Custom Recumbent Trike

gstrope · Oct 3, 2010

I am starting a new trike build. I am building it for someone who lives on a gravel road. Here are the design points.
1) trike design for stability on gravel.
2) Gearing to limit speed to 15 mph for safety
3) Recumbent seating for comfort and low center of gravity
4) Rear engine mount
5) Working pedals for starting and backup in case motor won't start
6) Powered by Raw 49cc engine
7) Wide front tires for better handling on gravel
8) Steering radius will be limited fo stability

I have started on the frame. Here are 2 pictures. The second one shows the approximate position of the motor. I will post more pictures as the build progresses.

NunyaBidness · Oct 3, 2010

I think this is going to be a really nice trike. I love ground up custom builds

Dave31 · Oct 3, 2010

Cool...keep us posted with the progress .trk

azbill · Oct 3, 2010

cool project

the long wheelbase should make it a nice ride, even on gravel

gstrope · Oct 4, 2010

I put on a temporary seat today and hooked up the pedals for testing. The seat and pedal arrangement works good. There is a handling problem with pivoting front axle. I am going to have to tear it down and go with a fixed axle and independant steering. I thought this might happen but I wanted to try it and see why it isn't used very often.

gstrope · Oct 10, 2010

Here is the first look at the fixed axle design with independant steering on each wheel. The pivoting wheels and tie rod are done. Next I will hook up the steering.

curtisfox · Oct 11, 2010

What you should do is find a garden tractor front spindles. They have the stearing geomatry built in. The one you have the pivets are to far in it will be about the same as the first axel. The center of the wheel were it hits the ground is supose to intersect the center of the spindle angle and meet at the same point. If you draw a V the left line of the V should go strieght up through the center of the tire were it meets the ground in the center. The right line of the V should go up through the center of the spindle
I think somewere on this post is a drawing someone posted of how....Curt

BarelyAWake · Oct 20, 2010

Yup - what he said

More info here: Rake and Trail Basics

curtisfox · Oct 20, 2010

Way to go BarelyAWake. I would just hate to see gstrope Get it all done and not have it work right and give it up,just because of that. How many wagons have tiped over because they did not have the proper stearing?
Thats what is greate about these forums you can learn how before you get flustrated and give up. At my age been there and done that many a time.

2door · Oct 20, 2010

Good luck. Surely one of the most interesting and ambitious projects I've seen here. Keep at it, solve the problems and keep us informed. Thanks for sharing.
Tom

ferball · Oct 20, 2010

Why not use a threaded rod and a turnbuckle on the steering to allow for adjusting

gstrope · Oct 20, 2010

curtisfox said:
Way to go BarelyAWake. I would just hate to see gstrope Get it all done and not have it work right and give it up,just because of that. How many wagons have tiped over because they did not have the proper stearing?
Thats what is greate about these forums you can learn how before you get flustrated and give up. At my age been there and done that many a time.

Thanks guys for the tips on steering. I have the motor hooked up now and mounted a temporary gas tank to give it a try. It runs pretty good. The top speed is about 15mph and it handles pretty good with the steering setup. I am going to do some extensive road testing at full speed and test out the handling.

I appreciate the tips on steering setup.

Note: this project is still in the rough stage. I like to try out my designs as soon as possible to find out the flaws. The final product will be more refined.

gstrope · Oct 20, 2010

ferball said:
Why not use a threaded rod and a turnbuckle on the steering to allow for adjusting

I looked at some turnbuckles at the hardware store but they seemed to week to hold up on a gravel road.

curtisfox · Oct 21, 2010

THAT LOOKS LIKE A FUN RIDE. Check out a old garden tractor front end they have all the angles right and ajustable tie rods. Did you know that it should have a 1/8 inch toe-in in front?
Then there is the Akerman principle. If you look at a garden tractor you see that the stearing arms are not stright out, they come out at a angle. Picture a line going from the hole were the tierod bolts on,through to the center of the kingpin should go to the center of the rear end. Just so you know.....Curt

ferball · Oct 25, 2010

What are you doing for brakes? I am liking your design and may attempt a variation of it, but I was wonder how you are doing the brakes. I like the idea of the front wheels being what they are, but it does not allow for the typical bike brakes, and my study of go kart braking shows that they usually put a brake on the rear axle, which is also lacking in your design. And typically speaking 90% of braking on bikes is with the front breaks. So V brakes on the back tire I am not seeing as a safe answer.

fleebell · Oct 26, 2010

If you are using those Harbor Freight wheels for front wheels, I have a suggestion for you. Take them apart and weld the center core solidly to the rim side that it's attached to.

Those are just pressed on with a rolled edge and the stress of going around corners will break them loose and they will get wobbly after a very short period of time if you don't.

I've built a trike somewhat like what you are building and learned the hard way.

Lee

gstrope · Oct 28, 2010

ferball said:
What are you doing for brakes? I am liking your design and may attempt a variation of it, but I was wonder how you are doing the brakes. I like the idea of the front wheels being what they are, but it does not allow for the typical bike brakes, and my study of go kart braking shows that they usually put a brake on the rear axle, which is also lacking in your design. And typically speaking 90% of braking on bikes is with the front breaks. So V brakes on the back tire I am not seeing as a safe answer.

I just got the brakes hooked up. They won't lock the tire or anything but with the 15mph top speed seem adequate - picture attached

gstrope · Oct 28, 2010

I have some updated pictures. I have the bike complete enough to start some road testing. I will post some updates after some road testing.

gstrope · Oct 28, 2010

After limited road testing I have already run into trouble with the small wheels. I had a bearing failure on one wheel and have noticed the tire worn to the cords already. I got these wheels on sale at tractor supply for $5 each. They are clearly marked not for road use but I thought they could handle this application.

I am going to redesign with different front wheels probably bicycle wheels.

gstrope · Oct 28, 2010

fleebell said:
If you are using those Harbor Freight wheels for front wheels, I have a suggestion for you. Take them apart and weld the center core solidly to the rim side that it's attached to.

Those are just pressed on with a rolled edge and the stress of going around corners will break them loose and they will get wobbly after a very short period of time if you don't.

I've built a trike somewhat like what you are building and learned the hard way.

Lee

I have run into some problems already with the small wheels, see other post. I am considering different wheels. I did notice the problem you mentioned on one wheel.

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