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Could the bikes of the future could be made from “super wood"?

US researchers develop super-strong and tough densified wood that's comparable to carbon fibre but much less expensive

Researchers at the University of Maryland in the USA have developed a simple strategy to transform natural wood into a high-performance structural material with a more than tenfold increase in strength and toughness. The researchers, reporting their process today in Nature journal, say that this treatment also results in a material with greater dimensional stability that could be substituted into any application where steel is currently used, such as cars, aeroplanes, buildings and, presumably, bicycle manufacture.

We’ve reported on wooden bicycles many times in the past, but what’s different here is that the University of Maryland researchers, led by Liangbing Hu, are proposing that bulk natural wood is transformed using a two-step process that involves the partial removal of lignin and hemicellulose through boiling in an aqueous mixture of sodium hydroxide and sodium sulphite. The material is then mechanically hot-pressed at 100°C, leading to a reduction in thickness of about 80%. 

According to the researchers, “[This leads] to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres.”

This treatment is said to work equally effectively for various species of wood – both hard woods and cheap and fast growing soft woods – and results in a material that has a specific tensile strength that's higher than that of high-specific-strength steel (HSSS), and even of lightweight titanium alloy (Ti 6Al/4V). 

Check out 10 stunning wooden bikes here. 

"This could be a competitor to steel or even titanium alloys, it is so strong and durable," said Liangbing Hu. "It's also comparable to carbon fibre, but much less expensive." 

“The large increase in tensile strength of the densified wood is not accompanied by a decrease in toughness,” say the researchers. “Both the work of fracture and the elastic stiffness of the densified wood are more than ten times higher than those of natural wood.”

Check out the full article here.

Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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20 comments

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janusz0 | 6 years ago
1 like

"Improved Wood" has a long history.

As usual, most modern innovations result from decades of reinvention.  I first read about it in a British 1930s magazine called "Wood".  Then it was describing wood impregnated with phenolic resin,  heated and compressed.  I recall that one use was to make durable telegraph pole insulators.  In my house I have a different kind of improved wood: Accoya, which is an acetylated timber, where the wood has been rendered waterproof and therefore rot proof and dimensionally stable.  It isn't compressed or void-filled so it's strength is probably not much different to the softwood that it's made from.  The abstract above doesn't mention it, but this new process would, presumably,  introduce a waterproofing resin as well.  This doesn't have to be another environmental disaster.  Sustainable forestry is already viable and subsequent manufacture should be energy efficient.

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ConcordeCX replied to janusz0 | 6 years ago
1 like
janusz0 wrote:

"Improved Wood" has a long history.

I get loads of junk mail about it. Must be my age.

Or my saddle.

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Toxmarz | 6 years ago
2 likes

So now we have to worry about termites.

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RobD | 6 years ago
1 like

I'm wondering what the mass of it would be like, if they're increasing the density that dramatically would it not become quite heavy? or has the prior process already reduced the mass? If it's light enough as a solid product then I could see this being a pretty cool product for hybrid type bikes, a good waterproofing sealant and it'd be great.

More interested in industrial processes for this, or the suggested use in cars etc, Morgan might be very interested.

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madcarew replied to RobD | 6 years ago
1 like
RobD wrote:

I'm wondering what the mass of it would be like, if they're increasing the density that dramatically would it not become quite heavy? or has the prior process already reduced the mass? If it's light enough as a solid product then I could see this being a pretty cool product for hybrid type bikes, a good waterproofing sealant and it'd be great.

More interested in industrial processes for this, or the suggested use in cars etc, Morgan might be very interested.

The density may increase, but because of the tenfold +  increase in strength you need one tenth the mass. Bamboo bikes are slightly heavier than a steel bike. I'd say a wood fibre frame could readily come in at a similar weight to a CF frame.

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JonD | 6 years ago
3 likes

As far as 'you can't deform wood', steam- bent timber and ply has been around for probably about as long as either material has been in use in furniture making, at least.

In some respects this sounds a little like 'thermowood' - treated under heat to make it far more rot-resistant than the original timber.

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No Sweat | 6 years ago
0 likes

Can the 'hot-pressing' be used to form the material into shapes? Like is already done with carbon fibre frames? I have only read the abstract so I may be putting 2 and 2 together and making 5.....

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Canyon48 | 6 years ago
0 likes

There seems to be a REALLY big issue here, in my mind at least.

Regardless of how much stronger it is than carbon fibre or Ti or Steel - how would it be made into a bike frame?

You can't extrude a tube from wood, it won't deform plastically to allow you to bend a sheet into the shape of a tube (like some MTB tubing) and you can't mill wood hollow (not without seriously compromising the structural integrity).

Sure you could mill/turn solid bike tubes from wood and glue them together, but that's just going to be pointlessly heavy.

The great thing about carbon fibre is you can lay it up into pretty much any shape you want yet it still be light and stiff - moreover, you can't control the mechanical properties by laying up the carbon fibre differently.

You don't have control of the grain of wood unlike you do carbon and you can't make it hollow - so it won't replace carbon.

It may be stronger than Alu, Steel and Ti but you can't easily extrude it, unlike the metals - so I don't see why it would replace them.

Chobham Armour is extremely strong and has it's place in engineering applications, but bicycles isn't one of them. I think it is the same for super-dense wood, (I imagine it could be a fantastic way of producing large strong girders for buildings though).

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madcarew replied to Canyon48 | 6 years ago
1 like
wellsprop wrote:

There seems to be a REALLY big issue here, in my mind at least.

Regardless of how much stronger it is than carbon fibre or Ti or Steel - how would it be made into a bike frame?

You can't extrude a tube from wood, it won't deform plastically to allow you to bend a sheet into the shape of a tube (like some MTB tubing) and you can't mill wood hollow (not without seriously compromising the structural integrity).

Sure you could mill/turn solid bike tubes from wood and glue them together, but that's just going to be pointlessly heavy.

The great thing about carbon fibre is you can lay it up into pretty much any shape you want yet it still be light and stiff - moreover, you can't control the mechanical properties by laying up the carbon fibre differently.

You don't have control of the grain of wood unlike you do carbon and you can't make it hollow - so it won't replace carbon.

It may be stronger than Alu, Steel and Ti but you can't easily extrude it, unlike the metals - so I don't see why it would replace them.

Chobham Armour is extremely strong and has it's place in engineering applications, but bicycles isn't one of them. I think it is the same for super-dense wood, (I imagine it could be a fantastic way of producing large strong girders for buildings though).

Not having read the study, it sounds like this is basically modified wood fibres in a sheet form (like single layers of plywood) and so can be treated in much the same way as carbon fibre. In reality, wood fibres are simply hollow carbon fibres, ply wood layers are .8 - 1.2mm thick, so these sheets (losing 80% of thickness) would be .15 - .25mm thick. Form them in sheets into tubes, the same as carbon fibre / kevlar / fibreglass, and resin them together.

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Canyon48 replied to madcarew | 6 years ago
0 likes
madcarew wrote:
wellsprop wrote:

There seems to be a REALLY big issue here, in my mind at least.

Regardless of how much stronger it is than carbon fibre or Ti or Steel - how would it be made into a bike frame?

You can't extrude a tube from wood, it won't deform plastically to allow you to bend a sheet into the shape of a tube (like some MTB tubing) and you can't mill wood hollow (not without seriously compromising the structural integrity).

Sure you could mill/turn solid bike tubes from wood and glue them together, but that's just going to be pointlessly heavy.

The great thing about carbon fibre is you can lay it up into pretty much any shape you want yet it still be light and stiff - moreover, you can't control the mechanical properties by laying up the carbon fibre differently.

You don't have control of the grain of wood unlike you do carbon and you can't make it hollow - so it won't replace carbon.

It may be stronger than Alu, Steel and Ti but you can't easily extrude it, unlike the metals - so I don't see why it would replace them.

Chobham Armour is extremely strong and has it's place in engineering applications, but bicycles isn't one of them. I think it is the same for super-dense wood, (I imagine it could be a fantastic way of producing large strong girders for buildings though).

Not having read the study, it sounds like this is basically modified wood fibres in a sheet form (like single layers of plywood) and so can be treated in much the same way as carbon fibre. In reality, wood fibres are simply hollow carbon fibres, ply wood layers are .8 - 1.2mm thick, so these sheets (losing 80% of thickness) would be .15 - .25mm thick. Form them in sheets into tubes, the same as carbon fibre / kevlar / fibreglass, and resin them together.

Ah, I see!

That starts to sound more interesting.

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burtthebike | 6 years ago
0 likes

Surely the greatest benefit is that it can be worked with hand tools?  Saws, chisels, planes, and you can glue it together with pva glue.  Who will be the first to produce a mortice and tenon-jointed frame?

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maviczap replied to burtthebike | 6 years ago
1 like
burtthebike wrote:

Surely the greatest benefit is that it can be worked with hand tools?  Saws, chisels, planes, and you can glue it together with pva glue.  Who will be the first to produce a mortice and tenon-jointed frame?

I wouldn't be using PVA glue it's water soluble, Gorilla glue or No more nails would be a better option  3

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madcarew replied to maviczap | 6 years ago
0 likes
maviczap wrote:
burtthebike wrote:

Surely the greatest benefit is that it can be worked with hand tools?  Saws, chisels, planes, and you can glue it together with pva glue.  Who will be the first to produce a mortice and tenon-jointed frame?

I wouldn't be using PVA glue it's water soluble, Gorilla glue or No more nails would be a better option  3

Ccement is water soluble too. There are really good exterior (water proof) pva's in standard use in the construction industry. For a whole host of reasons gorilla glue (very brittle) and no more nails (not a true glue) would be unsuitable, but probably an epoxy glue (as the fibres will almost certainly be resined) will be the go.

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Rapha Nadal | 6 years ago
4 likes

Some bikes give me super wood.

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BehindTheBikesheds | 6 years ago
0 likes

I would have thought the coating on the dried/compressed wood maintains weatherproof ability but the ingress of water on that type of material unless submerged shouldn't ordinarily be affected short to medium term at least but certain atmospheric conditions and being exposed to that continuously might have a greater effect and faster.

Crash resistance and having same/similar abilities to CF would be the major comparator if it's to become a big thing and not a niche product like bamboo. Steel, ti and alu are already a well known quantity, it's going to take a lot of swaying and investment plus a huge glob of faith based on saving money to make a big player change tack and go with this. With no known history I can't see anything but a couple of offerings in the bike industry even in 10 years but who knows.
The only other concerns are where is the wood coming from, how much waste is there, are the by products usable for something else and what kind of pollution does the caustic soda/lye and Sodium nitrate produce, the latter a bi-product from sulfurous acid IIRC

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earth replied to BehindTheBikesheds | 6 years ago
0 likes
BehindTheBikesheds wrote:

...  it's going to take a lot of swaying and investment plus a huge glob of faith based on saving money to make a big player change tack and go with this. ...

It's just never going to happen.  I just can't see anyone having faith in wood or getting excited about it.

The construction industry might be interested though.

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LastBoyScout | 6 years ago
1 like

Very interesting.

No comment on how hard/easy the material is to work with compared to various metals and I'd be interested to know about short and long term effects of exposure to water.

Possible limiting factor for some applications would be the length of the product.

Might be a good incentive to start planting more trees than are being felled...

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simonmb | 6 years ago
1 like

Wonderful news. If only there were still some rainforests that require denuding.

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cqexbesd | 6 years ago
0 likes
The (second) link is missing a :. It should be https://www.nature.com/articles/nature25476. It's behind a paywall though so most people will only get the abstract.
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shufflingb replied to cqexbesd | 6 years ago
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cqexbesd wrote:
The (second) link is missing a :. It should be https://www.nature.com/articles/nature25476. It's behind a paywall though so most people will only get the abstract.

 

They talk about it more in the Nature podcast this week https://media.nature.com/original/nature-assets/multimedia/podcast/nature/v554/n7691/nature-2018-02-08.mp3 . It sounds like an interesting, possibility more sustainable tech. As with all wood at the moment moisture is its Achilles’ heel.

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