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1 Posts

Posted - 07/18/2010 :  22:14:29  Show Profile
I just completed constructing a reverse-recombant trike... one 20" drive wheel in the rear, and two 26" (linked) front steering wheels. I use a half-handlebar on each side, angled inward, to steer, one in each hand. Again, both front (26" bike) forks are linked by a 2" aluminum bar. My question is this... I had no real alignment issues with the two quadracycles (pedal cars) I've constructed... very little wear on the tires; easy to steer. However, I seem to be in a nightmare when trying to align the front wheels on this reverse-recombant trike. Yes, I had an adult sit on it while attaching the front arms... the wheels are straight up and down, and maybe even have a slitht inward tilt. Yes, I have used narrow (1.25") tires. NOTHING I do seems to keep them from rubbing badly when I try to use it. Is there a link/plans for correction of this,perhaps the "tilt" I have seen in cars? Can anyone help? Thanks.

Douglas S. Hepler


2 Posts

Posted - 08/22/2010 :  13:37:16  Show Profile
Given how close together the wheels are on a tadpole trike, the camber angle and steering geometry has to be spot on to make it properly driveable and steerable. You will have to look on the internet for a source of formulas for that. I tried to do it but it wasn't readily available. It will take some dedicated searching.

For years, I had a plan in my Favorites but deleted it last year.

Sidewinder trikes have gotten around it with a differential, front wheel drive, and no camber required. www.sidewindrecycle.com

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Don S

88 Posts

Posted - 11/07/2011 :  11:40:05  Show Profile

What you have is commonly called a tadpole trike and basic wheel alignment is dependent on steering arm angles, caster, and camber.

There are formulas to determine steering arm angles based on the wheel base of the trike, steering arm length, and the offset of the tie rod connection to the steering bars but the visual concept is fairly straight forward for wheels connected by a straight bar like you describe.

Try matching the steering arm angles to a line drawn between the center of the rear hub and and the center of the king pins and make sure the 2" aluminum steering bar is parallel to a line drawn through the center of the hubs. In addition, all 3 tires must be aligned parallel to the axis of the vehicle when setting the bar and the steering arm angles and when making any adjustments to the steering linkage. It will also help to give the tires about 1/16" toe in.

King pin inclination (tilt) provides basically the same function as rake and trail on a bicycle. An imaginary line extended down the axis of the king pin should intersect the tire path at a point forward of the tire contact patch.


"it's important to understand what makes them fast. It's more important to understand what keeps them from going faster." DS
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