Build of Recumbent with RS 35cc

Discussion in 'Motorized Recumbents' started by Lee_K, May 1, 2012.

  1. Lee_K

    Lee_K Member

    I have built recumbent bikes before, but this is my first try at any bike with a motor. I have already spent a lot of time reading here and designing, so I will start with my design intent. It will have 20 inch wheels, it needs to freewheel easily with motor off, not too recumbent riding position so I can look around better while riding. Since I have been holding back on starting the build, I have taken time to make an accurate 3D CAD model. I have just started the actual build and will post photos soon.
     

    Attached Files:


  2. Happy Valley

    Happy Valley Active Member

    Looks interesting, I'd be intrigued to know more as the project develops. Good choice on engines.
     
  3. Lee_K

    Lee_K Member

    I started with the swing arm because I had the material on hand, it is made from 3/4 by .035 tube. Its simple miter cuts. I made a template from scrap plywood with cuts made on miter saw to get the angles.
    [​IMG]

    The swing arm bracket is made from 1.5 by .035 tube with large washes as end caps. The drop-outs are made from 3/16 flat steel.
    [​IMG]

    Next up is the frame.
     
  4. Happy Valley

    Happy Valley Active Member

    Excellent Lee!. Great to see a project of this scope taking shape and being documented again, been a while and reminds me of the old days here.

    Curious, what type or series tubing you'll be using and what weld process to join them?
     
  5. Lee_K

    Lee_K Member

    Happy, thanks for taking an interest. All tubing is Chrome-molly (4130) with .035 wall thickness. I am using a small mig welder. I will have the frame roughed out real soon, then it will start to look like it might amount to something.
     
  6. Lee_K

    Lee_K Member

    I use a lot of miter joints because I can't make bends without collapsing the tube. I don't like that look, so I am giving bending another try. This is 1.25 by .035 tube. I held my torch in one hand and pulled down with the other. I Heated the outside bend zone bright red while bending. I got just enough bend before the tube started to collapse. Good enough for me.
    I bent the tube over a 20 inch rim so the rim flanges supported the rim partly up the sides of the tube.
    [​IMG]

    I Made an accurate drawing of frame on tile board, then hot melt glued tubes in place for tack welding. I avoided the need to bend tubes by placing various brackets at transition points.
    [​IMG]
     
  7. Lee_K

    Lee_K Member

    The frame is tacked together and ready for full welds. Also, this is a fork from a bike I don't use anymore. I will be cutting the steer tube off and welding in a new one for this project.
    [​IMG]
     
  8. LR Jerry

    LR Jerry Well-Known Member

    Have you tried heating the pipe and using a conduit bender? Also I suggest using mirrors to increase your viewing area.
     
  9. Lee_K

    Lee_K Member

    LR, I have have tried bending 3/4 thin wall tube with conduit bender, but this thin wall high strength tube will still collapse. In this case I was bending 1.25 thin wall tube, I feel lucky to get the small bend with just a little bit of collapsing. What do you mean by using mirrors
     
  10. Lee_K

    Lee_K Member

    This shows how the the wheels are aligned to set up for welding the swing arm bracket to the frame. The Wheels are clamped between two lengths of 1-in square tube, then I used strings to pull each wheel perpendicular to the table. After getting the wheels straight, I welded the swing arm bracket.
    [​IMG]

    A rear view shows that the swing arm is offset. I Built the wheel using a hefty BMX rim and a Sturmey-Archer drum brake hub. I did not dish the spoke lacing, I centered the rim with spoke flanges not the center of the hub. This moves the cassette to the outside more than on a normal bike and will line up with my jackshaft.
    [​IMG]
     
  11. Lee_K

    Lee_K Member

    This is the jackshaft where the human power and engine power are combined. The two outer sprockets are welded together and welded to the shaft. The inner sprocket is screwed to a freewheel--this sprocket is driven from the engine, the freewheel allows the bike to be pedaled with the engine stopped. The middle sprocket is driven by human power. The outer sprocket sends both power sources to the rear wheel.

    I used a BMX style freewheel which is very noisy. The whole assembly is kinda heavy. So eventually I would like to improve this part. Are there other types of freewheels that are not so noisy. I intend to ride with the motor off a lot and this noise will start to wear on my nerves.
    [​IMG]

    A Sturmey-Archer 3-speed hub is used as a mid drive to help route the chain under the engine and to provides 3 pedaling speeds.
    [​IMG]
     
  12. PatrickW

    PatrickW Staff Member

    Lee...Keep on going! It looks like you are doing an excellent job. While I'm following your build, my mind takes me to my garage and the smell and taste of every motorized bike and trike I've ever put together. And, I agree that you sure chose the right engine. Good Luck.

    Patrick
     
  13. Lee_K

    Lee_K Member

    I like torsion bar suspension because I can make it myself. The rear suspension is the most unusual part of the bike, not better than typical coil springs, just different. It uses two 5/16 dia by 20 inch long 8620 steel bars.
    [​IMG]

    The torsion bars are inserted into the top tube. The push rods were made long. After its done and I ride it, they can be shortened to adjust the ride height. The torsion bars can be shortened to stiffen the suspension. The lever arms can be cut off and replaced with loner arms to make the suspension softer. Next job is the seat.
    [​IMG]
     
  14. Happy Valley

    Happy Valley Active Member

    I'm out here and following along Lee, checking in from time to time, liking what I see a lot! DIY frame work, drive train, suspension, you're getting it done and thinking for yourself outside the box. Kudos so far, heck if we lived closer and I'd be looking over your shoulder checking in, lol.

    Seriously, nice work, good to see some from-scratch innovation again, looking forward to all the steps to completion.

    PS
    frame builder near me packs tubes with aquarium sand and caps them before bending, claims they don't kink that way.
     
  15. professor

    professor Active Member

    Wow, brilliant stuff here. Good going Lee.
     
  16. LR Jerry

    LR Jerry Well-Known Member

    I've got mirrors on my handle bars to help see behind me. As for the conduit benders using a 1 1/4 inch hand bender with a kicker on the shoe on heated 1 inch ridged can be done without collapsing the pipe if you're a tall and large built person. Otherwise you'll need a multi shoe mechanical bender. If you know how to calculate bending radius' and mark your pipe you could do hicky style bending with a conduit hand bender.
     
    Last edited: May 13, 2012
  17. LR Jerry

    LR Jerry Well-Known Member

    I've got mirrors on my handle bars to help see behind me. As for the conduit benders using a 1 1/4 hand bender with a kicker on the shoe on heated ridged can be done without collapsing the pipe if you're a tall and large built person. Otherwise you'll need a multi shoe mechanical bender. If you know how to calculate bending radius' and mark your pipe you could do hicky style bending with a conduit hand bender.
     
  18. Lee_K

    Lee_K Member

    I am making the seat frame from 3/16 dia 8620 steel rod. Here, I have two bent sections. I am taking a lot of care to trim and line them up to be symmetric about a centerline. I have built seats like this before and they tended to be lopsided. By being real accurate at the start, I hope to get better results.
    [​IMG]

    Some of the cross bars are welded in place and it is ready for next bend.
    [​IMG]

    After the last bend, I added a mounting frame made from 1/2 square by .035 wall 4130 tube. Then supports as needed. There will be another bend and more supports, but I need to try this to see how it feels before moving up the frame.
    [​IMG]

    Here's how it looks so far. Next I will make two seat pads.
    [​IMG]

    Thanks for following along and leaving your comments. Those are both good techniques for tube bending. I will keep in mind in case I ever try this again.
     
    Last edited by a moderator: Dec 15, 2015
  19. LR Jerry

    LR Jerry Well-Known Member

    After 30 years of electrical work I got pretty good at it. What kinds of welds are you using? Every thing is looking good so far. What is the bike going be used for? (Around town, long trips or shows).
     
  20. Lee_K

    Lee_K Member

    Sometimes I think I am building this just for sake of building it. I try to do a fairly good job for a home built bike, but I don't have the artistic skills or patience to make a show bike. I expect to be using it for long rides. Part of the riding will be on bike trails where the motor needs to be turned off.

    I made the seat pans from 1/8 hardboard and used 10-32 carriage bolts to attach them to the frame. I found these foam seat cushions at a Meanards store. I'll give them a try for seat cushions.
    [​IMG]

    Here's the completed seat.
    [​IMG]

    I made a temporary rear brake cable and took it out for a ride. It handles and tracks real well, but needs a little front end weight to improve very low speed response.
    [​IMG]

    I am starting to work on an engine cradle and waiting for shifter/brake levers so I can work on those.
     
    Last edited by a moderator: Dec 15, 2015
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