Mongoose Envoy, a new longtail cargobike

March 9, 2019
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This isn’t an electric bike, but cargobikes are one of the best platforms for building an ebike. They have always been expensive, and this new contender is the most affordable one I’ve seen so far.


Why?

I can’t think of one instance when I wrote about a non-electric bicycle for electricbike.com before this. We have written on occasion on factory turn-key ebikes (Bafang Ultra, TQ-Clean Mobile, etc) and we have definitely written about kits (BBS02, BBSHD, TSDZ2, etc), so the casual reader can be forgiven for wondering what our focus is.

If I find a new ebike that I think our readers would be interested in, I check to see what information is available about it. First, I want to see if there is even enough info available to make it worth writing about, but also…to see if other web-magazines have already written about a given model. I have a full-time job, so why spend some of my spare time writing about something that already has ten articles about it out there?

So…I’m writing about this new cargo-bike because it is the most affordable longtail cargo-bike to add a kit to.

 

The 2019 Mongoose Envoy. Kickstands with two legs are awesome!.

 

Kits are selling well, but there is a surprising lack of advertising about them (compared to the media push for factory ebikes). For me, there are two huge benefits to a kit. First, they allow you to choose the bike frame in a style and size that fits you, and which also fits the job you plan to give your ebike (most factory ebikes have a limited selection of frames). Secondly, using a kit can save a builder a LOT of money, along with providing a much higher amount of performance (the vast majority of factory ebikes are expensive and weak).

So, you’ve decided to get a kit (my most-ridden ebike uses a stealthy 52V BBSHD kit @ 1500W, from Luna Cycles in Southern California), and now…you need to choose a frame to put it on. If you like off-road riding, then obviously, you’ll choose a full suspension frame for taking jumps (although many off-roaders still like a hard-tail downhill frame with a long-suspension fork). Many ebikes ride on streets (like me), and I don’t really like to go super fast. I often cruise at 20-MPH and sometimes peak at 30-MPH to avoid getting killed by a 3,000-lb car with a texting driver.

My medium-speeds and my upright posture means that I don’t really “need” a suspension fork, but I do have 3-inch mid-fat tires and a suspension seat-post, to smooth things out. The aluminum-frame Electra Lux Fat 7D that I often ride is a stretch cruiser, but…it is about $700, and the new Envoy is only about $500.


The Specs

There are dozens of specifications about this particular model, but only a few that I feel are important to us. The frame is aluminum to save weight, and many customers appreciate that kind of thing when we’re talking about a bike-frame that’s this large. The fork is made of steel for strength, and this frame comes in two sizes.

The 2019 Mongoose Envoy

 

The front gear-set in the bottom bracket is a 3-speed derailleur. That is good news, because that means the chain-stays of this frame are set far enough back that an ebike kit with a large chainring will fit (if you want).

The stock frame can fit tires that are 2.4-inches wide, which allows the popular Hookworms, Crazy Bobs, and CST Cyclops (for the street). The front brake is only a basic 160mm diameter disc brake. That is adequate for an unpowered cargobike, but I recommend an upgrade for electrifying it (click here).

Since the Envoy comes with disc brakes from the factory, it is easy to upgrade them. You might consider swapping to hydraulic calipers to add more clamping force, or adding the adapter that moves the caliper farther out so you can swap-in a larger 180mm or 203mm disc.

The seatpost on the larger size of frame (two sizes of frame) is 31.6mm in diameter, and my best advice for the first accessory is to get a suspension seat-post, you won’t regret it. I also recommend a left-side mirror, but of course there are a dozen other accessory decisions you’ll need to make, based on what you will be doing with your particular ebike…

The gear-set on the rear wheel is an 8-speed freehub cassette. If you decide to use a powerful mid-drive, you may only need 8-speeds, so the front derailleur could be removed to de-clutter it a bit.


The Cargo Rack

The cargo-bags are the main reason to get a cargobike. They add a level of convenience that most riders may not appreciate until they have one to test-ride for a while.

 

My grandson  on a custom-built toddler seat.

 

In the pic above, my grandson is on a toddler seat I built, but…more grandkids want to ride, so I’ll need a seat on the back. That means I’ll be riding a cargo bike soon. I don’t know what existing toddler seats will bolt to the rear of the Envoy cargo-system, but I’l be looking into that.

Of course they are convenient for stowing a couple bags of groceries, but I also appreciate using them for storing my helmet and gloves (along with a basic tool set), so I never have to go looking for them when it’s time to ride.

The 2019 Mongoose Envoy

The 2019 Mongoose Envoy


Mid Drive, or Hub Motor?

This frame uses a 68mm wide bottom bracket, with a common Shimano-style of cartridge. This means there should be no problem using the popular BBS02, BBSHD, and TSDZ2 (among others). The TSDZ2 is maxed-out at 750W if you are using a 52V battery, but it has a very smooth torque-sensor, if you like that kind of thing.

Many mid drive motors have a poor heat-shedding path, so we have recommended in the past that within the options available…you should raise the volts, and lower the heat-causing amps. The BBS02 can use 52V, and in that configuration, it has been successfully run at 1,000W. There’s nothing wrong with using only 48V on the TSDZ2 or BBS02, but…every little bit helps.

 

The unusually popular Bafang BBSHD, shown with the stock sprocket.

 

However…if you value my opinion, my favorite drive is the one that I ride the most, the 52V BBSHD at 1500W. I also recommend a smaller chainring as the best upgrade. Doing that does lower the top-speed, but it also improves the hill-climbing torque, which is important on a fully-loaded cargo-bike. The stock chainring has 52 teeth (the heavy steel “Frisbee of death” seen above), but I went completely in the other direction with an aluminum 30T. Of course, there are also several other sizes for any performance range that fits your needs.

But…what if you want the POWER of 2600W (52V X 50A)…or more? At those power levels, chains and sprockets on a mid drive might work, but they will definitely wear out faster than with normal pedaling loads. Not only that, but there are very few mid drives that can survive 2600W+ of heat. That means for high power, you might want to consider a direct drive (DD) hubmotor.

The most popular DD hubmotors have a stator diameter of 205mm. If it was larger than that, then the spokes would have to be shorter, which could cause some problems with breakage due to extreme spoke angles (hitting potholes on a hardtail). The most appropriate DD motors at power levels between 2600W-3500W have a 35mm wide stator, like the Leafbike 1500W and the MXUS 1500W.

For those motors, I recommend a 6-speed megarange freewheel, although a 7-speed should fit.

DD hubmotors can take these sudden and high power loads without damage. However, if you have committed yourself to a plan that uses a DD hubmotor, you can increase the hill-climbing ability and lower the motor heat and controller heat by swapping to a smaller diameter rim. The smallest bicycle rim diameter that does not have too extreme of a spoke-nipple angle is a 24-inch rim. Even then, that is the max when using bicycle rims and spokes. However…if you swap to a moped rim, you have several stronger options.

 

A 3000W DD hubmotor using a 16-inch moped rim, and a one-cross spoke pattern (equal in size to a 20-inch BMX bicycle rim)

 

Moped rims are measured like motorcycle rims. A 26-inch bicycle rim is roughly the same diameter as a 19-inch moped rim. But for this discussion, I want to point out that a 16-inch moped rim is the same as a 20-inch bicycle rim. Not only that, but moped TIRES are very heavy-duty (very resistant to flats), and also very affordable. If you swap to a smaller moped wheel, the top speed would go down a proportionate amount, but it will also help the hill-climbing ability of the system, and it will allow the motor to run cooler, even when it is under a heavy load. You can read more about moped rims and tires from our article (click here).

Moped rims are heavier and stronger than bicycle rims, but the reason they allow you to go to such a small diameter is because the spoke holes are angled, unlike bicycle rim spoke holes. However, be aware that moped rims have no allowance to use rim brakes.

If this idea appeals to you, and you will be reducing the height of the tire from 26-inches to 20-inches (a 6-inch difference), then the axle mounts need to be lowered 3-inches. That may initially seem to be a huge headache, but it doesn’t have to be. Powerful hubmotors need two strong torque-arms, so the design of the torque arm can also be the element that lowers the axle height.

Be aware that lowering the axle-height also means you must create a new mount location for the brake caliper. Although, this can be off-set or delayed by using a regenerative braking controller (and you can properly mount the caliper later). “Regen” does not harvest very many watts back into the  battery pack (when slowing down, or on a downhill), but it DOES force the motor to act like a very useful magnetic brake.

 

Here is one example of thick metal DIY torque-arms. They not only resist the counter-torque of the hubmotor axles, this style also lowers the axle-height a bit. These were prototyped in aluminum, and then later water-jetted in steel.


Here is a quick 2-minute video with the Envoy

 

There are plenty of customers who will pay extra to get a cargobike that has a factory-installed electric drive system, like Yuba, Luna, Rad Power, Juiced, and others…but…if you want to add an electric kit to an affordable longtail cargobike, the $500 Mongoose Envoy should be one of your top-three options for consideration.


If you liked this article, you may also like…

Joels Yuba Cargobike using Nissan Leaf cells (click here)

Teklektiks dual-motor Yuba Mundo (click here)

Juiced Rider ODK-II Cargobike (click here)


Written by Ron/spinningmagnets, March 2019

Grew up in Los Angeles California, US Navy submarine mechanic from 1977-81/SanDiego. Hydraulic mechanic in the 1980's/Los Angeles. Heavy equipment operator in the 1990's/traveled to various locations. Dump truck driver in the 2000's/SW Utah. Currently a water plant operator since 2010/NW Kansas


5 Comments

  1. Great article Ron. For banging around town, if you want to replace your car, nothing beats a cargo bike. This one is so much cheaper than anything else I have seen, and it’s an aluminum frame.

    I would totally go with a BBSHD and a 3-speed IGH. What a great design.

    • Thanks, Karl. I’ve been disappointed that some of the more famous longtail cargobikes have remained so expensive for so long. If a well-made entry-level bicycle can sell for $400, why has it taken so long for a longtail to sell for $500? It’s only a foot longer, and the rest of the parts are the same. I think it’s OK for the better cargobikes to sell for more, but this model will help a lot of people to leave their car at home more often..and that’s a good thing..

  2. I only see one frame size http://www.mongoose.com/int/envoy-21065

  3. Costco Canada have this but they won’t ship to the US. I tried Dick’s but was told they could not special order this model.

    • Thanks Dewey. hearing that is very disappointing, this is a great option for the public to have…

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