Seems to me there's an opportunity there for plastic bicycles -- light, stronger than steel depending on resin chosen, and the ability to 'cast' or injection-mold parts to whatever shape you need. Combine functions for effecient design. The gearset, etc. could be designed to take advantage of the fact that some plastics don't require lubrication, and I doubt that a human would exceed the yield strength of an appropriate design. Wondered if it was baked, but didn't find anything current online...Add rims that are solid extrusions, with a rubber cap and you have puncture-free rides, and the 'spokes' could be like blades (see spinergy(tm) wheels) that act as shock absorbtion or use a fork shock... Might reduce my bike's weight from 35# to a more reasonable 20#...-- ruxpin76, Mar 29 2004 (?) Swedish plastic bike, 1982 http://www.dtek.cha.../jpg/plastcykel.jpgmain problem was poor rigidity [FarmerJohn, Oct 06 2004, last modified Dec 04 2004] The XtraCycle project http://www.xaccess.org/index.htmlA great link and a reason to bake this ASAP [subflower, Oct 14 2005] Itera plastic bike http://en.wikipedia...era_plastic_bicycleThe same bike as refered to above. [BlueGiraffe, Apr 25 2007] As far as I know: Aluminium, Reynolds 531, Carbon fibre - All used before. Aluminium tends to crack, carbon fibre is extremely stiff and if used for forks without suspension would give a very uncomfortable ride. Reynold tubing is the best all round, since it can flex slightly (esp. good for forks). Plastic would have some tough competition, especially when it comes to roller bearings and chains. If your bike weighs 35lb, perhaps you don't need to look for plastic to solve your problem. My gut feeling is that plastic would be a heavier solution (..he says without checking material specifications).-- Ling, Mar 29 2004 Note that there is now a mandated minimum bike weight of 7kg for racing bikes (15lbs) and many are right on this limit, many of these use carbon fibre a strong form of composite.
You may just need to spend the money to buy a decent bike.-- PiledHigherandDeeper, Mar 29 2004 CF racing bikes are common, but not cheap.
Fluidformed aluminium frames are common. My brother-in-law has one custom-made by Eddie Merckx. It cost him $15,000 for the frame. He says it performed fine when he rode it as a "civilian" entrant in last year's Tour De France. The frame weighs 2.7kg, which is just under 6lb. CF rims and Ti alloy gearsets, brakes and pedals round it out to minimum weight. Cost of the whole bike? $26,400.
I imagine there might be a market for fibre-reinforced plastic bikes, especially if they were made from recycled plastics. Bicyclists tend to be greenies at heart. Gearsets and chains could be items replaced regularly. Tyres could be foam filled, to prevent punctures.
The more I think about this idea, the more it looks viable for impoverished nations.-- UnaBubba, Mar 29 2004 Ian is just a little obsessive about his cycling, as you might have gathered. He had a moulded case custom made for his bike, so he could fly it over to France.
Sorry, no coffee. It's about as minimalist as you can imagine a bicycle.-- UnaBubba, Mar 29 2004 I remember fellow club riders spending a fortune on titanium bolts and what-nots. I always thought that at this level, having a good crap and cutting your toe-nails before an event would have more effect. (A little training would make the biggest difference!). At the level that [UnaBubba] is talking about, absolutely everything counts, including shaving your legs and polishing your teeth.-- Ling, Mar 30 2004 He does about 1400km per week, roadwork. Add to that strength routines in the gym and he's devoting more than 40 hours per week to cycling. He only shaves down for races, letting wind resistance improve his fitness during training. Low GI starch diets, blah blah blah... My eyes glaze over after a few minutes of the science of cycling faster.
I shudder to think how successful his construction business would be, if he devoted more than 40 hours to it.-- UnaBubba, Mar 30 2004 I take my hat off to him: I marvel at the speed some of these guys can sustain. The really noticeable effect is that they can normally maintain a good pace up an incline, since it is nearly all wind resistance at those kind of speeds. Even at the more humble speeds at which I used to run around, it was surprising how little difference there was in average speed between a bicycle and a car on some journeys.-- Ling, Mar 30 2004 I don't know of any thermoplastics that have a better strength to weight ratio than good old crome- moly steel, and carbon fiber is definitely widely baked.
[below: [bungston], all that chrome moly hoohah was for the tightpants crowd 20 years ago. The aim of this idea was for lighter bikes, not cheap or recyclable or toy-like.]-- oxen crossing, Mar 30 2004 //polishing your teeth// Yeah, teeth are a luxury that will likely be removed in future racers.
I think this is absolutely bakable - not for high-performance bikes, but definately for inexpensive bikes. I'm picturing larger volumetric areas for weak points like the chain to deal with strength issues.-- Worldgineer, Mar 30 2004 Yes: disposable bike. All that chrome-moly hoohah is for the tightpants crowd. I want a bike that comes in a 3 pack, each a different color. A bike that I can ride into the ocean off a pier. A bike that makes you happy when someone steals it, because you know they are using it themselves for transportation.
Maybe I just miss my Big Wheel.-- bungston, Mar 30 2004 I think this is a great idea. The problem is that cost is not preventing bicycles from being used more widely for transporation. If this is jsut for rich guys, there are already lots of carbon bikes...mine is a Giant TCR Advanced.-- seriousconsult, Dec 04 2004 You have a giant bike? How do your feet touch the ground?-- Belfry, Dec 04 2004 Made from recycled materials a good bike can transport tons of useful stuff and make life a LOT easier for people who have no car or gasoline. see link.-- subflower, Oct 14 2005 I once met someone that takes old bikes and turns them into wheelchairs for people in 3rd world countries. Perhaps the cheap plastic bicycle company could also have a cheap plastic wheelchair product.-- Worldgineer, Oct 14 2005 This has already been tried about 30 years ago. I have seen one in a Materials lecture it didn't seem particularly great. The whole thing was too flexible which made riding difficult, especially steering.-- BlueGiraffe, Apr 25 2007 I'm surprised they haven't made CF skateboards.-- apocalyps956, Apr 26 2007 halfbakery