Front brakes tadpole trike

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Hi all, first post so sorry if its in the wrong place :sneaky:
My question is probably old school but im atuck for ideas..
Im building a recumbent tadpole trike from some designs i found on the internet and modified them a bit, theres pics in the gallery... Basically its made of old bike bits and a couple of stainless roof bars..
Ive managed to cobble some disc brake adaptors onto the front wheels which are trick 14mm bmx wheels and the rears also a disc brake...
problem is, Ive only got 2 hands and I want to operate the front brakes with one hand and the rears with the other but im unsure of the best way to split the front brake cable? theyre cable calipers...
Anyone done this before?
Any tips appreciated (y)
 
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You need one of these:-


They come in left or right hand. Or one of these:-


It's not that hard to make something resembling the latter one if you don't want to buy one.
 
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Thats perfect popshot! Many thanks, just ordered the first one (y), didnt even know they existed...
 
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Why would you want to do that ?

On any trike the single wheel should be unbraked , and if it does have a brake it should be considered a parking brake or extreme emergencies drag brake.

The only valid reason for coupling them would be through disability if the rider can only operate a single lever.

It actually says this in the advert !

If they are coupled they both have to operate at the very same time otherwise you risk brake steer [ if the trike geometry is poor ] and if one wheel locks up the only safe option is then to stop braking on both wheels.

The vast majority of commercial trikes only have 2 braked wheels.

Well that's my 5 pence worth.
 
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Why would you want to do that ?

On any trike the single wheel should be unbraked , and if it does have a brake it should be considered a parking brake or extreme emergencies drag brake.

The only valid reason for coupling them would be through disability if the rider can only operate a single lever.

It actually says this in the advert !

If they are coupled they both have to operate at the very same time otherwise you risk brake steer [ if the trike geometry is poor ] and if one wheel locks up the only safe option is then to stop braking on both wheels.

The vast majority of commercial trikes only have 2 braked wheels.

Well that's my 5 pence worth.
ok nice one..
Never built one before...
Reason for doing it is that my missus has early onset parkinsons and she gets a bit wobbly so cant ride a normal bike (this cropped up recently with the lockdown etc) so out came the old engineering toolbox and a tig welder and i set too it with some jetrike plans someone found on tinterweb..
few mods later and no drawings or ideas for brakes my thinking went like "this thing is gonna go like a scalded cat, especially downhill so its gonna need to stop well, and a rear brake to boot, as in motorbike 2/3rds on the front 1/3rd on the back" so i fitted 2 150 discs to the front wheels and a smaller one to the back as a drag brake as you said..
I had visions of her panicking and grabbing both front brakes hard and getting launched straight out the bucket seat ive fitted to it to keep her in the thing round the corners...
What I was hoping was gentle pressure on 2 levers would give a balanced enough set up so as not to tip the thing forwards if theres a drama..
The general front balance i was hoping to kind of fettle using the brake adjusters on the callipers and the lever to balance the front end and she can just lock the back up if she panics without any major drama except maybe a bit of a sideways freestyle...
Im also hoping to do a rear wheel ebike conversion on it too, not too sure if winding the power off it helps a bit with braking or theres a drum brake inside em?
All info much appreciated... (y)

this is the trike so far
 
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p.s. looking at the picture... that warrior racing trike (orange one) looks very much like its got 3 disc brakes???
 
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The only valid reason for coupling them would be through disability if the rider can only operate a single lever.

It actually says this in the advert !
It says those are reasons. It doesn't say they are the ONLY reasons and even if it did we often repurpose items from one intended use to another and this is no different.

The Warrior does indeed have three discs. It doesn't say in the plans how they should be configured.

They do obviously require some balancing but the system is tolerant of being slightly out. I've run such a set-up and never had any brake steer despite VERY heavy braking. Very heavy braking can lead to the front tipping down, rotating around the front axle. This is true regardless of using a rear brake or not. Indeed it can be fun if expected and anticipated. Doing a stoppie on a trike does make you look cool. Using the rear brake whilst the wheel is unloaded due to heavy front braking can lead to the rear locking up. Doing this in a corner can lead to the back end overtaking the front and I ought to have mentioned that warning sooner. If braking hard in a corner with such a set-up beware of using the rear at all. Try it in a safe place first so you understand what can happen. Again it can be fun if expected and anticipated. It can be lethal if not.
 
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ok nice one..
Never built one before...
Reason for doing it is that my missus has early onset parkinsons and she gets a bit wobbly so cant ride a normal bike (this cropped up recently with the lockdown etc) so out came the old engineering toolbox and a tig welder and i set too it with some jetrike plans someone found on tinterweb..
I though all the Jettrike's were tilting deltas ?

Would you not be better looking at a delta tandem set up where you are linked when out with the missus ?



I had visions of her panicking and grabbing both front brakes hard and getting launched straight out the bucket seat ive fitted to it to keep her in the thing round the corners...
A unmentioned side effect of 2 brakes into one lever is that you have to apply twice the pressure of a single lever/brake which needs some strength

All info much appreciated... (y)
Some people come for advice which we try to give , some people chose to ignore the advice and some people never ask.
So yes there are tadpoles out there with rear brakes and used responsibly that can be safe ?
However if you are not aware of the dangers you could end in an accident that could have been avoided ?

Good luck with your build , looks a quality trike.
 
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Many many thanks for the info (y) The trikes now at the point where i can get her in it for testing... Theres a seldom used road just outside the yard we can use for speed tests and the like and Ive every intention of making this as safe as is possible given its a low slung tricycle...

Im still in two minds (or 3 even) about the steering set up.. when i pedalled it round the yard for the first time the other day it seems ridiculously responsive to even small inputs and was wondering how i could tone that down a bit? maybe the push/pull system with bars on separate pivots at the side of the seat? I just dont know at this stage... I havent even made caliper brackets yet or fitted any levers so its all new at every stage..
Ive just got the chain on and the gears working but those twist grip ones just seem crap, and really stiff to boot so ive ordered some shimano button click sequential jobbies and maybe this weekend I can design the handle bars around her comfort.. shes had a push round in it before i got the chain on and tbh she absolutely loved it

I was also thinking maybe steering dampers would be an idea but ive no idea what kind to fit? Im aware they make them for motorbikes but not sure if they would be suitable for a human powered trike? Also I thought it would be good if i could get the steering to want to return to centre using such a system so even under the harshest circumstances, a kind of instant full lock scenario isnt going to happen?

I already ordered the twin cable lever and it didnt cost too many beans so ill give it a go and see, might as well now ive bought it but ill do it with the warnings ringing in my ears and will definately give it some serious testing myself with a crash helmet on before i let her go screaming down a hill with wild abandon (shes nuts, she would, trust me 🥳)

I also didnt know this forum existed or anything at all about these recumbent trikes before and tbh Im getting right into it although with the easy bit (building the frame) now done, the learning curve is steep... not least the steering, which ive tried to set up as "ackerman" steering (new phrase and info i learned recently) which somehow doesnt seem to work quite right and Im also getting quite a bit of what I understand is known as "wheel flop" which Ive read on here is too much rake so I can see me chopping that front end about quite a bit more before Im happy with it...

Up to now (or very recently) ive not had to buy any specialist gear to get it going but i will be fitting all new cables, levers, bearings, stainless bolts etc when it gets to final build after paint (which Im told by the missus is gonna be bright dayglo orange) and shes a dab hand with a sewing machine so shes taken the cover off the bucket seat to make a new waterproof version.

Im sure ill be popping in regularly with more (probably silly) questions so again many thanks for the advice guys (y)

this is the design i started with btw its supposed to be a 24" front and 26" rear but ive stuck the 20" bmx wheels on the front...
 
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Im still in two minds (or 3 even) about the steering set up.. when i pedalled it round the yard for the first time the other day it seems ridiculously responsive to even small inputs and was wondering how i could tone that down a bit? maybe the push/pull system with bars on separate pivots at the side of the seat? I just dont know at this stage... I havent even made caliper brackets yet or fitted any levers so its all new at every stage..
Ive just got the chain on and the gears working but those twist grip ones just seem crap, and really stiff to boot so ive ordered some shimano button click sequential jobbies and maybe this weekend I can design the handle bars around her comfort.. shes had a push round in it before i got the chain on and tbh she absolutely loved it
Now I don't build tadpoles however I will have a go....

That is called direct steering and one of it's foibles is .. well ..it's direct !
Steering would be better if it copied a non direct version



both explained


I was also thinking maybe steering dampers would be an idea but ive no idea what kind to fit? Im aware they make them for motorbikes but not sure if they would be suitable for a human powered trike? Also I thought it would be good if i could get the steering to want to return to centre using such a system so even under the harshest circumstances, a kind of instant full lock scenario isnt going to happen?
They are also mentioned in the above link , to try just add some bungee hooked around somewhere convenient , easy to adjust tension however you will have to overcome it to turn and you will end up with heavier steering at the ends of travel , unfortunately a downside of the tadpole design is poor turning circle and so you may end up at the end of the travel more often than you imagine ?

Ive just got the chain on and the gears working but those twist grip ones just seem crap, and really stiff to boot
usual problem with those is they are the ' wrong way around ' on a trike so you are trying to use the weakest part of your hand to turn them , also look for to tight bends in the cable outer , also a lot of cable outer introduces friction.

I also didnt know this forum existed or anything at all about these recumbent trikes before and tbh Im getting right into it although with the easy bit (building the frame) now done, the learning curve is steep... not least the steering, which ive tried to set up as "ackerman" steering (new phrase and info i learned recently) which somehow doesnt seem to work quite right and Im also getting quite a bit of what I understand is known as "wheel flop" which Ive read on here is too much rake so I can see me chopping that front end about quite a bit more before Im happy with it...
Ackerman is to reduce tyre scrub whilst cornering , rather hard to tell if it ' works ' if just riding with no brakes

What symptoms do you see of ' wheel flop ' ?

The other important angle is the one giving centre point steering , if this is badly out you may experience brake steer ..

Now you are beginning to see why I build delta's :D

Theree is some good stuff here BROL lots of riders with experience , less builders than on here.

this is the design i started with btw its supposed to be a 24" front and 26" rear but ive stuck the 20" bmx wheels on the front...
Sensible will give you a better turning circle
 
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Thanks again paul (y)
Im not too sure whether the ackerman problem is related to the wheel flop problem? What I was expecting was the inner wheel to turn more than the outer wheel but the opposite seems to happen getting close to full lock but that could also be a full lock problem?
http://datagenetics.com/blog/december12016/index.html
theres a graph here that shows the relationship between ackerman and ideal steering so i suppose it could be full lock thats causing the problem as there is definately some wheel scrub...
I did the stringline thing to get the position of the ends of the tie bars - ran string from the front wheel ctrs to the rear wheel ctr like the french guy in the link... but.... the rake angle could have made that an incomplete solution?
this weekend ill try and make sure the toe in is spot on and maybe make a lil vid...

I origionally had 24" inch wheels on the trike as per the plans but I also got hold of some bmx wheels with much stronger spindles so used them instead... The downside of this was it raised the front of the trike quite significantly (sounds odd but i had a different kingpin setup with the 24" wheels so simplified it)
this then increased the rake angle of the kingpins, not by a massive amount but I think it could be significant?
I think I made a mistake cambering the front wheels top in slightly too... just though it looked cool so I'll probably have to straighten them up..
Hence the wheel flop at full lock or close to...
 
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yes at this time you need a tadpole man , you have exhausted my limited knowledge :D
 
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Your kingpins are vertical (looked at from the front or rear) so you don't have centre point steer. It's not the end of the world but ideally the kingpins should point to the contact patch of the tyre. Not doing so will get you some tyre scrub in a turn. If you draw a line (wheels dead ahead) from the centre line of the kingpin through the centre point of the tie rod mount it should intersect the rear wheel contact patch on both sides. It's impossible to tell from a picture if yours does that. If you aren't seeing the Ackerman in action I suspect yours intersect way behind the rear wheel if at all. If it doesn't intersect at the rear wheel then do some cut and weld until it does and lengthen or shorten the tie rod to suit. It'll be a little harder to see the Ackerman in action due to your vertical kingpins as your front wheels will proscribe an arc as they turn. The tie rod you are using looks like it'll hold the Forth bridge together. Most are a lot less substantial than yours but that won't interfere with it's function. It looks like you have 3/8" axles on the front. If you do there's a good chance they'll not survive long being held at one side only. There's a lot of tales of 3/8 bending either immediately with a heavy rider or at the first sign of a pothole with a lighter one. If they do fail, unless hardened ones, they should fail in a manner that bends rather than breaks. It's usual to source 14mm BMX axles or go to 12mm Sturmey hubs or 15mm or 20mm thru hubs.

It looks like you have quite a lot of caster (kingpin angle leaning backwards). Some caster is necessary for the steering to self centre. Usually about 6 to 15 degrees would do. There'll be many folk argue for one particular figure over another. If you have too much that could be the cause of your wheel flop as the wheel pivots around it.

I'd agree with Paul on non-direct steering being the better option. I'm not a fan of the bars sticking in the kingpins but that's purely a personal preference and by no means saying direct steering isn't fine for others. I prefer a pivot under the seat for the bars and one link to the opposite wheel, leaving the tie rod in place as it currently is. The Warrior uses this system which is called under seat steering or USS for short.

I really like how you've gutted and lightened that race seat for the job. Very innovative.
 
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Cheers popshot, I have indeed swapped out the 24" wheels for the bmx wheels with 14mm (i think) axles (shown in later pics) but youre right those kingpins are dead upright... and the castor (thought it was called rake but hey ho live and learn) did lean back quite a bit when i swapped out the front wheels... i suppose i could cut and reweld the arms that hold them and drop it down a bit and set them kingpins to point at the contact patch then set the wheels vertical...
These are the things i need to know... its easy enough knocking a frame up but getting it to work right needs knowledge
(y)
I did wonder about altering the front wheel arms and maybe even introduce a bit of suspension like in a formula 1 car using the spring i got holding the back of the seat up which basically doesnt do a lot anyway... wondering if i could pivot the arms at the low point where they join the main tube and use just one spring?
got the twin cable lever arriving tomorrow so ill give that a shot too if i got time
 
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It's the difference between a free plan, abandoned to kick around the net and a pay one! Brad's plan sets the chassis up so it works very well. For someone new to bike building they are well worth the money and will probably save money overall. I hadn't noticed the suspension unit on the seat until you mentioned it. It's not a good idea as (if it can be moved) it'll absorb pedalling effort. You need to be able to push against an unmoving seat for best effort. If pedalling effort can't move it then it won't. As a quick fix you could wind on enough preload so pedalling effort doesn't move it. You could put suspension at the rear like a Streetfox does though I'd be tempted to get it up and running as is first then see if you want or need it.

Castor / rake - same thing. More people will probably understand if you use Castor though.
 
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The other thing not mentioned about the 2 in 1 brake levers ?

So you mount it on the left handle bar and on a busy road , you want to turn left ? so how do you indicate and brake ?

YMMV :rolleyes:

Paul
 
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