Generic E-trike Build - KMX+BBS02B and trailer

C

Conrad_K

1 mW
Joined
Apr 26, 2024
Messages
16
Location
USA
Starting point:

KMX Typhoon trike, all 20" wheels and a Shimano Alfine 8-speed rear hub. The previous owner also upgraded the brakes to Avid BB7s instead of the stock BB5s.

I've been riding it around the Arkansas River Trail area in North Little Rock Arkansas. I'm a new cyclist, and disabled; I used to have to stop and rest getting over some of the bridges. In three months of weekly rides I can make it up all the ramps, but some take a lot of effort even in the lowest gear, which is literally a slow walking pace - I've had walkers pass me on the Big Dam Bridge.

I expect to improve, but there are two further problems: the trike is geared so low that even pedaling as fast as I can, I'm regularly passed by old ladies on uprights, gliding along with an occasional flick of the pedals. Literally. I'd like to go fast enough not to be a rolling obstacle. Also, my wife, who is also disabled, wants to come along sometimes, which will slow me down even more. I ordered some bits so I can weld up a trailer for her to ride in.

Since the primary purpose of the trike is still 'exercise', I wanted a PAS instead of a throttle, and since almost all my riding is on 'shared use' bike/pedestrian paths, I can't use a whole lot of speed. Just a bit faster overall, and some help up the steep parts.

After looking at the options on motors and drooling over the high-power bits, I ordered a Bafang 750w BBS02B kit, the optional gear sensor, and a nicer display than the default. Actually, the 500w would probably have been enough, but I persuaded myself I needed the 750.

I'm going with the 42-tooth chainring for now; I'll buy a larger one if I need it. From what I've read the Alfine hub should be okay with the BBS02B.

I had already ordered a rear brake kit for the trike. The front brakes were badly scored and made horrible grinding noises; I tried sanding them smooth, but it didn't last long. Hmm. 203mm rotors are about the same price as 160mm rotors. I ordered 203s and new caliper brackets. The old brake pads were metallic, which is what probably ate the rotors. I ordered plain 'resin' replacements. Brake bits started arriving yesterday; the motor kit should show up next week, and the gear sensor two weeks after that.

I plan to go with a 48v 20ah battery, but held off ordering one since the battery box looks long and skinny and all the battery pictures look short and fat. When I get my hands on the box I can measure the inside so I can be the battery I order will fit.

I'm still collecting parts for the trailer. Basically an "Atomic Zombie" Aurora delta trike, except I'll be using a bolt-on snout so I can swap the hitch part out for a headstock and front wheel in the future. I'll have to help the Mrs. get up from it, but she'll enjoy zipping along a few inches from the ground.

This will (hopefully) be a big yawner to the experienced e-bike builders, but I'm going to document it as I go along. Hopefully some other newbies will find it useful.
 
Conrad_K said:
.... the trike is geared so low that even pedaling as fast as I can, I'm regularly passed by old ladies on uprights, gliding along with an occasional flick of the pedals. ....
Click to expand...
 
Twiddling my thumbs waiting for the Bafang kit to show up. Meanwhile, I found a place with a Hailong 48v,20ah battery with box on sale, and went ahead and snagged that. The box looks the same as the one with the kit; I'm hoping it will work with the same slide mount.

I wavered on going to a 52v battery, but decided to play it (relatively) safe and stay with the 48v for now.
 
Looking forward to seeing it!
 
I checked the mail a few minutes ago and there was a box with "e-bike motor" on the side. The kit was supposed to show up Friday or Saturday, by which I figured meant sometime next week.

Instructions are a URL in the multilingual pamphlet. It's the 21st century, I guess. A quick glance at the .pdf and the Youtube video seemed clear enough. I need to clear some space out in the workshop. Fortunately I already built a maintenance stand.
 
I took the trike out for a last ride this morning. When I got back the battery was on the front porch. The Hailong battery came with the matching bracket, so I should have everything I need to start the conversion this weekend.
 
Okay, my first questions:

#1: Motor Clocking

Every trike I've seen a picture of so far, the motor was clocked down underneath the boom. Probably to get it out of the sight line of the rider if the seat is raked back.

Is there any other reason for this? I'm thinking if I clock the motor up over the boom, it wouldn't smack the ground if I did a stoppie, and it would be easier to lift the trike into the back of my truck. I don't have ramps; I grunt the trike up over the tailgate. On days when I'm almost out of gas, I'll get the boom up over the tailgate, then muscle it forward until I get the front wheels over the edge. (I know, more barbells; I'm working on it...)

#2: Battery Box

I have the standard Hailong battery box. I also have a welder and machine tools, so I can mount the battery anywhere I want. I'm considering mounting it on top of the boom. I wasn't initially a fan of that location, but it would be simple, have the shortest wiring path, and it would be completely out of the way when I add a rear suspension later. I'm already tired of having bumps on the local bike paths jackhammer my spine.

Other than being somewhat in the way when mounting and dismounting, why would the boom be a bad place to mount the battery?
 
I have a rear brake for the trike, so the left handlebar has a rear brake lever. The right bar has a dual lever for the front brakes.

The trailer will have brakes since it will basically be a delta trike with a bolted-on nose piece; one piece will be for the trailer hitch, then other will be a nose piece with a steerable front wheel. Not much different than some of the take-apart designs.

I have been scheming ways to use the same brake lever for both the rear wheel and the trailer. I've come up with various designs, mostly 3.2 to 3.6 on the Goldberg Scale. (that's the Rube Goldberg Scale of Redundant Complexity)

This morning I realized I don't *need* the rear brake if I'm using the trailer brakes. Four wheels will stop as good as five, and I don't have to worry about jacknifing if there's too much bias to the trike's rear wheel. So I can use a quick disconnect on the cable to the rear caliper, and just switch from the trike caliper to the trailer calipers while hooking the trailer up. I ordered one quick disconnect to make sure it will do what I want, and I'll order another later if it looks OK.

Sometimes, giving up a small thing results in a large reduction in complexity.
 
Trike day. I lifted it up onto the stand, removed the pedals (15mm open end wrench), removed the left pedal arm and retaining bolt from the Patterson two-speed hub (5mm Allen), removed the BB retainer nut (with the wrench that came with the Bafang kit) and slid the crankset out from the right. I had to do it with the chain on, since while the chain has a master link, there wasn't enough slack to compress the quick-link for disassembly. I tried various needle-nose pliers, but none were narrow enough to get a grip.

There was an 8-notch spanner nut holding the shifter plate of the Patterson unit to the bottom bracket. Things came to a screeching halt there, as I didn't have the tool, nor would one be available in rural Arkansas on a Saturday.

The correct tool for the spanner nut, according to the Patterson web site, is the Park Tool BBT-18. I ordered one of those. Patterson says it takes a 36mm socket, so I ordered one of those. (a tool for a tool?) I ordered a KMC 8-speed chain. Most trikes take two or more "standard length" chains, so I'll run the whole KMC with some of the old chain as a temporary measure so I know how much more chain I need. I ordered some master links, and - hey, special chain pliers! The 6-7-8 speed width was $10.

Further observations were that the Patterson hub had a 28-tooth chainring, and the 42-tooth Bafang one would need more chain. Also, holding the battery up to the boom, the battery would have to be offset to clear the chain tubes. I wasn't sure if there would be pedal interference.

The difference in chainring offset between the Patterson and Bafang is unknown, so as a temporary fall-back I sat the battery on top of the luggage rack and measured for an extension cable, then ordered a 10gauge XT60 of the correct length.

I have a feeling I'm going to need an extension cable for the display, but I'm going to wait until everything is hooked up so I can get an accurate measurement. I can already see that cable management will be... interesting.

Fortunately I had budgeted for tools and adapter bits. This might be my first e-bike, but it ain't my first rodeo.
 
Not too different from my trike, I have a 48-tooth ring and a BBSHD mated with the Alfine 8. I shift gently and have had no issues. I am running a 52V battery. I use 203 rotors in front, no rear brake, and stopping is fine. I recently switched to some hydraulic brakes. I am using a piece I got from Utah trikes that holds the BBS motor in place under the boom. Keep in mind that torque generated will tend to pull the motor "up" so the down position is more at rest - you need some bracket normally to keep it there and not twist in the BB. Also, the trike stability can be impacted by the extra weight in the front - and it is advantage to keep the weight low to the ground. Chainline is forgiving with the longer distances on trikes. You do need to gather some specialty tools for these things. Keep us updated!
 
Patterson says you can shift their front "transmission" under full load. But I don't think the Alfine would put up that that, given the relative difference in diameter. "My God, it's full of gears!"

I'm hoping the BB7s will be OK with the new pads and 203mm rotors, but I'll go hydraulic if I have to. Lots of steep downhills on the Arkansas River Trail and surrounding area. (matching the steep uphills I bought the Bafang to help with) That's why I bought the quick connectors for the rear brake, so I can swap the cable to the trailer brakes when I have the trailer hooked up. [ahem] Mrs. C is a little chunkier than she used to be.

Putting the motor under the boom will lower the CG and get it out of line of sight, but I'll have to push the trike around to the truck and see how it affects loading it. I'm 65 years old, and it was already a mighty heave to get the all-steel KMX up high enough. On high-energy days, I lift the front wheels over the tailgate. On low-energy days, all I get is the boom over. Then it becomes a choice of "motor up" or "ramps." Unless the extra weight means I can't get the trike high enough at all, so I might as well mount the motor low since I'll have to use ramps anyway.

I know a lot of people use some kind of ramps and it's not the end of the world, but it's that much more *stuff* to drag around and keep track of. One trick I did notice, though, is that you only need two ramps, not three. Put each front wheel on a ramp, pick up the back, and push it up the ramp. Which is probably bleeding obvious to everyone else, but I always come up with the most complicated solution to a problem at first.

When going with the bike trailer, I'll use my old motorcycle trailer, which has just enough room to carry the trike and its trailer. Even though I extended the tongue after I got it, it's still short enough to be a hassle when backing up, and most of the trailheads are not pull-through, so I want to carry the trike in the back of the truck if its trailer isn't coming along.
 
Where I do most of my riding isn't nearly as steep as Manassas, but the pulls are longer. I think anything less than a 30 degree slope is a "level lot" there. I've been through Richmond a couple of times, but it was a long time ago, and I really don't remember anything but the tollbooths. Every few blocks through downtown cost a dime or fifteen cents.

I remember there was a pretty good pizzaria in the Shockoe Bottom area, though.
 
Finally got some shop time today. I spent about half of it trying to figure out where all the parts had got off to.

The lock nut for the Patterson hub spun right off with the Park Tool pin wrench. Well, after I found the tiny Allen head lockscrew that was hiding in the grease.

The BBS02B just slides into the bottom bracket. I checked the directions three times, looking for a shim, washer, locating cone, etc. Nada. There are raised marks in the "anti-rotation plate" that goes on the other side, apparently supposed to bite into the side of the bottom bracket. I'm underwhelmed by the design; I'd like to see a real torque stay of some sort, even if it doesn't actually seem to be a problem.

The battery is going up on top of the rack temporarily; I measured for an adapter plate and located some 1/8" aluminum sheet I'd been saving for a while. The 1-meter XT60 extension cable is perfect.

The chain had a master link. I used my new chain breaker tool to press a pin out, then spliced in a piece of the new chain since the Bafang chainwheel is 42-tooth and the Patterson was 28. Same out a-verra-nahss. Then I noticed the chain had fallen off the rear sprocket during some of the fiddling-around, and was therefore too short. I pressed another pin out and I'll add a few links later.

I wanted to put the rear brake on since the trike was up on the workstand. Loosen the 15mm nuts, start lowering the wheel... and the cable to the Shimano 8-speed rear hub has to come off. I eventually figured it out. I popped the new rotor on, added the locknut, and applied the BB wrench that came with the Bafang to tighten the center nut. Nope, it won't *quite* fit. [sigh] I could have done some filing to make it work, but it fit the Bafang nut just fine, so I'll leave it alone for now.

I ordered the "brake sensors" instead of the replacement brake levers. The sensors apparently attach to the housing somewhere with adhesive. I went to the web to look for directions, and the spirit of the shop PC apparently chose that time to join its ancestors.

Still no idea where to mount the display and PAS switch.

I sort of expected O-ring or Weatherpak seals on the various electrical connectors, but they're not sealed. Before everything went weathertight on cars, we used to pack connectors with dielectric grease to prevent corrosion.

The thumb throttle is made to be mounted the right of a handlebar, but on the trike that turns the open end upward to collect dirt and water. It will work for now, but I'll order a left-hand throttle later, which will put the open part on the bottom. Might not make a lot of difference, but at least it won't look so odd.

 
Conrad_K said:
Putting the motor under the boom will lower the CG and get it out of line of sight, but I'll have to push the trike around to the truck and see how it affects loading it. I'm 65 years old, and it was already a mighty heave to get the all-steel KMX up high enough.
Click to expand...
ever consider something like this ....
www.harborfreight.com

1/2 Ton Capacity Pickup Truck Bed Crane

Amazing deals on this 1/2Ton Capacity Pickup Truck Crane at Harbor Freight. Quality tools & low prices.
www.harborfreight.com www.harborfreight.com
pickup hoist.jpg
 
Not completely out of the question, but it would require surgery to the plastic bed liner. It would probably swing under the hatch of the camper shell, though.
 
Couple of questions...

1. Are the trailer brakes cable actuated? I'm assuming they are from what i've read so far... just curious.
2. What are you using for a trailer hitch?
 
Yes, cable on the trailer. Dry break hydraulic couplers actually do exist - they're used in some race cars - but the trike already has cable brakes, so I'm just staying with that.

I'll be using a spherical rod end for the coupler on the trailer hitch. That worked fine for a motorcycle trailer years ago.

Technically you want the coupler - ball, rod end, whatever - on the centerlines of the bike and trailer, but in practice a small offset isn't noticeable. You normally want the offset to be toward the side that's likely to make the tightest turn - the right, in countries where traffic uses the right lane. That turns the tire away from the hook on the hitch.
 
The only speedometer sensor cables I could find fell into the "too short" or "too long" categories, of course. I ordered a long one; for now I'll just coil up the excess and zip tie it out of the way. After I get everything field-tested I might try my caveman-level soldering skills to shorten the cable. I'm good enough now that I only occasionally set things on fire.

Same thing for the display cable.

Searching the web for "Bafang torque arm stay stabilizer" I came across the JohnnyNerdOut piece for $12. Just what I was looking for. I could have copied the design, but it was worth $12 to keep things moving forward.
 
Conrad_K said:
I'll be using a spherical rod end for the coupler on the trailer hitch.
Click to expand...
I use an air hose coupler assy. Male on the trike, female on the trailer w/short 2-3" length hydraulic hose. I ride a delta, so the hitch is centered and slightly below the trike's rear axle centerline. I copied the idea from Bike Friday eons ago.
 

Attachments

  • Bike_Friday_DoubleDay_folding_recumbent_tandem_bicycle_trailer_attachment.jpg
    Bike_Friday_DoubleDay_folding_recumbent_tandem_bicycle_trailer_attachment.jpg
    416 KB · Views: 10
Innovative use of the hose as a flex joint!

Today's work:

I got rid of the phone mount, flipped the T-bar bracket around the other way, and mounted the SW-M58 display as far back as possible, sitting on the boom. It clears the chain by about an inch. If the chain throws anything on it, I'll extend the chain tube.

I put the rear wheel back on, then tried to put the caliper on. [sigh] The caliper and luggage rack compete for the same space, by about an inch of overlap. I'm going to have to make an offset caliper bracket or cut and weld the rack. Right now, the battery is going on the rack, so the caliper went back in its bag to be dealt with later.

Looking around my "boxes of stuff" I found a short length of chain I cut from my recumbent, which same with a chain so long it dragged the ground. 7-speed, so it was the right width. I lifted the top chain up onto the Bafang's sprocket, bumped a pedal arm when picking up the lower chain, and the upper chain promptly slithered down the chain tube into a puddle under the seat. [sigh] I pushed it back through link by link. Pulling both chains tight on the Bafang chainwheel, I needed two additional links. I really need a better chain tool, but I managed to join all the pieces eventually.

The rear wheel goes into drop-outs with no fore-aft adjustment. The chain seems loose, but I can't rejoin it after taking a single link out. I didn't think the measure the chain play before taking it apart; whatever it was, was fine. I'm used to motorcycles where the rear wheel slides forward and back. After staring at the situation for too long, I realized I can slide the boom forward a bit if I have to, and the seat has some fore/aft adjustment if I need it.

I mounted the little speed sensor magnet on the right front wheel. Some clown at Bafang used a *security* Torx screw ifor the clamp. Fortunately, I have security Torx bits. Measuring for the mounting bracket took a while, but having dealt with cheesy speedo brackets on other cycles, I wanted to do this one right. The radius on the curved part of the sensor is .688" or 17.5mm.

A forum post mentioned using a gear sensor in place of switches in the levers. I have a gear sensor on hand; it would be a cleaner solution than sticky tape and epoxy if it works.

 
I had a piece of 1/8" aluminum plate on hand to make a bracket for the battery. I tried cutting it with my circular saw, which I've done before with up to 1" plate, but all it did was gnaw at the aluminum a bit. I flipped the saw over and looked, and there were no carbide teeth on the blade any more. Hmm. I normally use that saw for cutting up scrap wood; that blade has hit a lot of nails over the years. Oh, well. Time for a new blade. Meanwhile I scrounged a fine tooth blade for the jig saw and made a couple of more-or-less straight cuts, sanded the cut edges, rounded off the corners, and marked it to drill for the 7/16 Adel clamps that showed up today. Rubber-mounted, woot! Well, technically, anyway. I'm still planning to mount the battery down low somewhere later, but it sure is convenient to get to, up on the rack.

My Velcro tie-wraps also came in. They were way too long, which is what you get when you guess instead of measure. I managed to bodge them around the frame and wires enough to keep the wiring more or less under control.

An email notice said that the torque stay for the motor was on the way.
 
They're on the camera out in the shop, so they'll come in batches when I remember to bring the camera back to the house.

It always seems I never take as many pictures as I should have, though.
 
You must log in or register to reply here.

Similar threads

D
Help needed: first time build
Replies
10
Views
289
darbas
D
E
A recumbent build
2 3
Replies
62
Views
4,813
G8trwood
G
amberwolf
Help design a DIY middrive for this heavily customized trike
Replies
5
Views
590
amberwolf
amberwolf
C
Advice for a recumbent build - please
Replies
14
Views
1,024
chooks42
C
P
    • Like
My Mongoose Envoy build v2 - Goodbye EBikeling, hello Grin Tech
Replies
4
Views
991
phj
P
Back
Top