I’m using this bike, so here are my updates:

A bike that is a poor bike without electrics added will become an even poorer bike with all the weight and power of electrification. Start with a good bike.

I had to fix some derailleur adjustment issues but the chain still slips. I will replace the chain (note: the Walmart chain I used appears to be at fault, it slips right out of the box!). The tiller steering is very annoying, and the pedals aren’t forward enough for me (the bike was built for shorter legs). Also, the seat back is not quite cushioned enough to be riding for long periods.

First Lithium Powered Commute from Peter’s Bikes on Vimeo.

November 10th, 2008

I now intend to improve this bike. The tiller steering needs to go and the front fork with it. It is too thin and the brake mounts can’t be used with the motor on at the same time, since the chain occupies the same space as one of the brakes. Devising a new motor mounting could take some effort… Alternatively, I could use a switch, some relays (to disconnect the motor from the batteries and motor controller), and a coil of stainless steel wire to use the motor for braking. If you connect the power wires of the motor together, it will brake. Adding resistors between the power wires will vary the braking force; it’s tough to find big enough resistors, but you can use a coil of wire wrapped around a plastic pipe too– just vary the length of the wire.

It’s tough to compare bikes qualitatively so I mounted some guages on the bike to grab some actual hard data. I took a piece of plastic and dremeled two holes in it so I could attach it to the front boom with a hose clamp. I then held a voltmeter agains the plastic and drilled two holes through the plastic and the bottom of the meter and screwed them together. I wired the meter to the generator output. I also added an ammeter to measure the current flowing from the generator. I left room for another meter to measure battery pack voltage and then finally mounted the bicycle computer.

I added two Sterilite trash cans under the driver’s seat for cargo carrying. I placed them low enough to avoid interfering with the handlebars. Where to put the batteries now? They will likely hang behind the trash cans, but for now they are IN the trash cans.

Speaking of batteries, charging 12 batteries one by one is no fun. Each battery takes about 20 minutes tops– depending on how far it was discharged– but that’s still 12 batteries that need to be baby sat. I inquired on the Endless-Sphere forum about whether the Makita fast charger allowed charging of multiple packs in parallel and it does work. Fellow e-biker Jonathan D. hooked me up with 2 Makita LXT shells– battery packs with no batteries inside. I opened one up and soldered a wire to the + terminal and another to the – terminal and routed them out of the shell through a couple of holes near the front of the shell. I attached an anderson connector. I then tortured myself trying to work with the security screws that hold the shell together before I just dremeled their heads to turn them into slot head screws.

I then rewired the 2 packs I built to be 18v each– all batteries are in parallel. Now I can put the shell on the charger and attach it to one pack and it will charge the whole pack– theoretically. It should take 4 x 20 minutes for each pack, but at least I don’t have to baby sit it. Turns out, however, that the 7 little pins in a yellow connector on the battery report some sort of status information to the charger and the charge always fails after two minutes with the shell. DoctorBass on endless-sphere suggesting opening one of the working Makita’s and soldering the anderson connectors to it’s terminals.

Finally I fixed the kick stand; leaning the bike against stuff was getting really obnoxious as its now about 40-50lbs fully loaded and would probably get damaged in a fall.

Testing

Former partner in crime Eron V.’s holiday party provided another opportunity to test the bike. We took turns giving party goers rides and then turned the bike over to the more adventurous. So far about 12 people of varying stature and weight have ridden the bike, mostly in the tandem configuration, and I haven’t found any problems except that the seat post keeps coming lose and twisting in the socket. High speed ride and stability is actually better with two riders, but a very low speed oscillation in the steering gets worse with two people. If you ignore it, the bike moves in a straight line, but at about 2-3 mph there is a feeling that the bike wants to turn back and forth and it’s unnerving.

The greatest load carried so far has been 380 lbs with a 240lb rider in the back.

I rode from home to work twice, once alone and once with my significant other on the back.

Average cruising speed (alone): 17.5mph. The bike seems to hit some controller limit at 18.5 on the flat
Average cruising speed (two riders): 16.5-17.0mph (depending on rider). Max speed drops also by 0.5-1.0 mph.
The motor got much hotter with two riders.

Ride time (alone): 38 minutes
Ride time (two riders): 40 minutes

Battery state was

One rider: v₀=39.3V, v_f=35.3V
Two riders: v₀=39.3V, v_f=34.5V

Low voltage cut off is set below a safe level right now, but 28V would be a sensible limit. Voltage sag on full throttle acceleration is about 1.0-1.5v.

Odometer currently reads 43.8 miles.

Next upgrade is a head light! Very hard to ride through the marshes with no light.

I got the hall sensor wires worked out– the +5v wire was rubbing against a sharp part and actually got cut. I fixed it and the bike worked. I took it to work and to the San Jose EAA meeting and everyone took turns riding it and then going 2-up. Initial results are very promising: the suspension works great, even with two riders weighing 350-400lbs total the ride is very good. Acceleration, especially up hill at the low end, however, is poor. I’m not sure why it’s as bad as it is because the previous version worked quite well in San Francisco. Is the bike that much heavier now? Could there be some mechanical drag like the coaster brake engaged on partially? Or is it due to the hall sensor wiring?

I removed the now useless 2nd bottom bracket and drilled holes in front of the rear wheel in the triangle for an aluminum tube. The aluminum tube is super lightweight and should work just fine as a foot peg.

Best upgrade so far: I fixed up the driver’s seat. I used two L shaped pieces of pipe, attached the back rest at lumbar height with a 1/4″ bolt and large washers, then attached a padded seat to the bottom by using a piece of pallette wood. The real bastard was attaching the seat to the frame. This I accomplished by welding two tabs onto the frame that fit between the two L shaped pipes that are the frame for the seat. I welded 3 small pieces of 1/4″ steel plate together and drilled a 3/8″ hole through them to make the tabs. I then drilled 3/8″ holes in the two L shaped pieces of pipe and stuck bolts through. 1/4″ is not enough! I tried and the bolts simply bent and had to be removed with the Dremel.

I placed a large exercise machine seat for the rear passenger. To give them something to hang on to, I welded some kids bike handlebars (the type with a big U shape to them) onto a seat clamp, which I then clamped onto the original seatpost.

I added under seat steering. Tom Kabat of Woodenbikes.com had this on some of his bikes and it is super comfy. I cut some kids handlebars in half and welded a 90 degree angle in between. Tom bent some pipe into a large U shape, which would be preferable, except that I can’t bend pipes (yet). I think a V shape would be ideal. Basically, with a SWB layout, the steering tube is just a little bit forward of where it would ideally be. You can put above seat steering but it has to be high up to not interfere with your legs (if you use standard handlebars). With under seat steering, the handlebars have to come back far enough to reach your hands and have to avoid interfering with your legs when you are stopped but at the same time the closer in to the frame you bring the bars, the less you can turn the front wheel at low speed (because your hands hit against the frame).

Unfortunately the Kollmorgen’s hall sensor board did not like me resoldering the wires (which were flimsy after all the work done around the motor)! Two of the traces flaked off. I had to Dremel around the board to remove it and try some surgery. So far, the fix is not working, but I’ll give it one more shot before swapping motors. Never again will I buy these sensored BLDC motors/controllers! So much trouble for too little gain.

This is a continuation of the Serial Hybrid #2 bicycle. However, I decided to make some adjustments for comfort and to turn it into a tandem. Can this relatively compact bike be adapted for 2 riders and how will under seat steering and a better seat affect comfort? Now that I have 12 lithium power tool batteries, how will I manage luggage and charging?

Measure Once, Cut Twice, Throw Hands up in Frustration

Now that I have switched to lithium and the circuit work is still not completed, I have not ridden this bike much. I decided to convert it to a tandem and switch it to more conventional propulsion. I welded the old boom on to the back and then welded on two seat tubes– one in the usual configuration (almost vertical) and one at an angle, so I could attach a back rest to a seat post and place it in the angled tube.

I then spent a very long time trying to salvage a bottom bracket shell for the rear set of pedals (this is the tube that the pedals spin in). I could not use the original shell because with 20″ wheels the pedals would hit the ground. Removing the original shell would have created structural problems. So I needed to locate one higher. I would highly recommend purchasing bottom bracket shells from a place like UBI or NovaCycles, as salvaging an intact shell from rusty old bikes is not worth the $5 cost for a steel shell. I spent three evenings and three frames before I got one working shell. And that took a torch, a 4 foot breaker bar, a grinder, two dremel cut off wheels, and lots of elbow grease.

The previous seat was uncomfortable and deteriorating, so I built another one out of an office chair.

Unfortunately my other half was not around to provide measurements and I welded the shell on too far forwards. Oops. The seat also interfered with the rear riders pedaling. Oh, and I couldn’t get the chain routing worked out. I have now decided to return the bike to its original configuration except with the possibility of giving a lift to a rider on the back. I will weld foot pegs onto the rear so the passenger’s legs don’t just dangle in mid air.

This bike and simple serial hybrid setup works. Unfortunately I’m afraid of what will happen if I hook the generator up to lithium ion batteries. I am now working on an improved circuit for use with lithium batteries.

I’ve posted this to wikiHow! Check it out at this location.

What is it and how well does it work?

This is a very simple electric bike. A geared DC brushed motor is mounted in the triangle of the bike and turns one of the crank sprockets (the gears that your feet directly turn).

It works quite well. It’s easy to put together and it’s cheap and effective. Not as much power as a brushless motor, but it still provides a very nice boost especially when going uphill or when your legs get tired. The effective power band is much narrower than on the other bikes I’ve built, but since you can still use the rear derailleur it’s easy to change gears to match road speed and inclination. The one caveat I have so far is not to use heavy power assist while changing gears. This tends to throw the chain off.

Intro

After tooling around with recumbents, I decided I wanted to make the simplest electric bike I could imagine, as I still had some work to do on the actual bicycle building part of creating an ebike.

So I took an old chromoly frame MTB and decided the simplest electrification would be to use a brushed DC motor. These have just two wires and can use cheap brushed DC motor controllers (costing approx. $25). The brushes do wear out over thousands of miles, and they are less efficient than 3 phase brushless DC, but they are so cheap and easy to use that I figured it’s worth a shot. The MY1018z I used on the serial hybrid bikes is internally geared down so that when it is attached to a crank set it approximately matches a human pedaling cadence. I decided I would mount the motor inside the main triangle of the frame and dedicate a gear on the crank set to it. This would mean losing the front derailleur but I never use it on the street anyway…

Check out bike elektro antrieb for a refined version of this idea. In comparison mine is a total caveman conversion.

Parts

• MY1018Z motor
• Half twist hall effect throttle (I prefer these to the full twist, they don’t turn on if you lay the bike down or lean the handlebars against an object)
• brushed motor controller (YK42-3 in this case)
• 1/8″ single speed bicycle chain OR a grinding tool and 3/32″ multispeed bicycle chain
• Master link for the bike chain
• 36v worth of batteries (4x Makita 3.0Ah power tool batteries)
• wires
• 1/4″ washers, bolts and nuts
• 3 large 1/4″ u-bolts -> UPDATE: I have found that good quality hose clamps work much better, and are easier to install. The best are the kind that are tightened using a nut and a bolt; but stainless steel plumbing clamps work OK too
• >=1/8″ thick sheet metal, square foot
• Tools: Sharpie, ruler, sawzall, chain tool, grinder (optional, but very nice), drill, wrench, pliers, soldering iron, duct tape

The Plan

You’re going to attach the motor to a piece of sheet metal. This sheet metal will be ubolted to the frame (so you can just remove it later if need be). The motor attaches to a front sprocket with some bike chain. The idea is to approximate the position of the motor, throw some chain on, and then position the motor so the chain isn’t loose and falling off. Then drill holes in the sheet metal to run the u-bolts through. You’ll likely need to do some more drilling to get it just right, unless you’re the sort of person who measures things really well.

Instructions

1. Place the sheet metal against the bike frame
2. Roughly trace the bike frame tubes with the sharpie onto the metal
3. Place the motor in the triangle, and trace its outline on the sheet metal
4. Cut the motor hole out using the sawzall; grind down the sharp bits
5. Verify your cutting by placing the sheet metal back against the frame
6. Drill the screw holes to mount the motor; this takes some work. Start with one hole, then add another, then the third. I never get the third one spot on, so I dremel out the hole.
7. Now throw the bike chain onto the smallest front sprocket and use the chain tool to shorten the chain. This is critical. If the chain is loose and sloppy, it will fall off. If its too tight, you will wear out the bearings on the bike and motor and generally make your life difficult. Put the chain on the front sprocket, place the motor/ sheet metal in the triangle, and raise the motor/sheet metal until the chain is tight. Then give it just a little bit of slack. Use the sharpie to mark where the hose clamp holes should go
8. Drill or dremel the hose clamp/u-bolt holes. I used a Dremel cut off wheel and cut slits in the metal. For U-Bolts, use a small bit to make a pilot hole, then follow up with the 5/16″ bit
9. Attach the motor using the u-bolts
10. The position is probably off a little, so do some more drilling
11. Mount again
12. U bolt the motor controller on
13. Take a hand grip off and place the throttle on the bike
14. Wire up the throttle (this could be a nightmare if the color coding doesnt match)
15. Attach the batteries to the frame– I ubolted a $3 Big lots trash can to the handlebars and put the batteries inside
16. Follow the controller instructions for hooking up the wiring; I soldered washers to each wire and use bolts and nuts to hold the wires together; I insulated the connections with duct tape
17. WITH THE CHAIN DISCONNECTED, try out your new bike
18. Fix the wiring, which is inevitably incorrect the first time around
19. If it now works, put the chain back on
20. Voila

Photos

Test fit of the motor in the frame triangle

Sheet metal with the rough shape traced with a sharpie

I used the sawzall to cut the metal

Now I traced the outline of the motor on the sheet

Ready for cutting and grinding

Please wear gloves! I cut and smashed 3 fingers before I put mine on…

Looks good!

Now the slightly annoying task of drilling the motor holes… look closely, you can see I had to redrill some holes…

Here I’m marking on the sheet where the U bolts should go. Actually, hose clamps work better and you can be sloppy with the holes

Here is the motor mounted onto the frame. Time to add the chain

Throw the chain on and see how many links you need to remove

Masterlinks will make your life so much easier, and they only cost a couple of bucks. The other tool you need is a chain tool. The cheap Walmart ones are awful but will do; a proper $30 chain tool will do the job 10x faster (since I do this often I bought one)

Here is a masterlink installed on the chain

And two shots of the final product. The motor kept shifting downwards over about 5 miles so I added some hose clamps and it hasn’t needed readjustment since.

Lots of bike work in the past couple of weeks. The new sprocket arrived AND… it’s not a plain sprocket, meaning it has a collar with a set screw. Worse yet, it doesn’t easily line up with the generator shaft. Doh! Ben kindly offered to use his CNC to cut the center out of the sprocket, but I decided to go back to the beginning and see if I can’t find a better way. It’s a lot of work to get this motor to generate a high enough voltage to charge the 24v batteries. If I move to 36v or 48v, I’ll have an insurmountable problem.

After some recent thread about the MY1018 motor, it turns out the sprocket on the end of the shaft is for 1/2″ by 1/8″ bicycle chain. I dug through a box of old chains and found one that fits. I had to reverse the sprockets on a crank (they bolt on, so I bolted them to the wrong side of the crank) and was able to mount the chain. Now, the reason I never used bicycle chain was that the gearing isn’t high enough.

So what I did was instead of charging the whole pack, I hooked the motor up to one battery. And it works.

I put a volt meter and ammeter on. There is very little resistance at low rpm, but then once the generator voltage exceeds the battery voltage, you feel the resistance kick in. The highest voltage I achieved was 16V (with the batteries attached) and the maximum current was about 10-15amps. The average current was about 7amps, and the average voltage about 14.5V.

One quick note, the generator mounting holes did not fit well for the bicycle chain like they did for the no.25. I used some washers to make it work for now. To test how well the setup works, connect the positive and negative leads of the generator motor. This is the most resistance you will encounter while pedaling. If the setup survives this, you’re probably good to go.

Unfortunately the bike took a lot of abuse in the past week. I took it to the San Jose EAA meeting on March 8th where it received a good deal of attention. I left the bike at work because this week I moved into a house in San Mateo and began setting up the garage. We rode the bike around at the office until a high speed run into a speed bump broke the handlebars off. A subsequent fall damaged the battery box on one side and bent the crank assembly at the end of the extention tube. Rather than fix the bike, I decided to build another bike with a full suspension and some meters so I can finally make good quantitative measurements.

Max speed achieved: 21mph

Max speed achieved in one “short” block: 19mph

Average speed: 13-15mph

I build a head mounting for my Canon HV20 using a bike helmet, two large washers, a 1/4″ bolt, and two 1/4″ nuts. I used a small bicycle lock to make sure that if the camera fell off anyway, it would not fall far. I then rode both bicycles around to record the experience. This SWB bike could do with some adjustments to feel more like the LWB bike. The lower handlebar and pedal heights especially improve comfort and visibility. The SWB bike handles turns far better however.