Bamboo / BBS02 / Nexus IGH

I heard that isopropyl alcohol can be used for curing.

"Another method to reduce starches is to soak bamboo in Isopropyl alcohol (also isopropanol, propan-2-ol, 2-propanol, rubbing alcohol or the abbreviation IPA) This cheap liquid might be easier to use than to slow bake bamboo. Baking at higher temperatures to speed up heating the internal structure will damage the outside surface structure. Much like baking a rare roast at 320 to achieve a quick internal 140 temperature damages the surfaces to create a charred flavored. This is not wanted for bamboo.

Finally, a third world professor also has discovered that soaking bamboo poles, to treat, can be cheaply done by storing the un-split culm vertically and filling the one top cavity with the liquid. in about 24 hours the liquid has soaked most of the height of the culm or pole."

I have attached a couple of papers I had found on preserving and curing bamboo.
 

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Interesting reading, thank you!
My approach was sure low tech by comparison: 'stick some bamboo poles in the corner and see if they are useable once dry'.
The original stock was basically healthy, not infested with mold, fungus, beetles etc.
So no need for alcohols or heavier agents in treating and curing in this project.
Though some ethyl alc for the builder might have been nice option at times.
 
Update after riding the bike for a few weeks: I like it!

Comfortable, handles well, starting to trust that it won't fall apart under me.

Bike was intended as a medium-range around-town hill-leveling 'grocery getter'.
It has a small but punchy 6Ah battery (14S / 3P of Samsung 20R cells, so ~300 watt total capacity), built a while back by EM3ev.
Battery delivers plenty of amps for BBS02, but I was a bit worried about range.

Took it out for a ride this weekend, to garden store to get some parsley.
About 12 miles roundtrip, roughly half pretty hilly and half flat-ish streets.
Pedalled, but never hard enough to really raise heart rate or break serious sweat.
Tried to conserve power reasonably, but wasn't stingy with it -- I opened the throttle as needed.
Bike did great, and surprisingly used only about half the battery capacity (~3ah).
So implies 20+ mile range in mixed conditions.

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Drunkskunk said:
That's an epic build, man. I really like it.

Thanks! Like spinningmagnets said, turns out that bamboo/epoxy is a surprisingly easy and accessible technique for amateur custom builds. You still have to be pretty fussy with getting part alignment, clearances, etc right -- but the actual joints are easy to fabricate and very strong.

I've done some simple brazing in past, adding or repositioning brake studs and permanently joining the rear triangle on old Raleigh DL-1 frame with the 'bolt on' triangle design. Great results, and I'm tempted to try fabricating an entire metal frame at some point. But the metal working project that is the back of my mind right now is further modifying my old electrified Raleigh Twenty folder by stretching the rear triangle and making it a much longer wheelbase... then move MAC motor off another bike onto the Twenty... figure that combo might make a nice bike, plenty of power for hills and reasonable top speed for me. Basic Twenty frame is great bike, but with short wheelbase it is too prone to wheelies with any powerful rear drive, I think longer rear triangle should help fix that. And the MAC motor on its current 26" mountain bike is great in general but it runs out of grunt on steep hills a bit... I figure it might be ideal in a 20" wheel. Of course, that will leave me with the mountain bike that is going to need a new motor... jeez, it never ends :wink:
 
LewTwo -- Outside diameters of bamboo tubes in this build:
Top tube 1.5"
Seat tube 1.5"
Down tube 1.62"
Seat stays 1.1"
Chain stays 1.1"

I started with about twice the quantity of bamboo poles I actually used, in a range of outside diameters from about .75" up to about 1.7". Then I actually chose the pieces I used based mainly on their inside diameters... which poles mated most closely with the "stubs" on the salvaged metal frame parts.

Gave dimensions in inches since this was American grown bamboo :wink:

Also, there was very slight dimensional shrinkage from green > dried. Almost none in length, maybe 5-10% in diameter at a guess. Should have measured the green poles to start but I didn't think of that.

Hope this helps!
 
An update on bike.
Spent weekend riding on beautiful cycle path along American River near Sacramento, California. 5 star ride, do it if you have chance. 32 paved miles of flat to rolling hills, no cars, just bikes and walkers.

Happy to say that after 9 months and a few hundred miles I've had zero problems with this bike. No signs of failure in either bamboo poles or hemp/epoxy joints. No creaking or flex in bike joints, only in mine. No splits in bamboo. No trouble with drive train. It's a great bike.

I rode 30 miles on Saturday. Battery is tiny, 14s / 3p of Samsung 20R cells, so 52V and 6Ah, ~300W. Couple years old now, but it has had an easy life. Was very happy with its performance. This isn't exactly scientific data, but the profile I rode was ~10 miles with power coming mostly from me, ~10 miles of me and the battery sharing the load say 50/50 and going 10-15 mph, and ~10 miles of relying on battery only and going 15-20 mph. Of course, any section that was uphill... was battery only. Battery performed like a champ until it cut out at 29.5 miles. First time I'd ever had an LVC cut out by the BMS (I generally baby batteries). It was interesting. One moment the bike has electric power, albeit at slightly lower performance level due to voltage drop, the next moment the system has only leg power. No "hey, I'm about to shut off" message. Just gone. Makes sense.

American River.JPG
 
footloose said:
One moment the bike has electric power, albeit at slightly lower performance level due to voltage drop, the next moment the system has only leg power. No "hey, I'm about to shut off" message. Just gone.

Actually, not quite true. The battery glyph on screen remained at full bars for like 90% of the ride, then started dropping like a stone. So cutoff wasn't a complete surprise. It just happened way faster at end then I expected. Just tells me not to rely on the silly "fuel gauge" in future.
 
footloose said:
footloose said:
Just tells me not to rely on the silly "fuel gauge" in future.
That is why I finally broke down and bought a CA.
 
LewTwo said:
footloose said:
footloose said:
Just tells me not to rely on the silly "fuel gauge" in future.
That is why I finally broke down and bought a CA.

CA is brilliant device. I have an older version (2.3?) on different bike, love it. May upgrade to the newer version just for the current throttle functionality. That seems like a pretty useful thing.

On this bamboo bike I do have a simple 'watts app?' type watt meter.
But it is co-located with the battery, which is in small bag hanging off back of the seat.
Admittedly, that is a pretty difficult location to actually see the screen while riding :lol:
If I was smarter I would have stopped and taken a look at it when the "fuel gauge" started dropping, to see what the actual situation was and how much power really remained. Live and learn, I'll do that next time so I get a clearer mental map of what the battery bars on fuel gauge really mean in terms of power still available. Or better yet, just check the watt meter every few miles since what the "fuel gauge" really tells you... is that by the time the bars start dropping, you'd better be most of the way home or you're going to end up pedalling.
 
L2 -- That is a really interesting idea! Thank you for the suggestion. Could be good solution for any BBSxx user who is not happy with the stock battery indicator.

In my particular case, due to a trashed right shoulder, a right hand twist throttle isn't ideal. I've done some searching and haven't yet been able to find a left hand version of this throttle. But I'm tempted to order one of these, then see if I can do one of two things. Ideal would be to see if I can somehow modify the throttle to change it over to left hand use, but I'm doubtful that would be successful. If that approach isn't successful, instead I could simply pirate the LED readout from this throttle and mount it either on my existing throttle or next to the existing BBS dashboard. Think that might be the easier solution, would only require embedding the LED in a little bit of that Sugru stuff and figuring out where to tap into battery voltage for the feed.
 
Just load it in photoshop and 'flip 180 degrees' :p :p :p

I think converting it to left had would be challenging. You would need to reverse the LCD and it does not appear to be symmetrical. You would also need to reverse the throttle hall action or learn to operate backwards. Removing the throttle mechanism does look like it might be a valid option.
 
LewTwo said:
Just load it in photoshop and 'flip 180 degrees' :p :p :p

Alternatively, I could try that right-hand throttle and just change my riding position so I could use it left-handed... :wink:
Handstand Bike.JPG
 
I like it, great work.
It would be awesome to do your own design, like SpinningMagnets said.
What comes to my mind is a cruiser bicycle, but you know how they have the curved top bar, I wonder if that is possible with bamboo.
 
markz said:
I like it, great work.
It would be awesome to do your own design, like SpinningMagnets said.
What comes to my mind is a cruiser bicycle, but you know how they have the curved top bar, I wonder if that is possible with bamboo.

It is possible but from what I understand you need to start with green (fresh) bamboo and use steam to bend them to shape. I came up with a 'crank forward' layout. The bamboo is currently drying (aging).

https://endless-sphere.com/forums/viewtopic.php?f=3&t=81765&hilit=Bamboo&start=25
 
Update.
Bike is going on 2 years old now.
All good except I was having a problem with my original rinky-dink design for mounting kickstand, so I decided to add a new hard point for a better kickstand mount.
In the process I pretty much tore the bike down so I could inspect how the frame was holding up.

My original expectation was that the frame members might crack and the joints might fail over time, simply from seasonal expansion / contraction of the bamboo due to humidity changes.

Not so. No cracks in the tubes, and no sign of failure in any of the joints.

Very happy with this!

Shots of the new hard point in preparation, completed, and bike today.

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I am very interested in the bamboo frame concept, as I have an idea for a bike that does not currently exist and I would not want to have to learn to weld and buy a bunch of metalworking equipment plus rent the space.

How did you account for the diameter shrink of the tubes? Wouldn't that cause them to fall out of the joints?

Also, can you simply copy the geometry of a steel frame or do the material differences of bamboo make that impossible? If so, how do you determine the correct geometry for a particular build?

Is a custom build from the bare tubes and donor bike the kind of thing that a relative novice could do or would I be better off ordering a kit from Calfee or Bamboo Bicycle Club UK? I was also considering taking the Bamboo Bicycle Club workshop in person in London, since I have enough airline miles for the trip and could arrange a house swap so it wouldn't cost much.

My idea is very similar to the new Tern GSD (which I test rode last week, great bike)! 20" wheeled long-tail cargo with a standard overall length that can fit on bus racks and bike cages. The main differences are that I want to use an IGH instead of a derailleur, higher speed than 20 MPH, and much better bump / pothole handling than is possible with a rigid metal frame (bamboo + fat tires should do the trick). Compatibility with Xtracycle's accessories would be icing on the cake, as would S&S couplers for airline travel. I know it's an ambitious plan, but I feel that it's easier to learn and experiment with bamboo than with metal. I'll probably start with a much less ambitious mini-velo similar to the one produced by Respect Cycles.
 
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