Most Ecologically Benign Common Bike Frame Material?

deliquium · Post by **deliquium** » 2 Feb 2009, 12:13pm

Is it possible to answer the question with any certainty?

AND with any reliable evidence?

The question is regarding the most commonly available mass produced materials of steel, stainless steel, titanium, aluminium and carbon fibre.

Post by Si » 2 Feb 2009, 1:00pm

There are a number of wooden frames out there, as well as a few bamboo. Although these might incur overheads depending upon where they were sourced from.

meic · Post by **meic** » 2 Feb 2009, 1:44pm

Too many variables in real life.

It depends a lot upon the owner.

I have steel bikes made around 1980, the ones I ride are showing signs of rust. If I do nothing about it I dont suppose they will last another 25 years.
If I do do something they will last just as long as a stainless or titanium bike.
I am probably too lazy and would like the corrosion resistance. Will I do more environmental harm in washing and waxing the steel?

How many bikes will survive 25 or 50 years of regular use without a damaging crash?

The 1980's bike which isnt ridden is still in perfect condition and will last forever, so in that case steel was best. As a mass produced steel bike it must have had the lowest energy input.

Compared to the other options (except walking) ANY bike is orders of magnitude more environmentaly friendly.

keyhavenpotterer · Post by **keyhavenpotterer** » 2 Feb 2009, 1:45pm

Has to be bamboo, grows so fast!

frank9755 · Post by **frank9755** » 2 Feb 2009, 2:37pm

I'd say cycling was even better than walking, as a pedestrian needs to eat a lot more calories to cover the same distance as a cyclist. Depending on what he eats the pedestrian could end up being a fairly wasteful consumer of the Earth's resources

stewartpratt · Post by **stewartpratt** » 2 Feb 2009, 2:43pm

keyhavenpotterer wrote:Has to be bamboo

Given that we're limiting the choice to steel, aluminium, titanium or CF, I'd say it fairly clearly has to not be bamboo. Or wood. Or hand-knitted organic houmous. Or anything else that isn't steel, aluminium, titanium or CF.

dan_b · Post by **dan_b** » 2 Feb 2009, 2:51pm

meic wrote:The 1980's bike which isnt ridden is still in perfect condition and will last forever, so in that case steel was best.

Well, not really. If it's never used it's doing nothing to reduce the number of journeys you might otherwise make by less efficient forms of transport, and it would have been more environmentally sound not to have bought it and thus indirectly caused the smelting of the iron ore[*] for it in the first place.

[*] or whatever it is one does to get the stuff out of the ground. I never really paid much attention in materials science lectures

deliquium · Post by **deliquium** » 2 Feb 2009, 2:58pm

Maybe I should have worded the question thus - can it be determined what is the most ecologically benign COMMON bike frame material - UP to the point of buying a new frame or bike? Or doesn't it matter?

How the product is used afterwards is realistically unquantifable?

Post by **Mick F** » 2 Feb 2009, 3:01pm

Plastic?

A plastic bike would outlast any other material, wouldn't it? It won't rust, doesn't need structural maintenance, cheap to produce, and the technology to produce it is almost worldwide.

The downside is, of course, it's made from oil, but it could be made from recycled plastic - we've got enough of the stuff - even the Chinese don't want it now! It's either burn it, landfill it ...........

or make bikes out of it!

Post by Si » 2 Feb 2009, 3:06pm

Mick F wrote:Plastic?

A plastic bike would outlast any other material, wouldn't it? It won't rust, doesn't need structural maintenance, cheap to produce, and the technology to produce it is almost worldwide.

The downside is, of course, it's made from oil, but it could be made from recycled plastic - we've got enough of the stuff - even the Chinese don't want it now! It's either burn it, landfill it ...........

or make bikes out of it!

I spose that as well as material you have to figure in ecological mindsets, or the lack of. Plastic would be great (assuming it isn't prone to developing stress/use fracture over time?) if people are going to hang on to their bikes for life. If on the other hand they treat them like cars/TVs/PCs/etc and want a new one every few years then wood would be a better option as all the old ones would rot a away a little quicker.

Post by Si » 2 Feb 2009, 3:07pm

Oh, and not forgetting that bloke who was on the news a couple of months back with his card board bike!

Post by **Hemipode** » 2 Feb 2009, 3:10pm

Perhaps plastics Mick.
Plastic does stress & fail BUT some can be ground up & reformed again - so there is some saving graces in using it.
A factory I used to work in produced injection moulded bread baskets (the orangey brown Sunblest ones). The old & damaged ones were cleaned, turned into small chips & recycled at 10% of the virgin plastic used.
I wonder if there are any plastics in common use that are of a high enough grade to be recycled into bikes ????

meic · Post by **meic** » 2 Feb 2009, 3:17pm

I meant that steel was the best material for bikes that dont get ridden. Which is the majority of bikes in this country.

Of course when that particular bike isnt ridden (because it is too small for me and too big for the kids) we go on a different bike instead.

stewartpratt · Post by **stewartpratt** » 2 Feb 2009, 3:19pm

CF is just plastic with fancy string in it...

I would imagine the tensile strength of recycled plastic is pretty poor, though. You'd need a pretty weighty frame, and I'd have thought anything that was physically constrained (eg the BB/chainstay area) would end up quite weak.

Simon L6 · Post by **Simon L6** » 3 Feb 2009, 7:55am

Magnesium alloy. Made from seawater. Unfortunately mine is in the attic.