Bridgestone Assista, the electric mamachari (my craigslist bike)

The Bridgestone Assista, brought to us by the Land of the Rising Sun

Last month I mentioned that I bought a mamachari. When I saw it on craigslist, I assumed that given the less-than-a-new-bike-at-Walmart price that there must be something wrong with the electric assist. I was wrong and there was not. So for the past three weeks I’ve had the option, when I want to, of riding an electric pedal-assist bicycle. It is even better than I dared to hope.

This particular bike and its assist do not work miracles. My mamachari is a single-speed and it weighs 65 pounds. The motor, which sits in the rear hub, is not especially powerful compared to the BionX-assisted Big Dummy I rode in Portland; it is several years old and a first generation pedal-assist and evidently Japanese bicycles limit the power anyway. It does not have a throttle: if you want power, you have to pedal. With a 35 pound preschooler on the back the combined weight makes this bike really slow, even with the assist. Guys wearing lycra on light road bikes pass us going uphill, although we pass regular commuters. On mild to moderate hills the assist is helpful although not always necessary, but even with the assist it is still work to crank that much weight up a steep hill.

This is the only road to our daughter’s preschool.

All that said, this bike is a game-changer, because on the mamachari I fear no San Francisco grade. On a pedal-assist bike, San Francisco flattens out to something approximating a normal city. My daughter is getting regular rides to preschool because we now have a bike that’s capable of taking the hill safely. When Matt took her up to school once on the Kona MinUte, having her weight on the back meant he had to fight against having the front wheel lift right off the ground (this has happened to me on other hills). Plus he nearly passed out from the effort and has refused to ever do it again. On the mamachari, not only do we have the assist, but the weight of the battery, which is low on the bike and further forward, ensures that the front wheel stays safely on the ground. It is a lot of work even so—my heart rate usually doubles on the way up and I always end up short of breath—but I don’t break a sweat.

This is the battery; the English words are basically decorative

My mamachari was imported from Japan by a coworker of the woman who sold it to me. She works at Lawrence Berkeley Labs, which is about 2/3s of the way up a very long and steep hill. We live in San Francisco, which has countless hills that are steeper, but very few of them are long. The Bridgestone Assista does not seem to have been designed for the kind of extended use needed to haul it up the hill to LBL, so the previous owner of this bike wired a backup battery into the front basket that kicks in when the original battery’s charge runs down, and used the assist for the entire trip (I found her electrical skills awe-inspiring). The range on this bike is now apparently about 20 miles with hills, although I have yet to use the backup battery.

The pedal assist controller: Off at the top, On in the middle, and Eco at the bottom. The bars next to the plug symbol indicate how much charge is left in the battery.

This bike is really, truly a Japanese bike and it has some quirks. The electric assist controller and the battery charging instructions are written entirely in Japanese and my Japanese is pretty rudimentary, so I had to get some help with translation. The kanji and katakana on the controller read: “Off,” “On,” and “Eco.” Because the bike has no gears, I think of the pedal assist as creating three virtual gears: “Cruising,” “Going up a hill,” and “Riding into a headwind.” In Japan traffic is on the left, so the brake cables were reversed, which was especially disconcerting when I got it because the front brake wasn’t working at all. (Before I replaced the brake, riding the mamachari was a bizarre inversion of normal life because I casually rode it uphill and carefully walked it down.) The mamachari has 650b wheels, which are standard in Japan, and big wheels look odd to me on such a slow bike. And this bike is meant to meander. You sit bolt upright on a mamachari and putter along. It’s very relaxing.

This is the motor in the rear hub; it’s not particularly powerful, so it’s fairly unobstrusive

There are lot of ways that it’s clear that the bike is meant to be disposable. The wheels are junk (and would be hard to replace, given the quirky size and the integrated rear hub motor) and the original brake levers were plastic. They felt like they would snap in half when I was pulling them (without much effect at first). When I had the front brake replaced the bike shop also switched out the brake levers for metal ones, and that feels a lot safer. It has a hub dynamo front light that looks pretty ratty and works, uh, most of the time. The fenders are plastic.

And yet I am amazed at all the ways that a “disposable” Japanese bike is relentlessly awesome.

The back rest on this seat can flip over to convert it to a giant rear rack basket

The back support of the rear child seat (with integrated waterproof cushion) can be flipped over to turn the seat into a huge rear basket when a child is not on board. The rear wheel lock is virtually hands-free, and so well-machined that it makes Dutch rear wheel locks and the one on my Breezer look like something out of the Stone Age. Plus it is integrated with the battery lock, so when the rear wheel is locked the battery cannot be removed.

With the low step-through, getting on this bike is like sitting down on a comfy chair

The kickstand reminds me of a giant paperclip but it is bombproof. I can put my daughter on board and watch her lever herself to the side until she is almost out of the seat and the bike does not even wobble. The seat has the largest springs I’ve ever seen and riding the mamachari literally feels like bouncing on an exercise ball.  And for reasons I don’t understand, the mamachari is rock-stable at low speeds and can take corners more tightly than even my Brompton. And this is without even mentioning the giant front basket. I can’t put panniers on the mamachari but haven’t yet missed them.  The Bridgestone frame is also the prettiest and lowest step-through I have ever seen. Even the bell is mellow.

Why pink power? She just really likes the color pink; apparently it’s part of being three. The girls in her preschool all fight over who likes pink the most; it’s a thing.

When I ride this bike people ask me where to buy it (craigslist, or barring that, Japan), or if they can buy it from me (no). It is easily the most coveted bike we own, at least in our demographic, and although the mamachari initially left our local bike shop unimpressed, they have been reassessing it in light of its popularity. My daughter begs to ride the mamachari at every opportunity. When we are on the streets she shouts to everyone she sees, “I’m riding a mamachari!!!” And then she turns to me and says, “Turn on the pink power, mommy. I want to go FAST!” And yet the mamachari is a bike that is so obviously only cool to parents that no bike thief would be interested in stealing it. Why is no one importing these bikes?!?

To my surprise, my mamachari even has a pedigree of sorts. My brother-in-law wrote to tell me about it. “You now own a distant cousin to what bicycle aficionados consider the greatest production bike brand that ever was: Bridgestone USA. It was an office of three in Walnut Creek (or maybe it was San Leandro) that designed bikes to be built by Bridgestone Japan and sold only in the US. They were around for about a decade and were super duper smart bikes like never before or after (Kona and Salsa are the closest thing to them now). Bridgestones were known to be the best bang for the buck at any price range and were spec’ed in ways where nothing ever needed to be changed out at the time of purchase and nothing was on there just because it was new or cool. They also were the winningest bikes in history for folks who paid for their own rides (like amateur world champions), while at the same time being the only brand to really push utility bikes in the US. I had one in Minneapolis and it was most awesome. I should have kept because it’s now a serious collector’s item. If Bridgestone USA was still around, I suspect you’d be riding one or three.”

Riding the mamachari is crazy-fun.

The mamachari is the ride of choice on our trips to preschool, of course, because of preschool hill, which is why I bought it in the first place. But it is also my ride of choice on a new route in San Francisco, because it can take any hill that I didn’t realize was there from reading the map, because it is relatively uninteresting to bike thieves, and because it can carry almost anything I might want to borrow or buy (a dozen library books? no problem). I still usually ride the Breezer on my ordinary commute; I’m used to those hills and the mamachari is overkill. The Breezer is also the only mule that can haul the trailer-bike. And the Brompton serves its own niche, so it will always have a place in our lives.

Even without the assist, the mamachari would be fun to ride on weekends, when we’re going someplace flat, because it is such a mellow ride and because it is so easy to haul kids and other stuff. Yet although I adore this bike, it may not be with us forever. Having tasted the freedom that the assist gives us, I want a lighter pedal-assist bike with gears, so I don’t need to rely on the motor quite so much on moderate hills. Plus, to be honest, the combination of the weight plus a weak motor means that it can’t really go up every hill in the city, although it’s close. But I’d be better off on a frame that is designed for people who are bigger than the average Japanese mama—at 5’7” and change I’m a bit tall for this bike. Plus the mamachari is too heavy to go on a bus bike rack, which maxes out at 55 pounds.

The mamachari locked up after its daily conquest of preschool hill.

Although I will keep this bike at least until my daughter outgrows the rear seat, I think the mamachari’s ultimate destiny may be to carry my 5’2” mother up the somewhat mellower hills of my hometown. After all, in Japan it could be called either a mamachari or an obachari. And that way I would never have to part with it entirely. I am attached to all our bikes to some extent, but the mamachari, the first bike I ever felt confident enough to buy used on craigslist, the first bike that could ever haul our daughter up to her preschool, the bike that laughs at most San Francisco hills, and the bike that has already taken me to more new destinations than any other, is already special. It may have been intended to be disposable, but I’ll love it forever.


Filed under commuting, family biking, reviews, San Francisco

20 responses to “Bridgestone Assista, the electric mamachari (my craigslist bike)

  1. sho

    You should check out Rivendell– Grant Petersen’s shop in Walnut Creek is the successor to Bridgestone. (He was the bicycle designer at Bridgestone, though I’m not sure he had anything to do with the mamchari, which is definitely Japanese.)

  2. I saw on Craigslist some time ago someone selling several used mamachari in Santa Cruz– not sure if they were his personal bikes or if he was importing them and there will be more…. We like our Japanese bike too (I guess it’s a mamachari though it has a basket instead of kid seat). It’s the bike that can get the 10 year-old to church without ripping up the fancy, fluffy dresses she likes to wear. No electric assist though…

    • That’s brilliant! Giving a mamachari to a kid is so smart–they’re sized for short people and so easy to ride. An electric-assist single speed mamachari would be perfect for a kid in San Francisco: all the hill climbing advantages with none of difficulty involved with learning to shift.

      If we ever get to Japan I would buy one of the new ones with three hub gears and three levels of assist and bring it back here. New legislation allows a stronger assist (up to 200%) and new batteries give a 40 mile range, which would be pretty much perfect. Total cost for a bike like that is evidently ~$1000 in Japan including the baskets and wheel lock, which makes me want to cry.

      • Maggie Chesterman


  3. essbee

    You are SO right! You must get mom onto this bike, ASAP. The step-over height was the main problem she had with my rental, and the frame was slightly too big for her. I think she’d love this ride.

    Also, you have entirely convinced me that I need to take you up on your offer to try it out. We should trade one day…you can see how you like a mixte commuter (so light!) and I can see how I like a bike meant for life in the slow lane.

    Dan loves Rivendell. I wonder if he even knows the Bridgestone connection…

  4. Betsy R

    I am in Tokyo, riding my Bridgestone mamachari, carrying my 2 year old in front and 6 year old in back cruising up the inclines. AMerica needs these bikes that are utilitarian. Yes, it cost about $1600 but I have calculated I have saved $200 in gas bills in the past two months so it will even out in the end. AND my kids LOVE riding it and I don’t have to sit in traffic!

    • Congratulations! I couldn’t agree more. And $1600 is about half what you would pay in the US for an electric bicycle with comparable technology to your Bridgestone, but it would lack the child seats, rear wheel lock, and so forth. I would love to try one of the new models like yours! The Japanese mamacharis are like nothing else in the world right now.

      Also you’re not just saving on gas: the bike has zero insurance cost, minimal depreciation, and requires almost no maintenance, plus you never have to circle for parking (at least I don’t; maybe in Tokyo it’s different). That bike is a screaming bargain in anyone’s money. Thanks for writing!

  5. Carrie B

    I’m so glad I stumbled upon your article. I really like your bike. I don’t have a mamachari but I do have a bike made by Bridgestone (with a little help from Yamaha & Mitsubishi (?) ) called an i-MiEV e-bike. This is the only info I’ve found about it: I have the green one and I purchased it from Only thing is I don’t have the charger nor do I know how to get a replacement battery for it. I do not speak or read Japanese. Would you mind if I asked your help in finding a battery & charger for it? Do you know of any companies in the US or Japan that make compatible batteries for it? Your electric bike looks very similar to it so I figure maybe the battery on your bike would work on mine too. My bike is so super cute that I want to try to convert it with something US made if I can’t find the items I need. If not, I guess I’ll just have to try riding it without electrical assist but I live in a somewhat hilly area (not like San Francisco) that I would prefer if I could get the bike to work properly.

    • Lovely bike–I’d never heard of it before. I’d suggest for a replacement battery you do what I did and contact Shuichi of Mama Bicycle, who comments here at times. Check out the comments in “The mamachari returns” for some more about him. Email address is shuichi.kobayashi at His English is very good, he’s interested in exporting mamacharis and their parts as a small business, and he is very kind.

      If that doesn’t work out San Francisco’s Electric Bike Shop claims they can upgrade bicycle batteries at least some of the time–no promises as I’ve never asked them, but they may be able to help. If I hadn’t been able to get a battery from Japan that would have been my next stop. If you buy a US battery a charger would be easy to get as well.

      • Carrie B

        Thank you so much for the information. Isn’t it lovely? Mine looks exactly like the one pictured and was in near perfect condition. It’s not very heavy either. I will guess that it’s about 50 lbs. I am reading more of your stories in Hum of the City now and I have read some of Mr. Shuichi’s comments. I will contact him about the battery and charger (or the bike shop). My husband says he’ll rewire the motor to fit a U.S. made battery in case I’m unable to obtain the one I need but, hopefully, he won’t need to do so. I’ll post whether I obtain a battery or get it rewired as well as how the bike rides. Thanks so much again! I am loving your stories! You have a new follower!

  6. Cooffeemilk

    I hope some store sale even nomal bridge stone bike or kids bike in north america,women’s normal bike is very bad in Canada.(´;ω;`)

  7. Tia

    I am selling my mamachari (electric bike with 2 child seats) in the Boston area. You can check my posting on Boston craigslist. It is a Panasonic Gyutto DX. May 2016.

  8. What beautiful coverage! We run a small startup out of Dubai that up-cycles old and forgotten Mamachari’s. Their durability is just impeccable, we get the used and rusty and we re-model and customize them only to re-sell them and color the streets of the city with bikes that outperform. We love them dearly! Check out our brand on and let us know if our work interests you 🙂

  9. Laura Dawson

    I recently acquired a Bridgestone mamachari that someone was throwing away!! It is in running condition after a friend replaced the tubes.
    I am not sure of how old it is because all of the writing on it is in Japanese! I spoke with the gentleman who owned it, who gave me the battery charger and all the keys for it. The battery is the lowest that they make 4Ah. It has a child seat that clips on the front between the elongated handlebars and a bike rack with a detachable basket on the back, with a monster of a kickstand that raises the back tire off the ground and ensures that the bike could never be knocked over!
    I am wondering about the value of this beautiful brown mamachari. If I should attempt to sell it or if I should keep it for myself!
    Any information you could give me would be amazing!

  10. Zoha

    I know this post is several years old but I have this exact bike (Bridgestone Assista) that my mom got from Japan and I have a preschooler whom I’d love to ride on my back. What bike seat did you use? I have had no luck finding a compatible one online.

  11. Zoha

    I have the exact same bike and cannot for the life of me find a toddler seat that is compatible to it. Do you happen to know what toddler bike seat you had on yours? Or if you still have it, I would be willing to buy it from you. Any tips or help is much appreciated. We live in Marin.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s