bikes

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bikes
« on: July 06, 2017, 09:19:58 pm »
are pretty cool, especially when they are made of bamboo. http://ghanabamboobikes.org/product/bike-frame/

Re: bikes
« Reply #1 on: July 07, 2017, 04:59:00 am »
Looks like something one should try to make from PVC joints instead of dropping a whopping $250 on it. My initial thought would be to 3d print the joints, but I'm not sure if they'd be strong enough.

Re: bikes
« Reply #2 on: July 07, 2017, 07:23:37 pm »
I've been looking into bamboo a lot lately and 250 isn't actually that bad of a price. People seem to really like bamboo as an alternative to carbon fiber-- it's pretty light but extremely durable (although prone to splitting if not taken care of). A reasonable priced steel frame is about the same price and a carbon frame is easily a thousand dollars.

I don't think pvc is durable enough to work as a bike but i'd love a 3d printed bike.  This bike is made from straight carbon tubing and 3d printed lugs:https://vimeo.com/78347167.



Re: bikes
« Reply #3 on: July 08, 2017, 05:40:33 am »
I didn't know it was possible to 3d print titanium! that bike is 14500 euros. that is a lot.
m'lady

Re: bikes
« Reply #4 on: July 08, 2017, 05:58:00 am »
I'm just on the other side of the spectrum when it comes to bikes. I'm not into high quality bikes and traveling fast and all that fun stuff, despite living in a heavily bike-oriented community. I'm thinking for casual, low-income bikes.

I didn't know it was possible to 3d print titanium! that bike is 14500 euros. that is a lot.
A laser sintering printer is probably going to cost you quite a few nice bikes worth, let alone ordering the various powdered metals you're using with it.

Re: bikes
« Reply #5 on: July 08, 2017, 06:46:52 am »
the "cool and easy" bamboo frame construction techniques i've seen involve using heavy duty shrink plastic that is heated with a blowtorch, it contracts and hardens. i don't know where you buy that stuff tho.

anyway 3d printers are PLA and ABS.. ABS can get pretty strong, I'm not sure how strong! but, you'd have to make a tapered joint for the bamboo to slide in. That's tricky. And you still have to secure it with a pin or a wedge or something. Or a clamping cutout?

PVC pipe is nowhere near strong enough.
m'lady

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Re: bikes
« Reply #6 on: July 08, 2017, 06:49:27 am »

does this count
dudeweed😂

Re: bikes
« Reply #7 on: July 08, 2017, 08:09:25 am »
the "cool and easy" bamboo frame construction techniques i've seen involve using heavy duty shrink plastic that is heated with a blowtorch, it contracts and hardens. i don't know where you buy that stuff tho.

anyway 3d printers are PLA and ABS.. ABS can get pretty strong, I'm not sure how strong! but, you'd have to make a tapered joint for the bamboo to slide in. That's tricky. And you still have to secure it with a pin or a wedge or something. Or a clamping cutout?

PVC pipe is nowhere near strong enough.

Most bamboo bikes I've seen use bamboo poles with carbon fiber or rope wrapped around the joints which is then covered in epoxy and sanded smooth. It seems like that would be easier than needing to make custom connectors that perfectly fit bamboo which often varies in size.
*spork*

Re: bikes
« Reply #8 on: July 08, 2017, 08:49:48 am »
the "cool and easy" bamboo frame construction techniques i've seen involve using heavy duty shrink plastic that is heated with a blowtorch, it contracts and hardens. i don't know where you buy that stuff tho.

anyway 3d printers are PLA and ABS.. ABS can get pretty strong, I'm not sure how strong! but, you'd have to make a tapered joint for the bamboo to slide in. That's tricky. And you still have to secure it with a pin or a wedge or something. Or a clamping cutout?

PVC pipe is nowhere near strong enough.

Most bamboo bikes I've seen use bamboo poles with carbon fiber or rope wrapped around the joints which is then covered in epoxy and sanded smooth. It seems like that would be easier than needing to make custom connectors that perfectly fit bamboo which often varies in size.

that's pretty cool. I didn't know you could weld wood like that.
m'lady

Re: bikes
« Reply #9 on: July 08, 2017, 09:31:33 am »
Looks like something one should try to make from PVC joints instead of dropping a whopping $250 on it. My initial thought would be to 3d print the joints, but I'm not sure if they'd be strong enough.

Honestly $250 is pretty cheap for a quality bike, most road bikes cost hundreds if not thousands of dollars. I like the idea of trying to make super affordable bikes, but have you looked at how much just the wheels / gears / breaks would cost individually?

As for building a bike out of PVC, I couldn't find many examples, but I did find these:

Side by side tandem bike made out of PVC:



Super bulky PVC bike with a basket:



Have you ever used PVC for holding weight over a long period of time? It will inevitably bend unless you use super thick tubes.
*spork*

Re: bikes
« Reply #10 on: July 08, 2017, 10:18:00 am »
my bike cost $800 and it was done at cost for wholesale price (10% off catalog) it's also too small for me. unfortunately there's not a very big bike community here so no way to run into random people and swap. I do wonder if I could move all the parts to a homemade frame.
--
regular PVC thickness is schedule forty (SCH40) and "really thick tubes" is schedule eighty (SCH80) just in case you want to buy some at a plumbing supply house. Low pressure pipe for sewer is huge and cheap but is also very thing (SCH10 or SCH20 i think) and breaks easily.

PVC gets pretty brittle when it's cold, even when it's not full of water. and floppy when it's warm.
--
m'lady

Re: bikes
« Reply #11 on: July 08, 2017, 09:09:38 pm »
I can pick up a decent bike at my school's surplus store for less than $20.

Ya'll are bad at money.
Shit Ass

Re: bikes
« Reply #12 on: July 08, 2017, 09:10:58 pm »
yardsale bikes are often really good deals, heavy fucking steel frame bikes from the 50s-80s that last forever and have bearings that can be repacked by hand. they weigh a ton, but last forever.
m'lady

Re: bikes
« Reply #13 on: July 11, 2017, 05:22:58 pm »
yardsale bikes are often really good deals, heavy fucking steel frame bikes from the 50s-80s that last forever and have bearings that can be repacked by hand. they weigh a ton, but last forever.

Its really hit or miss. Road bikes started to get really big in the 70s and a lot of manufacturers started making cheap shit to fill a gap. The trick is to look for butted steel tubing: http://www.reynoldstechnology.biz/materials/how-butted-tubing-is-made/.

Re: bikes
« Reply #14 on: July 11, 2017, 05:48:36 pm »
yardsale bikes are often really good deals, heavy fucking steel frame bikes from the 50s-80s that last forever and have bearings that can be repacked by hand. they weigh a ton, but last forever.

Its really hit or miss. Road bikes started to get really big in the 70s and a lot of manufacturers started making cheap shit to fill a gap. The trick is to look for butted steel tubing: http://www.reynoldstechnology.biz/materials/how-butted-tubing-is-made/.

What's the difference between butted tubing and non-butted tubing? Why do you need to look for it?
*spork*