would wish you geared it lower. It's a compromise that sometimes can't be well judged in advance. Riding with lots of stops & goes gets frustrating with too high a ratio. A limited top speed on a long, open, Kansas road trip would get frustrating as well.
    Harbor Freight, Northern Tool and various go-kart suppliers are easy places to find parts you need. You've got a good start here. Keep us informed.
    Thanks for the pictures so far.
    Last edited by a moderator: Jan 1, 2010
  7. habcores

    habcores New Member

    another hinge method

    I built a push cart from the plans of You may already know about them. The hinges are a clever idea . If you feel like you need something a little stronger, take a look at the AZ site and their push cart plans. The guy that has the site must have several garages full of old bicycles. That, plus he lives in Canada and with their long winters , gives him plenty of time to build and think up new projects.
  8. Wheres my dog

    Wheres my dog New Member

    Taking a look at the hitch you made there with the two door hinges, very creative idea and the welds seem to be very solid by looking at them...

    You may want to do some low speed testing at first and make sure there is no weakness in that setup with the stress of the engine torquing or hitting bumps and bouncing around a little.

    Better safe then sorry!
  9. loquin

    loquin Active Member

    FYI: Burden's Surplus Center has a nice, inexpensive rod end that would probably work very well in a trailer/push trailer hitch role.

    In addition to this surplus rod end, they also carry a line of brand new rod ends, where they have more options and sizes. This one, for instance, may be easier to use, and it's only a few bucks more.
    Last edited: Aug 24, 2010
  10. james65

    james65 Member


    Good job and very creative. Just by looking at it, I would weld 2 gussets on the gold to silver hinge(4 would be better)

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