2WD (dual motor, two wheel drive) Trike build.
- Thread starter llile
- Start date
If you had to, you could do a "mag" wheel in segments, so it doesn't have to be machined from a single expensive large block. Would be a lot easier to bolt to the hub flanges, too, since you could make the segments so that they are inserted into the space between the flanges, then use the spoke holes to bolt them to the flanges. On the rim end, just have them drilled and tapped for the nipple holes in your rim, and shaped to fit the contours of the rim itself, and screw the rim down onto them via the nipple holes.
As long as your rim is a relatively flat "inside" surface this should work fine. If it's a deep aero rim it probably would require some careful thought on designing the ends of the 'spokes" so they can be inserted as a "spiral" and hten brought upright between the rim and the hub.
As to the strength of half-radial / half 1x, my rear wheel is built this way right now (20" rim, Crystalyte HS3540), and it is tremendously better than the full-radial lace it had before. I have less than a couple hundred miles on it so far, though, I think (need to total it up and figure that out, soon, to start keeping proper track of it in the CrazyBike2 thread), so time will tell on how well it holds up. But it has the same problem yours does, as far as too-large flange holes for the spoke heads. Even using washers in them only keeps them from pulling thru, so what I'll do if I ever have to relace it again is to drill new holes between the existing ones, at the exact size for the spokes I use.
Alternately, I think Ypedal once laced up a wheel with spokes way too long for it, passing htem thru the spoke flange, bending them in "half", and just twisted them up around themselves, and I think that wheel is still in service years later.
As long as your rim is a relatively flat "inside" surface this should work fine. If it's a deep aero rim it probably would require some careful thought on designing the ends of the 'spokes" so they can be inserted as a "spiral" and hten brought upright between the rim and the hub.
As to the strength of half-radial / half 1x, my rear wheel is built this way right now (20" rim, Crystalyte HS3540), and it is tremendously better than the full-radial lace it had before. I have less than a couple hundred miles on it so far, though, I think (need to total it up and figure that out, soon, to start keeping proper track of it in the CrazyBike2 thread), so time will tell on how well it holds up. But it has the same problem yours does, as far as too-large flange holes for the spoke heads. Even using washers in them only keeps them from pulling thru, so what I'll do if I ever have to relace it again is to drill new holes between the existing ones, at the exact size for the spokes I use.
Alternately, I think Ypedal once laced up a wheel with spokes way too long for it, passing htem thru the spoke flange, bending them in "half", and just twisted them up around themselves, and I think that wheel is still in service years later.
Drunkskunk
100 GW
Just a random thought, but since you are willing to drill holes anyway, who says they have to go in motor's spoke flange? If you drilled holes in the side cover, and fet the spokes through from the outside, you would have a much wider base for the spokes. If you did just the inside cover, you could move the rim closer to the centerline of the steering knuckle, and releave a lot of tension that way
llile
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An interesting and fortuitous problem arose today.
For some time, the bike has pulled to the right. I've fiddled with tire inflation, which helped a little, but never made it go away. checked for dragging brakes, other issues. Not sure what else to change. recenlty is has been pretty severe, I actually got a little sore in one arm from pulling the steering all the time last ride. My wife, who is not as strong, thinks it is really objectionable.
Yesterday about two miles from home I executed a rather spastic and unintentional maneuver that put a lot of stress on the tie rod, when the dust settled I had a broken tie rod, leaving the two front wheels flopping independantly. Broke right at one of my welds. Looks like poor penetration.
I disconnected the remaining shards of the tie rod, cursed my terrible welding skills, but proceeded to ride home anyway tie-rod-less. The two front wheels would track pretty well and steer OK, but if I let go momentarily they would wobble and fishtail. Otherwise the vehicle worked fine without a tie rod. Since each wheel has a tiller, wheels are set with proper trail, the vehicle steered OK. and ...
NO DRAG TO THE RIGHT!
Fantastic! There is something wrong, apparently with the way the tie rod was adjusted. I had it adjusted, by tape measurement, to just the merest hint of toe-in, had a friend help me to get it super-precise. Perhaps these measurements are incorrect? Maybe I should keep playing around with the settings until it doesn't pull to the right, instead of trying to set it to a measurement?
LATER:: this theory proved to be grabbing at straws.
For some time, the bike has pulled to the right. I've fiddled with tire inflation, which helped a little, but never made it go away. checked for dragging brakes, other issues. Not sure what else to change. recenlty is has been pretty severe, I actually got a little sore in one arm from pulling the steering all the time last ride. My wife, who is not as strong, thinks it is really objectionable.
Yesterday about two miles from home I executed a rather spastic and unintentional maneuver that put a lot of stress on the tie rod, when the dust settled I had a broken tie rod, leaving the two front wheels flopping independantly. Broke right at one of my welds. Looks like poor penetration.
I disconnected the remaining shards of the tie rod, cursed my terrible welding skills, but proceeded to ride home anyway tie-rod-less. The two front wheels would track pretty well and steer OK, but if I let go momentarily they would wobble and fishtail. Otherwise the vehicle worked fine without a tie rod. Since each wheel has a tiller, wheels are set with proper trail, the vehicle steered OK. and ...
NO DRAG TO THE RIGHT!
Fantastic! There is something wrong, apparently with the way the tie rod was adjusted. I had it adjusted, by tape measurement, to just the merest hint of toe-in, had a friend help me to get it super-precise. Perhaps these measurements are incorrect? Maybe I should keep playing around with the settings until it doesn't pull to the right, instead of trying to set it to a measurement?
LATER:: this theory proved to be grabbing at straws.
llile
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Still not sure about this pull to the right thing. Went through a long series of adjustments and trials of various toe-in settings from absolutely parallel to toed in about an inch. None of them really changed anything.
Most recently I did a very detailed measurement of the alignment of all three wheels. This isn't easy, as you can imagine. But I began to realize that there was a slight tilt of the rear wheel to the left, which would rear-steer the vehicle to the right. No amount of adjustment of the tire within the range allowed by the frame was able to pull it into alignment. So I recently took everything off the back end of the bike, batteres, cables, and all, and actually notched a part of the frame in order to straighten out the wheel and weld it back. As best I can measure it all three wheels are totally parallel now. I have yet to put it all back together to see if this effort was worth anything.
The bike is certainly not built very accurately - two of the wheels are not exactly vertical, have a slight cant to them. I had made great efforts when constructing it to clamp all this stuff rigidly while welding it up, but the result still leaves a bit to be desired. It is a lot easier to get this right on a two-wheel frame, which is essentially a two-dimensional being that can be constructed off of a flat plate. In three dimensions it is harder to line things up. One should spend as much time constructing a clamping jig for a three-dimensional bike frame as constructing the frame itself, even going so far as welding up a jib out of square steel stock that is accurately square. Most of my jigs were cobbled up out of wood, and I should have taken more care to make them accurate.
Most recently I did a very detailed measurement of the alignment of all three wheels. This isn't easy, as you can imagine. But I began to realize that there was a slight tilt of the rear wheel to the left, which would rear-steer the vehicle to the right. No amount of adjustment of the tire within the range allowed by the frame was able to pull it into alignment. So I recently took everything off the back end of the bike, batteres, cables, and all, and actually notched a part of the frame in order to straighten out the wheel and weld it back. As best I can measure it all three wheels are totally parallel now. I have yet to put it all back together to see if this effort was worth anything.
The bike is certainly not built very accurately - two of the wheels are not exactly vertical, have a slight cant to them. I had made great efforts when constructing it to clamp all this stuff rigidly while welding it up, but the result still leaves a bit to be desired. It is a lot easier to get this right on a two-wheel frame, which is essentially a two-dimensional being that can be constructed off of a flat plate. In three dimensions it is harder to line things up. One should spend as much time constructing a clamping jig for a three-dimensional bike frame as constructing the frame itself, even going so far as welding up a jib out of square steel stock that is accurately square. Most of my jigs were cobbled up out of wood, and I should have taken more care to make them accurate.
llile
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I have finally hit upon the answer to the mysterious "Pull to the Right". No, the bike is not haunted by Rush Limbaugh. As readers will remember, the bike always trends to the right side, and it is actually quite a struggle to keep it going straight down the road, to the point my left arm gets tired of pulling on the tiller.
Careful measurements of the entire trike's geometry reveal the following: Both front wheels are absolutely parallel to each other, within the limits of my tape measure. However both front wheels are not perpendicular to the ground when pointing straight. They both camber or lean to the right about 3/8". This may also explain why I have broken spokes on the right side (which would camber or lean out in a way that stresses the spokes every revolution) but never on the left (which cambers in).
I pondered this problem for some time, and then was able to figure out how to make a bird's mouth cut in one of the tubes, close it, and weld it back, then make a symmetrical cut on the opposite wheel on the opposite side, welding it shut as well. This was able to adjust the front wheels so they are truly perpendicular to the ground. The whole bike was subjected to several measurements before welding it shut. It is not particularly easy to make such a measurement, since the trike is a 3 dimensional system, and just the tiniest bit of misalignment is sufficient to cause trouble.
I reassembled the trike and voila! No more pull to the right! This problem has been vexing me for quite some time! Now if it would just warm up enough to ride it ...
Careful measurements of the entire trike's geometry reveal the following: Both front wheels are absolutely parallel to each other, within the limits of my tape measure. However both front wheels are not perpendicular to the ground when pointing straight. They both camber or lean to the right about 3/8". This may also explain why I have broken spokes on the right side (which would camber or lean out in a way that stresses the spokes every revolution) but never on the left (which cambers in).
I pondered this problem for some time, and then was able to figure out how to make a bird's mouth cut in one of the tubes, close it, and weld it back, then make a symmetrical cut on the opposite wheel on the opposite side, welding it shut as well. This was able to adjust the front wheels so they are truly perpendicular to the ground. The whole bike was subjected to several measurements before welding it shut. It is not particularly easy to make such a measurement, since the trike is a 3 dimensional system, and just the tiniest bit of misalignment is sufficient to cause trouble.
I reassembled the trike and voila! No more pull to the right! This problem has been vexing me for quite some time! Now if it would just warm up enough to ride it ...
Rassy
1 MW
I've been following your build, and glad to see you found a solution to the "pull to the right" issue.
Many have been skeptical about the success of a two wheel drive trike and concerned that one of the motors would cause unequal pull and make steering and cornering difficult. I think you have put that issue to rest. My experiences with two wheel drive pusher trailers showed that matched electric motor/controllers would work like an anti-slip differential, and figured that would still be true on the front wheels of a tadpole trike.
Many have been skeptical about the success of a two wheel drive trike and concerned that one of the motors would cause unequal pull and make steering and cornering difficult. I think you have put that issue to rest. My experiences with two wheel drive pusher trailers showed that matched electric motor/controllers would work like an anti-slip differential, and figured that would still be true on the front wheels of a tadpole trike.
llile
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E-e-e-every once in a while I can feel the motors pulling harder on one side or the other. It might move an inch or two to the right or left. However it self-corrects rapidly and requires a brief steering adjustment. Hell every bump in the road also requires a steering adjustment. This asymmetrical pulling may be from noise in the throttle signal. Keep a common throttle line until as close to your controllers as possible, split the common throttle line symmetrically, and keep the connections to the controller throttle inputs short. Establish a common and short ground (or Minus battery terminal) connection between the two controllers. I really haven't had any trouble along this line, but I have to admit that it can be felt.
So far I've put 1400-odd miles on the bike, it is working fantastically.
So far I've put 1400-odd miles on the bike, it is working fantastically.
johnrobholmes
10 MW
Great to hear it is still going strong after the rebuild!
llile
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John Robert, I'll be calling you soon about making a few spokes!
Broken spokes are the bane of the three-wheeler. It can be a cattrike, a homebuilt, or anything in between, if you haul on it around corners, eventually you'll bust a few spokes. So far John Robert's pattern of radial spokes outboard, crossed spokes inboard has worked better than anything else we've tried. Just recently broke two spokes ont he back wheel, others probably fatigued.
Broken spokes are the bane of the three-wheeler. It can be a cattrike, a homebuilt, or anything in between, if you haul on it around corners, eventually you'll bust a few spokes. So far John Robert's pattern of radial spokes outboard, crossed spokes inboard has worked better than anything else we've tried. Just recently broke two spokes ont he back wheel, others probably fatigued.
John in CR
100 TW
llile said:
That's why I believe trikes should be leaners, so the issue of side loads that bicycle and moto wheels are designed to withstand go away, and best safety becomes the front/rear weight distribution to take advantage of the traction of 3 wheels.
llile
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John in CR said:
You are correct, and I spent a long time trying to make a leaner, then gave up on the idea. It isn't particularly simple to build. Keep in mind I have built some rather complex things. The potential to have a bike that just flops over to one side or another is pretty real. I'd love to see the design on a successful shop-made leaning trike.
Some wheelchairs have both front wheels canted in at a small angle, presumably this helps with avoiding spoke failure on corners as well as with stability. These are usually chairs meant for athletic use. This might work on a trike if one couldn't pull off the leaning mechanism. I haven't tried it though.
docnjoj
1 GW
Steintrikes has a leaner tadpole which seems to work well. Their website has a video.
otherDoc
otherDoc
oatnet
1 MW
Great fun, thanks for sharing! 
-JD
-JD
llile
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How to buy bananas: https://www.youtube.com/watch?v=NkUpDsXAX5Y Seriously, has very little to do with bananas and a lot to do with Ebikes
Here is what to do after you built your E-bike: https://www.youtube.com/watch?v=8k-3S4DbEnI&t=201s
Here is what to do after you built your E-bike: https://www.youtube.com/watch?v=8k-3S4DbEnI&t=201s
Regarding the negatively cambered wheels, I've done this first on SB Cruiserllile said:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&start=600
to a small degree (though it is to widen the track for stability rather than for spoke issues, of which I haven't had any), and now to a greater degree on a new trike here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=80951&start=50
The new trike is only tested a little bit around the local block, not yet traffic-tested or load-tested, as it's just tacked together so far.
SB Cruiser has been tested with vertical wheels (no camber) for some time now, without spoke issues (though I've broken an X5304 axle from a pothole with a load in the cargo bed), and this trike sees some side-loading for sure.
The cambered wheels have only been that way a few months.
llile
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Well here is an update on the dual motor trike:
This is the most successful hack I've ever made, bar none. (most of my hacks are still in a pile in the corner of the shed.)
The original battery, a 40AH, 72V LiFEPO4 from EM3EV has lost some capacity. Last fall, I was left walking about three miles from home a couple of times. During colder weather I measured the capacity to BMS cutoff at about 36 AH, or a 10% capacity loss. That might have also been cold weather, I will check it again in warm weather.
I've hacked on some spare batteries. I have two LiFEPO4 36V batteries, seriesed-up with a Schottky diode network. Now, the diodes are probably not necessary, but I've learned that some BMS FETs are not able to handle 72V, and may fail if exposed to that much. One of the batts is a Ping 10AH, and it is probably fine, the other is an LiFEPO4 that I bought used and know almost nothing about. That's probably 9AH, so the pair in series is 9AH. LiFEPO4 batteries may be parallelled without regard to capacity (mostly) and the additional batts have served well. However the whole system still seems to be losing range, or else I am driving it farther, one. I find it harder and harder to get an opportunity charge in town (about 20 miles away) in the middle of a 40-50 mile trip, so I'm trying to achieve a good 50 miles of range. Bike uses about 1 AH per mile (80 WH/Mile) at 35 mph top speed.
I'm at about 7000 total miles and 250-ish total charge cycles.
Currently I'm working on an 18650 pack that will be my range extender. It should be about 14 AH when completed. Although it could theoretically be paralleled with LiFEPO4 using diodes, I'm planning to just unplug the LiFEPO4 and plug in the 18650 (Li-Ion) so as to avoid problems. I've got the packs arranged so I can charge either battery with the same charger - 24S LiFEPO4 works out to about the same charge voltage as 20S 18650.
Here are pics of me and my buddy, also on a trike e-bike, on a camping trip. Not great photos of the bike, but I'll post a few of those directly.
This is the most successful hack I've ever made, bar none. (most of my hacks are still in a pile in the corner of the shed.)
The original battery, a 40AH, 72V LiFEPO4 from EM3EV has lost some capacity. Last fall, I was left walking about three miles from home a couple of times. During colder weather I measured the capacity to BMS cutoff at about 36 AH, or a 10% capacity loss. That might have also been cold weather, I will check it again in warm weather.
I've hacked on some spare batteries. I have two LiFEPO4 36V batteries, seriesed-up with a Schottky diode network. Now, the diodes are probably not necessary, but I've learned that some BMS FETs are not able to handle 72V, and may fail if exposed to that much. One of the batts is a Ping 10AH, and it is probably fine, the other is an LiFEPO4 that I bought used and know almost nothing about. That's probably 9AH, so the pair in series is 9AH. LiFEPO4 batteries may be parallelled without regard to capacity (mostly) and the additional batts have served well. However the whole system still seems to be losing range, or else I am driving it farther, one. I find it harder and harder to get an opportunity charge in town (about 20 miles away) in the middle of a 40-50 mile trip, so I'm trying to achieve a good 50 miles of range. Bike uses about 1 AH per mile (80 WH/Mile) at 35 mph top speed.
I'm at about 7000 total miles and 250-ish total charge cycles.
Currently I'm working on an 18650 pack that will be my range extender. It should be about 14 AH when completed. Although it could theoretically be paralleled with LiFEPO4 using diodes, I'm planning to just unplug the LiFEPO4 and plug in the 18650 (Li-Ion) so as to avoid problems. I've got the packs arranged so I can charge either battery with the same charger - 24S LiFEPO4 works out to about the same charge voltage as 20S 18650.
Here are pics of me and my buddy, also on a trike e-bike, on a camping trip. Not great photos of the bike, but I'll post a few of those directly.
llile
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Here's a pic of my trike lined up with two other electric trikes (some really nice Bionix setups) at a bike rally. I got to try these little trikes, they were pretty sweet rigs.
Note small differences. My trike is taller - thus more visible in traffic (an important consideration for me) but less aerodynamic. Wider, thus more stable at speed, with the disadvantage that it doesn't fit some places, such as between trail traffic barriers sometimes. My bike is pretty heavy, built out of steel and probably overbuilt, and having long range batteries, also adding weight. Two motors are not the lightest configuration either. I've got a lot of cargo area, compared to most bikes. Well, camping gear expands to fill all available cargo area. The faring is nice in bad weather, I only really get wet above the waist, shoes stay totally dry. I'm built with the rigidity needed for a 35 mph cruising speed, which many bikes are not, also a reason for a lot of weight.
Note small differences. My trike is taller - thus more visible in traffic (an important consideration for me) but less aerodynamic. Wider, thus more stable at speed, with the disadvantage that it doesn't fit some places, such as between trail traffic barriers sometimes. My bike is pretty heavy, built out of steel and probably overbuilt, and having long range batteries, also adding weight. Two motors are not the lightest configuration either. I've got a lot of cargo area, compared to most bikes. Well, camping gear expands to fill all available cargo area. The faring is nice in bad weather, I only really get wet above the waist, shoes stay totally dry. I'm built with the rigidity needed for a 35 mph cruising speed, which many bikes are not, also a reason for a lot of weight.
johnrobholmes
10 MW
The radial / single cross relace still holding up?
