and I have finished desiging just about all of a recumbent trike that is front wheel drive and steer. I remember seeing a russian machine a few years back that had the same concept but it was made for road use unlike the off road monster I am trying to craft. I have started to machine up the small fiddly stuff first to see if I am capable of doing it, but I think if the uni joints hold up then it will all be ok. I still want to keep it very close to the weight of my current trike which is 15kg but I will use cro-mo this time which will help.
I am looking to make something that can go up inclines and terain that no other bike can. Also I am looking into leaving the option open for electric assist on the rear wheel to make it all wheel drive (3x3! ehhehee) with a lithium iron phosphate battery pack.
I want to hear form anyone who has any ideas/sujestions/questions/etc..
I built a front wheel drive tadpole trike this spring.I made a small diff using gears from an angle grinder and I'm using 1/2" ball end allen wrenchs for steering u-joints. I have a goldenmotors e-drive on the rear wheel for help with hills and when I'm just lazy! I have ridden it about 150 miles since I built it aand have no problems yet! Except a bad dose of recumbent butt because I had the pedals to high! I have lowered them and have no problems now!
I also built a rear wheel drive tadpole with a intermediate that I find much easier off-road simply because it has much lower gears. The all wheel drive certainly has much better traction though, I can spin the rear wheel on the rear wheel drive but haven't slipped a wheel on the front wheel drive yet!
I used 5/16" heim joints for tie rods and kingpin bearings which seems to work well and leaves my to-in and camber fully adjustable. this trike is very stable and I have ridden it downhill at almost 50 mph with complete confidence! I used disk brakes from a pocket bike on all three wheels, and though I cannot lock up the front wheels, it stops better than any bike I've ever ridden.
I used 20" front wheels with homemade hubs and the rear wheel is 24".
Brake rotors are 160 mm
that sounds awesome and impressive. I thought about using the grinder gears but I thought that the two gears where a different amount of teeth and an angular cut making it not possible to have a spider gear arangement. Anyway even though I know different now I have a design that doesnt use a diff at all. To stop my smashing the uni joints I have a system where as I have it so the axles can free-wheel so the outside wheel around a corner can ratchet. Even though its really primative compared to what you have it looks to lets me have a design that is practical in a few areas I am trying to accomodate but its hard to descibe.
I am going to use uni joints out of a 3/8 drive socket set, I hope they hold up!
I would use a simple motor for the rear however I would have it massively geared down so its pretty much an offroad thing only.
Would you be able to post some pictures of your trikes? sounds like you did an awesome job. Or would you like for me to send you a PM for it?
Just go to edsceations.blogspot.com to view pictures of mu all wheel drive .
I have lowered the pedal crank about 4 inches since these pictures were taken. I haven't photographed my other bikes as yet because I haven't painted them yet.
There is very little change in driveshaft length because the effective kingpin is right on the center of pivot of the "ball end" allen wrench. The joint works like a cv joint in a fwd car.
A freewheel on each wheel as, i think you are describing, will be very good in a off-road type trike. It will give a sort of limited slip effect. A true diff like I built would be better if you wanted to pedal to back up but the only problem with a freewheel might be some small amount of torque steer.(The inside wheel will be driving alone on turns)
another advantage of a diff is that the torque is divided between both wheels all the time which would make it easier on the u-joints but I think 3/8 socket set type joints will be quite strong enough even 1/2 inch are quite small if you were worried about it
My trike as seen in the pictures is 41 kg with the electric drive but there is 9 kg of batteris and 8 kg for the hub motor and controller etc. I have used just cheap bicycle parts in it too and all the components I built are steel. I'm sure I could build it somewhat lighter with al rims and components.
I also in my designs figured that if I create the pivot perfectly inline with the pivot point of my univeral joint then there would be minimal shaft movement. However there still has to be some as having any sort of castor angle introduces that. This was my longest running design problem and right now I am pretty sure I have the solution. I plan on get a peice of high tensile bar (or a big arse bolt!) and machine it ot have 12 sides, drill the middle out and thats one side covered, for the other side I would machine the non drive part of a socket (from a socket set) and weld it to the inside of a pipe, this would slide over my 12 sides shaft and effectively be a spline.
So I understand what your using at the ends, but makes up your actual driveshafts?
For myself I am planning on going for a very different approach that yours in that I am going to have a hollow kingpin type design with external shafts. However your design is in my eyes is ingenious and its appealing to me in that it allows for a straight arms for the wheel supports and also protected drive shafts. I will do some designs for myself and see if I can get it to work for me.
Your very right that I might have the equivolent of torque steer with the ratcheting shaft design. I have ridden an upright tricycle that only powered one of the two outside wheels and when it would do a sharp turn in the same direction as the powered wheel it because very hard to peddle. I am accepting this compramise though as it gives me the following advantages: modified off the shelf bits, light, tough, more ground cleanence, relativley easy to put together and it allows for me ot have an under-drive. You see I plan on having the gears on one shaft with a single 13T sprocket at the other end, and this then powers the twin ratchets with an 18T sprocket that are all located on their own shaft lower down inline with the center of the wheels. This is hard to explain but I think I have it all figured out.
I think that you having a machine like that with those sort of parts weighing in at 24kg is no where near as heavy as I expected, its like as you said you used heavy parts, tubing, everything in the build. I would be really interested to see how you put that diff together as I think its an increadible effort.
I am doing every last trick in the book to make this thing light as, its hard going but I think it will work out for me. For example the shaft for my sprocket cluster has an OD of 20mm and I am drilling out the inside larger where it needs less strength and vice versa. I want to have my final weight without an electrics at 17kg or so, my current trike was 15 last time I checked. I would use only Cro-mo tube unlike the mild steel previously.
out I forgot to add I have been thinking about purposefully moving the kingpin pivot away from the uni-joint center point to gain some structual strength at the compramise of additional drive shaft length change.
My diff has two sets of angle grinder gears (5" grinder) the big gears are used as side gears and the small ones as pinions. The small gears run on the 5/16" bolt you can see through the barrel in the center of the drive. The output shafts are 5/8" allen head bolts. The front wheel axles are also 5/8" allen head bolts machined down to 20 mm. The drive shafts are the 1/2" allen wrenchs with the short arm cut off so they are effectively 1/2" HARD hex shafts. I put a small spring in the diff end socket to keep the ball end at the wheel fully engaged. there may be some change in drive shaft length but it is accomodated by the two socket head bolts.
My electric drive is 36v 500w with 3 7ah batteries to keep the weight down (it's not enough battery though, 10 ah would be much better! or lithium ion)
I certainly agree! Lithiums would be great! The regulations in Alberta where I live are that a powered bicycle is 35 kg or less and travels less than 35 km per hr on bat alone. with lithium I could become LEGAL. LOL
The sla's are still so much cheaper though and I don't really go that far with my bikes. ( I mostly build them to see if I can and commute to work on them but that is less than a mile.)
The wheel bearings are in the spindle. the 5/8" socket head bolts that I use for axles are machined to 10mm through the bearings and into the wheel hub. the outer ends are machined to 7/16" and threaded unc (left hand thread on the right side and right hand thread on the left). The actual wheel hub has a press fit part the same dimensions as the wheel bearings on the inside and similar on the outside but with a 7/16" thread to match the axles. the wheels simply thread onto the axle in such a way that pedal torque tightens them.
again its not a technique I thought of at all, I did plan on initually using a spindle for the bearings as well but instead using some steel wheel chair hubs which are welded directly to a axle. However now i am thinking of something thats a more profesional approach which is to knock the bearings out of a disk brake hub, install spacers in their place which have a larger inside diameter, then make a flat/bell shape that attaches to outside the disk brake so both the disk and the axle are both secured to the hub through the disk brake mounts. That which good for me as i know the disk brake mounts are made for the job and quite strong and that I get front brakes for the first time.
on a side note my machining is going well and i might post some pictures soon.
I'd sure suggest you do whatever it takes to get brakes on the front wheels. If you get your KPI (kingpin inclination) and camber set right you'll have negligible brake steer ( I can't detect any on my trikes) and have vastly better braking I have driven my rearwheel drive trike with only rear brakes and any sand on even a moderate downhill will allow rear wheel lockup. In fact I hardly use my back brakes now that I have fronts. I made a lever that pulls both cables for my front brakes. But I may try just individual front brakes if I do it again.
It looks like you sit further back on your trike than I do. that would make your rear brake more effective. I'm not very heavy either, 165 lbs in my "riding gear"! I often feel sorry for those BIG bikers but they can fit a lowracer better than I can! Wish I had longer legs for my swb bet though!
I have had a change of plans in one area. It looks like I am going to have a 30mm hollow cro-mo axle from the "hub" to the spindle. I plan on now instead of having an assembly on the axle bolt to the disk brake mounts on a disk brake hub to alternatively making my own eqivolent of a hub up using two independant disk like peices with the spoke holes in them, one of them would also have mounts for a disk brake still. From here I would directly weld/braze the two peices onto my axle to make the eqivolent of a hub. To remove I would just undo a circlip and the uni joint and then slide the wheel with its fixed axle right out together. This would allow for total design freedom and would help me in removing even more unwanted weight. As a bonus thats two less thigns to buy as I have found its almost impossible to buy second hand 36 hole disk brake hubs.
Also I am thining more about abandoning the electric rear assist and instead just going for three wheel drive by peddle power. I am pretty sure it would be easy to change my current plans to incorperate this. Either way I will definately put the sprocket on the front drive axle to allow for either choice.
Is anyone still building or have built a front wheel drive and steer trike ? I have seen one prototype built and I love it but the builder isn't wanting to sell any just yet so I am trying to see if there is any front wheel drive and front steer trikes out there that I could buy ?