Cargo bike transmissions

I’ve focused rather heavily on cargo bike brakes in recent blog posts (like here), so I thought it would be a good idea to round things out with thoughts on other weak links in my cargo bike hardware.  After a year of biking in Copenhagen, and another year here in Seattle, the components that have required extra maintenance or occasionally interrupted my ride are these:

  • Brakes
  • Gears
  • Chain
  • Tires

The guy who built my Hammer Truck/BionX cargo bike knew that a flat tire would be challenging – especially if I had to change the rear tire under the cargo bags and with the added complexity of the hub motor.  To forestall that scenario, he installed extra heavy-duty tires filled with puncture-healing gel.  He wanted my tires to be “bullet-proof.”  Although I had several flat tires in Copenhagen, I’ve had no similar difficulty with my cargo bike (knock on wood!)  I haven’t even needed to top off inflation of the tires during the past year.

The drive chain was another source of problems in Copenhagen.  Occasionally, it would stretch enough to start falling off my crank when I went over big bumps.  I took it to a bike shop where a mechanic would re-tension the chain, and everything would be fine for a few more months.  On my cargo bike, with a longer chain and heavier loads, I feared chain problems would be more frequent.  Fortunately, that hasn’t been the case – no chain problems during the past year.

But alas, my gears have not been trouble-free.

The phantom gear and the wedged chain

Last week, my kids returned to school, and my 4th-grader and I resumed our daily journey up the hill to his school.  I have this deal with him: if he rides his bike twice during the week, I’ll give him a free ride on my bike on the third day.  The other two days he walks.

A couple of days ago my son was riding his bike, and I was riding the cargo bike without motor assistance so that our speed and effort would match.  To tackle the steepest part of the hill, I shifted into my lowest gear.  It took me a moment to remember: I don’t have the lowest gear.  This is part of the compromise I made when incorporating the BionX motor.  The width of the motor precludes a full 8-gear cluster.  My rear wheel has only 7 gears, but my shifter still shows eight.

My bike builder solved this mismatch by compressing the range of the shifter.  This allowed me to select only gears 2 through 8.  I hit a stop before I got to gear 1.  That worked fine for awhile, but the tolerances were pretty tight.  As time passed, there were other gears I couldn’t select.  I took the bike to a different shop, and they brought back the missing gears by expanding the range of the shifter.  Now there is no stop at gear 1; I just have to remember that there is no gear there.

When I temporarily forgot that important fact, the chain fell into the gap between my biggest gear and the hub motor.  Unfortunately, that gap is just wide enough so the chain can wedge itself so snugly that it can’t be extracted without tools.  It took me at least ten minutes to retrieve a couple of screwdrivers from my house and perform the necessary operation.  I arrived at my son’s school late and with very dirty hands (cooking oil works great to loosen tough chain grease from your skin, by the way).

This was just the latest episode in my love/hate relationship with bicycle gears.  I love the beauty and efficiency of this transmission system, but it still requires too much care and maintenance.  Not too mention the fact that I often seem to be in the wrong gear at the wrong time.  Even after two years of concentrated cycling, I don’t feel that I’ve mastered the art of smoothly shifting to precisely the right gear for the situation.  If biking is going to achieve broader acceptance, more fool-proof transmissions will be required.

My bike in Copenhagen was superior in this regard.  It had a 3-speed hub with internal gearing.  Shifting was smooth and easy, and there were no fiddly adjustments or maintenance required.  Three speeds were fine in the table-top flatness of Denmark.  One gear would probaby have sufficed if it weren’t for some pretty stiff headwinds.

Hubs for hill-dwellers

Rohloff Speedhub

Hubs with more gears and wider ranges have been available for at least a decade.  One example is the Rohloff Speedhub with 14 gears and an impressive 526% ratio between its highest and lowest gears.  It provides low maintenance, smooth shifting, shifting while stopped, and very reliable operation.  When you see the cut-away of the mechanism inside the hub, you’ll probably agree this is a miracle of engineering.  Unfortunately, it requires a miraculous number of dollars to buy: over $1000 on Amazon last time I checked.

NuVinci mechanism

On the day I wedged my chain, I coincidentally stumbled on an announcement for a new version of the NuVinci hub.  Unlike other hubs, NuVinci uses a clever system of balls rotating in oil to provide a continuously-variable transmission (with a 360% range) rather than discrete gear ratios.  The main disadvantages have been weight and price, but the new version (NuVinci N360)  has reduced both (less than 5.5 pounds and $350). 

Shimano Alfine 11

When I asked a cargo bike dealer about the NuVinci hub, he gave it a thumbs’ up, especially now that the weight has decreased.  But he was also getting quite excited about Shimano’s new 11-speed hub with a 409% range (Alfine 11).  If it debuts at $419, as has been speculated elsewhere, this will also be a hub to consider.

Stuck with my gears

As you can probably tell, I would ditch my derailleur and gear cluster for one of these hubs immediately, except for one major problem: my BionX motor is mounted exactly where these hubs need to be!  To me, this is the most serious disadvantage of a rear hub motor: you’re locked into the traditional bike transmission.  If this is an issue for you, perhaps it’s enough to give bikes with a front hub motor (like the elMundo or Electric Ute) a second look.

In my opinion, a hub transmission on the Electric Ute would be a pretty interesting combination because of the Ute’s torque-activated assistance.  To change your level of effort, you simply change gears, and the motor adds assistance depending on the level of torque you’re exerting on the pedals.  On the elMundo, you need to choose both the gear and the amount of electricity to use.  To my mind, that is one degree of freedom too many.  When I start to climb an incline, do I lower the gear or increase the motor effort, or some combination of both?  Perhaps some riders will find joy in mastering that art, but I have too many other things to think about.

Updated recommendations

It has been a few weeks since I published my last post comparing the elMundo, Electric Ute, and Transport+.   I’m hoping that my somewhat breathless description of the Transport+ doesn’t leave the impression that I think it’s the “best” bike.  That determination depends on what you want to haul, the geography over which you want to haul it, and who you are, physically and mentally.

For example, I’ve had a tendency to discount the Electric Ute because of its smaller motor and unimpressive performance on a steep hill.  These are important considerations for me, personally.  But if you have a longer, flatter commute, you might appreciate the Ute’s battery, which delivers 13 amp-hours compared to 10 for my (and Trek’s) BionX battery.  With its less thirsty motor, the Ute might have a 40-50% greater assisted range.  And at least one dealer I know of is selling the Ute at a discount that competes with the elMundo’s low price.  When you consider the possibility of upgrading to a hub transmission (I would love to see that as an option from Kona!), the Ute is a bike that is difficult to say no to.

If you’re planning to carry heavy loads, you should still consider the elMundo, unless you’ve got hills that would make the extra 30-40 pounds of its steel frame an issue.  I like the heavy-duty frame and the option of front and rear disc brakes.

With Trek’s Transport+, we’ve entered the awkward period between the announcement and the actual release of the bike.  Since we can’t easily get our hands on one for the next couple of months, speculation is ramping up.  One concern that has been hotly debated in cargo biking forums is the Trek’s weight distribution.  Like my bike, the Transport+ carries its motor and battery in the rear.  But the Transport+ battery is mounted waaay back (to incorporate the tail light) and quite high.  The side racks extend farther behind the rear wheel than any other cargo bike I’ve seen.  If you’re carrying a big load, will there be enough weight on the front wheel to steer precisely?  Will you be able to control the momentum of heavy cargo back there during a quick turn?  Of course, Trek claims this is not an issue, but time will tell.

It saddens me that I can’t include my Hammer Truck in this list of pre-built electric cargo bikes.  I’ve written a couple of emails to Rans, asking if they have any plans to include a motor as an option on the Hammer Truck.  I haven’t gotten a response, or even acknowledgement that they’ve received my emails.  That’s too bad, because the crankforward design of the Hammer Truck is, in my opinion, a significant advance in cargo bike design.  The lack of pressure on my hands, shoulders, and crotch make it more comfortable to ride than most bikes.  I wish it were more competitive in this arena.

Dreaming of a maintenance-free bike

Shaft drive bike

It’s hard to imagine that any bike will ever be maintenance-free, but with heavy-duty tires, a hub transmission, and good brakes, it’s possible to reduce maintenance and breakdowns.  The chain is the only item left in my list of trouble areas.  There are several companies that offer bikes with a shaft drive instead of a chain (and internal hubs, of course).  Nothing like that for a cargo bike yet, but perhaps that will be the next step in the evolution.

Nostalgia for Copenhagen

My family and I have been back in the U.S. for a little over a year now, after living in Copenhagen for a year.  As I’ve mentioned previously, we didn’t have a car in Copenhagen – all our travel was accomplished by bike or occasionally, by bus or subway.  When I saw this nicely-produced video of Danes on their bikes in all seasons, it reminded me how much I miss the bike-centric lifestyle there.

I’m not sure the video will have the same impact for anyone who hasn’t lived or visited there, but if you haven’t seen the rush hour in Copenhagen, it may surprise you.

If you want more, check out the other videos in this post from the Copenhagenize blog.  Although it’s a little long, the travelogue showing Copenhagen in 1937 shows that the bike culture has roots going back at least three-quarters of a century.  No helmets, lots of fancy clothes — both videos look quite different from biking in America.

Cargo bike brakes with kids on board

To avoid developing brake monomania, I’m promising myself that this will be my last post (at least for awhile) on the topic of cargo bike brakes.

But I noticed something interesting during my emergency braking tests yesterday: my bike had approximately the same stopping distance when carrying 180 pounds of cargo as it did with no cargo.  How could I explain the physics of that?

I think it’s because stopping performance depends on the friction generated between the tires and the pavement.  On an unloaded bike, the front tire does extra duty as the weight of the rider bears down on it – just like the front of a car dips down during hard braking.  In this scenario, the unloaded back tire can’t produce as much friction, and it’s easier to lock into a skid.

With 180 extra pounds over the rear wheel, the back tire carries more weight, and the job of slowing down the bike will be more equitably distributed between the two wheels.  The greater momentum of the extra weight just about matches the extra friction exerted by the back tire, and stopping distances remain about the same.

That was comforting to me until I realized that the bike’s center of gravity is also an important consideration.  I carried my heavy containers of water relatively low.  If I were carrying a passenger on the cargo deck, the center of gravity would be higher, and once again a lot of that weight would be loaded onto the front wheel during hard braking.  Stopping distance would probably lengthen.

Trying to stop on a downward slope would also increase the load on the front wheel.  For some combination of slope, speed, weight, center of gravity, brake type and condition, and road slickness, there will be safety issues.

Skidding

As my experience shows, things get dicey if your tires begin to skid.  A skidding rear tire isn’t too bad, except that it might indicate less-than-optimal weight distribution and diminished stopping power.  There’s also a slight loss of maneuverability; it’s easier to steer the bike if both wheels are rotating.

A skidding front tire is another story.  It’s nearly impossible to steer when your front tire is skidding.  If you try, the tire is likely to catch the pavement, at which point your handlebars will be wrenched from your hands or you will be removed from your seat.  The outcome of that situation is up to God’s mercy.

Moral of the story

The main thing that motivated me to write about this topic again is the realization that emergency stops with human cargo may be riskier than heavy loads with a lower center of gravity.  Especially if you’re carrying kids, you should practice a series of quick stops at progressively higher speeds until you find your comfort limit, and then you should stay below it.  Holding on during quick braking is good practice for your kids as well.

In addition, you should be extra, extra careful on hills or wet streets.

With kids on board, I am planning to reduce my speed and rethink my transport strategy in wet weather.

Cargo bike stopping distance

Regular readers of my blog know that I have been worried about cargo bike brakes for the past several months.  Yesterday my wife and kids left for a multi-day camping trip, and I decided this would be the perfect time to do some braking experiments with a loaded cargo bike.

In my mind, there are two kinds of braking I’m asking my bike to do: long, steady descents where I just need to keep my speed in check, and quick emergency stops.  I have a lot of experience with the former category – practically every weekday I pick up my kids from the school at the top of our hill and carry them down the steep slope.

On the other hand, I’ve only made a couple of emergency stops during the past year, so I haven’t been as confident in the ability of my brakes to stop a heavy load.  This morning before dawn, I loaded our mini-van with the bike and containers of water weighing a total of 180 pounds.  My destination was the parking lot behind the Seattle Museum of Flight.  I was looking for a long stretch of flat pavement that would allow me space to accelerate and skid to a stop.

And now I’ll cut to the chase.  When it comes to the Hammer Truck’s emergency stopping power, the big news is that there is no big news.  The bike stopped a combined weight of 420 pounds (180 pounds of water, 160 pounds of me, and 80 pounds of bike) travelling at 20 miles per hour, and it brought me to a complete halt in about the width of a parking space (less than 10 feet).  That wasn’t significantly longer than the stopping distance for the unloaded bike.  For that matter, it was on par with the stopping performance of our mini-van, and that’s comforting given the frequency I have to ride in mixed traffic.  However, I caught the unmistakable whiff of hot brakes and skidding rubber with the increased load.  The brakes were definitely working harder, even though they still felt solidly in control.

With considerable relief and bolstered confidence, I decided to repeat the experiment on a patch of wet pavement that had been moistened by the museum’s sprinklers.  That turned out to be a mistake.  The tires locked and I went into an uncontrolled skid, followed by an awkward low-speed crash.  I ended up on the ground, chain torn off the crank, and front wheel turned backwards.  Fortunately, neither bike nor rider was injured (but I was grateful there were no spectators at that hour of the morning).

This won’t come as a surprise to experienced cyclists.  Braking on wet pavement is a completely different story, and adding a heavy and somewhat badly-balanced load makes things even worse.  Perhaps I haven’t given slick pavement the caution it deserves during our damp Seattle winter – now I will.

How applicable are my results to cargo bikes in general?  My concerns about emergency braking have been mostly mitigated by these experiments, but with disc brakes on both wheels and the BionX motor assisting with regenerative braking, my bike is probably near the top of the class.  It’s possible that less favorable results would occur if you tried to stop a heavier load travelling faster with less capable brakes. Don’t let my unscientific results make you over-confident in your brakes.  I recommend doing your own experiments to give your equipment the opportunity to earn your trust.

More about my Hammer Truck

I recently received the following email from a reader:

I was researching cargo bikes and just kept seeing your blog pop up. I am very interested in doing a similar set up as yours.  I also was interested in elMundo initially.  A sidenote on the weight of the elMundo: they are now selling it with the electric components already attached and the shipping weight of the bike and box was 100 lbs. which seemed like a lot.

My question is pretty simple. I haven’t tested a Rans Hammer Truck in person since this is just the planning phase.  I read the height of the bike had a 31- 38 inseam. I am 5’5″.  I wondered about the comfort of the frame.  And if your wife was shorter than you and found the Hammer Truck comfortable… ?  Also just to pick your brain (and thank you very much in advance)  how did you like the Hammer Truck handling without the electric assist? You mentioned you test rode it for a day…

My plans are just like yours, I want to use it to take my 2 kids to school and errands and fun – reduce car use in general.  The kids are 6 and 4 and the bike trailer is just not cutting it these days.

Oh yeah! one more question. I read your post worrying about brakes.  Currently with the bike trailer I often hop off and just walk up the hills.  My question is, is a cargo bike easy to walk with when it’s carrying about 50- 60 lbs.?  Or very tippy? 

Thanks for the blog. I am surprised the Yuba people haven’t offered to let you test drive their bike. Surfing I ran across another cargo biker’s blog who actually bumped into the founder/owner while on a bike tour in Europe and had a very good impression of him and a good talk with him.

Thanks again. Happy biking! I am so happy I stumbled across your blog.

Best,
Jessamin

Thank you, Jessamin.  Your email reminded me that there are still a few things I can say about the Hammer Truck.  For many months, I have felt a bit uncomfortable about my bike’s relatively high cost, and I have been researching less expensive bikes that might appeal to a broader market.  That has been an interesting project, and I intend to continue doing it for a while.  But I don’t own these bikes or ride them on a daily basis.  My real expertise is my particular bike, and answering your questions gives me an opportunity to return to familiar territory.

To answer your question about bike height, my wife rides the Hammer Truck very comfortably.  At 5’4″, she is a little shorter than you.  As you can see in this photo, the seat stem for the Hammer Truck is angled at approximately 45 degrees.  When you lower the seat an inch, you also get an inch closer to the handle bars.  This seems to scale well for most body types.

Hammer Truck seat stem

While you’re looking at the seat, I will also mention that the inclination of the seat is adjustable.  When I first started riding the Hammer Truck, I had the seat almost parallel to the ground, like a normal bike.  However, the Rans web site shows their seats tipped forward, so I tried it.  It feels a bit like standing and leaning against a wall.  Tipping the seat puts a little more weight on your feet, and that’s what you want when you’re riding.  The slight curve of the seat back allows you to dig in for a little extra leverage when you need it.  These are all helpful when you really need to crank!

The Hammer Truck worked fine without the motor.  If we still lived in Denmark where it’s notoriously flat, I wouldn’t have needed the electric assistance.  I’ve spent so much time on this blog bemoaning the hills in our neighborhood, I decided I really needed to show you what I mean.  Yesterday afternoon, I put my 9-year old son behind the camera, and he took a video of me pushing my daughter up the hill, riding without assistance, and riding with the motor providing maximum assistance.

As you will see, this hill is a monster.  When I write about heating issues with my motor and brakes, you need to understand that I’m pushing both to a limit that most people won’t encounter.  Despite my occasional complaints, it’s pretty amazing that this bike can handle this kind of challenge.  (Note: the scraping noises heard in the video aren’t the bike — my son was balancing the camera on a mailbox to keep it level, and scraping as he pivoted the camera.)

You can also see from the video, pushing the bike uphill is possible, but not fun.  The side bars that carry loads so well are approximately where you want to put your feet, so you have to lean over a little.  It might be hard to see in the video because I’m already leaning against the hill so much.  It’s not as tippy as I thought as long as both hands are on the handlebar.  It would be almost impossible to do one-handed.

You might notice my slightly hunched posture when I’m riding in this video.  With the Hammer Truck, you generate power by pulling back on the handlebars, engaging the same muscles you would for rowing.  In my case, I can produce more cranking force this way than I would standing on my pedals on a traditional bike.  It’s more of a full-body workout, especially when I turn the motor off.  However, this might not be a good idea for people with fragile knees.

Speaking of cargo bikes on hills, this is probably a good place to mention one of my favorite web pages: Cargo Weight Calculator.  The calculator which gives you a rough idea about how much weight you can expect to haul up hills of varying steepness.  Another page on the same site shows you how to measure the grade of a hill.  Every time I turn off my motor and I’m reminded how hard it is to climb a hill with a load, I return to this web site, punch in the numbers, and I’m assured that there are real, mathematical reasons why it’s difficult.  It’s not because my motor is making me lazy.  🙂

Sometimes I get distracted by all the details of this project: the specifications, the prices, the compromises.  My blog is kind of heavy on that sort of thing.  I occasionally need to remember that there is an emotional and even inspirational side to cargo biking, and my favorite blend of practicality and inspiration comes from the Couch Potato to Full-Time Cyclist blog.  If you haven’t seen it, check it out — it’s really a great counterpoint to what you read here.

Cargo bike brakes and safety

Yesterday I took my bike back to the bike shop to replace a brake rotor that was warped and making loud screeching sounds all the time.  For awhile, I tried to convince myself this was a great safety feature: everyone could hear me coming for at least a city block.  But the joy of riding in near-silence was missing, and dogs were more likely to bark as my bike squeaked by.

Disc rotors are prone to warp when they get too hot.  In most cases, my brakes stay relatively cool, because the BionX motor bears the brunt of braking.  There is a little magnetic sensor on my rear brake lever that engages the motor’s highest level of regeneration when I pull slightly on the lever.   Usually, the drag of regeneration is enough to keep my speed in check.  When the hill gets a little steeper (or the load is heavier), I apply my brakes in addition to the regenerating motor, but most of the time I use the brakes lightly and for short duration.

However, there is a problem.  If I sprint up our hill at maximum speed, there is some limitation in the battery or the motor which shuts off regeneration on the way down unless I wait for 10-15 minutes before I descend.  Perhaps something is getting too hot, although I haven’t noticed excessive heat in either the battery or the motor.  I called the motor manufacturer to ask if they were familiar with this situation, but the technical assistant who answered said regeneration shouldn’t turn off unless the battery is fully charged.  I am quite sure my battery is only partially charged when I lose regeneration.

Riding down our hill and carrying two kids (about 150 pounds total) without regeneration, my front and rear disc rotors get very hot.  Hot enough to leave scorch marks on the rotor, actually.

To be fair, this is a steep hill (12-18% grade for about 1/3 mile), and the total weight of the bike, rider, and cargo is around 350-400 pounds.  But the duration of braking is less than two minutes.  It’s hard to imagine a situation where I would worry about hot brakes after two minutes of braking with a car or motorcycle.  Are cargo bike brakes really up to the tasks we’re asking of them?

According to the owner of the bike shop, they are not.  Most cargo bikes come with disc brakes that were designed for single-rider bikes.  A beefy cargo bike carrying a heavy load could easily double the weight the brakes have to stop.  Add a motor and a battery, and you’ve not only increased the weight, but you’ve also increased the capacity to carry big loads up a hill.  What goes up must come down, and the brakes better be ready for it.  I haven’t done rigorous research on this topic, but it seems fairly obvious that the brakes need to be upgraded to handle bigger loads and higher speeds.

Unfortunately, this isn’t a problem that the biking industry has squarely addressed.  To absorb more heat, the mass of the disc rotor must increase.  My rotor is 6 inches in diameter and 2 millimeters thick.  Apparently, there is a company that makes a thicker rotor (3 mm), and that would help.  Instead, I decided to lay out $100 to buy an 8-inch rotor laser-cut from stainless steel (http://dirtydogmtb.com/designandsafety.htm).

The first problem we encountered was that my brake cable wasn’t long enough to move the brake caliper mechanism the extra inch or two to accommodate the bigger rotor.  In the process of replacing the cable, I upgraded to “compressionless housing.”  The idea is that very stiff housing transmits more of your braking force to the brake rather than deforming the conduit through which the brake cable moves.  I had already done this for the front brake on a previous visit to the bike shop, and I can tell a difference in braking responsiveness.  The new cable and housing cost $38 for parts.

Bar precludes repositioning of brake calipers

With the brake cable replaced and the rotor bolted on, all that remained was mounting the wheel.  That’s when we discovered that the Hammer Truck panniers are supported by a bar in the exact position where the brake calipers need to be for that 8-inch rotor.  The shop owner said we could crimp the bar to make room for the calipers, but I was concerned about compromising the integrity of the bike.  Also, the caliper adjustment wheel (red in this photo) would be inaccessible if it were nestled into the dent he was proposing to put in the bar.  (Click on photos to see them full-size.)

In the end, I decided to buy another 6-inch rotor.  It’s nice and true right now, and my bike is quiet again.  I’ve learned enough that I might be able to avoid warping this rotor.  First, I should allow more time to let the BionX motor cool, or I should climb the hill at a slower pace (and perhaps a lower assistance level).  With a little experimentation, I should be able to reduce motor/battery strain and avoid regeneration drop-out during my return trip.  Although it might take a little more time or effort, this strategy might even extend the life of the motor and battery.

Second, my daughter just graduated from elementary school.  Now I will have only one kid to carry down the hill in the afternoon, and that should reduce the braking load.  My immediate concerns over our safety have been reduced.

But my concern for other cargo bikers is escalating.  The electric cargo bikes that I have mentioned in earlier blog posts, Kona’s Electric Ute and Yuba’s elMundo, have no motor regeneration and only one disc brake in the rear (both bikes have a rim brake on the front wheel).  I’m concerned that this might not be adequate to stop a heavy load after a moderately long and steep descent.  It wouldn’t take more than a few mishaps to cause legal problems that could restrict the electric cargo bike market before it has a chance to develop.

Sometimes I try to convince myself that this is just an issue of setting expectations appropriately.  When we get really excited about the economic and environmental advantages of cargo biking, we talk about our bikes as being “car replacement vehicles.”  But it has been over a century since Ford’s Model T was first sold.  Since then, cars have benefited from continuous technological improvements and fierce competition between many different car companies.  The electric cargo bike has barely reached a comparable level of development to those first Model T’s.  Manufacturers are still treating the motor like an after-market option rather than an integrated design feature.

Arrows show exposed pressure plate

My safety concerns aren’t just limited to the brakes, by the way.  As the shop owner was re-installing my rear wheel after the rotor replacement, we got a good look at how the BionX motor mates with the Hammer Truck frame.  The critical interface is where the motor axle bolts onto the frame — the C-shaped flanges called “drop-outs.”  The owner pointed out that my drop-outs weren’t deep enough: at least one-third of the pressure plate that the drop-out should be holding is left dangling below (noted by arrows in this photo).  If you’ve been reading my blog for awhile, you might recall that I stripped a hub nut during the first month I owned the bike.  The results were catastrophic: the motor wiring was damaged beyond repair and a new motor had to be installed.  When the nut stripped, the rear wheel twisted a little and locked up against the brakes.  The bike went into a skid, but fortunately I wasn’t travelling very fast at the time.  Even though there were cars nearby, I managed to stay out of traffic, and escaped unscathed from the incident.

If I had been travelling a little faster, or if — God forbid! — I had my kids on the bike when that nut failed, it’s not pleasant to imagine what could have happened.  It seems obvious to me that this problem could have been avoided if the Hammer Truck had been designed with deeper drop-outs to accommodate the motor.  This is what I am looking for: a manufacturer that designs the bike, the motor, and the brakes to work together, rather than putting these pieces together and hoping their designs and capabilities mesh well.  So far I have not seen a bike that impresses me in this regard.  It feels like a classic chicken-and-egg problem: manufacturers won’t spend the time and energy to develop that bike until they see a significant market opportunity, but the market won’t grow quickly until there is a serious bike that people can see, test drive, and feel confident about its safety and reliability.

There are still some breakthroughs required in battery and motor technology (and price) that may be required to make electric cargo bikes attractive to the mass market.  However, those same advances will also benefit electric cars.  The market for an electric car is so much broader than electric cargo bikes — I think Americans are going to jump straight from gasoline-powered cars to electric cars, and cargo biking will remain a tiny niche of ultra-environmentalists and fitness freaks.

Of course, that’s only the most likely scenario.  A massive and sustained increase in energy prices would obviously benefit bikes of all kinds.  A generational shift of mindset is also possible and can’t be underestimated.  For example, if teen heart-throb Justin Bieber decided that cargo bikes were the only way to travel, who knows how fast cargo bikes could sell?  But at this point, most of the people reading my blog are more likely to be the parents of the Bieber generation.

I’m in a strange position.  For nearly a year, I’ve been riding my bike and enthusing over this method of cutting carbon emissions, burning some extra calories, and seeing more of your neighbors, nature, etc.  Now suddenly I’m worried about safety.  I’ve always known it’s a little risky competing with heavy metal boxes for a few feet at the edge of the road.  But if you’re not sure your equipment is fundamentally safe and sound, there’s another set of issues to worry about.

Do you think my concerns are overblown?  Does your cargo bike inspire confidence?  Let me know in the comments below!

Cargo bike economics: maintenance

Today I took my bike for its first checkup after 7 months and over 500 miles of hill-chewing.  As you may recall, I have done no maintenance on this bike other than one application of chain lubricant.  Since I rely on it to provide safe transportation for my family, I wanted to ensure that no latent problems were developing.

For the diagnosis, I went to one of Seattle’s pricier bike shops.  I deliberately chose a different shop than the one that built my bike, because I wanted a second opinion — especially on those mission-critical brakes.  The owner of this shop is a big fan of the Big Dummy/Stoke Monkey bike, and I thought it would be enlightening to talk with someone who is somewhat skeptical of my bike.  He has a reputation for pulling no punches, so I prepared myself for some rough sledding.

But actually, things went quite well.  The owner found several occasions to point out advantages of the Stoke Monkey, but these were arguments that I’ve written about previously.  He complained that the BionX hub motor makes it harder to adjust the rear disc brake calipers, because the hub blocks easy access to the dial that positions the brake pads.  He charged me an extra $10 for the additional effort required.

The total bill was $75 for labor.  He adjusted and lubed my derailleur to recover my lost gears, cleaned and tuned the brakes, and lubricated various cables.  I paid another $25 to upgrade the front brake cable for better responsiveness, but that wasn’t critical.  Using the $75 figure for essential maintenance, I calculate a cost of about 15 cents per mile.  On the one hand, this figure is probably high due to the difficult geography this bike has to tackle.  On the other hand, it’s probably too low on an annualized basis, because I didn’t have to replace any parts this time.  In another 6 months, I may have to replace at least one of the disc brake rotors and possibly the pads, but that shouldn’t cost more than $50.  As I suspected, the regenerative braking of the BionX motor seems to be extending the life of my brake components.  What isn’t clear is how often other components will need to be replaced, and how much that will cost.  Although it will be pretty cheap compared to repairs/maintenance of a car, the number of bike miles will also be less, so it remains to be seen which is cheaper on a per-mile basis.

Just to be complete, the electricity to help propel me during this time period averaged about 1/2 cent per mile.  Hardly worth mentioning compared to the maintenance.

One sweet moment occurred while I was paying my bill: a customer was admiring my bike and asking questions about it.  He was initially attracted by those huge Xtracycle-incompatible pannier bags.  He was really intrigued when I told him the bike was assisted by a quiet (and virtually invisible) electric motor.  He was standing less than a yard away from the owner’s Big Dummy at the time, but it was my bike that caught his eye.  I have no doubt that the owner had him converted to a Big Dummy shortly after I left the shop, but my bike and I had our moment.

I plan to return to the same shop after another 7 months and 500 miles.  The owner did a good job and seemed to know what he was doing.

Looking for the Ute

I went to the “Sustainable West Seattle Festival” with my family on a rare sunny Saturday afternoon, hoping to see a Kona Electric Ute that a local bike shop was scheduled to show there.  It was fun to see many like-minded people showing various sustainable choices — bee keepers selling local honey, farmers selling organic chicken feed for your home-raised chickens, Zip cars, small wind turbines, and various kinds of electric bicycles.  Unfortunately, the Ute was not one of them.  Apparently, the Kona rep had not gotten a Ute to the bike shop in time for the festival, so this elusive bike foiled my best efforts once again.  I know a bike shop in our area that definitely has one, but it’s a bit of a drive and a ferry ride to get there, so I’m hoping to combine that trip with another outing sometime.

If my efforts to see a Ute have been challenging, getting a demo of the Yuba elMundo seems nearly impossible at the moment.  There is only one bike shop within 100 miles listed as a Yuba dealer.  When I contacted them about the possibility of seeing the elMundo, what I got instead was a strong recommendation to steer clear of this bike as well as the Ute and any other inexpensive cargo bike.  The bike dealer recommended the Surly Big Dummy with a Stoke Monkey motor as a superior way to handle our hilly geography.  This came as a surprise to me, because the Big Dummy was the bike I first intended to buy, but I was disuaded by several factors.  I’ve listed these elsewhere, but the main problems were the size of the bike (my wife wants a bike that is easy to ride) and maintenance of the Stoke Monkey (frequent alignment is necessary to avoid problems with the second chain).

The bike dealer pointed out that the Stoke Monkey is better for climbing hills, because it works through your bike’s gears.  In contrast, a hub motor like the BionX applies torque after the gears.  When you climb hills, a hub motor is running at low speed where it is inefficient.  I can verify that: on the steepest part of my hill where you want the most help, the motor does not feel like it is working as hard as you would like.  The bike dealer says his Big Dummy climbs 20% grades (steeper than mine) with less effort than my bike.

So, if you’re serious about replacing your car and hauling big loads up steep hills, the Big Dummy and Stoke Monkey are probably the best choice for you.  But unfortunately, it requires a custom build, and it’s a pretty crude system compared to my bike.  This video shows what I mean:

Everything demonstrated here seems like it’s a generation behind my bike.  The controller and burrito bag seem pretty crude: my controller must be built into the BionX battery case, which is beatifully mounted under my cargo deck.  Putting that big battery in the XtraCycle bag seemed primitive in comparison.  I could go on, but you can watch the videos and form your own opinions.  (If you haven’t seen my bike video, it’s here.)

I hesitate to criticize the Big Dummy and Stoke Monkey, because it’s a great bike and people have done a lot of amazing things with it.  For example, the BikeForth.org blog is one of my favorites — the author is pushing the boundaries of car replacement with weather coverings and solar power for his Big Dummy.  It’s really great stuff, but I sometimes feel like he’s quite a bit ahead of his time.  My practical side is struggling to find ways to get more people on bikes, even if only for some of their trips.  I would love to jump directly into a future where bikes are as prevalent in my country as they are in Denmark, but to enable that future we have to find a way to make our bikes more mainstream.  I feel like my bike is closer to that practical ideal than the Big Dummy/Stoke Monkey, but the price is still a barrier unless you’re completely replacing a car.  Even as a cargo biking advocate, I still drive our mini-van, frequently.  With our current infrastructure and suburban location, it’s not possible for me to transport my busy family without the car at this time.  So the cost of the bike comes on top of the cost for the car, and that is a challenge for many family budgets.

On the other hand, I don’t want to recommend the Ute or the elMundo if their inexpensive price comes at the cost of reliability, functionality, or safety.  Until I see them first-hand, or a good bike magazine does a thorough review and comparison of them, I can’t say if these are good candidates for advancing the worthy cause of cargo biking.

Stats for Don’s Rans Hammer Truck electric cargo bike

Just for fun, here are a few numbers I measured this morning, in an effort to make my blog a little more precise:

70 pounds — the unloaded weight of my Hammer Truck, battery, motor, bags, lights, etc.  That’s actually somewhat heavier than I expected.  And that doesn’t include the canvas shopping bags, rain cover, bike lock, water bottle, bungee cords, and other things I keep in the side bags for easy access.  No wonder I feel a little weak when I turn off the motor (only occasionally) and try pedaling up our hill.

30 pounds — the weight of my non-powered bicycle for comparison.  But I almost never ride it if the cargo bike is available.

10% grade — the incline of the road in front of our house.

18% grade — the incline on the steepest section of road on our way to school every morning.  It lasts for about 100 yards.  When I’m hauling a 70-pound kid and 20 pounds of books and instruments up that part of the hill, the motor and the human are both close to their limits.  This is when you begin to appreciate the miracle of cars.  Just press that accelerator a bit more towards the floor, and 10 times the mass of my load leaps up the hill at 5 times the speed.  But that challenge only lasts for 100 yards, and most people don’t have 18% inclines in their daily routes.  The 10% grade feels more reasonable, as you can see in the first part of my Electric Cargo Bike video (http://mycargobike.net/2010/05/06/cargo-bike-video), where I haul my son and his stuff around the corner and up the hill.

7 months — the length of time I’ve been riding my bike down that hill, often with two kids as passengers, without any brake replacements or adjustments.  I think that is the best aspect of the BionX regenerative braking system.  I’m just beginning to think that an adjustment might be necessary in the next month or two.  My wife wore the brake pads on her traditional bike down to the metal in that same span of time.

Good news: I’ve found an owner as well as two local bike shops who have the Kona Electric Ute.  I hope to take it for a test drive this weekend at a local sustainability faire!

Dawn of the (U.S.) cargo bike revolution

[NOTE: I originally posted this article on May 27, 2010.  Since then, new information has become available.  I edited this on August 24 to incorporate some of the new developments.]

The title of this post might be a tad premature, but today I’m feeling a little more optimistic than I have in recent weeks.  That’s partly due to encouragement from my readers (you are a wonderful bunch!)  And perhaps some of the credit goes to a break in our Seattle rain that is allowing work to proceed on the solar panels being installed on my roof this week (soon I will be motoring up the hill using electrons harvested very locally).

But the biggest boost in my outlook came from news that two of the biggest names in cargo bike manufacturing — Kona and Yuba — are offering electric assistance as a pre-built option for their bikes.  Regular readers of my blog will know that this is a development I’ve been waiting and wishing for, and I think it signals the beginning of a new chapter in the annals of this kind of transportation (at least in the U.S.)

Why is it significant?

First, customers will no longer have to build these bikes themselves.  That requires either mechanical ability or a good bike mechanic and some extra cash.  But the process isn’t streamlined: which motor do you use?  Where do you mount the battery?  Are the specs on the motor a good match for the loads on the bike?  I’ve read several blogs where the build process took months to complete.

One can assume that the bike manufacturers have matched an appropriate motor to the bike.  If there are issues with the bike, there is a single contact, rather than wondering if the problem lies with the bike, the motor, or the installer.  To date, electric cargo bikes have been one-off custom builds, and there is no easy way to leverage knowledge or share solutions.

Economies of scale will reduce prices (both of the new bikes are significantly less expensive than mine), and competition will keep those prices within reach of people who need an alternative to a car for financial reasons.

So here’s a quick comparison of the bikes, with mine thrown in for context:

  Kona Electric Ute Yuba elMundo

Rans Hammer Truck / BionX
Price $2,599 $2,297 (includes tax and shipping!) $3,887 = $1,997 (bike) + $1,890 (BionX)bags/runners/deck not incl.
Motor 250W front hub 500W front hub 350W rear hub (BionX)
Links http://www.konaworld.com/bike.cfm?content=electric_ute http://yubaride.com/yubashop/28-e-mundo.html http://www.ransbikes.com/Hammertruck09.htm

http://www.cycle9.com/c9store/electric-bicycle-kits-c-5/bionx-pl-350-rear-hub-motor-kit-p-48

When I originally wrote this article, I included a row in the table above listing the carrying capacity of each bike.  Since then, I have become concerned about the ability of cargo bike brakes to stop loads that approach the carrying limits of the bike.  Yuba has actually removed any mention of carrying capacity from its website.  In my opinion, that is the responsible thing to do.  There is already a tendency for enthusiastic cargo bike promoters to put very large loads on these bikes and post photos for bragging rights.  Even though it’s fun, I don’t think it’s in the long-term interest of cargo biking to promote unrealistic or unsafe behavior.

Since I wrote this article, there have been further developments for the Ute and elMundo, and there is a new bike coming from Trek.  You can read about them here.