Tadpole using BMX forks

Any particular reason (other than convention) one doesn't see many tadpole builds using a set of BMX front forks, either pivoting Fortrike-style or by building the crossmember to attach to the fork headtubes?

I'm sure there's some weight savings to be had by going the conventional route; however, if you're using caliper brakes you still have to build mounting arms like on the StreetFox, and using the forks would alleviate the need to find wheels with the larger, less common 14mm axle.

Also, obviously, the outboard fork legs are going to count towards whatever your target width is and against your available wheelbase within that target width, but aside from those issues, is there anything else that I'm missing here?
 
Any particular reason (other than convention) one doesn't see many tadpole builds using a set of BMX front forks, either pivoting Fortrike-style or by building the crossmember to attach to the fork headtubes?

This site is to support Brads plan , and none of his adult trikes are build like that.

Fortrike are a commercial tadpole builder who make their own forks Fortrike

Google will turn up a few like this ? built in that manner also.

1280px-Recumbent-trike-homebuilt.jpg



I'm sure there's some weight savings to be had by going the conventional route; however, if you're using caliper brakes you still have to build mounting arms like on the StreetFox, and using the forks would alleviate the need to find wheels with the larger, less common 14mm axle.

Can't see where the weight saving is coming from as you are adding a pair of front forks , and BMX forks are very heavy.

Also, obviously, the outboard fork legs are going to count towards whatever your target width is and against your available wheelbase within that target width, but aside from those issues, is there anything else that I'm missing here?

track not wheel base ;)

it is far easier and makes more sense to build a delta using 2 front forks and probably not much heavier , the track problem still exists however that depends where you ride as to whether it is a problem or not being a bit wider and having some hardware on the outside of the wheel ?
 
I'm aware that none of Brad's trikes are built that way, but Brad also welcomes and encourages creativity amongst his builders, and indeed many of the cycles built from Brad's plans show various minor (and sometimes major) deviations from the plans. So I didn't feel that someone using forks for the front wheels would disqualify a build from being an Atomic Zombie trike, or outside the realm of possibility for an Atomic Zombie builder to do.

And the weight savings I was referring to was if one built the front wheels in the conventional way, i.e. no forks. In other words, you would have a weight increase if you used forks.
 
I'm aware that none of Brad's trikes are built that way, but Brad also welcomes and encourages creativity amongst his builders, and indeed many of the cycles built from Brad's plans show various minor (and sometimes major) deviations from the plans. So I didn't feel that someone using forks for the front wheels would disqualify a build from being an Atomic Zombie trike, or outside the realm of possibility for an Atomic Zombie builder to do.

Yes I just meant to the best of my knowledge there is no experience here of people using front forks , we try to advise anyone who comes along asking questions , whilst I have bought lots of Brads plans and both his books my trikes are only built in ' the style of ' I have yet to build one of his designs . However there is always tomorrow ;)

The trickiest part of a tadpole build is kingpin angle , being angled both back and inwards I suspect that will be made many times harder if you have to do it for the head tube and then also for the front fork being used ? Also some forks also have rake which will complicate getting the angles right.

And the weight savings I was referring to was if one built the front wheels in the conventional way, i.e. no forks. In other words, you would have a weight increase if you used forks.

Sorry missed the word ' conventional ' , seems to completely change the meaning of the sentence :rolleyes:

At this point you really need a tadpole builder to come along and comment , I am purely a delta man and have a slim understanding of all this castor , centre point and Ackerman voodoo ....
 
I think the trikes that use the full front forks often look somewhat cobbled together. The design just doesn't flow.
 
I would have thought also that the full fork would have made for a stronger and safer axle/wheel mount and
simplify the design. Here's the idea. Looking down at a wheel on a standard bike from above, cut the handlebar
stem and weld a tab to connect both forks together with a tie rod?
I think for the Fox design, have the part where you place the brake caliper (going across the wheel) continue and
reconnect to the other side of the wheel axle? Don't know if I'm explaining right what I see in my head, but
the wheel would be supported on both sides?
 
OK I see this in my head so bear with me, it's kind of empty and dusty in there.....

Another idea, if you look at the plans from the top down, you'll see where on the Street Fox:

There is a bar that goes from the Cross Boom to the rear, then across the wheel where one
mounts caliper brakes. How about extending that to continue, back to the outer wheel hub?
Instead of making a tab with a hole for the wheel to mount, open that hole so that it's like
a standard drop in for a wheel? I think that's what they call it. I would think that would make
it wider by about the width of the boom * 2, but you'd have support on both sides of the
wheel, eliminating the need for a thicker hub?
Cut the tabs (is that what they're called?) where the wheels mount off donor bikes double them up for strength,
and instead of having to make that thick tab thing with the hole, mount double tabs to the head tube.
It would make for removing wheels easier too in the event of a flat.

Since I have only bought the Fox plans, I only have those to refer to.
Since you need at least 2 bikes to build the Fox, the tabs from the front and rear wheels should be enough.

Thoughts? Comments?
 
That wouldn't have any clearance to turn the wheels. and the outer wheel mount would be solid to the chassis and unable to turn.
 
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Hmmm, well, you have the one bar that comes off the crossbeam and points to the back of the trike.
Then you have the little bar that goes behind the wheel where the brake caliper is mounted.
Extend that bar to point to the front of the trike to the other side of the wheel hub.
 
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