End of Summer report on the Breeze semi recumbent bicycle

The Breeze this summer (click on pictures to enlarge)

It's nine years ago that I gave up my car because I had become too disappointed with how I got around.  This was very unexpected, because in my family I've been the gearhead who had the Porsches, Mercedes, Fiat Abarth, Austin Healeys, the BMW, Yamaha, and Honda motorcycles.  I've put 356C engines in a VW bug and a Karmann Ghia, had a souped up 1957 VW bus, and took part in SCCA Formula Vee.  Because I think it's such a neat car, I still have the broken Porsche 912 I blew up.  It took a lot for me to become disillusioned with cars.  But I think our transportation system is now mostly expensive bandaids over systemic problems.   There's now twice as many drivers who travel twice as many miles each year compared to when I was younger, and we knew cars had serious problems back then.  One third of people can't drive, and cities need less traffic not more.  Unless you're a fossil fuel company looking to misinform people for another year of record profits, it's just plain poor planning to expect everyone to drive.  I decided I'd rather be working on better solutions.

Taking measurements before drawing

I started this bike by building a seat, and then using a mockup of 2x4's and plywood to position the seat and pedals so that I could measure the clearances to my legs for the bodywork.  I positioned slats of wood so that my legs would just clear them while pedaling, while also experimenting with different seat, pedal, and handlebar positions.  The RANS Stratus parked next to the mockup is for comparisons because I have experience riding it.

I've used NanoCAD free but have switched over to QCAD

Then I transferred the measurements to a 2D CAD drawing to adjust everything to fit together.  In this closeup the sloping red line in front of the handlebars is the maximum height of my legs, and the red circle above the pedals shows the top of my shoe clearance below the front bin.  The clearance between my knees and the brake levers was the most difficult part.  The finished bike has 1 1/8" clearance to my shins and knees.  Although there is + 3 inches of seat adjustment and the handlebars are adjustable, this bike is generally a tailored fit for my size.

All of my bikes have been meant to make my everyday errands safer and more comfortable on a rural road network designed for cars (i.e. with unwalkable distances between destinations).  When it became apparent that the F(when all you have is a car everything looks like a speedway)HWA  and my state Departments of  Transportation (Vermont and New Hampshire) were very capable of widening interstates I-89 and I-95 within a few years but not able to provide good bicycle infrastructure for me in my lifetime, it meant I had to start building the transportation system I wanted from my end.  The Breeze was designed to be the equivalent of a car.  I started off the design by using measurements from the RANS Stratus semi recumbent bike that I enjoy, combined with measurements from the similar Easy Racer semi recumbents.  But the best all around cars I've owned, (1989, 1990, 1992 Saab 900 hatchbacks), had the same seat height and foot placement, so I also copied the Saab steering wheel and seat angles too - this bike is like driving in my Saabs.  While the Breeze is a semi recumbent and uses different muscles to pedal and balance than an upright bike, (I steer by tilting my head slightly, and I would not be able to climb local hills without the electric assist), I have truly zoned out in comfort on this bike.

A tall roof would affect balance  Photo credit: Unternehmer TUM GmbH

Sometimes bike designers have used full bodywork for weather protection, such as velomobiles and this bike from the Technische Universität München "Mobilität neu erleben mit dem Reisefahrrad Läufer" (New mobility experience with a rotor pedal bicycle) project.  I'm concerned about the top heavy weight of a tall roof and the stability in side winds, and though the Lit enclosed motorcycle uses gyroscopes to deal with this problem, I wanted to keep it simple.

Minimal frontal area   Photo credit: Porsche Newsroom

I decided instead to take a Le Mans Prototype (LMP) approach with minimal bodywork covering each component, and used a cargo bin in front of the rider as the primary aerodynamic/weather protection  device.

The front bin is the main aerodynamic device, however in the future I could also add a Vee shaped panel under the bin in front of the pedals similar to the engine shroud on Ninja style motorcycles.  The aero is designed for front to back flow while minimizing the side area.  The bin is made from 3/16" Luan plywood (sometimes called Philippine mahogany).  When I was a carpenter we used this as underlayment to smooth out lumpy floors, and I had saved some pieces with quilted grain which I used for this bin.  Although the bin floor is level, the bottom of the sides slope down to the front (parallel to the solar panel) to provide more leg weather protection.  The sides were kerfed to bend the rounded front and it's coated with a spar urethane varnish.

 

The bin floor and the solar panel have a small arch to prevent drumming.  I left the back of the bin open for access to snacks, gloves, glasses, etc. while riding.  The solar controller is on the right, with a 48VDC to 5V USB-C converter in behind it, the dashcam display in the bin opening, and the BBSHD display on the handlebars.

Between the smaller semi recumbent frontal area and the rounded bin, this bike is fast.  I made 40 test runs coasting down moderate local hills to compare it to my mountain bike (which has the same tires).  Rolling at a commuter speed of 10 mph at the top of each hill, the average speeds (coasting, in mph) at the bottom were:

1. paved 700 feet @ 3.3 degrees:  MTB 24.7 / Breeze 28.1,  (difference 3.4 mph)

2. gravel 75' @ 8.4° then 200' @ 5.2°:  MTB 25.1 / Breeze 28.4,  (difference 3.3)

3. paved 680' @ 3.8°:  MTB 25.7 / Breeze 29.9, (difference 4.2)

4. paved 1250' @ 2.8°:  MTB 21.4 / Breeze 25.9, (difference 4.5)

5. paved 790' @ 4.8° then 600' @ 3.7°:  MTB 30.3 / Breeze 39.1 (difference 8.8)

Overall the average Breeze coasting speed was 4.8 mph faster than the MTB, but it shows up at higher speeds.  The aerodynamics made hardly any difference at regular commuting speeds around 12 mph, but the fastest test hill was 8.8 average (9.6 peak) mph faster.  This hill was a bit scary, because while my coasting MTB would peak around 30 mph and stay at 30, the Breeze was already at 34 at the bottom of the first slope and continued increasing to 40 mph through the second slope before I called it off - there is third steeper downslope after that and I wasn't willing to bring a new unsorted bike up to 50.  These aren't my steepest hills though and once the testing is done I expect 50 mph coasting will be crossed, this is a good situation for adding regenerative braking (however this will require custom hardware).

A typical chart of speed versus chances of death

Graph credit: ITE Community of Transportation Professionals

At 40 mph enough air pressure builds up at the front of the bin that the solar panel lifts up an inch even though it is angled down to the front, and I started to think about a side gust of wind or pavement rut knocking me over.

Perhaps this bike is unnecessarily fast.  In the big picture I measured the approximate time it took me to ride the coasting test route and the Breeze's extra coasting speed wasn't that significant.  I won't give an analysis here because I stopped at least 12 times to write notes over the 12 mile route, but the Breeze test routes took maybe 52 minutes versus maybe 55 minutes for the mountain bike.  It's mainly because the higher top coasting speed lasted for a shorter time than the slower climbs up the hills, often one gear slower for the Breeze because it's 50 pounds heavier.  (This reminds me of the power versus speed conundrum, where traveling twice as fast uses power squared but this lasts for half as long.)  Also the 4 stop signs took the same amount of time for each bike.  While bicycle commuter routes should be planned to be safe at coasting speeds higher than the legal ebike 20 mph limit, there are other significant factors road engineers should optimize when conscientiously minimizing bicycle commuter travel times the same as they would for car drivers.

On the other hand the extra speed helps me control passing cars better.  Although 80% of people rate themselves as above average drivers, I've noticed that car drivers mindlessly expect to pass me on any of my bikes, even when I've experimented with riding 28 mph in a 25 mph zone - they still pass.  To increase my safety I try to control where a car passes me by speeding up or slowing down ahead of time to make them pass in a location or gap in traffic where I prefer them to pass.  This will change with the Breeze because it is harder for a car to pass a fast bicycle than a slow one, and most likely I will see an increase in stupid driving maneuvers.  (There are times when I wish I could press a button and change my bike into a tractor pulling a full manure spreader.)

The solar panel is a 100 watt ERA Flex Pro 100MD that I cut 3/8" off each edge to remove the grommets and reduce the size, and then painted the edges black.  The solar controller is an SX Electronics that I was delighted to find because the Genasun GV Boost on my other bikes were far too expensive.  However I have not put a meter on the solar output yet and can't report how well this setup works.  The panel is mounted with a flexible silicon/vinyl hinge and extremely light aluminum clip and elastic cord latches that are attached with 3M VHB double face tape.  (The improvements of this setup are hard for me to believe compared to the solar I put on the bakfiets 12 years ago.)  There is a tremendous amount of air coming off this panel above 20 mph, and I'm thinking of attaching a 1950's style small sports car polycarbonate windshield to the back edge of the solar panel and increasing the panel arch to divert more of the air flow to the sides.  The dashcam display is visible between the handlebar display and the panel.

This mandatory Class 1 sticker is because while about 40% of people actually love bikes and another 40% are fine with them and don't think twice, the remaining 20% are loud and not afraid to display their misconceptions.  Since I can coast twice as fast as the motor will power the bike, this sticker serves a narrow demographic.

I used a BBSHD motor because the BBS02 on my other cargo bikes was sometimes a little too warm after a trip (I could just barely touch it).  This is the same line of thought as the oversized heavy duty diesel engines used in tractor trailers.  While I've programmed this motor to meet legal requirements and stop assisting at 20 mph, this bike has no problem coasting up to 40 mph.  It takes only a slight incline to reach coasting speeds of 25 to 29 mph and then it just keeps rolling. Since the bike coasts much faster than rolling under motor power, I think the arguments about ebike top speeds should be about the situation not the motorized speed.   Bikes are quiet and if you pass a walking person from behind, even at 8 mph, they will be startled and say you were going too fast.  This is not an excuse for the illegal high powered moto-ebikes that are actually mopeds, but looking beyond the need to ride appropriately for the situation, I've been thinking instead about how fast I actually wish to ride because I enjoy bicycling for many other reasons.

left - panel retracted, right - panel in canopy position

There is a pivot in behind the seat for a solar canopy.  I haven't built this assembly yet so you'll have to imagine a 60 watt solar panel in place of the horizontal white board in these photos.  The pivot is just a square taper bottom bracket and I'll extend the crank arms on each side to form the support linkage for the panel canopy.   This would function as a roof during rain and then retract for better aerodynamics when dry.  A drop down clear polycarbonate windshield to steady the canopy would attach between the canopy front edge and the back edge of the solar panel using Velcro.

I installed a dashcam because I'm trying to convince my Regional Planners to improve Route 5 (the main Connecticut River valley road through Vermont and New Hampshire) as a bicycle corridor.  I wanted to take documentary pictures of the dangerous spots to bring to legislators.  I started off with a GoPro camera on the handlebars because that is what everyone uses, but found that it could only film for 12 to 18 minutes before shutting down from overheating.  The picture quality is superb with stabilization, horizon leveling, and GIS, but it's really best for shots lasting only a minute or two not hours.  I then installed a car dash cam which also had GIS, but because it's not waterproof I attached everything with Velcro to be able to take it in during rain and then promptly lost the rear camera when it shook enough to fall off.  I now have a bolted on weatherproof motorcycle dashcam, but it doesn't have GIS and I can also say that VGA resolution (640x480) is not good enough.  This camera breaks the filming session into 5 minute long files which is convenient, but 32 GB stores only 7 of them.  While I'm figuring out a better setup I'm using Google Maps Street View and QGIS instead.

The front dashcam camera mounts under the edge of the solar panel, and the rear camera is under the tail light.  I've used about 20 different ebike headlights over the years and find this Sate-Lite C7 Plus the best for my rural use with the most focused beam, good side lobes, and a strong anti glare cutoff.

This bike is pretty good but I would like to build a second improved version with the lessons learned.  I should explain a few of the more complicated improvements in separate posts, but here's a brief list of some ideas:

- It should be lighter - it weighs 49 pounds on the front wheel and 54 on the back (includes everything except the rider)

-move handlebar support tube forward an inch for more clearance getting on and off

-move swingarm pivot 3/4" forward (due to 44T to 36T chainring evolution)

-dual chain loops are great but motor speed could be faster and pedals slower

-the front chain loop could be 2 speed not 3, with a chainstay style derailleur

-I used a 71 degree head angle to reduce front end drop/flop and it's nimble on pavement but too quick on loose gravel

-steering linkage versus cables, and steering ratio (a long story)

-make rear rack 3 inches shorter and increase to 6 inches wide

-axial generator for regen in place of rear brake disc

-16 inch seat width, and move one inch of the side tubing from top to bottom

-test comparison of SX Electronics vs Genasun mobile solar controllers

- inverted Tee battery support with a larger wiring box+frame reinforcement

-the dual battery combiner won't accept regen

-wiring solar into one battery sometimes turns on displays under flickering sun

-front suspension

-APT 750C motor display has problems

-BBS02+single battery versus BBSHD+dual battery???

-motor programming is different than for my MTBs

-motorcycle style roll on/off kickstand, not expanding leg style

-solar canopy

-parking pawl on front wheel for short term locking

-seat heater and heated hand grips

-aero windshield

-4th try at a dashcam

I live where most people hike, bike, kayak, and enjoy the outdoors in the Green Mountains, the Connecticut River valley, and the White Mountains, and it's ironic that I've built a bike to simulate a car.  This bias in US transportation can be traced as far back as the 1920s, (such as Herbert Hoover's policies as US Secretary of Commerce), and I'd think that the drawbacks with unilateral car based travel for everyone have become so obvious that our infrastructure would be different by now.  It isn't.  This bike helps me fit into a car based system, but most people don't have this choice.  I'm going to build another bike with lessons learned, but I'm hoping the road designers and builders also build more inclusive roads. Whether they admit it or not, serving only cars is a conservative political choice shaping how all people move, and now that much of road funding is from general tax funds not the gas tax, it's unprofessional.  If you can build a multilevel highway interchange, you can build a bike lane.  If you can provide free parking, you can provide a bike lane.  When I ride in a safe space I like to say thank you to the road builders who understood this.

The Breeze, the Stratus frame (S1E2)

I'm only moderately familiar with recumbent design, and my first step was to figure out what the Stratus was supposed to be like originally, before years of different owners had worked on it.  I didn't find any original documentation from 1985, but there was a 1992 review in the Recumbent Cyclist News archives (https://rcnpdf.com/ , Vol 6 No 12).   Amazingly my bike was pretty much whole, with the original Shimano 600 group set.  I was going to have to change some of that out because I didn't think a 35 year old freewheel would be reliable enough for my use, but I'd be changing the front chainring anyway with the addition of a motor.  There was also no way I'd use the shifter and brake on the joystick. But overall the frame was straight, and mainly needed a new coat of paint.  It had a sticker on it from Dana Point Cycle and Sport, and I imagined the original owner cruising up and down the California beach front listening to "Hey now, Hey now, Don't Dream it's Over".

The RANS Stratus A as received

Out of the many bikes with a lower seat height, I was lucky to receive this Stratus.  This model and the Easy Racer Tour Easy (https://easyracers.com/toureasy.html) appear to be 2 classic bikes that are so popular that one blog writer claimed they are the bikes that have crossed the US the most times.  It's a very good place to start from.

An Easy Racer Tour Easy with an early electric motor drive kit added under the seat.

Photo credit: I don't know the original source, I found this photo on recumbentbike.com back in 2014, and that site now appears to be dead.  I've seen this picture on a few other sites since then.

The Stratus has a bottom bracket height of 14 inches off the ground and a seat height of 21 inches, while the Tour Easy has a slightly more upright position at 13" BB and 22" seat.  I had been planning on a seat height of 18" for The Breeze frame to match many household chairs I have and also the seat height in my old Saab 900, but I found while riding the Stratus I liked a 1" pad, which gave me a 22" seat height that matches the Tour Easy.  However the Stratus BB height is better at 14", as the heel of my shoe was often less than an inch from the ground.

The frame after welding the rear dropout and painting, with the new wheels

(It's mounted in an old exercise stand to prop it up.)

Evaluating the frame design while cleaning it up was lot of fun!  There were a few things I wouldn't have done, such as the plastic cap closure for the seat tube, and the termination of the stays on the rear dropouts (which I'll say more about in the drivetrain post).  Also I was wondering how the BB to seat to rear dropout triangle would handle the torque of a motor.  Otherwise the frame was thought provoking!

A 59 degree head angle with a centering spring added to counteract flop

The 59 degree head angle confirmed something I've learned since I wrote my blog posts about steering geometry back in 2014- the basic function of the head angle is to put the handlebars comfortably within the reach of the rider, and handling is secondary.  Here's an example that demonstrates the important aspect is trail, not head angle:

Tony Foale rides his modified BMW with a 15 degree rake (motorcycle terminology, or 75 degree head angle in bicycle terminology).  Tony modified his motorcyle for testing with rake angles of 15 and 0 degrees, which under some conditions performed better than the stock 27 degree angle which could oscillate. 

Credit: Motorcycle Chassis Design: the theory and practice, Tony Foale and Vic Willoughby, 1984, Osprey Publishing Ltd, page 62

The Stratus head bearings were notchy, and I found a current version that looked the same but now had seals!  The front wheel wasn't original, it had nuts and 90 mm Over Locknut Dimension (OLD) while the fork had 100 mm spacing.  I dug out an old Shimano 100 mm quick release front hub that looked period correct and built a new wheel using an aero shape rim.  A major side effect of the 59 degree head angle is a tremendous amount of annoying wheel flop, and after a couple of weeks of having the front fork turn sideways whenever I let go of the handlebars, I made a centering spring.  It's just 4 inches cut off of an old spring for a wood screen door (the kind that always slammed shut with a bang), and is attached to the fork with a little ell bracket on the brake caliper bolt, and onto the frame by hooking it on to a hose clamp.  I still have to figure out a front fender though, because RANS cut it a little too tight with less than 1/8 inch between the tire and the fork crown.

While I did remove the central joystick, I wanted to keep the front fairing + storage cubby.  I added bar extensions to the hoop handlebars instead of the usual update of  "ape hanger" bars.  This bike is steered by leaning, not by turning the handlebars, and it took me a while to learn to steer with my seat.  I had to not lean on the backrest for about 20 miles before it started to become more natural.  There's a small amount of tiller effect during slow, sharp corners, but at speed it's not noticeable at all.  The handlebars aren't very solid and mostly just a place to put your hands, but the fairing does block the wind, and the cubby is really handy! 

The cockpit with a pair of Dia-Compe SS-4 two finger brake levers and a Shimano Mega9 shifter sandwiched in between them.  The BBS02 keypad is on the left handlebar extenion, and it's LCD display is on a custom bracket that mounts to the fairing in front of it.  (The handlebar extensions are cut off in this photo.)  All cables and wires fit under the bar tape for a comfortable grip, although it is a pretty close fit.   The brake switches are the inline cable type and hidden inside the fairing.

I've adjusted the hoop so that my knees have just an inch of clearance to the underside, and realized that while a fixed solar panel could be mounted over my knees on a bike frame that has steering with a remote linkage, there wouldn't be much space for a front trunk underneath it.  Also a solar panel over my head would be much taller than I had planned, so the next step is to reconsider the seat height again.

The rear wheel is also new.  I had planned on upgrading the antique freewheel hub to a freehub to better handle the motor torque, but I found a complete wheel that I was able to modify, so I simply replaced the whole thing.  I'll cover this part a bit more in the next post about the drivetrain.

The seat cover had shrunk and I had to make a new one.  Also the original kickstand simply spun around on the chainstay, so I took a standard Greenfield kickstand and lengthened it by epoxying on a 4 inch piece of a salvaged seat stay that I had hammered into a profile that slipped on the leg nicely.  (This took three tries:  on the first try I hammered too hard and snapped the leg off, the second time I tried using a torch to soften the tube and melted the aluminum kickstand.  The third time I applied a lot more patience.  It's good that these kickstands are common and inexpensive.)

The extended Greenfield kickstand

The chainstays are very slender and could be bent, so I made top and bottom mounting plates out of 1/2" CDX plywood with grooves routered in them that cupped the tubes to spread out the force of the kickstand   Then after mounting the kickstand I scribed the end of the leg to the correct angle and welded on a circular foot.  I had originally planned to combine the kickstand mount with a pair of chain idler pulleys, but the pulleys weren't necessary.  I'll write more about this in the drivetrain post.

The almost finished Stratus project, (it still needs a front fender and another layer of foam on the seat)

I finished the bike in September and rode it for a couple hundred miles before snow started and then I parked it to keep the road salt off of it.  It's very fast- easily able to keep up with cars in 25 mph zones, and under most situations it's very comfortable.  It's definitely in it's element on a paved road, but it's been fine on all the dirt roads here except for the worst ones where the town has dumped a lot of 3 inch stone.  For The Breeze I'll probably go one size wider in tire width, from 1 1/4" (32 mm) to 1 1/2" because of the stone, but I don't wish to go wider because I also need to cover distance quickly.  I've found it hard to choose between cruising along on this bike or the more upright posture of my converted Marin eMTB and I split my time half and half between the two.

For the next post I'll take a closer look at the drivetrain.

DIY E bike Conversion Workshop- step by step video and tips

A little over a year ago I wrote about a couple of DIY workshops we had held on converting a regular bike to an Ebike.  The first half of that post "Converting a regular bike to an ebike workshops" was primarily from a workshop organizer's point of view and didn't have a lot of instructions for doing the conversion, (although the second half did have tips from a 2 page handout that we used at the workshops).  This post is meant more for the DIY person, and has information that I've learned from converting 17 bikes so far, and holding a third workshop.  I've written a brief history of events leading up to the workshop, then there's a short summary of my currently preferred parts, and then the workshop video (1 hour 26 min) covers about everything, ending with a few short notes about tips that I forgot to include in the video.

Converted Finiss MTB with a Bafang BBS02 motor with lights and P850C color LCD display ($442), 48 Volt x 17.5 Ah (840 Wh) down tube battery ($422) and new chain ($16).  Total of $880 (includes VT tax and shipping, NH residents would pay 6% less).

Why DIY?

If you are the type of person who likes to work on your house or your car, you can build a very nice Ebike with specs that are better than most Ebikes on the market for under $1000, resulting in significant savings and a custom ride to fit your needs.

First a little bit of the background story leading up to this DIY workshop: the UV EV Expo and the UVEL.  If you just want to work on your bike, skip to the next section.

Here in the Upper Valley of the Connecticut river in Vermont and New Hampshire, our group of energy committee members have now held 5 UV Electric Vehicle Expos.  (I wrote about the first one back in May 2014 in this post "Upper Valley Electric Vehicle Forum and Demo".)  These developed into a very big outreach for us- to give you an idea of the effort there were usually around 2 dozen vendors and exhibitors, speakers, food, (and of course Ebikes in every one), here are the attendance totals:

2014 Norwich, VT           250 people

2016 New London, NH   350 people

2017 Hartford, VT           550 people

2018 New London, NH   375 people

2019 Hartford, VT           550 people

These were most likely the largest EV events in New England each year, and it was actually nice to have a break in 2020 when COVID restrictions were imposed.  However we still had a little bit of money left from the 2019 budget, so we decided to use it on an Ebike library (with disinfecting the bikes, distancing, and masks the safety precautions turned out well).  Back in 2010 when I was just starting to figure out Ebikes as a substitute for my car, Dave Cohen of VBike down in Brattleboro was also starting work on a consulting service for ebikes.  He arranged for a few Ebikes that he could loan out for short trial periods to people who wanted to see if an Ebike would fit into their lifestyle.  After a few years of doing this, our statewide bicycle organization Local Motion up in Burlington ramped up the concept into a widely available library of several Ebikes.  However the bikes were often not in the Upper Valley, and we Expo people decided we needed our own library.  With Local Motion's help, we combined our Expo funds with donations and bought a Specialized Turbo Como 3.0 ($2800), a RAD Wagon longtail cargo bike with a child handrail ($1800), and I converted a Specialized Hard Rock MTB ($977) for loaning out.

The DIY Specialized Hard Rock conversion for the UV Ebike Library.  It has a Tongsheng TSDZ2 500 Watt motor, a 48 Volt x 14.5 Ah (696 Watt hour) battery, with new tires, brakes, chain, lights, fenders, rack, and mirror for $976.96 (including VT tax and shipping).

The Parts:

At this point I've installed hub motors (MAC, MXUS, Leaf, and generic cheap ones) and bottom bracket (BB) motors (Bafang and Tongsheng).  I'm finding that the BB motors work all around the best.  These have been my preferred parts for the last dozen bikes:

Motors (both of these are street legal in VT and NH):

First choice: Bafang BBS02 48V, 750W, 120 Nm torque, about $435.  This is a very good, strong motor, and I recommend it for riders who are experienced, carry loads, or have distance to cover.  By programming the first two assist levels to be less, this motor on the Finiss bike conversion feels pretty close to the Turbo Como bike in our library, while still having more power at the top assist level.

Second choice: Tongsheng TSDZ2, 48V, 500W, 80 Nm torque, about $365.  This is a good quality motor. and because it has less output and a torque sensor it is very smooth and an easy ride.  I recommend it for beginner riders or people who haven't ridden in a long time, smaller bikes, or shorter distances.

Batteries

Bike handling is better using a down tube battery than one in the rear rack.  I'd now use a rear rack battery only if I needed 1 kWh or more of capacity, or a battery couldn't be fit any other way.  The latest down tube Reention DP-6 case with 4 mounting tabs down each side plus heavy duty flat contacts (drain water better than round) and a full length aluminum mounting channel is a very nice package.

First choice:  48V x 17.5 Ah, (840 Wh), about $405

Second Choice: 48V x 14.5 Ah, (696 Wh), about $320

Workshop step by step video

All the bikes held up well over the season with only minor repairs, (there were about 230 borrowers from 7 towns), and the Hard Rock generated a lot of DIY questions from people who wanted to convert their bike.  We decided to hold one more DIY conversion workshop, but this time we had to hold it online because of COVID.   Norwich Energy Committee arranged with our local Community Access TV to film a step by step conversion that I did outdoors in the doorway of my barn for COVID distancing, and once that was edited we used the video for a Zoom meeting.  (A thank you also to Norwich Women's Club for funding parts for one of the bikes!)  This recording covers much more than I could write in this post, so I'm going to go straight to it, and then end this post with six small tips that I didn't cover in the recording.

E Bike Conversion Workshop

The tips that I forgot to include in the video are:

-On a Mountain Bike often the shifter cables are routed through a plastic guide underneath the bottom bracket, and this guide sticks out so far that the motor won't slide in.  Remove the guide, and then route the cable to the rear derailleur through a piece of cable housing running over the top of the BB instead.  You can keep the factory cable housings at the handlebars and at the derailleur, and just cut a new piece that fits between the cable braze ons on the downtube and the chainstay.

-Do not convert a carbon fiber bike, tightening the motor nuts may crack the bottom bracket.

-Roughly half of the bottom bracket motors have loosened up the large retaining nuts after riding a couple hundred miles.  After a second tightening they have stayed tight.  I now use the upper end of the recommended torque range for the nuts instead of the middle.

-I didn't say enough about the Tong Sheng speed sensor- it is very sensitive to the gap, requiring an extremely large one of 10 to 15 mm.  I've had to mount the magnet on a spoke on the other side of the wheel to get this gap.

-The motor gear housing on one of the dozen bikes with BB motors pressed against the chainstay when the large nut was tightened up.  Some people dent the chainstay in for clearance, but a better way is to use shim washers on the motor.  (The Chinese vendors often call these narrow washers "gaskets".)

-Several people have asked if the Bafang motor could be made slow for puttering along.  This is easily done by simply turning the assist off, but for those who wish to have a tiny bit of assist, I've reprogrammed the first (and sometimes second) assist levels to about half of their original settings.  This has turned out to be the main motor programming I do, another is to set the thumb throttle to a continuous medium power level so that an inexperienced rider can't burn the motor out by holding the throttle down at a stop.

Bonus Material!  An updated "Operating Tips for Owners"

In the earlier DIY post I finished by copying the 2 pager handout of tips.  The handout has since been redone 4 times for the parts I'm using, here is the latest version:

As with any bike, please check tire pressures, the brakes, and take a quick look for any problems before going out on a ride.  The chain should be lubricated at least every several hundred miles depending on riding conditions.

The Bafang BBS02 motor is a globally proven design with several million produced, and is on it's third version with robust gear and electrical improvements.  10 display styles are available, I use a P850C display.

-It is 750 Watts (the legal limit in New Hampshire and below the 1000 W limit in VT) and 48 Volts

-It has both a cadence sensor (about 1/4 turn of the pedals to activate) and a thumb throttle for turning on the motor

-There are switches on the brake levers to be sure the motor shuts off in an emergency situation

The downtube style lithium battery is removable with a water resistant plastic case.  It has a quality Seiko battery management system (BMS) that monitors the charge levels of the Samsung brand cells to balance them, and also provides short circuit and low voltage protection.

-The battery size is 48 volts by 17.5 Amp hours, or 840 Watt hours

-An extra water bottle mount has been installed on the downtube to strengthen the battery attachment.

-Order a 46 tooth front chainring for 26 inch wheels to provide a normal pedaling cadence range, maxxing out around the legal e-assist limit of 20 mph.  The rear cassette or freewheel should be a wide range 11 or 12 tooth top gear to a 32 or 36 tooth low gear size range to have a good gear for all situations.

-Test rides that I've taken have averaged around 15 Watt hours per mile.  This gives a range of about 50 miles with an 840 Watt hour battery (rated capacity less a 10% safety factor, divided by an average 15 Watt hours per mile).  Your range will probably be different depending on factors such as how much you pedal, heavy loads, hills, wind, etc.

-The 2 Amp charger takes 10 minutes of charging time for every mile traveled.  This is about 9 hours to charge a completely empty battery.

-There are 10 displays available for the BBS02 motor, I use the P850C model because it has the most info for the best price, has a USB port for phones or GPS devices, has a light switch with auto dimming built in, and has one of the largest and easiest to read displays.

Bicycle operating tips:

Keep your cadence between 60 to 90 rpm, (which is the normal recommended range for regular bicycling).  The motor is more efficient the faster it is running, and it will turn all the way up to 120 rpm.  Don't pedal slowly with the motor doing all the work, because when the motor is turning slowly it is not moving you down the road and most of the energy going into it is coming out as heat, not as a rotating shaft doing work, and this heat could burn the motor out.  Shift down for hills just like on a regular bike to keep your cadence in the regular bicycling range, and the motor will also be in a good speed range.

The thumb throttle is great for getting rolling under difficult circumstances, such as getting started at an uphill intersection, and (just like a regular bike) it works much better if you have remembered to shift down to a lower gear before you stop.  Note that using the thumb throttle will reduce your range.

Battery operating tips:

The battery will last the longest if you keep it charged in the middle of it's range, and don't go below 10% or above 90%.  It's best if you store it half full or a little above that, and keep it in a cool (but not below freezing) place.  Charging it fully a day ahead of a ride is fine, but keeping it sitting there over a long storage period all the way full or all the way empty eventually causes chemical changes inside it that will shorten it's life.  With poor storage the battery will last a year or two, with good storage it can last 4 to 5 years.

If you want to keep the battery charged enough for a spontaneous ride, then storing it at 3/4 full is OK, just not as good as 50% to 65% full.  A battery of 17.5 Ah at 48 volts, (840 Wh), is on the larger side and there is room within it's capacity to run it at less than a full charge for making several smaller trips before recharging.

Don't charge below freezing.  The electrolyte inside the battery is similar to water, and doesn't work very well below freezing.  Never charge the battery below freezing because the thick electrolyte can trap chemical reactions in small spots in the battery and damage it.  It is OK to ride below freezing, (down to around 0 F) because the battery is releasing energy when it is discharging and this helps keep the electrolyte moving around.  However the electrolyte is sluggish when discharging below freezing and as a result the battery will have less power and range.

If you want to monitor your battery more exactly than on the bike's display, there are DC meters available with 4 functions (Volts, Amps, Watt Hours, and Time) that can be spliced in between the motor and battery.  A second way of monitoring is to use a Kill A Watt household appliance meter when charging the battery.  However this measures after the ride not during it, and it is less accurate because you will need to figure in about a 10% to 15% loss due to efficiency of the charger, (the battery is getting 85% to 90% of what the Kill A Watt meter reads for Watt hours.)  For example if the Kill A Watt meter reads 0.10 kWh (100 Wh) when the charger finishes and the light turns green, then about 85 Wh went into the battery and 15 Wh were lost inside the charger.  You can divide this 85 Wh by the number of miles you rode to find out your Wh per mile.