An Ultra Reliable Ebike Battery Charger…

… Some Assembly Required

I originally published this article in the Sondors Owners Forum.

Please take note:  What I am describing here is not for everyone.  You need to do this right.  If you have any qualms about doing this kind of basic electrical work, don’t try it.  Mean Well LED power supplies have been used by the DIY ebike community for years.  The concept is not new.  The weak link here is you and if you screw this up consequences could be profound   If you know your way around a crimper, or a soldering iron… great this will be easy.  Kid stuff.  If not, don’t pick this project as your first learning experience.

Why reinvent the wheel here?  What benefit could be gained?

Ebike battery chargers tend to be dodgy.  The interwebs are filled with stories of frequent flyers whose chargers keep dying.  Its either a dead fan that in turn lets the charger heat up and fry, letting the smoke out of the internals (never a good sign) or perhaps the most common:  the charger stops cutting off at its cutoff voltage and keeps on charging … with potentially catastrophic results.

So… what is better?  You can see that in a popular commercial battery charger:  The Grin Satiator.  Its so efficient it needs no fan to cool it (or to fail).  It is also largely weatherproof and highly reliable.  The only demerits it gets from users – which have largely gone away over time – are programming/firmware issues.

Grin-technologies-Cycle-Satiator-24-48volt-waterproof.jpg

Oh and its cost is US$300+  once you figure in a programming cable, along with a couple of adapters.  I bought one.  It works perfectly.  But with an AWD bike with 2 batteries that I ride every single day and charge both at home and at work, I found convenient charging means walking up and plugging in.  Not carrying chargers with me, unloading them, setting them up etc.  So 2 batteries x 2 locations = four chargers.  $300×4= not happening.  And I carry a charger with me in case I get stranded.  $300×5=crazy talk.

What to do?  Use the same core hardware that gives us the $300 charger but without the fancy user interface.  That costs around $40.  We won’t have a fancy display screen or onboard memory, but it will still be adjustable with a screwdriver.

IMG_20180903_083144.jpg
The dollar is for scale – and to remind me what money looks like since I can’t seem to stop handing it away.

 

I have worked with three different models that can serve my purposes.  Remember that volts x amps = watts and this will be important when figuring out what to set your charger for:

CLG-150-48A

  • Available regularly on Amazon for about US$55
  • Rated to 150 watts
  • Rated as adjustable from 40 to 56v but actually adjusts from 39v to 58.1v
  • Usable as an 83% to 100% charger for a 36v battery
  • 80% to 100% for 48v battery
  • 80% to 96% for a 52v battery
  • Minimum amperage selectable is about 1a
  • Lower wattage rating means it must be set to lower amperage on 52v batteries (2.5a max for a 52v battery)
  • Designed for LED lighting and ‘moving sign’ lighting applications
  • IP65 rated for indoor and outdoor use.
  • Usable at EU or USA voltages.
  • Mean Time Between Failure (MTBF): 303,700 hours.  Yes, really.
  • Spec Sheet Here

HLG-185H-54A

  • Available often on ebay for about US$40.  Normally on sale in the $49-$75 range.
  • Rated to 185 watts
  • Rated as adjustable from 49 to 58v.  Actually adjusts from 48.3v to 60.0v
  • Usable as an 80% to 100% charger for 48v and 52v batteries.  Not usable on 36v systems
  • Higher wattage rating means can be used for faster charges than 150w CLG.  Typically this is a good 3a charger for 52v batteries.
  • Adjustable to very low current (about 0.85 amps) for safest trickle charging, ever.
  • Seems to ramp power down more slowly and precisely than 150w CLG as it approaches target voltage (not a meaningful feature; just an observation).
  • Mean Time Between Failure (MTBF): 192,200 hours, or almost 22 years of continuous use.
  • Designed for LED lighting and street lighting applications
  • IP65 rated for indoor, outdoor and wet/hazardous locations
  • Usable at EU or USA voltages
  • Spec Sheet Here

HLG-320H-54A

  • This is the Big Daddy.  As in bigger and heavier and more power output.
  • Street Price around $90.  Often available on EBay for around $50, even down to as little as $25 each if someone is selling off a pair of them wired together as Zero e-motorcycle chargers.
  • Essentially same specs as the HLG-185H-54A but is instead rated for 320 watts
  • Current can only dial down to about 2.0 amps.  But the high wattage rating means it can be dialed UP to make it a 5 amp charger (only aftermarket battery plugs like XT60 or Andersons are able to safely handle this current level).
  • MTBF: 157,100 hours (just under 18 years of continuous use)
  • The 320H units I have bought on the aftermarket were originally wired together in pairs in series and used as onboard 115v Zero Motorcycle chargers
  • Spec Sheet Here

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

HLG-480H-54A

  • New addition to the product line since this thread was originally created.
  • $125 street price.
  • 480 watt capacity
  • Minimum 4.4a rated current rate (max 8.9a) means not safe for anything but an aftermarket battery connector (XT60 Yes, barrel connector No)
  • Supports a dimmer function via bare +/- leads.
  • Strictly a fast charger for a BIG aftermarket battery that can safely take 4-9 amps.
  • Not for novices – know what you are doing insofar as batteries, chargers and battery chemistry is concerned before you go this big.
  • MTBF 95,300 hours
  • Yes it is big.  Not the sort of charger you want to be carrying around.
  • Spec Sheet Here

HLG-600H-54A

  • New addition to the product line since this thread was originally created
  • $170 street price
  • 600 watt capacity
  • Minimum 5.6a rated current rate (max 11.2a) means not safe for anything but an aftermarket battery connector (XT60 Yes, barrel connector No).
  • Supports a dimmer function via bare +/- leads.
  • Multiple power outputs enable charging multiple batteries at once, so maybe it makes some sense for multi-bike households.
  • Not for novices – know what you are doing insofar as batteries, chargers, charge capacities and battery chemistry are concerned.
  • MTBF 76,900 hours (a mere 8.7 years of continuous use)
  • If you thought the 480H was big wait until you see this one.
  • Spec Sheet Here

SIDEBAR
IP65 Enclosure – IP rated as “dust tight” and protected against water projected from a nozzle.  So these chargers are safe with:

  • Garden hose spray (or heavy rain) – Yes
  • Ocean waves – Maybe 
  • Bottom of fish tank – Hell no

Myself, my bikes have 52v batteries.  I do use a couple of CLGs at work for my charging station there but only because I hadn’t found the HLG-185’s yet.  The HLG-185’s are ideal chargers as they can charge at levels safe for the Sondors battery plugs (3a max) and can handle any voltage asked of them for a 48v or 52v system.  If you have an aftermarket battery that does not use the pin plug as do the Sondors batteries, then you almost certainly have an Anderson Powerpole, an XT60 or an XLR connector.  Those plugs can handle the higher amperage the 320 is capable of delivering.  I use a 320 as a travel-with charger under the theory that if I am stuck somewhere I want to grab as much charge as I can, as fast as I can.  But a 185 is perfectly capable of being a 3a charger and weighs probably half what the 320 does.

IMG_20180902_085021.jpg
This pic was supposed to show everything needed to make the charger, but I sort of overdid it.  No need for a whole bag of connectors, or heat shrink, and that grey cutter isn’t needed either.

 

So… enough details already.  Lets make a charger!  Here’s what we need:

  • A Mean Well power supply.  The process is identical for all models.
  • A pigtail’d grounded electrical plug.  They are sold on Amazon typically as replacements for corded drills and similar power tools.  NOTE: I am using a USA standard plug, but these units are made to accept worldwide voltage/current so just go to your local hardware store and choose your local version of a pigtail’d, grounded power cord if you live outside the USA.  Oh, and read the spec sheet to confirm what I just said applies in your country.
  • A digital watt meter to tell us what we are outputting to the bike.  For almost all of my chargers I use $15 inline watt meters.  This is optional but very desirable.
  • An interface from the charger to the battery.  I will use an XT60 as the direct connection, which is what a lot of aftermarket batteries use.  You can then plug just about any adapter into that for your Sondors or whatever else you have.  Note in the picture above, bottom center just to the left of the little adjustment screwdriver we will keep with the charger, that there is a pin plug adapter for use with Sondors batteries.  That one came from Luna Cycles.

A note on battery/watt meters.  Here’s the short version:  They suck.  Or more accurately they are oftentimes off by  a bit, and there is no way to calibrate them.  Its not uncommon to see a battery meter accurate to within 2%.  That sounds ok unless you are charging to 58.8v, which could be 59.98v with a 2% error and that is very, very bad.  So you want to take a multimeter or similar *known safe benchmark* (in a pinch the reading on your LCD screen will work once you have disconnected any charger from it) and use it to learn where your chosen meter is in terms of its accuracy.  I do this and then I take a labelmaker and make a label telling me how much a meter is + or – actual voltage.

So for example, if my target voltage for a 52v battery is an 80% charge of 55.4v, and my watt meter is reading 0.50v higher than it should be, then I create a label that says

+0.50v

UPDATE:
This link is to one of many cheap Chinese watt meters.  The last two I have used, purchased across a span of 4 months, exhibited a new and consistent behavior:  Plug them in and they are WAY high, by like 1.2v.  But sit and watch the meter over a span of about 5-10 minutes and you will see it slowly auto-correct itself down to a steady reading.  This steady reading will still be off by a bit but not so bad… these last two meters were both off by only about 0.20v… so I recommend these as your best option – and recognize they have a calibration stage at startup that you need to wait out.

So now, we have our parts in hand and its time to assemble them.  In order the steps are

Step 1
Attach the pigtail’d cord to the input side of the Mean Well unit.  For the USA plug and the Hanvex drill cord I have been using, the wire sequence is green (cord wire)  to green (charger wire) for ground, black (cord) to brown (charger) for AC+ and white (cord) to blue (charger) for AC-.  Note that the wire colors are noted on the charger left side, but as ACL and ACN.  DO NOT SCREW THIS UP.   These are international standard designations and colors which as usual the U.S. does not follow.  If you want to check my work, start googling.  Myself, I use marine heat shrink butt end connectors to connect the wires.  I also use rather expensive electrician’s-grade crimping pliers.  There is a big difference between proper crimping pliers and … well, pliers.  Use the right tools for the job.  After I crimp, I heat shrink the connectors, add heat shrink around each individual wire and then do a heat shrink around that entire assembly.  How you do it is up to you (i.e. soldering or whatever).  Remember that this is mains power you are fooling with here so get this right.

Step 2
Attach a battery side plug.  In this case I am using a male XT60 which both works for my aftermarket batteries that have female XT60 charge plugs, and my bottle batteries where I use my XT60-to-pin-plug adapter.  Same procedure as in Step 1 although a little simpler as there are only two wires.  Note that some of these charger units do not use red and black wires.  If you are not familiar with what the colors mean, the casing on the unit specifically tells you which wire is which (V+ and V-).

When you are done, you will have something looking like this:

IMG_20180902_093002.jpg
A completed 320w charger without the watt meter stuck on the end

Step 3
OPTIONAL – attach an inline watt meter to the output side of the Mean Well unit.  This is your power display.  I call this step optional because you could just calibrate your charger output once and not use a meter to monitor progress (easy enough to turn on the bike display during charging, which will hurt nothing).   Myself personally, even though meters are pesky insofar as getting them calibrated, I prefer to have a real time progress monitor I need only glance at.
NOTE:  Source side of the meter gets connected to the charger.   Load side goes to the battery.

Step 4
OPTIONAL – make an extended output cord.  Essentially one big extension cord on the battery side. You’ll know real fast if you’d like to have one of those as whatever you made doesn’t reach.  You could just hardwire this to your output lead on the charger.  But then you are stuck with that length alone.  I prefer to make a cable as I have no problem using a couple of 12 AWG XT60 pigtail ends to make a dedicated extension.

Step 5
Connect an interface to your battery.  For a Sondors, this is a pin plug connector.  For many batteries the generic standard is a male XT60 connector.  You can either buy a direct-connect bottle battery adapter (see link) or connect a male XT60 pigtail and then buy an XT60 Female-to-bottle adapter.  Doing it the latter way makes your charger able to connect to any battery (if you have another battery with say XLR connectors you can make an XT60-to-XLR adapter via a couple of pigtails).  You just swap in the adapter you need.  In this case I am picturing a Luna-sourced XT60 female to pin plug adapter.  A different source for the same thing is in the parts list below

Step 6
Go out and buy a little Phillips head screwdriver.  This tool will live with your charger forever so you should buy a new one unless you have an extra already. Its a must-have for the next step.  Also required if you plan on changing your settings (lets say you want to charge 80% one day and 100% the next).

If you have performed all of the above steps, you now have a parts pile that looks like this (well sort of, the meter and the charger have already been labelled with calibrations but just pretend we haven’t done that yet):

IMG_20180904_074621.jpg
Charger, adjusting screwdriver, extension cable and watt meter complete with sticky note showing how far off it is.

Step 7
Dial in your output voltage.  Once you have connected an AC plug, and a battery side connector AND connected the inline watt meter, you simply have to plug the new charger into the wall.  Amps will read zero and volts will read whatever the unit is currently set for.  See the little rubber whatsits that are capping the voltage (Vo ADJ) and amperage (Lo ADJ) adjustors?  Pull those off and stick the screwdriver into the Vo ADJ hole.  Twiddle it around gently until you feel it seat into the adjustor.  Now turn it first one way, then the other.  Watch the voltage readout on your meter.  One way goes up, the other down … and the directions are different on my 185’s and 150’s vs. my 320 so you figure out what direction does what yourself with your own unit.

Step 8
Calibrate your meter to reality.  Remember what I said above about meters.  You need to figure out how far off your meter is from your display.  As you can see if you look closely above, this meter is off by +0.50v.  Thats a fair bit.  The good news is when these types of meters are off, they are consistently off so you just need to know by how much (and if you can find a meter that is consistently accurate tell me.  I can’t find one at any price).  this is a pain but you only have to do it once.

Step 9
Dial in your output amperage.  OK… moment of truth time.  You are plugged into the wall.  Time to plug into your battery.  Maybe you should do this out in a field with a long extension cord.  Don’t do it in the baby’s nursery or in Grandma’s bedroom while she’s asleep.  Plug the battery in and now watch the meter.  The voltage switches to now show the battery state of charge.  The amperage comes to life and shows the current level (amps) being fed into the battery.

Once again, like you did with the voltage adjustment, use your screwdriver this time in the Lo ADJ socket and twiddle it until you see the safe amperage rate you safely want to safely run your charger safely at.  Did I forget to mention safety?  And volts x amps = watts ?  Pay attention and get this right.  If your meter is off – especially if it is reading lower than actual voltage – you will want to find out by what percentage it is off and adjust your indicated meter amperage less that percentage amount.

IMPORTANT SAFETY TIP:

  • Your charger does not switch its power feed on and then off like a light switch.  Instead, it will slowly ramp down its current delivery level (amperage) as the battery approaches your target voltage.  So that means if you plug in a battery that is fully charged or nearly fully charge, you will get a really tiny reading of current going into the battery – and this will give you a false idea of the amperage your charger is set for.  Because of this, when performing calibrations you must have a battery that is at least a couple of volts low.  At least.  If you are charging to 54v (100% charge on a 48v battery) then plug in a battery at no higher than, say, 50v state of charge.

If you are using a pin plug, NO MATTER WHAT make sure this value does not exceed 3 amps.  The plug can’t safely take more.  Again, remember that volts x amps = watts.  So if your 185w HLG-185 is feeding the max of 3.45 amps, that means at 58.8v it will be sending 203 watts which exceeds its 185w rating and thats VERY bad.  Here again.  Use your brain and don’t screw up.  Best to leave a safety margin.  For example I have one of these set to a ‘full’ charge of 58.3v and 3.0 amps.  175 watts.

Step 10
Add a carrying case?  Your basic MOLLE water bottle bag will fit this all beautifully.  the slightly larger Condor bags available on Amazon will do so with a little more fudge room.  I got two green ones on sale for $5 and $8 respectively.  Sometimes they are more.  Happy hunting.
In the end what do you have?  A charger that you can expect to be reliable literally for years.  Not necessarily cheaper, but dependable.  If you buy this once you won’t have to buy it again in 6 months or a year… and thats the usual story out there in ebikeland for the more demanding users in the DIY world.

Parts (remember oftentimes you can get these chargers for a lot less on clearance on Fleabay).  Especially the HLG-185 which is commonly used in street lights):

Mean Well CLG-150-48A
https://amzn.to/39zvW6m  ($62.88)

Mean Well HLG-185H-54A
https://amzn.to/2Hm2PaJ  ($58.25)

https://www.onlinecomponents.com/mean-well/hlg185h54a-43123124.html ($49.69)

Mean Well HLG-320H-54A
https://www.onlinecomponents.com/mean-well/hlg320h54a-43123431.html ($84.58)

Hanvex 18awg 3-prong AC power cord, 6ft, pigtail’d
https://amzn.to/2URh3Zc ($10.99)

XT60 male and female pigtails (need 5 total if you are using an inline watt meter, extension cable and xt60 lead for battery)
https://amzn.to/2OTj6bg (8.99)

Inline watt meter
https://amzn.to/2UPmZlB ($15.55)

Option: Female XT60 to male barrel plug adapter
www.progressiverc.com/female-xt60-to-male-barrel-plug.html ($4.99)
https://lunacycle.com/xt60-female-to-barrel-male-plug/  ($6.95)

Carrying case – MOLLE water bottle pouch
https://amzn.to/3bFYxZZ

IMG_20180904_074404.jpg
Everything nice and neat in its own traveling package

 

IMG_20180904_074322.jpg
Thats a size 10 1/2 shoe there for scale.

UPDATE:

I had the opportunity to make another charger over the weekend for my daughter and son-in-law.  They also live in the EU and as such I needed the appropriate plug – the charger will auto-sense the voltage coming in and adjust accordingly.  So for those of you folks outside the U.S., here’s what one looks like.

My daughter’s locale uses a 2-prong grounded ‘Schuko’ type plug.  One nice thing about using international parts is they conform to the same international specs.  So there is none of the translation necessary to pick which wire goes to where.  Just match the colors and you are done.

IMG_20181014_105356.jpg
Proof I am not colorblind (ps that dress was white and gold)

 

This time I took the time to take pics before and after during assembly.  The heat shrink and adhesive on the marine-grade splice connectors make for a very solid connection.  There is a trick to doing the best crimping:

  • do it on the very ends
  • don’t crimp so hard you tear deeply into the plastic covering the splice
  • ensure the pointy prong on your crimper faces AWAY from the other wires so if you do overcrimp and tear into the plastic, you won’t expose metal facing the other wires.
  • Use a halfway decent crimper.  I think I made this point in the original post but it bears repeating.  Use the wrong tool for the job and your results will suck.

There is also a trick to heating the adhesive connectors – First, use a nozzle on your heat gun that narrows the heat exhaust so you can better direct it to a small area.  Next, heat the ends that you actually need to shrink up and grip the wire.  Stay away from directly heating the metal center.  If you do that, any tearing of the plastic over the crimp tends to actually seal itself.  If you heat the center, those tears will break open further as the adhesive plastic shrinks from the heat.  Its actually pretty easy to do… you just have know to do it… and now you do.

imageproxy.jpg
If you live in the USA, no I did not use the wrong plug.

 

Heat shrink over top of those adhesive connectors and you have a stable, solid connection you need to look for to notice.

IMG_20181014_110354.jpg

Do it again for the XT60 ‘universal’ output connector.  Make sure that external heatshrink is plenty long.  In this case I made sure I had plenty of exposed wire on the end because I like the flexibility.  If I wanted to reinforce it and maintain that flexibility, self-adhesive silicone tape (sticks only to itself; spiral wrap it around the wire) is the perfect solution.  The Sondors-compatible bottle connector I chose for this charger had a male plug end on it, so I needed to make another connection using a short female-to-female XT60 extension.  It is important to get your genders right on a charger.  You do NOT want a male XT60 or male anything else exposed on the battery side as an arc between the terminals is much more likely on a male plug, and that can destroy your battery.

IMG_20181014_113508.jpg

Here’s the whole thing put together with a meter added to the end and the Sondors-compatible 5.5mmx2.1mm barrel connector attached.  The meter is showing it is configured for an 80% charge on a 52v battery.  After I took this pic I realized I needed to set it up for a 48v battery and changed the voltage on the charger and the label on the meter.

IMG_20181014_140924.jpg

Lastly:

These chargers are sturdy enough and water-resistant enough to mount on your bike as an onboard charger. Here is one bolted onto a front rack. The cords are gathered up in a MOLLE dump pouch attached to the handlebar bag. Just open the flap and pull out the cords.

Mongoose – Chapter 8 (Build Sheet)

I’ll try and keep this as simple as I can and simply list parts in what passes for a table in basic WordPress which does not support tables.  Over time as this project is filled out the reasons why I chose what I did will be covered in the various articles

Mongoose Envoy Bike               Amazon              749.99
Ursus Jumbo Superduty kickstand   Amazon               79.99
Jones H-Bar SG Loop Handlebars    Jones Bikes          79.00
Jones 205mm Kraton Soft Grips     Jones Bikes          20.00
Magura MT5 disk brake set         bike-discount.de    137.00
Thudbuster LT 27.2 XL             Amazon              119.99
ISH-203 203mm rear disk adapter   bike-discount.de      6.86
QM5 203mm front disk adapter      bike-discount.de      6.86
Tektro 203-17 downhill rotors (2) ebay (hi-powercyles) 42.40
Continental Contact Plus City     Amazon               69.54
   26x2.20 tires (2)
Sunlite thornproof 26x2.35-2.50   Amazon               33.90
   Presta valved inner tubes (2)
BBSHD motor kit                   Luna Cycle          699.95
   68-73mm standard motor
   Mounting hardware
   wiring harness
   speed sensor
   basic crankarms
   Luna 500C mini color display
   Universal thumb throttle
Second Bafang inner lock ring     Luna Cycle            5.95
Battery Solution
   Wolf V2 52v 12ah battery pack  Luna Cycle          549.95
   Potted, QD mount, 50a BMS and 
   Samsung 30Q cells
    -OR-
   52v 12.5ah battery pack, basic Bicycle Motorworks  369.99
   pack construction, 50a BMS and
   Samsung 25R cells
Luna Eclipse chainring            Luna Cycle           99.95
   Anodized black face                  
   Anodized gunmetal chainring
Lekkie Buzz Bars (crankarms)      California-ebike     99.00
SRAM EX1 144Lnk mid-drive chain   Amazon               28.99
 -OR-
KMC X9.93 (7 feet - more links)   Luna Cycle           57.75
Shimano HG400-9 12-36T cluster    JensonUSA            25.99
 -OR-
Shimano HG400-9 11-34T cluster    Amazon               24.60
Shimano RD-M591 9spd derailleur   Amazon               40.16
MicroSHIFT TS70-9 shifter         Amazon               23.99
ROCK BROS Wide Platform Pedals    Amazon               21.99
Raised rear deck
   Moose Skateboard Deck          Amazon               28.95
   aluminum unthreaded spacer     McMaster-Carr        10.88
      13mm OD, 25mm long, for 
      M5 screw (qty 8)
   countersunk M5 wshrs (qty 10)  McMaster-Carr         4.84
   stainless hex/flat head screw, McMaster-Carr         9.35
      M5x55mm (qty 25)
Front Rack
   Axiom Streamliner Front Rack   Amazon               47.99
   Delta AxelRodz skewers         Amazon               13.60
Wheel Build
   Sun Ringle MTX39 26", 30mm     Amazon              126.00
   Internal, 39mm external width 
   32H downhill rims (qty 2)
   DT Swiss 350 Classic Hybrid    Amazon              249.00
   rear hub, 148mm Boost, 32H 
   QR end caps for DT hub         Local Bike Shop      35.00
   Shimano HB-M475L front hub     Amazon               37.43
   DT Swiss Alpine spokes         Local Bike Shop     250.00



Mongoose – Chapter 4 (Motor Choice)

I have chosen a mid-drive as the best tool for the job on this bike.  It will not only be hauling cargo, it has to be able to do it in a steep hilly area.  If I was building for flat ground, a maintenance-free direct drive hub around 1.5-2kw would be the answer.

I’m not doing that though.  So mid-drive it is.  Now, which one?  there are plenty on the market and I have owned and in some cases still own several different ones.

Originally when I was planning this article, I was going to describe all of the major players in the market, and why I chose the one I did.  Instead I’ll limit my scope to the top two choices to better stick to the subject.

Second Choice: Bafang BBS02

This should be the first choice for most people.

I do want to say that as far as I know, as Bafang’s largest USA dealer, only Luna Cycle sells a BBS02 I would want to buy.  Luna uses their buying power to spec more robust controller internals that keep the BBS02 from frying its controller under sustained load … that was something of a known drawback of these motors in their heyday.  Also, Luna’s pricing strategy means their BBS02 kits are among the cheapest, if not *the* cheapest, BBS02 on the USA market.

Bafang mid drive motor kits are at the bottom of the the difficulty curve in terms of installation.  With one of these, you can have a bike up and running in an afternoon.  You’ll find a zillion Youtube videos and blog entries telling you what to do and how to do it, as well a multitude of experienced users in online communities ready to help you through whatever specific, quirky question you may have.

bbs02

Sidebar:  Bafang is a mainland Chinese motor manufacturer that is essentially the 800 lb gorilla of ebike motor manufacturers.  If you think companies like Bosch are market leaders, their volume is a fraction of Bafang thanks to their massive installed base in the Far East.  Bafang motors, while not perfect, are typically overbuilt, rugged, dependable and not very exciting.  Workhorses.  Chinese products have a reputation for ‘optimistic’ spec sheets and shaky quality.  Bafang is pretty much the opposite of that.  They underreport their motors’ capability – It seems one reason for that strategy could be so they can sell the same motor with different power ratings, with a higher price point for the ‘bigger’ one.  Again they are not perfect by any stretch, but for the beginner, working with a USA dealer of their products (do NOT be tempted to buy cheaper from an overseas vendor), its hard to go wrong.

The ’02 has been around for awhile, and what is sold as the ‘BBS02’ in the USA amounts to Bafang’s first effort at a kit offering (you can still buy BBS01’s – mostly overseas – and they are essentially a low-power BBS02).  It has long since been eclipsed in terms of power, and its aftermarket support for upgrades is not what you find for its successor, the BBSHD, but still the ’02 remains a rock solid product (IF you heed the caveats above).

A 750w or 1000w ’02 would have been my motor of choice for this project, except I already own two other BBSHDs.  As such I decided to keep one set of common parts across the fleet, so to speak.  I went with the more powerful next generation: the BBSHD.  More on that below.

Another Sidebar:  If you see these motors with the label ‘8FUN’, thats Bafang’s house label.  Usually those motors were manufactured for sale overseas in the Far East.  You can also find BBS02’s and BBSHDs with private labels on them.  Thats common.  Bafang will sell a private-labeled motor to anyone who will give them a big enough order.  Some vendors – like Luna Cycle, Bafang’s largest USA dealer – private-label and sell at a competitive price to builders.  Others just add their own label and crank up the price.

First Choice:  Bafang BBSHD

Bafang updated the BBS02 with the BBSHD (its called the BBS03 in some overseas markets).  The ‘HD is essentially more of everything you get in the ’02.  More robust.  More aftermarket support.  More power.  And more money.  But its still a bargain, with a bare motor running around US$450.  A complete kit providing you with everything you could ask for, plus programming upgrades (Bafang motors have a robust capability to customize their behavior, ranging from total power output to precise tailoring of each of the 9 pedal assist levels). should run you about $750 before you get to the battery.

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Myself, I paid less than that simply because I already have two other bikes that use this motor, and I have quite a few spare parts on hand.  I can just pick stuff up off the parts pile for zero added cost.

Stealth

You’d think this motor sitting in front of the bottom bracket like a giant wart would be obvious to people, but it turns out it isn’t.  Oftentimes, I get asked “Is that thing electric?” and when I point out the motor I see the questioner’s eyes light up in surprise.  So visibly it doesn’t stand out to people.  Especially since I keep the battery in a triangle bag – not to keep that part stealthy, but because that makes it easy to haul out and carry into the store with me.

The next component of stealth on an ebike is sound.  How loud is this motor?  To all intents and purposes, the motor is completely silent.  If you fire it up on the workbench, they definitely make an audible whirring electric-motor noise.  But on the road, even at the slowest speeds with no wind noise in your ears… you’ll be lucky to hear a slight hum.  And anyone next to you – like that poor sap you cruise by while he struggles up the hill in his analog bike – they won’t hear anything either.

Mongoose – Chapter 3 (Motor Types)

I am making a particular choice with regard to the motor I am putting on the bike that is the subject of this series.  I’m familiar with the various types – their strengths and weaknesses – but for the sake of the reader who may not be, I’m going to do a quick-and-dirty on each mainstream type.  If I’m not covering that motor type (looking at you, friction motors)  there’s a good reason that further research on your part will reveal.

There are three types of motors that make it into the mainstream of the ebike world

  1. direct drive hubs
  2. internally geared hubs
  3. mid drives

Direct Drive Hub Motors

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DD hubs work with no moving parts and are effectively maintenance free.  The axle of the bike is also the axle of the motor itself, which is just a brushless DC motor with magnets running around the outer case of the motor (the rotor), copper windings wrapped around the interior stator etc.  Apply electricity and the stator repels (or attracts) the rotor, which results in the rotor spinning, and there is your powered motion.

Relative to the other motor types, DD motors produce much less torque.  That means there’s not much oomph behind the motor and you either help it along with a lot of muscle if you want acceleration, or you sit back and wait for it to spool up (in a worst case scenario you are hoping to get to the other side of the intersection before the light turns red again).

To get around that lack of torque, you use a really big motor and a really big, powerful battery.  Once you get into the 3kw-5kw and greater range, with a 60v or higher voltage battery, now you are talking about a bike that is accelerates acceptably (or insanely depending on how big you went) and can climb hills easily, even loaded with extra people and groceries.

The drawback to the above is that big motor, with its big metal magnets and large amounts of copper wiring is … big.  Heavy.  And so is the 2XL battery you needed to get big power out of that motor.

For a serious bike that can carry cargo, passengers etc. up a hill at speed, you are probably talking about a 125 lb bike, with a lot of that weight inside of the back wheel.  The battery is likely going to be on your rack as well (not your cargo) reducing your carry capacity.  At lower power levels (particularly those that are less illegal than the above noted 3-5kw) you aren’t looking at that kind of weight penalty.  But you get low performance as a result.  A direct drive motor that is not in the hi-power league will need a long run-up to get to cruising speed.  And if you want to climb a hill… well its the worst choice for that job of the motors you can choose from unless, again, you go big.

If you want to research the ins and outs of this type of motor further, you need to also look into ‘torque arms’, why they are needed with this kind of motor, and when.

Geared Hub Motors

Geared hub motors do a good job of providing more torque than DD hubs at similar power levels.  They do this by installing a planetary gear reduction inside the motor which connects the stator to the outer casing.  The motor spins nice and fast as it likes to.  The axle in turn spins the planetary gear.  This finally turns the outside casing and the wheel at a slower speed, so you and the bike can go down the road at a comfortable rate of acceleration.

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I opened this motor up for its semi-annual re-grease.  I also needed to deal with that rust you see.

Geared hubs tend to be lighter than their direct drive cousins, which helps with range and acceleration.  At sufficient power levels – lower ones than what a direct drive motor needs to do the same job – a geared hub gives some pretty good torque.  80 Nm in the case of the above pictured motor.  Mate that to a 35 amp controller and a commonly available, medium-voltage 48v battery and you have a really peppy ebike.

Whats the down side?  Those nylon gears will take a lot of abuse (really a lot), but they won’t last forever.  Especially if you subject the motor to regular extended hill climbs, or you are subjecting it to a lot of stress… like a full cargo load.  If you try to solve this problem with steel gears (Chinese Ali Express specials that may not have been the best re-engineering job) you find out why motor manufacturers use nylon:  noise… and metal shavings.

You will also have to open those motors up every few thousand miles and re-grease them, as the grease perishes over time.  Lastly, geared hubs really do not exist at the higher power levels (most I have seen are the MAC motors peaking at around 1500w with a special controller to get them up that high).  Any higher than that and the gears really can’t handle the power.  Unofficially, A Bafang G060 fat motor like in the picture above can handle a 60v battery and 35a controller that delivers 2.2 kw peaks … forever.  But I wouldn’t bet my motor’s life on it being able to do long term that under severe loads like cargo duty or living in steep hills.

Final thoughts on hub drives

Both geared and direct hub motors power your bicycle directly through your hub axle.  They are the hub in fact.  What this means is, your bicycle powertrain is entirely irrelevant to what the motor does.  The power to the ground is transmitted directly from your axle.  In fact, if you want to have some fun with your hub bike, you can remove the chain.  Then ride down the street with your pedal assist turned on, and pedal the bike.  It will work just great.  Of course you aren’t getting any exercise and likely you don’t want to ride like this, but it illustrates the fact that the traditional bicycle powertrain is not needed.

Your pedals and chain now exist almost solely to provide you, the rider, with exercise.  You put as much effort into pedaling as you want, and that can be just mild pressure or pushing hard the way you would riding an analog bike.   It is now the motor thru the axle that is doing the real transportation work.  This fact is not lost on ebike manufacturers, and this greatly reduced duty cycle means hub-based ebikes tend to have cranks, chainrings and rear clusters that would not survive long if given the hard life an old-school analog bicycle receives.

Geared hub motors need torque arms just like direct drive hub motors, albeit not so much at the lowest power levels (i.e. 250w and 350w).

Lastly, both types of hub drives have this significant benefit:  they don’t require any special knowledge or care to use.  You can jump on the bike as a complete newbie and start riding.  So long as you aren’t riding some kind of hot rod that is hard to control, you already know everything you need to ride happily down the road and not cause any issues.  That makes hub motors of one sort or another preferred for most casual riders who are not challenged by their terrain.  That isn’t true of your more powerful mid drives, but I’ll get to that below.

Mid Drive Motors

‘Mid drives’ are known as such because the motor sits at the middle of the bicycle.  Typically replacing the bottom bracket.  As much as hub drives dominate the lower-cost, DIY and upgrade ebike markets, mid drives dominate the big-name commercial-manufacture market.  In particular, and most telling as to the benefits of the mid drive, E-MTB’s are exclusively mid drives, and for good reason.

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Yes, this is an ebike (and yes, its mine).  Look closely at the chainring.  See the mid drive motor hiding behind it?  This motor peaks at around 440 watts of final output which in the USA is well under the legal limit.

Mid drives work on an entirely different principle than hub drives.  Hubs, as we noted above, power your bike thru the axle, and your drivetrain is just along for the ride.  In terms of assistance, the hub drive bike is a 1-speed, and this is part of the reason hub drives don’t do so well in hills or fast acceleration, unless you start getting into big power.

But a mid drive works just like you do:  It pours on the power thru the bicycle chain.  That means if you hit a hill, you can downshift into a lower gear, keep the chain spinning fast and get up the hill more easily.

Gee thats great.  And since much of the world has legal limitations to 250w of final drive power, you can’t really put enough power into the system to break anything.  An average person in good shape can put between 50 and 150 watts of power into their drivetrain during a ride.  Thats what an old-school analog bicycle drivetrain expects to put up with.  250w isn’t a whole lot more than that (a trained cyclist can pour on roughly 400w or so… and sprint briefly up to around 1500w… which is still not really enough to make a slice of toast).

About that 250w limit… First of all, here in the U.S. that number is typically “less than 750 watts” according to our national manufacturing/consumer safety standard.  Many of the individual U.S. states have vehicle codes that separately define what is an ebike vs. a moped vs. a motor vehicle.

Beyond that, in the last year or so we’ve started to see rebellion from major E-MTB manufacturers against the almost-a-joke 250w EU limits.  What we are seeing is the complete disappearance of any mention of wattage output.  Instead all you see references the Newton Meter (Nm = torque) output of the motor.  Unstated is the *ahem* potential for the motor putting out more than 250w.

Really, torque output is what matters in terms of figuring out how much assist you are getting, and mid drives just pour on the torque.  A Bafang BBSHD, the de facto volume-sales king of the American DIY market, puts out 160 Nm continuous torque when it is fully utilized.  That is about double the momentary peak of what the big geared hub pictured above is capable of (and that geared hub is among the biggest of its genre).  Direct drive hubs are in the 40-60Nm range unless you go all Mad Max on the power levels.

So … easy choice everyone needs a mid drive!  Well, not so fast.  With great power comes great responsibility repair bills if you don’t use your head.  That means build it right and learn how to ride it.

Remember the wattage output a normal human is capable of?  The level that a quality drivetrain is expected to be able to handle?  Well, the above referenced BBSHD in off-road mode, pouring out those 160 Nm, is feeding about 1500-1700 watts to the drivetrain.  Continuously.

You want to figure out how much wattage is going to your motor?  The formula is Volts * Amps = Watts.  So a 52v battery running at its nominal 52v rating, multiplied by a BBSHD running at 30 amps is… 52*30=1560 watts.  At a full charge that battery is 58.8v, so 58.8*30=1764 watts.  Continuous output.  Yes, really.

So, when we build a DIY mid drive bike, we first want to buy parts that are meant to take this kind of punishment.  They are out there on the market but frankly a lot of DIY builders, riders and even most ebike sellers are ignorant of this.  You want:

A good narrow/wide front chainring

Made of 7075 alloy most likely, but if you can get a steel ring, do it (Wolf Tooth is the only one I know of and they only come in 30T and 32T sizes).   This style of ring typically has wider, taller teeth that eliminate chain dropping issues.  In particular rings made specifically for mid drives are sold by Luna Cycle, who manufactures their own here in the USA, and Lekkie, a New Zealand company with a stellar reputation who sells thru ebike vendors everywhere.  The latter two names are focused primarily on the BBS02 and BBSHD markets although Luna does make rings that will work on other platforms.

An ebike-specific chain

The interwebs are filled with complainers crying about how their chain snapped.  When you ask how many of them re-used their $6 stock chain, or who just bought a ‘nicer’ bicycle chain, the numbers pretty much climb up around 100% of chain failures (chain alignment will be dealt with below).  E-bike specific chains in various widths for various speeds are sold by KMC (my favorite is the X9e/E9 9-speed) in 136 link lengths.  SRAM’s EX1 ebike group has its own 144 link chain.  Lastly there are the Connex chains by Wipperman.  The common factor in why people don’t use them (besides not knowing they exist) is price.  These are US$35+ chains (you can buy smart and get them for less if you know where to shop).  But… They.  Don’t.  Break.

Lastly, you can find a specialty vendor and buy a specific length of chain all in one piece, so you don’t have to section two chains together (if you do that, it creates a potential weakness at the joining point).  This is by far the most expensive option.   I bought a 7-foot length of 9-speed chain from Luna Cycle and it ran me about $60.  But my Mongoose Envoy, with the long-cage Deore derailleur I added, needed 152 links to be set up right (I keep a 144-link SRAM EX1 as a hot spare and it will work fine in a pinch).

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The KMC X9E.  Those mushroomed pin ends will be torn off if you use a chainbreaker on them, so if at all possible just remove links to make it shorter, don’t add any to lengthen.  re-attach with master links.

A steel cassette cluster

You have two choices for this, generally.  First is the SRAM EX1 cluster that is an 8-speed, has a range of 11-40, is made of tool steel and meant to be used with the EX1 shifter which will only shift one gear at a time.  The rub is the cluster alone runs about US$385.  Its worth every penny (I have one on my E-MTB, so it had better be), but that cost is insane.  How about spending US$15-25 instead?  Just buy any cheap Shimano rear cluster.  In particular the HG-200, the HG-400 or the HG-50.  All in 8 or 9-speed.  They use steel, not alloy, cogs, and most importantly the entire cluster is welded together into a single unit so the punishment dealt to the cassette body is distributed across its entire width.  These Shimano clusters are an excellent example of something that is awful for an analog bicycle and highly preferred on an ebike, where durability is vastly more important than light weight.

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This is the 12-36T 9-speed cluster I am using for my Envoy build.  Don’t look for any bolt heads to allow disassembly.  Only the 12T cog is separate from the 1-piece body.

A steel cassette body

Here again, what sucks for a bicycle is great for an ebike.  A steel body will last.  An alloy one won’t.  Take a look below.  On the left is an alloy DT Swiss cassette body with about 1600 miles on it.  It comes from a DT350 hub, which is at or near the top of the line as bicycle component brands go.  The cassette cluster I used was a welded steel Shimano, so those notches you see still tore into it despite the gentler damage the welded cluster does.  I almost exclusively used the 11T small gear on this bike and on the far right you can see that section is torn into further than the rest (the last cog is free floating so no help from the welded together body on that one… we’ll come back to this and discuss further below).

bodies
eek… and this happened with a 1-piece cluster, too.  With a nicer cluster that has removable cogs, the damage would have been much worse.

 

On the right side is a steel version of that DT350 cassette body.  Unlike the alloy version, it is much heavier – and I expect it to last forever.  Worth noting:  DT Swiss has now released a “Hybrid” version of the 350 hub specifically meant for ebikes.  It includes the steel cassette body out of the gate as just one of its durability improvements.

Get a ‘star ratchet’ rear hub

There aren’t many of them.  DT Swiss, Chris King and Hope are the only big names that sell freehubs with this sort of splined engagement instead of the traditional 3- or 4 pawls.  A splined engagement provides dramatically better contact with the hub from the cassette.  See that nearly-ruined cassette body above?  the stock 18-tooth star ratchet wheels inside went right back into the bike with the new steel cassette body… they were still perfect.  Since DT’s patent on their system ran out, other makers have begun to use it and you can now find star ratchet replacements and complete hub systems on Ali Express, EBay etc.  Myself, I still buy DT Swiss 350’s.  But you can save hundreds with the Chinese hubs.

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Learn how to ride it

I mentioned this briefly above.  With a couple of narrow exceptions (don’t mash the throttle going up a long hill) you already know how to ride a bike that has a hub drive.  thing is, no matter how seasoned and smart you think you are, chances are excellent you are clueless on how to ride a mid drive.

Here’s the short version:  Keep the motor spinning.

Now the longer one:

Keep the motor spinning

Lug it and the torque that is pouring out of the motor will focus on tearing your chain apart, or taco’ing your chainring or rear cog, not to mention generating enormous heat (remember the nylon gears in a geared hub motor?  Guess what?  Mid drives use nylon gears inside too).  Even a BBSHD set to off-road power levels is not strong enough to tear up your cogs or chainrings.  But it can snap a chain that you are mistreating.

When coming up to a stop light, downshift.

Always.  Either that or stay in a gear that is in the middle of your cluster so that when you start up again, the motor can spin up quickly without any brutality being visited on the chain.

When coming up to a hill, downshift.

Always.  Can you guess why?  Thats right so you can keep the motor spinning.  And ‘coming up to a hill’ does not mean ‘already started up the hill’.  Anticipate and shift in advance of the climb.

When you want to go faster, upshift.

But wait until your motor is spinning fast before you do.

When you up- or downshift, NEVER do so under power.

Shifting while pouring huge watts into your chain is an ugly thing.  You will recognize your mistake the instant the result hits your ears.  It won’t kill the chain outright, but as you hear that chain smash from one cog to another you will know your bike hates you very, very much.

You can invest in a gear sensor that will protect you automagically from this.  It installs inline on your shifter cable and, when it senses the tiniest amount of movement, it cuts power for an instant.  The result is a safe shift.  I have them on one of my three BBSHD-equipped bikes and it works great.

But for the two I don’t, I just stop pedaling/freeze my legs, click-shift and then do a single crankarm rotation to seat the new gear at low power.  Result is perfect shifting and only a minor blip in pedaling rhythm.  But that is a learned behavior.

Others have perfected the use of the brake levers as a clutch where they only slightly actuate the lever.  This triggers the safety cutoff which in turn allows a safe shift.  If you are like me and you cheaped out and don’t have safety cutoffs, this won’t work.

Keep chain alignment as straight as you can

Mid drive motors tend to work in a lot wider range than humans do.  So you can leave the motor in a gear that would be too low for your cadence and let it spin away like crazy… it actually likes it that way.  So, this piece of advice is partly about how you ride the bike (i.e. what gears you let it sit in) but also about how you build it.  You really only need three or four gears in the middle of your cluster on a mid-drive-powered bike.  You want them to be the ones that let the motor spin fast.  You also want the cogs the bike is happiest to not be cockeyed, front to back (i.e. bad chain alignment).

On an analog bike you can get away with a lot, since you are only feeding back 150 watts to it.  Feed it 1500 and that sideways-skewed chain will become a saw and chew right through your front chainring and rear cog teeth.  Be smart when you build the bike, and learn in your first outing or two whether there are any problem gears you should stay away from.  There are all sorts of offset chainrings (and 1mm and 2mm shims) available for a BBS02 and BBSHD… they cost money, but spending that money now means not spending it later after you have walked home.

What happens if you don’t do some or all of these things above to install and use a DIY mid drive bike properly?

Well of course it means you go on the internet and blame the equipment.  Its not your fault you used the wrong components.  And its not your fault you didn’t know how to ride it.  Its the mid drive’s fault.

This is the secret message hiding behind a lot of “don’t buy a mid drive” posts on the interwebs.

… If you build with appropriate components, and ride it smart, even a high powered mid drive will essentially last forever.  Yeah sure you will wear out the chain and rear cluster in say three thousand miles, the smallest cog in half that, and the chainrings in 10.  But thats peanuts considering how many miles you put on the bike.  How much does an 11T cog cost (about $6)?

Wrapping it all up

Whew that was a lot of typing.  This article lays out in broad terms the characteristics of each motor type.  It doesn’t get into what kind of riding each is good for.  Lets finish with that:

Direct drive hubs

  1. Lower/legal power:  maintenance free cruiser bikes for paved streets where speed and acceleration are secondary to bulletproof reliability.  Want a bike for Mom?  Your kids (who aren’t future BMX pro riders) A direct drive 250w-750w hub motor is a viable candidate.
  2. High power: Sky is the limit in terms of power:  Light electric motorcycles only thinly disguised as bicycles.  Can range across a wide variety of cycling genres including cargo, dirt and pavement.  But big and heavy.  Single speed is usually a bad choice for offroad/singletrack riding but there are exceptions, in particular the famous B52 Stealth Bomber and similar.  They have so much power they use brute force to overcome the weight issue.  But you’d never pedal one of these things.

Geared Hubs

  1. The Swiss Army Knife of motors.  Not ideal for anything but good for almost everything.  Only runs into trouble under very heavy use, particularly in an area that is all hills.
  2. Their only drawback is maintenance if heavily used.  Semi-annual teardowns to re-grease a high mileage motor is advisable.
  3. Bad choice for singletrack/offroad.

Mid Drives

  1. Best choice for singletrack/offroad
  2. Got hills?  Mid drive.  Strong power delivery without significant weight added to the bike.
  3. Good for hard-use applications.
  4. Arguably the most efficient in terms of power consumption.
  5. Requires the most attention to build detail and demands the most attention and learning from the rider.
  6. Even with proper use and components, more wear and tear on the drivetrain than any other option.
  7. A kid who gets his right hand caught inside the chain of a mid drive is going to be named ‘Lefty’ from that day forward.

Mongoose – Chapter 1 (Raised Deck)

The Envoy’s rear rack is about 27″ long and 6″ wide.  For a cargo hauler, I wanted it to be able to handle more.  The rear deck is very low over the back wheel, and thanks to my inseam, the seatpost is going to be set high.  Add all that up and you have a lot of available vertical room for cargo mounted on top of the rack.

We can do better than 6″ wide.  Especially since Mongoose has dotted M5 bosses seemingly everywhere on the rear of the frame.  I just did a quick count and saw 32.  And thats not counting the 4 additional lower rack bolts you can piggyback onto.  Also not counted are the 12 brazed-in hook mounts for the included panniers (that I’m only temporarily using due to their frustrating 6″ depth).  So what does that come out to?  This bike has 50 (fifty!) discrete attachment points.

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Visible here:  4 of the 5 sets of bosses that pepper the top of the rack.

This thing is begging for home brewed solutions so lets come up with one.  I don’t want just a regular deck on top of the rack, I want it to be wider than six inches so its a bona fide cargo platform.

My buddy Houshmand finished up his custom cargo bike build a few weeks ahead of me, and one of the things his framebuilder did was haul a skateboard deck off of his shop floor and decide it looked like a decent rack deck.  I agreed and informed my friend I would be stealing this idea.  So I did.

I started looking for a bare longboard deck.  I found decks as large as 48″x9.5″ for a dancer style, but it was something that doesn’t quite have that cool skateboard look I was going for.  I ended up settling on a 33″x10″ double kick deck that, while it doesn’t fully extend across the entire rack, its overall concave surface provides a sort of natural cradle for the duffel bag that will be cargo netted down to it.

The shorter 33″ deck also isn’t long enough to use all five sets of M5 bosses, but the four it does use it fits to perfectly.  Part of the concept I wanted was an overhang to the rear to ensure my back side stays dry if riding in the rain, and the board is bolted down to its most rearward flat location as a result.  Really it would not have fit well further forward or backward unless I shifted to the front four bosses and moved it quite a bit forward.

For hardware, I went to my old-standby for weird fittings: McMaster-Carr.  I know from previous projects they sell metric spacers in a variety of sizes and increments, and I had no trouble finding them in a wider 13mm diameter size.  However, my usual choice of stainless steel resulted in a hefty price tag.  I found they offered the same sizes in alloy which is perfectly fine for this application.

My original choice of 30mm spacers turned out to be problematic as well.  That size in 30mm x 13mm diameter isn’t stocked, so delivery is measured in weeks.  However, 25mm was available for next day delivery, and the cost per unit was about half what the 30mm’s would cost me.  Sold.

Ordinarily I will use socket caps on a job like this, but their squared-off and tall caps aren’t the best fit here.  I also did not want to mess with countersinking holes on the deck itself.  Besides, for durability I wanted metal to metal contact, not metal to wood.  In the end I decided on countersunk Phillips head bolts (50mm), with countersunk washers sitting on top of large-area stainless washers – the latter to distribute the clamping force across as much of the board as possible.  Under the board, between it and the alloy spacer, is another large-area washer to help further stabilize the connection.  Multiply this by 8, torque to a modest 4 Nm (the threads in a frame boss, which could be alloy themselves, are not the sort of thing you want to apply serious torque to) and you have something solid enough to sit on, that is completely rattle free.

After this article was written, I substituted longer, 60mm hex drive screws.  the added length gave me max thread engagement in the boss, and the countersunk hex head… looks nicer.

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Those bolt holes look a lot more even than they really are.  Thats the frame’s doing not mine.

Drilling the board to get the result above was a minor adventure.  I discovered quickly that the frame bosses were all, well… totally uneven.  You might be able to see a little of that in the picture above but I assure you the photo above is deceiving.  Its worse than it looks in the picture.  Trying to graph out a precise template that would then map perfectly to the board was clearly a Pain in the ass I didn’t want to suffer.  So I tried to think of a way to put something pointy in the hole so I could see marks directly on the board.  Stuff like finishing nails or similar just didn’t have the precision to sit perfectly centered in the hole.  And then I remembered grub screws.  “What the hell is that?” you ask?  Let me just show you.

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Behold, the M5x16mm grub screw made of the finest Chinesium. $7 for a bag of 16.

They were delivered to me next day by Amazon.  I chose the longest ones I could get my hands on so I would have plenty of thread engagement to get them to center up.  And they worked splendidly.  After I used painters tape to cover my likely drill areas on the deck, (helps keep the wood from splintering), all I did next was screw in one of these screws, pointy side up, into the outer four boss holes, I then gently centered the board atop them just right (I tried measuring frame overhang and in the end just eyeballed it) … and pressed down.  Instant markings on the board, and my drill holes are already started.

Next I drilled the four marked holes, flipped over the board and test fit the screws to the rack.  Perfect match.  Now for the four inners:  I screwed the board down with the four outers I just drilled.  This gave me perfect positioning on top of the four inner holes … which now had pointy grub screws in them.  This in turn pressed the board onto the pointy bits.  Once done, I again had a set of marks that were perfectly aligned with an installed board.  Using the new marks I drilled again and perfect fit again.  The rest was just inserting the rather fiddly combination of spacer and washer under the board.  

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On the road this new upper rack is rattle free, and so solid you can grab the bike by it and drag it around without worry

The end result works well I think.  I want the load’s center of gravity moved back a bit, effectively giving me a longer tail than I really have, for the top load, at least.  Additionally I still have a fair bit of unobstructed rack up front to play with.  When I put together my pannier solution, I have the option of using those standoffs, as well as what is now the ‘lower’ rack surface, for anchor points.

The Mongoose Envoy Project

I’ve wanted to build a cargo bike for some time.  I’ve gone halfway a few times, with Frankenbike (front and rear racks, plus a handlebar basket on fat 4.9″ tires, with a 48v, 20a geared hub drive) being the closest I have gotten to the mark.

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Frankenbike on the job. And yes… that frame really is Max’s MFP Yellow (google it)

When Mongoose began offering a mid-tail ‘urban’ frame — in a complete bike that retails for less than half of anything similar on the market —  I had to jump in and give it a shot.

So here it is, fresh out of the box in its stock form.

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Which lasted about a day.

As I write this, the bike has had its cranks and bottom bracket removed, its chain and derailleur detached, the brakes have been upgraded, and of course there’s the double-kick longboard raised upper deck …

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… and thats only the beginning.  With that said, this bike is going to be left outside unattended (but securely locked) at local shops.  I don’t want to pour money into its components in case someone manages to make off with it.  So I will be keeping the changes to a minimum – or at least minimum for me.  I’ll be doing just what is needed for improving drivetrain reliability, safety and of course, adding a motor.  And a front rack.  And a suspension seatpost.  But that is it.  Really.

EDIT:  As you can see from the content in the other chapters of this project… all that talk about keeping things under control went out the window.  In the end I decided to just go for it and ended up with what I think is a top line cargo hauler capable of handling 450 lbs+ total system weight (or more… 450 is just how much I have loaded so far) with ease, as well as being an easy commuter.

The Day After

So… I started this blog – and abandoned it – something like 7 years ago (I deleted all the posts except the very first, keeping it for posterity’s sake).  I’m resurrecting it now so I can have a more permanent platform to post stuff that I can link to from various Facebook groups I belong to… Its almost a waste of time to describe anything in detail on that medium as it lends itself to a couple-three sentences, tops, and whatever post you make is gone from sight within a day.

We’ll see if anything worthwhile shows up here.