Fat Tad Clone.

Joined
Sep 16, 2018
Messages
181
Location
Netherlands
You can ad suspension to the front by cutting a part out off the arm neer the wheels.
The spring can put flat next to the arm, standing up or even inbetween. It depends on the size and how you do the construction.
It's not a real adon, because you need to change your front, but you can ad it and as you do it right, you can make that you can lock it.

I can make a sketch for you if you want.
 
Joined
Sep 16, 2018
Messages
181
Location
Netherlands
thanks Emiel.
If you can do up a sketch that would be very helpful.
tom...
I remembered that it is a steering. The way I did it, made that it would steer a tiny bit by each bumb.
As you want to remove that, you need to do the front suspension over the complete arm or rotate it and than you get the same system as ice trikes has.

Ice trike front suspension

I had something similar, but with the spring next to it.

I will make a sketch tonight.
Going to shower. Just worked on my trike.
 
Joined
Sep 12, 2012
Messages
2,457
Location
Apple Valley, California, USA
Hi tomzah

Here are a few drawings originally intended for the StreetRunner.
However, the direction of the build meant these would not be used.

I never actually put these into practical use, so have no idea if they will work, or may need modifying.
If no, maybe they will help with making up your own design,

Other members may have tried this, or know more than I, about their use ability.
Bump steer may be a concern here, that will need to be addressed.

Good luck with your build
Ed








 

Radical Brad

Garage Hacker!
Staff member
Joined
Mar 13, 1999
Messages
5,744
Location
Kakabeka Falls, Ontario, Canada
Here is a crazy thought...

With all that effort to make the cross boom suspended, why not just suspend the seat?
The only goal is a smoother ride, correct? The boom does not care.

You also avoid all those tilting issues that tad front suspension will introduce.
Independent front suspension is even more complex to make behave.

Brad
 
Joined
May 31, 2013
Messages
2,297
Location
South Benfleet, Essex, England, UK
If it doesn't shake you to bits, how can you enjoy the ride? ;)
 
Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
Addressing the tendency to lean outwards in a corner is difficult to engineer out. About the only way to control it is to make the suspension travel very small somewhat negating the point in having it at all. The only way to truly offset the effect is to lean the whole trike into the corner which itself then introduces a lot of compromises into the steering.
 
Joined
Dec 25, 2012
Messages
3
Location
USA
To Combat lean, what about anti roll bars or torsion bars like cars use.
Many suspension systems use torsion now dayz :p
 
Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
An anti rollbar would indeed limit lean but not exclude it.

Here's a Scorpion FS20 front suspension set-up with an anti-roll bar.
 
Joined
Jan 28, 2015
Messages
15
Location
Colorado
An anti rollbar would indeed limit lean but not exclude it.

Here's a Scorpion FS20 front suspension set-up with an anti-roll bar.
Yep. I've test-ridden a Scorpion - really plush ride, but even with the anti-roll bar there is noticeable dive when cornering. The HP approach does have the benefit of being pretty customizable, since you can change up the resiliency and order of the elastomers/spacers inside each shock. There's a "Laid Back Bike Report" video somewhere that walks through how to do that.

One more commercial system you could look at for inspiration is the Steintrikes double-wishbone approach. Never ridden one myself; from what I've heard it's got even more front travel than the Scorpion and is great for off-road, but doesn't handle as well as others on pavement:




I'm personally a big fan of the Azub Ti-Fly front suspension, but that's not a practical suspension to try to DIY. Even for someone capable of welding titanium, sourcing enough of it for a pair of quarter-inch-thick leaf springs is going to be costly.
 
Joined
May 31, 2013
Messages
2,297
Location
South Benfleet, Essex, England, UK
The answer is......"Schwalbe Big-Apples" or similar. Let the tyres do the shock absorption of the poor roads. ;)
 
Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
Now that's VERY interesting. It's the only design I've ever seen that eliminates roll completely (in theory at least). It does so by not independently springing each side but treating the entire axle as one unit and allowing it to move only in the vertical plane. I was surprised to see two suspension units given it's acting entirely as one unit. I'd have initially expected one unit would suffice but it looks like it has the bracketry for one unit but a decision subsequently taken to use two to help limit flex in the chassis which is allowing some roll. I note the steering is mounted on the suspended part meaning that steering geometry is unaffected by the movement of the suspension, but the bars will rise and fall relative to the pilot. I'm not convinced about that being the better option. Certainly though, the best design for tadpole front suspension for road use I've yet seen IMO. I may even apply that "whole axle" principle to my next trike I like it that much. What's been done here is to take a trailing arm swing axle rear suspension set-up from a car and turn it around for the front - both ingenious and simple.

There's a video of it here. It does show some small amount of roll. I suspect that's a function of some twist in the chassis rather than anything else hence the move to twin suspension units. The chassis is an inline tandem and looks quite minimal so is very long and much more prone to being twisted because of it.
 
Last edited:
Joined
Jan 28, 2015
Messages
15
Location
Colorado
That's fascinating. It does add unsuspended weight, and not being terribly experienced with shocks I kind of wonder about what the failure modes look like.

Given that the two shocks form a narrow pivot point, it seems like it might feel a bit tippy side-to-side for the rider, compared to designs that do the suspension out near the wheels and further away from the center of gravity. Hard to really tell from the video, and maybe it's just a matter of getting the shocks tuned right to the rider's weight. Might be a better front suspension for a quad than a tadpole?
 
Joined
Oct 19, 2012
Messages
408
Location
Wakefield, UK
Certainly a quad would be far less likely to twist in the first place. I think they'd have less twist in the set-up by keeping the fore / aft rods shorter. Longer rods make for a more vertical swing but given you're only after 2" of movement or so for road you could go shorter and still not see enough of an arc to worry about. Also given they have the steering unsuspended, proscribing an arc doesn't affect geometry at all. All the twisting forces transferred to those rods are vertical so using rectangular box rather than round would limit movement further.
 
Joined
Jan 28, 2015
Messages
15
Location
Colorado
At this stage, you are getting closer to my typical answer to the tadpole suspension problem.... just suspend the seat!
If I'm not mistaken, the Greenspeed X7 (and maybe other Greenspeeds, I've only ridden the X7) uses elastic shock cord to lace up the back of the seat, for exactly that reason. Just based on my test ride, it did seem to make a difference - not nearly as much as a dedicated front suspension would, but still notable and with much less complexity and weight. No idea how long the shock cord lasts in a setup like that, but shock cord is cheap and easy to replace.

And of course, as DannyC points out, larger/lower pressure tires like the Big Apples make a difference too.
 
Top