How I Bleed My (Magura) Ebike Brakes

This is sort of a companion post/supplement to my Mongoose Big Brake post (go there for links to resources on cable cutting and bleeding).  Worth putting up separately as its a topic that comes up from time to time in my travels, and putting it here will let me just link it into a discussion.

These directions assume you are working with Magura brakes.  However, they should translate reasonably well for a generic application (for best results find specific instructions for your model).

Next time I do it, I’ll take some pics so I can spruce up the page a bit.

  1. Toss a small towel on the ground under the caliper you are bleeding.  Just in case Something Bad happens.
  2. Leave the caliper on the bike.
  3. Get everything ready because once this process starts oil is going to be dripping out of and onto things.  ‘get ready’ means in part to get your lower syringe with the bleeder hose fully filled in advance, with the hose filled with fluid not air bubbles.
  4. Loosen the lever on the handlebars and re-orient it so the brake reservoir is level to the ground
  5. Remove/open the top bleeder.  Since the bottom bleeder on the caliper is closed, nothing is going to be leaking out yet.  Attach the top syringe/reservoir.
  6. Open the bottom bleeder and haul ass to get the syringe screwed onto it.  I usually manage to get only a small dribble onto the caliper.  Tighten the syringe onto the bleeder with an 8mm wrench and make sure it is on tight (not ‘crank arm’ tight…  go just a skootch past ‘snug’).
  7. Do one cycle of bleeding, bottom to top and back to bottom, gently, to establish vacuum and  ensure you have a good setup and don’t have any leaks or surprises.  While doing this, periodically tap the caliper and fluid reservoir in the lever with something firm like a *small* dead blow hammer (or the handles of your pliers) to help dislodge any stuck bubbles.
  8. With a full bottom syringe, push the fluid up through the system… hard this time.  Not enough to break the syringe or do something crazy, but enough so you can see the oil well up in a wave in the top syringe.  On the return stroke back down, be gentle so you don’t suck any air in via the edges of the top syringe seal.
  9. Repeat Step 8 until you no longer see tiny occasional streams of bubbles.  You can stop when fluid is in the bottom syringe, drained from the top syringe, with just a bit of fluid in the top syringe (say… 2-3mm or so) for the next step.
  10. Using the 8mm wrench, break the lower syringe loose and as soon as you are able, spin the thing off the bleeder by hand.  Have the bleeder screw ready to pop back on asap because fluid will start dripping out immediately.  Important:  The little bit of fluid you left in the top syringe will keep the reservoir topped up unless you screw up and are too slow to get the bleeder bolt back on..
  11. Remove the top syringe and replace the cap screw, taking care not to overtighten … its a plastic bolt and need to ONLY be snug (0.5nM, officially).
  12. Mop up.  Chances are good you only got a little on the caliper from Step 9.

Mongoose – Chapter 7 (Odds & Ends)

This section holds various bits that I changed that do not fit anywhere else or do not merit their own Chapter.


The 76L (each) Panniers

This needed its own writeup and, since it happened after the bike and these chapters were finished, got its own pair of standalone posts.  In the months since I first put them together, they have proven perfectly durable and saved me about $200 over commercial bags of about the same size.  Big And Cheap: DIY Cargo Bike Bags.

Front Rack

This bike cries out for a front rack.  It is after all a cargo bike, and loading it up is part of the game.  Sure, weight on the front wheels is not conducive to stability, but if you have ever done a bicycle tour, you’ve learned to deal with the issue.  Besides… for a grocery getter, a front rack with a couple of nice big panniers is perfect for bags o’ potato chips, loaves of bread or similar high-volume, low weight delicate items.  I do have to admit… one time I loaded the front bags up with soup cans.  That made for a hair-raising ride home.

Normally on my fat bikes, I use an Axiom Fatliner rack, which is rated for a whopping 50 kg (110 lbs).  For this nonfat bike, the Axiom DLX Streamliner is the next best fit, and it too is rated for 50 kg.  Now… you’d be out of your mind to load that much onto it, but its nice to know it can handle a lot more than I will ever put on.

Axiom racks use an oddball kind of armature that threads thru the QR skewer and shifts the rack rearward a bit.  In this case, I am going to take a rear rack and stick it on the front… so those mounting arms will shift the rack further forward.

Here’s where it gets weird:  A common complaint on this rack is the arms add *just* enough width to make it difficult or impossible for your skewers to fit over the arms.  I had exactly the same problem.  No way was it going to fit.  I tried using Axelrodz skewers whose front skewer was – on paper at least – long enough to work.  It wasn’t.  So I came up with an alternative that ended up, if anything, working better than if things had fit right (and still used an Axelrodz skewer).  Look at the front axle closely in the pics above.  It doesn’t look quite right…

I keep a supply of stainless steel 5/32″ fender washers on hand as they are cheap, easy to buy by the box at Ace Hardware in any US town, and a perfect fit for an M5 bolt.  More snug than an actual M5 large-area/fender washer, in fact.  Since they are large-area, they are just a smidge wider than the skewer’s contact area with the fork.  They are also just as wide as the contact area of the rack mounting arm.  If I stack a half dozen of them on the axle, the rack – which was meant for a 135mm rear mounting – fits much better, with perfect full-contact with the washers.  If I stack another half dozen or so on the outside of the rack arm, then clamp down a REAR 135mm axle rod… Job done.  If I remember right, I used 6 washers on the inside, and 6 more on the outside.  I set it up so there is absolutely full thread engagement on the rod.

Doing this also eliminates the risk of someone walking up, flipping the QR skewer off and wandering off with my front wheel.  An M5 hex key lets me pop off the wheel easy-peasy, almost as quick as a quick release.

Parts List:

  • Axiom Streamliner DLX rack
  • Axelrodz QR skewer replacements
  • 5/32″ stainless steel fender washers

Thudbuster LT

I have maybe 3 of the Thudbuster Short Travel posts on other bikes, and one Satori Animaris – a $50 alternative that I found well worth the money with virtually no downside vs. a Thud ST.  But for the Mongoose, I decided to go to a Thudbuster Long Travel post.  I bought the XL version which is a full 450mm long.  Not so much because I need it (on this large frame, a normal 400mm would have worked fine) but so I can potentially use it on a smaller frame if I ever need to swap it out.  At about $150 a pop these suspension posts are pricey.

Having many thousands of miles under my … belt … riding short travel suspension posts, this is my first long travel version.  I wish I had bought long travel all along (and in fact since I got this one, I retired my Satori Animaris for another Thud LT on my daily driver bike).  The trick to getting this to work right is to adjust the pre-travel screw so its already pretty stiff when you give it a shove with your hand or upper body while standing next to it.  When putting your full weight on it, it will move quite a bit but you won’t realize it.  But your bum will.

I installed a thudglove neoprene cover.  Not so much to keep it clean – its a city bike after all – but to make my use of a $150 seatpost a little less obvious.  I took a black sharpie to the white lettering on the glove to tone down the advertising volume a bit.

I also used a seat leash.  These are not ironclad theft protection, but they will stop anyone from a quick grab, and if you have a bolt-on seatpost clamp like I do, even loosening that will not let someone walk away with the seat.  They will have to disassemble the seat from the post itself to be able to walk away with the seat, or the post, or both.  Of course, if the thief has a decent set of bolt cutters, or an angle grinder, they’ll make short work of this, but the leash is a great security measure against all but the prepared, dedicated thief.

Parts List:

  • Thudbuster Long Travel XL (450mm total length) in size 27.2
  • Thudglove
  • Seat leash cable for a bit more theft protection

Dual Seatpost Clamp

A seatpost clamp?  Really?  Picking nits, are we?  I’ll explain.  This is kind of a big deal, actually.

The Envoy comes with a typical quick-release seatpost clamp.  It works, but you figure out real fast you have to absolutely clamp the bejesus out of it to get the post to stay still… Unfortunately it turns out the seat tube of the frame is just a hair over sized.  So the seatpost is going to require unusual amounts of force to fix it in place.  This is not so great for the frame.

Its even worse when you want to substitute in a quality seatpost; in my case a Thudbuster to soften the ride.  The Thud’s ribbed-but-polished-anodized surface is just slick enough that the QR post clamp simply will not work unless I clamp so hard I fear for the frame’s survival.  This is after all an alloy frame, and alloy often prefers to break before it bends.

I did manage to get myself a thicker wider-clamping-area carbon fiber clamp on Amazon for about $12.  When clamping that to frightening levels (and only then) I found it could hold the Thudbuster steady… although I did not test it for more than a couple of rides.  I replaced it with this doodad as soon as it arrived:

seatpostClamp
You want the exact sizes shown in the image above.  27.2mm for the seatpost and 31.8mm for the seat tube of the frame.

I bought it on EBay for about $25 (You can also find them on AliExpress.  Amazon sells the ‘KCNC twin seatpost clamp‘ for about $40).  It turns out dual clamps exist because carbon fiber seatposts tend to slip.  Why does this design fix the problem?  Clamping both post and tube solidifies the connection.  Considerably.  I have had no shift whatsoever in my post height since installing this piece, and I didn’t have to put undue stress on my not-replaceable frame.

You may have to do a little extra searching to find this specific type of “double seatpost clamp” versus one that simply is thicker and has two bolts.  Those frame-only clamps put all the extra stress on the frame which is not my preference.


Ursus Jumbo Kickstand

The stock kickstand is a good product, but when you have loaded up the Envoy after a Costco run, you’re on shaky ground even if you are absolutely level: Bump the bike wrong or let the handlebars with their laden panniers flop around, and the bike can easily tip over.  It does after all, weigh probably another 140 pounds or so and thats before you climb on.

I asked around at the Cargo Bike Republic group on Facebook and one of the options was the Ursus Jumbo kickstand.  Its an $80 option, but believe it or not its not the most expensive option by a long shot.

IMG_20191019_154232
You can see the extra wide Ursus stand above.  In this picture, the bike is loaded with well over 100 lbs of Costco booty.  Note I loaded the bike way too close to the rack. I was unable to roll it forward to raise the stand.  Next time:  turn the bike completely around before loading.

The stock stand spreads about 7 inches, or just under 18 cm.  The Jumbo on the other hand spreads over 40 cm.  It also keeps the front wheel only *barely* off the ground.  Perhaps a half inch.  Thats a good thing as I see it.  Raising the kickstand while the bike is loaded is a different approach to the stock stand, where you push the bike forward and gravity + momentum force the stand to retract (with a thunk, and the bike plops down at the same time).  With the Jumbo, you physically pick the bike up at the front and retract the stand while its in the air.  Different, and more difficult for sure.  But the added stability is dramatic.  Its worth the extra effort.

 


Jones Handlebars

With clear/soft Kraton grips. 

I’ve taken to Jones H-Bar handlebars on all my bikes after an inattentive driver hit me back in December of 2016.  The resulting injuries left me with wrist pain that I can only deal with for short rides.  The Envoy has a similar handlebar design, 710mm wide with a less-pronounced 27-degree sweep vs. the Jones 710mm and 45 degrees.  Unfortunately I’ve decided the sharper angle of the stock handlebars is too much for me.  They are a good effort from Mongoose to provide a well-functional bar out of the gate… but if I want to go on 15+ mile commutes the discomfort is unfortunately spoiling the ride and lasting well into the next day… when its time to go ride again.  The Jones bars are a known fix to this problem for me.  Highly recommended on general principles.

Parts List:

  • Jones SG flat bars
  • Jones clear/soft Kraton grips

Custom Built Wheels

Given the kinds of weights I am dealing with in a cargo application, I wanted an indestructible wheelset.  Worth noting:  The stock Mongoose wheels never let me down and never took so much as a shimmy; always staying true.  Further, the steel cassette body showed zero wear after 300 miles of use with the BBSHD motor in play.

I knew right off the bat I wanted to build the wheels with a DT Swiss 350 Hybrid rear hub.  The Hybrid is an insanely sturdy hub designed with ebikes in mind.  Compare it to the already mighty 350 Classic and its … well, you’ll never break it.  the 350 Classic’s super strong splined engagement system has been upgraded from the already-best-in-class 18T to a 24T for even faster engagement, and the spline wheels are solid rather than the stock units which are now skeletonized.

A DT FR560 is my rim of choice for indestructibility on an enduro bike, and they would have been my choice here, but I’m trying to keep the cost down… and I found the Sun Ringle MTX39, which is tailor made for downhill and freeride nightmare rides, making it also perfect for cargo.  It makes for a crazy strong wheel like the FR560, at half the cost (and maybe twice the weight 🙂 ). 

SIDEBAR:  I went 32H not realizing the 350 Hybrid uniquely comes in the unusual-but-preferable 36H configuration.  Since the MTX39 is also available in 36H, and so are Shimano front hubs… I could have done an even stronger wheel build.  Frankly given the components in use here (DT Alpine spokes are just as overbuilt as everything else on the parts list) its almost hard to imagine needing that extra bit of strength, but I would have done it if I had realized the rear hub had that option before I ordered my other parts.

  • Sun Ringle MTX39 Rim 26″ 32H (30mm internal width)
  • DT Swiss 350 Hybrid ebike/tandem rear hub.  Steel cassette body, 24-tooth splined ratchet engagement.  148mm thru axle converted to 141mm QR.
  • Shimano M475 32H front 6-bolt disc hub
  • DT Swiss Alpine spokes

Stock Mongoose Envoy rims are on the spec sheet as 26mm internal width, when in actuality that is their external width.  Internal width is 20mm which is ok but nothing to write home about.

Likewise I could spend much more on a front hub, but a workhorse basic Shimano hub will do the job just fine.


12ah Portable Battery

Full description pending.
My battery needs to be easily removable as I carry it into the store with me.  It also needs to be easily concealed in the store as I don’t need someone seeing thick red wires and thinking I have a bomb in the bottom of my shopping cart.  Also, my runs to the store are usually only a few miles from home, so I can get away with a smaller battery, which – double bonus – is easier to lug around.


Tires

I’ll admit it.  I’m a tire whore.  I’m always looking for something a little better, a little different, and oftentimes I don’t wait for one set to wear out before I jump ship and throw on a different set to see if I have finally found the Grail.  Usually, I have a stack of the things sitting in the garage, as a result.  Since the Mongoose has 26″ wheels like my old Stumpjumper FSR, which I converted to a street bike powered by a Cyclone mid drive, I already had some tires in the pile to play with.

Naturally, I didn’t use them right off and instead bought more.

Firstly, the stock Chaoyang tires are decent.  They are rated 26×2.35 but in a first for Chaoyang, exceed their size spec and measure out to have a casing 2.5″ wide at a comfy 50 psi.  Pulling them off the rims, I found their casing to be thin-ish but not unnervingly so.  A basic tire I would expect to work well with no special flat protection.

Continental Contact Plus City 26×2.20

I replaced the Chaoyangs with the largest flatproof tires I could get my hands on.  The Contis are bigger than the Other Leading Brand best-in-class tire, the Schwalbe Marathon Plus.  I know from past experience that Continental seems to be trying to beat Schwalbe by putting out comparable tires and selling them at much lower prices. I use the Contact Plus tires in 700Cx37 and they are absolutely as good as the Schwalbe competitor, but are half the price.  That tread is not available in a large 26″ size, but the ‘City’ version is.  And since the Marathon Plus only goes up to 26×2.0, this appears to be the biggest flatproof tire out there.

Like the other Conti tires I use, the tire casing is actually smaller than rated, and stretches over time to approach but not quite reach the rated width.  At installation these tires were 2.15″ wide.  After a week or so, they had stretched to 2.2″.

81sob6j+stL._AC_SL1500_
Why is there a caption here?  You can read the label in the image.

A smaller casing is not really what you want on a cargo bike, but I expected these tires to be really solid; making up for the loss of volume.  So far that expectation has been met.  These tires qualify as tank treads, and they roll smooth as silk.  There is enough tread articulation to make me comfortable using them in the wet, and not so much that there is any vibration of any kind while rolling.

Under load, with my 250-lb self, 140 lbs of cargo, 55 lbs of ebike and a 60 psi max inflation, the tires performed just fine without any worrisome flattening of the tire profile under load.

Some other tires I have in the parts pile:

CST Cyclops 26×2.40

20-x-1-95-cst-c1381-cyclops-tyreStupid cheap but well made tire that is essentially a Maxxis Hookworm – reportedly made on the same tooling as the Gen1 version of that wonderful tire.   The Cyclops has thinner sidewalls but really, they are decently thick.  The Hookworms are thicker still.  This is a really nice, smooth roller with grippy tread articulation for a sure grip.  If you want a $25 tire you can count on (I got mine on sale for $15 each), this is it.

 

Schwalbe Crazy Bob 26×2.35

513CxGYqhdL._AC_I use these on another bike and in this size, these tires are E50 rated for moped use (says ‘moped’ right on the tire casing).  They are really thick, solid tires although they lack puncture resistant belts.  The bead-to-bead tread means you can heel a bike over hard with these shoes on.  Not something you need with a cargo bike, but these tires are a solid choice.

 

 


Tubes

I’m not doing the tubeless thing here.  Instead, I’m going for the monster bulletproof setup.  The outside layer being the super thick Conti tire, with the inner layer being a slightly oversized thornproof tube.

4115tFiMDhL._AC_

An oversized tube is good since it does not distend/stretch as much when inflated.  Long term they are less flat-prone.  This particular brand of thick tube has issues with the tube separating from the valve stem if it is stretched.  I am experimenting with applying Shoe Goo to reinforce this area.  We’ll see.

A big part of the draw of these tubes is not only are they thorn resistant, but they also have removable valve cores, which facilitates the addition of slime into the tube.

So…

  • flatproof tire
  • Thorn resistant tube
  • Slime in the tube.

Hoping for no flats, ever.


The Ridiculous Lock

Nothing, and I mean nothing, is safe from a portable angle grinder.  But this is as close as you can get.  This setup rides in the brown bag you see in many of the pics about this bike.  This 14 lb ensemble and its keys are permanently along for the ride.  Details to come.

  • Pragmasis DIB motorcycle grade U lock
  • Pragmasis 13mm boron steel chain, 2 meter length
  • Lockitt motorcycle roundlock
IMG_20191019_145024.jpg
This is how the bike looks when its left outside.  Roundlock nooses the frame and rear wheel.  U lock grabs the front wheel.  four separate 2-minute cuts with an angle grinder are needed to get this bike rolling.  Note if I was being smart I would have done something to get that chain off the ground.

.

IMG_20191011_135210.jpg
All the bits laid out.  The cloth cover for the chain has been slit at just the right spot and sealed with heat.  The bag has since been lined with some custom cut foam padding so this abomination doesn’t rattle while riding.

Mongoose – Chapter 2 (Brakes)

 

“My brakes are too effective” 
— said Nobody, ever

I am a firm believer in Big Brakes.  I learned when building a hot rod track car that everybody pours money into motor and suspension, but brake upgrades often come as an afterthought (usually accompanied by soiled underpants).

As a daily bike commuter, I also want trouble-free operation.  And since what I usually ride is a big, fast, heavy ebike, I appreciate big brakes a whole lot more since I am riding a rolling worst-case scenario.

Now, the Mongoose Envoy donor bike is the subject of this series, and it is not a fast bike.  It hauls lots of stuff though and thats probably worse than merely shucking speed.  So far, I have loaded it with about 140 lbs of groceries in addition to my own 250 lb self.  Add to that the bike’s roughly 50 lb weight.  With all that, the brakes that come with this bike from the factory really have their work cut out for them.

I suppose those factory brakes are OK… If I set aside how spoiled I am with my usual upgrades.  I can see they are about average for a low-cost bicycle.  While I wanted to keep this bike’s cost down, a couple things pushed me to upgrade.

First, out of the box the front brake essentially did not work at all.  It seems it was so poorly adjusted that all it did was caress the front rotor and do nothing to help stop the bike.  This was after I adjusted the inner and outer pad positions (the stock brakes have a dial for each side) as well as the caliper on its mount.

The rear brake … well, it did apply what I would consider to be moderate pressure.  A bit light but in the ballpark of what you’d expect from a cabled system.  But there is a long cable run to the back of that long frame.  A fair bit of my brake lever travel was eaten up by flex in the brake line, between lever and caliper.  An inspection of the brake housings showed they were not lined/compressionless – not a shock given the bike’s price point, but bad news for braking.

My initial solution was a game I have played before, and I should have known better… but I wanted this bike to be low-cost, so I tried a half measure:  I upgraded the calipers to Avid BB7’s (I had a spare set in my garage), which have a very good reputation.  But no matter what they are still cabled brakes.  I ended up wasting half a day trying to get them just right and never did.

The front brake came together quickly.  It didn’t want to stay in adjustment but thats what you get with cables.  Its stopping power was just fine.  It was the rear brake that was a waste of time.  I tried every trick in the book to get it to be effective – perfect was never an available option.  Most of the blame goes to the aforementioned flexy cable housings.

And mounting them?  Avid calipers use a semi-hemispherical washer set above and below the caliper to allow it to be angled if need be, and that makes its positioning options quite fluid.  The height was never correct and there was always some kind of rubbing somewhere.  Regardless of how I shimmed or re-jiggered it, something was not right somewhere.  I like to think of myself as something of a brake whisperer – if a brake set can be finessed, I can get the wheel spinning perfectly without so much as a touch from a misaligned pad or rotor.  Not this time.

So I said to hell with it and went back to my old standby.  Magura MT5 hydraulic brakes.  This makes my 5th set across my 2-wheeled fleet so I am pretty familiar with them.  Why these brakes?

  1. They are powerful.  4-pistons in the caliper means four clamping points onto the rotor.  Its like the difference between grabbing something with one hand versus using both.
  2. They are smooth to activate.  Unlike cabled brakes, you can use one or two fingers to gently tug on hydraulic brake levers.  For the Maguras, they have lots of travel so it is easy to modulate the force applied.  Despite their power they are very gentle unless asked to be otherwise.
  3. They are dirt-simple to install.  Use a Magura adapter to match your rotor size and bolt the caliper directly to it.  Done.  The use of Magura adapters coupled to their caliper results in a perfect height every time.  No shimming.  No dinking around with axes and semi-hemispherical washers… just bolt it on, eyeball it to center and tighten down.
  4. They self-adjust.  Yup thats right.  You centered the caliper at installation.  The pads align themselves.  Really.  You won’t mess with them again until you wear the pads out.

Ordinarily you pair these brakes with a Magura Storm HC rotor.  These rotors are 2.0mm thick, which is thicker than the typical 1.80mm thickness most rotors(including the stockers on the Mongoose) come in at.  In addition to having more meat on them to do their job (a rotor is a heat sink and more metal = more heat sink) thicker rotors are less inclined to warp.  In fact I’ve never seen one do that across any of my bikes and thousands of miles.

20170415_112904.jpg
This is a fresh Magura Storm HC 203mm rotor just after installation on an ebike.  Notice the heat discoloration from the brake bedding that was just performed.  Also note the caliper is bolted straight onto a Magura brand adapter with no need for shims.  Matching the brand on caliper, adapter and rotor makes for perfect alignment.

With all of that said, I have found a better rotor than the Storm HC – the Tektro Type 17.  Its designed for downhill bikes, who need to stop under the most extreme of circumstances.  These rotors are 2.3mm thick and as such are even more substantial – and even less likely to warp.  They fit perfectly on a Magura braking system, with the tops of the rotor ‘waves’ matching the top of the pads, and only a hair of lower rotor surface being untouched… not because the calipers are misaligned… there’s just more rotor face than you can use.

Here is one of these monsters, installed.  Note the marks left by the pads on the surface, and its noticeable thickness.

IMG_20190622_113631.jpg
The Tektro Type 17 mated to a Magura MT5 caliper.  Once again note this caliper is bolted straight down onto its adapter and fitment to the rotor is essentially perfect.

Its worth noting both the Magura and Tektro rotors discussed here are generally too thick to use with normal brake calipers.  Not so with the MT5’s.  And if you are guessing the extra-thick, never-warping rotors are going to last longer, you’d be guessing right.  the rotor above on the orange bike… so far I can’t seem to wear it out.  That bike is my daily driver and I can’t measure any wear after about a year installed.  I have worn out a set of the Maguras, but it took thousands of commuting miles.

Thats nice.  How Much?

So all this is wonderful.  What did I spend?

I’ll give you a couple different answers on that.  On every bike of mine but the Mongoose, I used the Magura MT5e brakes, which include a safety cutoff that wires into the BBSHD via the brake lever.

Here’s what an MT5 versus an MT5e lever looks like:

Note: the comparison above is deceptive as the MT5e lever appears the same size as the MT5 on the left.  It ain’t.  The ‘e’ lever is actually a fair bit larger.

Thats the only difference between the two brake sets, but its kind of a big one.  First of all, the MT5 lever on the left is often cited as feeling cheap or unsubstantial.  I do not find it so, but I understand where the sentiment comes from.  Most riders who use these do so on singletrack MTB’s where there is a lot of banging around, over and up against things.  On a street bike this need for durability – and bend-ability – is not so much a factor.

The lever on the right has the obvious connection that leads to your motor, so that when you depress the lever, your motor power cuts off for safety.  This lever is also constructed completely differently.  Its larger, made of alloy and its shape is much more… substantial.  Also note the metal pin in the middle of the lever itself.  This is a hinge.  It allows you to gently touch the lever and activate the cutoff while not activating the brakes.  This can be handy if you are using the brakes as a sort of clutch to cut the motor out during shifting (the reasons for doing this are discussed here).  This second hinge also gives you a surgeon’s precision when modulating brake pressure.

Currently as I write this in October of 2019, the cheapest source for MT5 and MT5e brakesets is here.  This is where I bought the MT5 brakes I have on the Mongoose.  I have also bought MT5e sets here in the past.  Note that while this is a web site in Germany, and you will have to pay shipping charges, they are reasonable and the prices are so low you still save money.  Especially if you get a few sets of extra brake pads, which are roughly 1/3 of what you will pay for the same name brand pads in the USA.

If you are using the MT5e levers with the cutoffs, then you also need an adapter to mate their red HIGO/Julet plug to the yellow one on the Bafang motor used in this project.  Those are found here.

Brakes (two options)

  • If you are just going the lowest cost, max-functionality route like I did, you’ll pay about $150 for a complete set of brakes (MT5 only).
  • If you instead go with MT5e’s (you must select the version that is “Normally Open” a.k.a. “Closer”) you are looking at around $100 per axle at the above German web site.  $125 if you buy from a USA dealer (I like Planet Cyclery on EBay – they are a Magura dealer and performed a free warranty replacement for me a year after a sale).  Add to that about another $30 for the cutoff adapters.  So about $280 total.

Brake Caliper Adapters

Adapters for the rotors are going to run you $7 to $10 each.  I used 203mm rotors front and rear so a Magura QM9 / ISH-203 in the rear and a QM5 / ISF-203 in the front.  Buy these with your brakes and pads and save the shipping cost.

Rotors (two options)

I am only listing two options here in case you cannot get hold of the Tektro Type 17 rotors.  Make sure they are specifically the Type 17 as Tektro makes other rotors that look almost exactly alike and are very common on the marketplace, while the 17’s are relatively rare.

  • Magura Storm HC rotors are meant to work with these calipers and do so just fine.  They are available for about $21 at the same source as above, and at many other retailers for only a little more.  The only reason I don’t use them anymore is I found something better…
  • Tektro Type 17 rotors are only regularly available from two sellers I am aware of, although I am certain there are more out there.  The first is from seller hi-powercycles and is where I buy all of mine.  The second source is at Empowered Cycles.  Empowered also sells the Type 17 in a 180mm size, so if for some reason you decide you need a smaller size in the rear, they can sell you one.

Replacement Pads

You have two choices, but if you are smart, there’s only one you should pick

  1. MT5 pads (Magura Type 9) – These 2-piece pads provide a single surface for the two caliper pistons to press into.  They do provide excellent response, but the type 8’s are … more better.  Plus in order to remove Type 9 pads, they have to come out the bottom of the caliper.  You have to remove the caliper from the mount to make that happen.  More work for you.  Unless for some reason you decide you want to use the Type 9.C Comfort pads (hint: you don’t) there is no reason to use Type 9 pads past using up the set that comes with the new calipers.
  2. MT7 Pads (Magura type 8) – These 4-piece pads are better in every way than the Type 9.  Most obviously, they can be removed from the brake caliper from the top, so you just undo the screw-in retaining bolt, pull the pad out with your fingertips and slide in a new pad (they set nice and easy thanks to ingenious magnets inside the caliper).  Not so obvious:  the independent Type 8.P pads have been measured to add a significant increase in clamping torque to the rotor.  They also come in a Type 8.R pad, which has a sintered pad compound.

Whats the Down Side?

Just one:  You will have to learn how to cut and bleed brake lines.  Honestly… its easy to do.  But you will have to do it.  Check out the videos at the bottom of this post.  They are what I used to figure it out.  You will need a bleed kit to get the job done.

HOWEVER…

You can cheat.  Each brake set comes with 2200mm of cable, pre-bled and fully operational.  Just use it.  Run the cable, then loop the excess and stuff it into a handlebar bag.  There’s a little for the rear and a lot for the front.  I added a front rack and the little bag I have on top is where my extra cable went.  Its kind of disgusting how well it works and how its so low key I could get away with just leaving it like this forever.  But it is definitely a lazy kludge.  I’ll do the job right some weekend or evening this winter.

Performance

ummmm.  Awesome!  Duh…

  • They are not grabby.
  • You never have to squeeze hard.
  • They don’t fade.
  • There is always more brake available than you need.
  • They are silent (the sound of Magura pads on a rotor is sometimes referred to as “blowing bubbles” and this is actually accurate.  I’ll leave it to you to experience what that actually means for yourself.
  • The pads never need adjustment.
  • If you use the MT7 pads, you replace the pads without removing the caliper from the bike (and you also get a lot more clamping force as a bonus).  But since the MT5 pads come with the calipers for free, use them up.
  • The lines do not leak.  I have heard of hydraulic brake systems that leak fluid and Maguras … don’t.
  • These brakes use mineral oil rather than DOT hydraulic fluid… thats a big deal because DOT fluid is nasty stuff… corrosive to paint just for starters.  Mineral oil, on the other hand, is harmless.

 

Mongoose – Chapter 5 (Motor Install)

There are about a billion step by step Youtube videos and forum posts describing the steps that go into installing a BBSHD onto an existing donor bicycle.  They already do a great job so I won’t try to get too deep into the weeds on that.  I will say that installation on the Envoy was simpler than my previous builds on different bikes, which is only a good thing for you if you aren’t familiar with installing a BBSHD onto a bike.

Step 1: Prepare the bicycle

You are going to be pulling apart some things and replacing them, so you’ve got some prep work to do.  Myself personally, I decided to do the following which you should consider optional.

9 Speed Conversion

I converted the bike to a 9-speed from its factory 8-speed.  You already have to say goodbye to the stock shifters Mongoose gives you with the bike since they are integral with the brake levers, which themselves have to go.  So I decided to bump up my options a tad.  8, 9 and 10-speed systems will fit interchangeably on the same hub.  I also have other bikes that are 9-speed and I like to have common parts between them.  Plus, I already had a cluster in my parts pile that was 9-speed :-).  So 9-speed it is.

As noted in the Motor Choice chapter, if you decide to stay 8-speed, you still need to replace your cluster as part of your mid drive upgrade.  A Shimano CS-HG31 8-speed cassette in 11-34T is about US$17.50.  You can bump that up to an HG-50 with nickel-plated steel cogs (not a bad idea) for about US$22.  At that point you will need to buy yourself some 8-speed shifters since, as noted above, the stockers can’t stay.  You’ll be able to keep the derailleur that comes with the bike (which frankly is not something that appealed to me… the one on my bike worked poorly and was clearly a basic, commodity component).

So here was my prep given this 9-speed conversion:

  1. Remove the handlebar grips without destroying them.  I used a jeweler’s screwdriver to lift up the edge of the grip, which let me get a WD40 straw nozzle in there and give it a spritz.  A couple of those and I was able to work the grip loose without having to cut it off.
  2. Release the brake cables.  This entails releasing the cable from the brake caliper so the lever flops free.  Then you can easily remove the cable from the lever.
  3. Release the shifter cables.  Release the cable from the derailleur and then pull the cable out of the housing so it is free.
  4. Remove the shifter/brake lever from the handlebars.  Just loosen the screw and slide them off.
  5. Remove the chain.  The Mongoose chain does not have a master link, so you will need to use a chainbreaker.  This chain will not be re-used.
  6. Remove the front derailleur from the bicycle.  Not used on a mid drive, so it goes into the bin.
  7. Remove the front derailleur cable housing.  Since the cable is routed thru the frame, this will give you an unused entry and exit hole in your frame which you’ll want to seal up with something.  I used a bit of rolled up mastic tape.
  8. Remove the rear wheel and replace the rear cluster.  You’ll need a chain whip and a cassette removal tool for this.
  9. Remove and replace the rear derailleur (optional.  See above.)
  10. Remove both pedals from the crankarms (or better yet don’t install them in the first place when you take the bike out of the box).
  11. Remove the crankarms.  You will need a proper sized socket to get the bolt out, then a crank puller tool plus a big wrench to finish the job.  Repeat for the other side.
  12. Remove the bottom bracket.  You’ll need a standard bottom bracket tool such as a Park BBT-32, and again a big wrench to turn it.

Prep work complete.  The bike now looks like the picture below, minus the big cargo net.  You’re ready to install the motor now.

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Fig. 2:  At this point your bike will look about like this:  No pedals, nothing on the bars and loose wires hanging around.

Step 2: Attach The Motor

It will fit right into the empty hole that used to house your bottom bracket.  At this point the motor is hanging straight down in the bottom bracket thanks to gravity.  You will want to dig into your installation kit’s parts bag and retrieve the two M6 bolts and the fixing plate that will clamp your motor to the bottom bracket.

One side of the fixing plate is ridged. These ridges are there to bite into the bottom bracket.  they go a long way (most of the way) towards holding the motor up and in place.  Before you slide that plate onto the motor’s axle, you need some spacers between it and the motor to support the plate, but not so many that you get in the way of the plate clamping to the bottom bracket.  Usually I use fixed-size steel spacers that I get from McMaster-Carr (you can buy them in various lengths in 1mm increments), but in this case I just used three M6 washers and got a perfect fit.

IMG_20191008_174717
Fig. 2a: The fixing plate, with those all-important ridges that must directly contact your bottom bracket.  In background: a couple of outer trim rings, and the  M6 bolts you’ll use to attach that plate to the motor.

Using just this plate clamped gently to the bottom bracket, its possible to get a provisional fit on the motor without fully tightening it.  Here’s where, essentially, the only hiccup in the installation occurs:  The rear shifter cable exits the frame just ahead of the bottom bracket, and travels under it.  If you rotate the motor up as high as it can go – which is the most desirable position – it will pinch the cable and seize it up.  So you have to back off a bit.  The picture below shows what my cable looks like after a successful positioning of the motor that allows the cable to move freely.

mongoose01.jpg
Fig. 3:  The arrows point to the shifter cable exit point and the allowable bend.  Also visible is a wad of mastic tape I used as a makeshift bumper to help solidify the motor’s position during installation

To ensure you’ve got the motor positioned right, use your replacement shifter cable and just manually run it down into the housing.  If you can get it thru easily so it pops out the other end, you are good to go.  Once you get the motor positioned up so that it a) gives max ground clearance and b) does not interfere with shifting, its time to tighten it down fully.  You will use two clamping lock rings over the axle and bottom bracket.

Typically, you use a grey, thick inner lock ring to do the real work, and the thin polished black outer lock ring – which is essentially just there to look good and perform sort of like a jam nut.

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Fig. 4: Note the thick black Sharpie registration marks running along the top of the two outer rings and the bottom bracket.  If I ever look down and see those marks not lining up, something is slipping and needs attention from a torque wrench.

However, using an inner and outer ring requires two tools.  The inner lockring is physically covered by the outer lock ring, so you can’t see it, but if you look in your parts bag the differences are clear.  Pictured above is the same installation done with two inner lock rings stacked on top of one another.

The outer ring is essentially a trim ring.  Its there to look nice and serve light duty as a jam nut.  Using two inner rings means you can torque the bejesus out of each of them.  And speaking of torque, I use a 1/2″ torque wrench to put 100 ft lbs of torque on each of these two rings.  Yes, 100 each is well above the ‘official’ spec but it is proven to work.

A note on tools:  Cheapie Bafang wrenches made of thin steel will let you ‘get by’ with a basic tightening of these lock rings. They are widely available for roughly US$15.  I don’t recommend their use given the lack of ability to use a torque specification, and their small size.  Pass on these and your knuckles and palms will thank me, as will you when your motor does NOT loosen since you used proper tools.  To do the job right, you need to use something like the socket found here.  You want the ‘inner’ socket only unless you want to use the trim ring instead of the two inners.  Worth noting: This socket is also sold at Luna Cycle (they also make their own version that is intermittently in stock) and California Ebike.  Pair this up with the torque wrench of your choice.  Mine is this bad boy.

Step 3: the Chainring

The stock BBSHD chainring is solid steel and, well… its awful.  Not only is it the ugliest chain ring in the solar system, its design is known to drop chains and generally make owners’ lives miserable.  And it also weighs a ton.

IMG_20191008_174708
Fig. 5: the Disc of Death.  A medieval throwing weapon that coincidentally is also used as a Bafang BBSHD chainring.

You want to use one of the aftermarket alternatives out there.  Generally I buy Lekkie Bling Rings, where the 42T size (there are many available) with its 18.3mm offset is the size of choice (there are now Chinese clones of the Lekkie and they are so expensive its not worth taking the quality risk to save so few dollars) and works great to correct the chain line offset that comes from the BBSHD’s secondary housing sticking out as it does on the drive side.

However, for the Mongoose project I finally had a bike whose frame would allow me to use the other king of the BBSHD chainrings:  The Luna Eclipse.

As you can see in the gallery above, the Luna Eclipse ring has a serious inward offset.

24.8mm in fact, which brings it in more than 6mm close to the frame than the Lekkie can.  Add to this the unique, wicked narrow-wide tooth profile on the Luna that effectively means you will never, ever suffer a dropped chain.  Lastly, needless to say, it looks gorgeous.  But, the biggest deal is the enormous offset, which allows perfectly centered chainline… not easy to accomplish on a BBSHD build.

Step 4: Size and attach the Chain

I made this part difficult to illustrate because I put the bags on – so they don’t come off – before I took pictures of the chain and derailleur.  I’ll do my best to get through this without good pictures.

First and foremost, let me say that a great many builders get chain length completely wrong.  Unfortunately, a lot of them may have gotten their examples from bike manufacturers who skimped on chain length and did ‘good enough’ instead of ‘best’ to save a few bucks.  What do they get wrong?  They let the derailleur cage stretch forward; not understanding that it is the cage’s job to wrap excess chain… so let it do its job!  The only reason to stretch the cage is to use less chain (i.e. you are a bike manufacturer out to save a nickel or so).  By the way, stretching the cage also extends its springs, and which lasts longer… a device whose springs are at rest, or that are under stress?

Here’s just about the only published source I’ve seen that boils down how to do it right, although they don’t shout out to the high heavens what they are doing right that so many others get wrong.

I’ll lay out the process very briefly here:

  1. Shift down into your highest gear (your smallest cog, the furthest outboard from the frame)
  2. Run your new chain thru the drivetrain, so its unattached ends are on the underside of its loop, halfway between the front chainring and the rear axle (this is simply the easiest location to work with).
  3. Pull the unattached chain ends together so the rear derailleur cage is only slightly tensioned.  That means in the case of the Mongoose, where we have a long cage derailleur added into the mix, that the cage is pointed straight back behind the bicycle.  Believe it or not, thats how its supposed to work on the low gear.  The cage is wrapping as much chain as it can while still maintaining tension on the chain.  Here are low and hi gear shots taken at two different chain lengths on a different bike.  On the top-left-pictured setup, I was a little too generous.  But only by two links.
  4. Assemble your chain with your master link.

Forget about all the other tricks associated with determining chain length.  If you have a single front chainring, this is all you need to do.  Ensure there is sufficient tension on the little cog in back.  At this point you have added as much chain as you possibly can, so the big cog will take care of itself.  If you find you cannot wrap enough chain to make your big rear cog work, then that usually means you need to step up from a short cage to a mid-length, or from a mid- to a long cage.  Or just live with what you have because you physically can’t add any more chain.

Step 5: Cable Hookups

Sidebar: Why I used a triangle bag.
For this build, I chose to use a battery that is NOT hard surface mounted on the down tube of the bike (for now I am using the very safe, waterproof, crashproof LunaCycle Wolf Pack but I am not using its excellent magnetic mount).

I have decided to use a triangle pack simply because it hides a multitude of sins.  In particular it saves me the trouble of routing cables neatly and tidily across the frame, which in the case of the Envoy is made more difficult to do cleanly since there are no cable guides to piggyback onto, thanks to its internal cable routing.  The use of a dedicated ebike frame bag means I can just run my wires thru one hole and out the other without worrying about what they look like inside the bag.

A triangle bag also helps me with my goal of easy portability:  Long term I have a very specific small battery in mind that will sit inside of a cloth MOLLE pouch.  it will be a snug fit inside the triangle bag (thus no need for a hard mount), and when I am going into the store, I just unzip the triangle, grab the pouch, haul the battery out and set it in my shopping cart.  That internal pouch means my fellow shoppers are not looking at a bare high voltage battery with red wires sticking out one end.

Getting a triangle bag to fit your frame is often a challenge.  Getting one with ebike wiring cutouts doesn’t make things any easier.  Especially since the Envoy’s triangle is relatively large.  larger than pretty much all mass produced battery bags.  Except one.  The FalconEV triangle bag is one of the largest bags of its type and just happens to be a nearly perfect fit for this frame.  I’m using that bag here.

Hook up the Speed Sensor

I was pleasantly surprised to find I did not need to use an extension on the Envoy’s mid-tail frame.  However it was a close call.  The speed sensor must pass within 1/4″ of the magnet to be reliable.  To accomplish this I used a trick I have used with fat bikes.  I first wrapped the chainstay in a bit of silicone tape to make it grippy.  Then I used more silicone tape to affix a small rope/cable crimp sleeve onto my chosen spot on the chainstay.  The rounded exterior of the sleeve will mimic the chainstay when I stick the speed sensor to it, and finally a couple of zip ties in the prescribed loops on the sensor lock that little sucker down so it works perfectly and is going nowhere.

Connect the Battery Adapter

The motor comes with the ubiquitous red and black wire for its power feed, terminated by a pair of quasi-standard 40 amp Anderson powerpole connectors.  Actually, the Andersons are kind of dated, with an XT90 (and particularly the anti-spark XT90S) being a much more common, reusable and weather resistant connection to your 48v or 52v battery.  My kit from Luna Cycle came with another length of red/black wire, also terminated with a pair of Andersons on just one side and bare wires on the other.  The point of this ‘pigtail’ is to connect to whatever your battery wants as a connector.  Most likely that battery is going to have either another pair of Andersons attached to it, or a (hopefully female, for your sake) XT90S.  You use the Anderson pigtail to connect to another pigtail that uses whatever your battery wants.  Yes, this means you either need to a) solder or b) crimp together the two to make a proper connection.  If you have no skills in this regard, you can probably find a pre-made cable somewhere for an exorbitant sum.  Make sure it uses 8 or 10-gauge (thick!) wire.

(I Didn’t) Install the Gear Sensor

One way to trash your bike with a mid drive motor is to go hammer down on the throttle and then try to shift.  The bike will shift alright, with about 1000w of power behind it.  The sound that makes will tell you what a horrible thing you just did, and if you want to walk home some day with your snapped chain lying somewhere behind you on the ground, go right ahead and keep doing that.

There are many ways to keep this from happening.  Most of them old-school techniques developed before gear sensors came into common use.  Since I started riding before that time, and I already know you Don’t Do That by instinct, a gear sensor is optional for me.  Also since I am lazy I didn’t feel like wiring it in.  For others – especially for those new to mid drives, its probably best to use the sensor.

Here’s what you do:

  1. Attach the gear sensor to the motor – its the yellow cable end.  I am assuming you have one of the more modern BBSHDs and you don’t have to mess around with any sort of Y connector.  So we’ll pretend that problem doesn’t exist.
  2. Once the sensor is attached you now know where it can go on your frame.  See where it will line up best with your rear shifter cable, because you are going to fit it inline into/onto the cable.  So… pick your spot.
  3. Disconnect your shifter cable from your derailleur and pull the shifter cable out of the housing.  If you were following my prep steps above, you have already done this as I didn’t include a ‘replace the cable’ step there for this reason.
  4. With the shifter cable out of the housing, cut the housing at the place where you intend to install the gear sensor.  Place a shifter cable ferrule over each cut end of the now-separated cable.
  5. Run the shifter cable down the housing until it exits the cable where you cut it.  Push it out some more and then work it into the gear sensor, and out thru the other side.  Once you have it thru the sensor, run it in to the back portion of the separated cable housing and all the way back down to the derailleur.
  6. Cinch everything up so the sensor and the cable housing are all nice and snug against one another, and the now-inline sensor is placed as unobtrusively as possible.
  7. Reattach the derailleur cable.  Job done.
  8. Optional:  the gear sensor is nothing more than a little wheel inside of a box.  It senses when the cable is moving – when your shifter and derailleur are pulling on it.  As soon as the little wheel detects motion, it kills the motor and its torque for a split second.  That lets you can shift – even under full throttle – safely.  So… that little wheel can get crusted up with grit, and fail.  Early designs were infamous for this.  Modern ones seem to be free of the problem but be sure… spiral wrap that rascal in some silicone tape.  That seals out any possible crud ingestion so it will work forever without maintenance.

So, without the sensor here’s what I do instead:  While pedaling I …

  1. Stop pedaling and while not moving my feet
  2. Click my shift (always just one gear)
  3. Perform a single pedal rotation to make the shift happen (this is not enough to engage the motor with any worrisome level of torque) and stop pedaling.  the motor will engage and spin a little further, completing the shift as part of its brief power up/power down.
  4. Resume normal pedaling

That sounds like a lot but it takes about 2 seconds total.  Other folks have perfected the use of a brake lever as a clutch.  With some experience in the saddle, they can gently touch the brake lever just enough to activate the safety cutoff without also engaging the brakes.  Then they shift and release the lever.

Sidebar:  Magura MT5e ebike brakes have special levers that include a second hinge, mid-lever, that facilitates this brake-lever-touch cutoff method.

Wiring Harness Cable

A nice thing about the BBSHD is it has a single bundled cable that is meant to run up from the motor to the front of the bike, under the handlebars, where it splits off to connect up to the throttle, display and both brake safety cutoffs.  As clean as you can get given the multiple connections.  Just plug the harness cable into the motor, run it up and into the top rear of the bag, and out the hole in the front side.  The remaining dangly bits will connect right up to what you stick on the handlebars shortly.

On the Handlebars:  Display, Brake Levers and Throttle

These are pretty straightforward.  Place them where convenient for you, connect the color-coded plugs and job done.

Go Ride

Thats it!  You’re done.  I can guarantee you this:  It takes more time to write this article than it does to install the motor.  I think all in I needed only a couple of hours for the motor part, not counting all the extra work I made for myself swapping out everything else on the bike.

Li-Ion Ebike Battery Charge Charts

Quite some time ago, I produced a series of charge status charts for a variety of common lithium-ion battery voltages.  They’ve become a fairly common link to help folks out on various Facebook groups who use these battery voltages in their ebikes.

I built them using Google Sheets, so they are not web pages, which I suppose has kept them from being widely linked in search engine results when people are looking at such things.

Here for the first time are direct links to the charts on a normal web page.

Remember, these charts show ballpark values that are as numerically correct as they can be.  Individual cell characteristics will cause variation in the numbers here.  Read the notes on the chart for a little more detail.  Bottom line: cells degrade differently, but imperfect charts like this are still good baseline references.  Use these and teach yourself how to read the voltage gauge on your display screen.

36 Volt (10S) Battery Charge Chart

The first link is to the lowest voltage:  36v.  Generally this is the lowest voltage you will find on an ebike.  Note that its called ’36 volt’ but really that is the ‘nominal’ value.  A 36v battery is actually fully charged when it is at 42.0 volts.

36v_Thumbnail.jpg
Click on the image above to be taken to the actual 36-volt battery charge chart.

48 Volt (13S) Battery Charge Chart

The next common size is 48v.  These batteries are fully charged at 54.6 volts.

48v.jpg
Click on the image above to be taken to the actual 48-volt battery charge chart.

52 Volt (14S) Battery Charge Chart

The next battery voltage is 52v and very common.  52v batteries will work on systems designed for 48v, and why is easier to understand when you become aware that a ’48v’ battery really tops out at over 54 volts.  A ’52v’ battery tops out at 58.8v, so it essentially lets you use a 48v system for a longer time at higher voltage levels that it is already designed to utilize.

52v.jpg
Take a guess what you are supposed to do to see the 52-volt battery charge chart.

60 Volt (16S) Battery Charge Chart

With a 100% charge voltage of 67.2 volts, when you have one of these you are more or less now using high voltage electricity

60v.jpg
Yup.  Click it.

72v (20S) Battery Charge Chart

72v.jpg