August, 2010

Bike infrastructure / Bike to Work — No Comments
31
Aug 2010
by don

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.

Bike Safety / Cargo Bikes — 4 Comments
28
Aug 2010
by don

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.

Bike Safety / Cargo Bikes — No Comments
27
Aug 2010
by don

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.

Cargo Bikes / Electric Bikes — 7 Comments
23
Aug 2010
by don

Electric Ute official debut, Trek coming

Finally! It has been months – even years – since rumors of an electrically-assisted Ute cargo bike first surfaced on the web.  Kona recently posted its 2011 catalog online, and there it was: the Electric Ute in all its beauty.  At $2599, Kona has allowed the Yuba elMundo to keep its low-price crown ($2297 including tax and shipping).  However, the Ute and the elMundo are such different bikes, price should be among the last factors to consider if you’re choosing between them.  There have also been changes in the elMundo since I last wrote about it, so there are good reasons to take another look at both these bikes.

Kona Electric Ute

Kona Electric Ute - Click for larger image

Despite its workman-like name, the Ute gets my nomination for most beautiful cargo bike.  Kona has paid attention to the details, and the electronics are nicely integrated.  The Ute approaches my ideal of a bike and motor that were designed together.  Unfortunately, Kona’s marketing is a little coy about what their design target really is.  For example, the website introduces the Ute with this sentence: “The Electric Ute is a battery-assisted version of our very popular Ute, a long wheel base bicycle designed to carry loads of up to 100kg-perfect for transporting goods in the urban environment.” [their emphasis]

This might be an accurate statement in a superficial sense, but it deserves some careful disection.  If you live in an urban environment that is relatively flat, and if you can fit your load into the comparatively small Ute side bag, the Ute will be perfect for you.  On the other hand, if you manage to load 100kg (over 200 pounds) of cargo on the bike (that might require some creativity), you’ll find the motor is not powerful enough to help much on even moderate inclines.  During my test drive (see my in-depth review here), the motor shut down while climbing a short, steep hill of about 15% grade – no load, medium assistance level.  At first, I thought the failure was a battery issue, but now I’m pretty sure the controller was temporarily disabling the motor to prevent overheating.  If you live in Seattle or San Francisco, you may have to pedal up the steep hills without assistance from the motor, just when you want it the most.  I also have concerns about the ability of the front rim brake and rear disc brake to safely stop a heavy load in an emergency.

Kona’s description of the Ute ends with this: “Serious power for carrying heavier loads. Ditch the truck, people.”

I’m not a marketer (and thankful for that), but is it really necessary to hype the bike past the point of reasonable expectations?  I mean, the Ute is a great bike for commuters who have some extra stuff to carry.  It feels more like a normal bike than its bigger and heavier competitors.  Maybe those facts aren’t sexy enough for the marketing department, but this is a bike that could satisfy many customers.  The big question is how it will compare to Trek’s bike which will be released late this fall.  I’ll talk about that shortly.

Yuba elMundo

Yuba elMundo - Click for larger image

The elMundo has quietly undergone some changes since I corresponded with a company representative in late spring (here).  The only clue that the bike has had another transformation is the addition of “v3.0″ to the bike’s name.  Photos on the website have not been updated.

Yuba has ditched its 750W motor from Aoetema and now uses a 500W motor from eZee instead.  The fact that Yuba mentions the brand of the motor on its website is progress, but I still have a question.  The only motor I know of from eZee is rated for 400 watts nominally, and about 800 watts peak.  Is the 500W figure quoted by Yuba fudging a little?  Not that I’m focused exclusively on the wattage of the motor: even at 400W, the geared eZee motor might deliver more power when it’s needed than the Aoetema motor.  But the effort to be scrupulously accurate on these specs would be a welcome development in the cargo bike market.

I would love to know what inspired the motor change, but I have a couple of guesses.  First, the eZee motor uses internal planetary gears, which should help deliver higher torque at low speeds for climbing hills.  The elMundo is a big, heavy bike (due to its high-tension steel frame), and it really needs a high-torque motor.  Yuba is also calling attention to the disc brake mount on the motor.  Although the standard elMundo comes with a rim brake on the front wheel and a disc brake on the rear, I would encourage anyone who intends to descend hills with a loaded elMundo to invest in a front disc brake. 

Interestingly, Yuba has removed any mention of cargo weight capacity from its descriptions of both the Mundo and elMundo.  The company previously claimed an absurd figure of 400 pounds, plus rider.  Although the frame may be able to handle that, it was hard for me to imagine the brakes (and perhaps the tires) would be capable of stopping that load in a reasonable distance.  If my complaints helped motivate this change, I am pleased.

As before, I must add a huge caveat to my descriptions of the elMundo.  Although I’ve read blogs and emails from people who are very happy with their Mundo bikes, I’ve never ridden one or even seen the bike in person.  The scarcity of Yuba dealers in my area makes that challenging.

The elMundo is also likely to have a competitor in the upcoming Trek bike, so I’ll move on to that.

Trek Transport+

Trek Transport+ - Click for larger image

The entry of bicycle behemoth Trek into the electric cargo bike market is huge news.  Trek’s annual sales are at least 100 times those of Kona, and I couldn’t even find sales figures for Yuba.  If Trek decides to put any weight into the marketing and support of their bike, other cargo bike manufacturers are likely to become asterisks in the margins, at least in the U.S. for the next couple of years.  Besides my bike, I’ve never seen an electric cargo bike being ridden in my city.  At this point, I’ll bet the first one I see will be a Trek.

With an MSRP of $2679, the Transport+ has the Ute squarely in its sights.  Like the Ute, the Transport+ includes a bunch of accessories at the base price: folding rear load racks, front rack, Bontrager Transport cargo bag, fender, wide-stance kickstand, front and rear lights.  With the front rack, rear side racks, and bigger cargo bag, the Transport+ appears to be more serious about hauling cargo than the Ute.

These features alone could justify the extra $80 for the Transport+, but Trek’s choice of motor is an even more compelling reason.  It comes with a beefier 350W motor which is essentially the same direct drive BionX motor I have on my bike.  This motor offers superior load-carrying and hill-climbing capabilities compared to the Ute. It is quieter, the pedal activation system works a little more smoothly (in my opinion), and it offers regenerative braking which takes some of the load off your brakes.  The advantage of direct drive (as opposed to planetary gears) is that the BionX motor is very, very quiet.  The downside, as I’ve mentioned in earlier posts, is that motor assistance starts to fade at speeds below 6 mph, and this can be a challenge when hauling a heavy load up a steep hill.

BionX has incorporated additional features since I bought mine a year ago.  When you turn the console light on, the lights in the front and rear of the bike turn on too, powered by the same battery.  On my bike, I have to flip at least 4 switches to turn lights on and off, and I have to keep all those separate batteries refreshed.  This is a welcome advance!

Trek explains their “Ride+” motor technology in a series of videos available here.  One of the videos mentions a 250W motor, but that’s a less powerful version than the one Trek is using for the Transport+.

Another feature I like about the BionX system is the integrated battery/controller.  If you compare the photos of the Ute and the Transport+, you’ll see the latter doesn’t need the extra black box mounted near the cranks on the Ute.  The console for the BionX also gives better feedback about the level of assistance requested and received from the motor.

It’s always easy to get excited about a bike when it’s merely a photo and a set of specs, so I’m trying to temper my enthusiasm for the Transport+ until I can actually ride one.  There are still opportunities for Trek to misstep.  But with an attractive bike, good technology, a large dealer network, and marketing muscle, it seems like this is Trek’s game to lose.  But we’ll all be winners if this bike helps bring cargo biking into the mainstream.

Big year for cargo bikes

A year ago I was shopping for an electric-assisted cargo bike.  None were available pre-built from a manufacturer.  The state of the art was an XtraCycle like the Surly Big Dummy driven by a Stoke Monkey, but it wasn’t easy finding a bike shop that wanted to build one for me.

Today we have ready-made electric bikes from two manufacturers, and the biggest U.S. bicycle company is about to enter the market.  I’ve been riding my bike almost daily for 11 months.  There have been few problems and virtually no close encounters with cars.  My blog receives over 1,000 unique visitors per month from all parts of the world (but mostly U.S. and Canada), indicating an encouraging level of interest in this transportation alternative.

Sometimes the pace of change seems slow, but looking back, a lot has happened this year.  I wonder where we’ll be next year about this time?

Cargo Bikes / Electric Bikes / Xtracycles — 3 Comments
19
Aug 2010
by don

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.