Sambo's Bamboo Bike build

With Xmas looming I thought I would have a go at a bamboo bike.
For my first attempt I'll be keeping the power low, maybe a 28mm DD rear hub or gearmotor.

I am amazed by the cheap price of building with bamboo. A lot people seem deterred at building their own bike due to cost and opting for Chinese clones so I am hoping a few people might give this a go too as a show of individuality.

For geometry, I think I will take the flat footed cruiser style of a KHS Smoothie / Electra Townie where the bottom bracket is kicked forward about three inches. I'd like to be able to cruise on this bike and maybe add some cargo front and rear features too.

Whilst I'd love to be able to do curved bamboo lengths, this is my debut with this material. So I will be keeping the lengths of bamboo linear and simply seeking to join up the critical geometry points of a Townie style bike with straight lengths.


I've converted a few Eletras to electric and found that the headstem was about 30mm too far forward for all but one guy who was over six feet tall.

So I am bringing the headtube back toward the seat by about 30mm.

I've got a Yuba Mundo in my ebike stable and this style of triangular frame using the foot forward geometry is what I am gonna chase.

Here's my Yuba with three motors (gotta have a test bed).


Protip: telling your wife its a legitimate child hauler gets results on toy spending.

I've seen a few bamboo haulers online with the top tube split two ways, and I like the idea of the seat tube running between the top tubes, so I am gonna try that. Here's an indication:

I like the integrated rack.

So I've taken this style of triangular frame and cadded it to the key geometry points of a KHS or Electra and bought the head tube in to my liking.


I've reduced the length of the headtube though as the KHS and Electra have really long ones, finding forks to fit is a frocking pain.

I'm mindful of the extreme angle of the seat tube so I will need to ensure the structure can handle my less-than-petite weight at that point joining the top tubes.

I've also nominated a 170mm rear dropout, I've got plenty of fatbike gear so I think at least 3 inch wide tyres would be cool. Maybe if it's stiff enough I'll pop a 170mm wide mxus motor on.

Apparently the harmonics of bamboo are good over bumps - will be interesting to compare with steel, aluminium and carbon bikes I've built. Carbon being frankly awful.

I've noticed some rear triangle braces on my dirtjumper frames (these are frames made for frightening abuse). I plan to put these braces into action on the rear triangle and notice a few other bamboo frames are doing this too.


TIme to gather up some bits.

Fifty aussie bucks later I have enough material for two bike frame tubes.


Instructables has some really good threads on what to look for on building bikes. Here's an example.
http://www.instructables.com/id/Bamboo-Bike-2/

My first impression of the bamboo was wow. I placed the medium thickness length between my legs like stringing an archery longbow and attempted to bend it. There was very little deflection even in the unbraced state.
As a building material I think its underrated. One of those things you read but until you try it you don't appreciate it fully.

Drew up some dropouts with a bit of room for sliding on the hub and disc tabs.
Didn't add any rack tabs yet - maybe enough room for them on the sliders. Although some frames just build the rack into bamboo - might need that anyway for the seat tube brace.

New waterjet cutter at a business around the corner. 8mm stainless done in a couple of hours. I'm gonna love my new friends!!!


I could drill and tap these for clamping but I don't think a total of 16mm of stainless is the first in line to fail under load. I think the bamboo stays will be the first mode of failure. Could insert some metal inside the stays or structural epoxy, but I don't want to try to make a hummer from light materials.

Bought myself an extremely cheap (7 dollar) holesaw kit. One and two inch sizes look ideal.


Now I can notch the bamboo for joints to bottom bracket and headtube etc to this kind of arrangement:

Here's the list of things for other metal parts:
Headtube: Aluminium 50mm OD with 3mm walls to give 44mm ID> to suit 44mm headset. Advantage of fitting 1 and 1/8 forks as well as 1.5 inch forks.
BB tube : Aluminium 40mm OD with 3mm walls for 34mm ID> can take a standard BB if screwed in tight enough without tapping tools. Also looks like a BBS01 will fit ok without too much play
Seatube: have found some stainless 31.8mm OD tube with 1.6mm walls for an ID of 28.6mm > with a bit of reaming I hope a 28.6mm seat pole will fit.

There are good premade BB and headtube parts to be had online from two websites: Paragon and Nova Cycles. But I am keeping this pretty dumpster level for an extreme budget job so I am trying to use rough tubestock from my local metal supply.

And some other bits for binding:
- DP810 epoxy for structural joints (cheaper alternative to DP420 or DP460)
- kevlar/carbon weave for binding the joints from Hobbyking (could use jute or hemp twine with high tensile strength)
- West system epoxy for the less vigorous epoxy points (could use Hobbyking cheap epoxy)

I may inject some epoxy and void filler inside the frame around the BB tube. I think I might play with spent dried coffee grounds as a filler for the epoxy inside.

It would be possible to wrap the whole frame in carbon/kevlar and just use the bamboo as a captive mould. Carbon is great in tension, ok in bending and crap in compression. So for the top tubes at least I would benefit from some decent Bamboo.

Hey Sam, good luck with this I always wanted to play with bamboo for ebike frames. I just don't have enough patience to wait for the glue to dry. So welding bits of steel it is for me :lol:

Make it full suspension

Bamboo bikes are damn cooool. Grew up with neighbours with loads of bamboo, was awesome for making things strong!

I was actually thinking about how exceedingly practical it would be to have a cargo bike on the way home... and that I couldn't justify the expense of another bike... perhaps this is the way! I have seen old bikes sacrificed as a poor mans way of making the dropouts. I have seen them cut a bit longer to spread the force further down the bamboo length, not sure how effective/necessary it really is, then jammed in the end of the bamboo, less neatly than you have.

I wonder if the longer head tube is a similar story - attempting to support it further away from the fulcrum point?

I also wonder if filling in that brace and wrapping around the whole thing could act like a gusset?

The joins are definitely where the work is.

Very cool.

I had always assumed that the inordinately long headtubes on the Smoothies, Pure, and Townie were a function of the geometry. You are going to get a flat foot without the longer head tube?

BTW, When you decide to roll, it's best to step back and give you wide berth....man, exciting to see this happen so fast! Great fun!

What was the final cost of the dropouts? They look great. Your extending the the chainstay sections looks like another good move.

Will you build a jig like the young ladies blog showed?

You go SAMBO!

Yah know? Lots of bamboo showing up in ES thread on wood bikes eh?

Inspiration for Flux Beta?

Hahahhaa! Thats a classic. Is that a toilet roll headtube?

Progress?

Xmas hols from tomorrow fella!!!

What was the outcome?

Storage and too many other e-distractions


Sent from my iPhone using Tapatalk

A bamboo e-bike. Never thought I see that. I saw a bamboo kids bike once but I quickly dismissed a wooden bike-toy suitable only for light weighters [kids].
I guess the bamboo will give a little over pot holes and curbs? With fat tires maybe no need for full suspension?

Hehe I liked the FLX bamboo frame Lurkin, if the bonding is done properly I guess that would make a real stiff and light frame.
Maybe we see a DIY bamboo frame kit soon? With bamboo swing arm and a proper t(h)ree crown fork? Imagine the savings for shipping? Just roll all the pre cut bamboos into a cardboard tube and on the bottom of the tube is the metal parts and ship away. And the happy buyer gets to build his bike LEGO style, with a little help of composite material and resin that is also included in the DIY kit. Even a proper "jig" could be rolled around the bamboo sticks to aid the puzzle.

And there could be different bikes to build. A bamboo trike, or a bamboo cargo bike. Bomber style hooligan bike or stylish single gear town bike.

Heck I think I would have gotten at least one of those just for the pure joy of LEGO'ing a bike and to show proper green foot print.

macribs said:

A bamboo e-bike. Never thought I see that. ... .

Click to expand...

See this thread: https://endless-sphere.com/forums/viewtopic.php?f=6&t=74252

Thx LT will read :wink:

Samd said:

... I've seen a few bamboo haulers online with the top tube split two ways, and I like the idea of the seat tube running between the top tubes, so I am gonna try that....

Click to expand...

I like that idea as well.
I wonder if a dual tube 'mixte' frame might not make a good donor for the metal bits (head tube, bb, rear dropouts and fork).

I note that footloose lengthened his rear triangle on his bamboo e-bike.
https://endless-sphere.com/forums/viewtopic.php?f=6&t=74252
I was thinking 2-3 inches of added length there might allow a bit wider rubber in the normally narrow 'mixte' frame.

A mixte would be perfect!

Hmmm. I have a few frames which will be going to the local co op shortly.. makes me wonder if I should keep a couple of dropouts etc. How critical do you think the angles of the donor frame are?

Samd said:

A mixte would be perfect!

Click to expand...

I thought a lot about mixte frame for my recent bamboo build, and reached same conclusion: perfect.
Would have gone with mixte design except I couldn't find a donor frame at the right (cheap!) price.
Maybe next time.