Yet Another E-Trike

[llile]

If you check the sig at the bottom you can find a link to my Trike construction project. It's a big, heavy machine, dual motors in the two front wheels, started with a 40 AH 72V LiFePO4 battery from EM3EV, then added some Lipos as the range fades out on the original. I think I have about 7000 miles on it now and it's still a great ride. 35 MPH tops, 50 mile range, wieghs 500 lbs with my skinny ass on it, as long as I keep it under 30 it is technically still legally an E-Bike according to the laws of the State of Missouri and if I keep it under 20 MPH allowed on the wonderful Katy Trail rails-to-trails system. It is about 49" wide at the wheel bolts.

Fast forward several years and the world is now catching up with us E-Bike hotrodders. My big trike is starting to get outlawed on some local trails in a nearby trail-happy city, and is definitely outlawed on most other state rails-to-trails systems. The Trike is a great road bike and really rocks for touring around on asphalt. It keeps right up with traffic in town. But it isn't going to allow me to do many trails and eventually it will be banned everywhere except the streets. Many of the trails I'd like to travel and try out are now saying that one must have a PAS, and keep the E-bike under 20 MPH to be legal on trails. They all allow trikes AFAIK, but trikes over four feet wide might raise eyebrows, and I've had some near wrecks on crowded trails with two-way traffic. I think it's time to get my big bike off the trail system, before I ruin it for everybody.

I've embarked on building a smaller trike, about Catrike sized, with PAS, a tiny little 250W hub motor, but able to use some of the same batteries and other kit as my big trike. I'm hoping also to have up to 100 miles range at 14 mph, able to haul a snack and some water if I'm on a short trip or pull a bob trailer if I'm on an overnight. I want something I can pick up (The current trike cannot be loaded onto a pickup truck bed, at least my efforts have failed) but still have the comfort of a recumbent trike. I don't want fast, I want high efficiency. I'd probably get better efficiency with a stokemonkey, but I let my buddy use that kit. His bike regularly doubles the efficiency of my big trike in watthours per mile.

Recumbent is the way to go for an old geezer like me. No more buttbusters! Once I went recumbent, I never looked back, and once I tried to put heavy batteries on a two-wheel recumbent, and fought the balancing act, I built a trike and never looked back to two wheels. I rode thousands of miles (One particular year I logged 4000, without a motor!) on a standard two-wheel bike when I was a young lad, but those days are long gone and good riddance to the sore butt.

One of the junkers I have laying around is a Curry folding e-bike, converted to hub motor. I've used this on some traveling expeditions, it's stealthy enough to not attract attention, but as a ride it is terrible. Uncomfortable at best, when I've let others try it out they said "no thanks" after a couple of miles. As a folding bike it is also terrible, heavy steel, heavier still with a motor and batts. Worst of both worlds. I'm scrapping it out for parts for the trike build.

 

[llile]

These parts are coming from Grin Cyclery:

Cycle Analyst Version 3: As a gas gauge, the Cycle Analyst helps on long trips, but the Version 3 also interfaces directly with a PAS, tracks your history, all kinds of other perks.


24 pole PAS sensor. Not a torque sensor That's out of the budget.

Rear Torque Arm

Up/Down buttons that allow easy PAS assist adjustment.

 

[ScooterMan101]

Have you already order that 250 watt motor ?

I have one of those, I had a Mac , and now a DD rear hub.

You will be better off with a motor like a Mac . ( or the equivalent that Grin Has )

With that and the C.A. V 3 you can stay within all legal limits . Just adjust the power down to where you want it, my Mac could run for many miles at 200-400 watts when traveling apx 12 mph average speed over entire ride .
And when I needed the power for passing, merging with traffic, starting off from a traffic light with many car's lined up behind, the power was there. not so with my smaller motor.

 

[llile]

Have you already order that 250 watt motor ?

I have one of those, I had a Mac , and now a DD rear hub.
You will be better off with a motor like a Mac . ( or the equivalent that Grin Has )

You certainly have a sound argument.

Yeah, I've certainly enjoyed the luxury of having thousands of watts available on the big bike, and I get it that it is sometimes nice to take off like a jet. In fact I think it is safer for a bike to keep up with traffic, in many situations. But that won't be this bike.

I'm not planning to use it in traffic much. I don't like trikes in traffic - they are wide. Catrike-style trikes are low and hard to see (My big bike is not low and it has American Flags all over it). This one will have a big visible flag and also lots of flashing lights, but it is mostly for exploring trails, and happily there are many of these in my state and neighboring states.

I do have the motor already, and plan to use it on the new ride. I really have no idea what the specs are, I picked up this electrified folding bike used, it has whatever the original builder put on it. I think 250 is what the guy that sold the bike to me thought it was. It is certainly a small hub motor with halls. I'm hoping that translates to efficiency.

If it's unacceptable I can always change it out later, with a new controller. For right now I'm going with inexpensive components already on hand. This isn't going to be an expensive build, and it will no doubt evolve over time. I plan to have about $200 - $300 in new parts, everything else scrounged, or interchangable with my other ebike.

 

[llile]

So there are several interesting challenges on a recumbent trike:

1. The seat is really critical. A crappy seat will ruin your ride. Recumbent seats support your whole spine, ideally, but a crappy one sweats, isn't rigid, isn't padded right, or doesn't fit your back. I'll post my solution to these problems in a future post.

2. The front wheels (this is a tadpole trike) are best done supported from only one side. Bike wheels obviously are supported from two sides. There are two solutions I've used for this problem. Will elucidate later.

3. The chain line is the main line. A recumbent has about three bike-chains between your feet and the rear wheel. You need to make sure the driving side of the chain has a pretty straight path. Any angles reduce efficiency. One trick to get around this is to use this chain idler. But the other trick is to use an intermediate transmission. On my last bike this was an old hacked three speed hub that changes the gear ratio between the front cranks and the rear derailleur or internal gears. It can also change the angle efficiently.

4. Caster and camber of the front wheels are important. Again I'll go into this in a future post.

 

[Triketech]

Sounds like quite a beast.
We added a MAC 10T to our Scorpions a few years back, made the ascents far more enjoyable in the mountain region we live in.

Been playing with the design of a new stealth tadpole to ride in areas assist is verboten. Inboard rocker arm front, boom mounted Rohloff, power system inside frame channels.

Several CNC parts that are becoming far more affordable among the growing number of proto shops. Tempting.

 

[llile]

Sounds like quite a beast.
We added a MAC 10T to our Scorpions a few years back, made the ascents far more enjoyable in the mountain region we live in.

Been playing with the design of a new stealth tadpole to ride in areas assist is verboten. Inboard rocker arm front, boom mounted Rohloff, power system inside frame channels.

Several CNC parts that are becoming far more affordable among the growing number of proto shops. Tempting.

ELI5 what is a rocker arm front? Did you have to fabricate it from scratch? What are the advantages or disadvantages over other approaches?

 

[llile]

The front wheels (this is a tadpole trike) are best done supported from only one side. Bike wheels obviously are supported from two sides. There are two solutions I've used for this problem.

First, one can simply purchase a single sided hub from Sturmey archer, complete with internal hub brakes. One of the trikes my buddy built used this idea, and it was really effective. He's had that trike almost 20 years, rebuilt the internal hub brake once, and been quite pleased with it. Here's a link to Sturmey Archer's listing for the single sided brake hub, and a pic:

Those hubs are hard to source, Can cost $150 apiece, and take some lead time to obtain.

The other method is to use a 7/16", 12mm, 13mm or 1/2" Grade 8 hardened bolt as an axle. I used a 7/16"-20 fine thread because I thought the nuts would resist unscrewing better than with a course thread. Axles for normal bike hubs are often 10mm, but can be drilled out to 7/16" no problem. I've used a 12MM axle, supported on one side only, on a 500 LB trike for 7000 miles with no sign of failure. My buddy's previous trike, which he rode for maybe 15 years, used a 1/2" hardened bolt anchored into a slab of aluminum block. Next post I'll go into the considerations for this method.

 

[llile]

I'm using a pair of front aluminum hubs off some old mountain bikes, with a bolt pattern for disk brakes. I'm also using some forks off those bikes for disk brake actuator mounts.

The bearing races for these hubs come tapped for 10mm. They are hardened steel, and one can't just pop them in the drill press and expect to drill them out. It works best if you de-temper them first.

Here's a dissassembled hub with a 7/16" hardened bolt:

Toasting the bearing races. Once they are red hot, I will cover wthm with high temperature insulate (Fiberglass works) and let them cool until they are room temperature. This softens the temper so they can be drilled out.

Once they come off the drill press, I heat them again to a low red glow and temper them in oil. Do this outside because it could be a fire and toxic smoke hazard. Now they will be hard enough to survive in a bearing race.

Here is the completed hub assemble with the races and a spacer that puts the disk brake at approximately the same position as before relative to the brake actuator on the fork.

 

[llile]

The seat on a trike is really critical. A crappy seat will ruin your ride. Recumbent seats support your whole spine, ideally, but a crappy one sweats, isn't rigid, isn't padded right, or doesn't fit your back.

Most commercial recumbent seats stink, in my opinion. They only support your lower back, leaving your neck straining, and giving you little actual support. They are too wide. You only need to support your spine - your skeleton does a bangup job of supporting the rest of your body from your spine - no need to put a sweaty seat anywhere else. A thin seat that just supports the spine allows the rest of the back to cool off. A seat that supports your head allows you to relax your neck in the recumbent position. I've worked out a system that uses two 3/4" aluminum tubes, s-curved to fit the spine, that start at your tailbone and end above your head. It's comfy without any padding, but with commercial upholstery foam and an aluminum sheet keeping it from falling between, it's a woderfully comfy seat that I've ridden thousands of miles on.

Here's a photo - my butt sits on a backwards-facing cushy seat, the tubing supports my back. Next post shows it with struts

 

[llile]

A trike is a three-dimensional beast. It is impossible (I have proved this) to weld together a decently straight trike by eye. One needs a sturdy frame to hold the parts plumb and level for welding. Your magnet that came with your welder won't cut it.

I've assembled a unistrut frame that will allow me to support frame parts absolutely plumb and level for welding. You can see the strust that support the back of the seat. This sturdy frame also allows me to sit on the prototype and make adjustments and measurements of my body.

 

[llile]

And of course here's how you fit the trike to yourself. The sturdy frame allows you to sit on it and make adjustments before committing to a weld.