Build of Recumbent with RS 35cc

[SimpleSimon]

Lee, beautiful work!

I note you dispensed with the diagonal bracing member between the top and bottom tubes that your sketch showed - I wondered if that was truly needed.

I'd like to suggest that you make a "floor shifter" type shifting handle to mount to the top tube - I can just see an old 8-ball top knob on the shifter shaft. Easy enough to make a positive detent snap shifter with a Dremel tool and a little aluminum. That way you have less clutter on the handle bars and the shifter cable is much shorter.

[Lee_K]

I don’t really know if the diagonal tube is needed, but I still intend to add it after the motor is in place. All the frame tubes are thin wall (.035) and if vibrations are transferred from the motor or deflections from pedaling they could eventually stress crack. That extra tube is intended to stiffen the frame and prevent this problem.

That’s an interesting idea for shift control. I might try something like that for the 3-speed hub, it would be very direct. It will take a very long cable from a handle bar shifter to the rear derailleur which could be a problem for index shifting, I am going to stay undecided on the 8-speed shifter for a while.

I have built several recumbent bikes, but have no experience with adding a motor to any bike. I am doing this how I see it best for me. I may cause myself problems and will deal with them as I learn more. I made my own aluminum clutch & housing. There is a steel band in the clutch drum to provide the correct friction surface. It uses skate bearings which are small enough to fit inside the 4-groove pulley.


Here’s the clutch assembly mounted to the motor.

[Lee_K]

The motor will be screwed to this cradle then the cradle will be mounted to the bike frame using rubber mounts. I used every mounting point I could find on this little motor and it still dosen't seem like enough. Dose this work for other people, are rubber mounts necessary.


This is the motor mounted to the cradle.

[Happy Valley]

Again, admirable work Lee and I believe an adequate mounting scheme for the engine. The 4 threaded holes around the clutch opening are the main mounting points for a number of different kits and those alone seems to serve well enough. Can't quite make it out in your pic but I assume you probably also used the 4 holes underneath on either side of the fuel tank, 2 into the aluminum shroud and 2 into the recoil starter plastic. Can't see that would hurt but don't depend on those too much if you did use them because the manufacturer only meant for them to hold an under-tank guard.

Rubber vs non? Some debate there. I prefer fixed mounts but my applications are different than what you're doing here. I'd say trust your own sense of engineering on it, from what I've seen of this project so far, you're a lightyear ahead of most DIY stuff.

[Lee_K]

Thanks Happy, that's what I thought. It seems like hanging the motor on just those four points wouldn't be enough. But it works, so I'll move ahead with what I have.

I am starting to work on shifter and brake controls. I want to complete the bicycle parts so I can take it for a couple long rides to see how it feels before it installing the motor.

[Lee_K]

I just finished the motor mounts and have to photos to show how they work. The motor cradle is mounted using O-rings to isolate the cradle from the frame. It’s hard to explain, but if you study these two photos you can see it.


There are two 3/4 by 4 tubes welded to the frame. The four aluminum parts insert into these tubes and have O-rings to isolate them from the tubes. The motor cradle is attached using the aluminum parts.

[perilous]

Hi Lee,

Thanks for directing me here.

I just finished reading this whole thread and what you are doing is incredible!!!

Keep up the great work.

Along with everything else I really like your clutch arrangement, so elegant and compact.

I bet you already have at least 500hours in this project.

[Happy Valley]

Another neat piece of engineering on the mount, the O rings should provide enough iso without being sloppy and you can always replace them. Bout the only thing I can add is the rubber might prevent a good ground with a single lead to a one wire kill switch in the cockpit. That's happened on a couple of full suspension bikes of mine. Easy remedy was go with a 2 wire switch and run a ground back to the engine block.

Onward!

[Lee_K]

I have been taking care of details needed so I can ride without the motor. Cables, rear carrier, brakes, shifters, speedometer.

After taking this photo, I took the motor out and brought it out for a ride. It needs a few tweaks, but mostly working real good. Next, I will be working on the jackshaft assembly that will be driven from the motor, there’s a lot to it, so will probably take awhile.


I think I am under 500 hours of building, but it will still take several years to get as many hours riding as building. I did make a custom shift lever for the 3-speed mid drive. Then I will be using the the front derailleur shifter for a 3-position throttle control.

[perilous]

Looks really good, I like that shift lever I can image that being a lot of fun to ride. If the shifter you are planing to use for the throttle is like the one on my bike you can hold it sort of half way in between gears as well and if you try to shift past high range it will pull the cable a bit more, I think thats a cool concept.