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Si: I think, you'd struggle to argue against carbon fiber being the ultimate frame material at least in performance terms. It can be incredibly light, super stiff, amazingly compliant and bonkersly aerodynamic. There are though of course, stacks of other frame materials out there from which you can build brilliant bikes. Steel, titanium, aluminum, magnesium and then there's also wood. Now I have seen wooden bikes before at bikes shows and the like but I've always thought they were a bit of a novelty item but are they? Today, is the first day I'll ever been actually able to ride one and I cannot wait to find out what it's like. [music] Si: This is a Twmpa Cycles GR 1.0 and the
frame as you can clearly see is made out of wood but this is no delicate road bike built for nursing along smooth tarmac. This is a gravel bike. Now it's made out of ash which is a hardwood, actually one of the strongest out there, about on a par with oak but a lot lighter. This frame weighs just 1800 grams. That is considerably more than carbon but about on a par with top-end steel and unlike both of those other materials this one treads far lighter on the planet. It is of course, completely sustainable and it requires a lot less energy to manufacture. Now before I get to take this for a spin and see just how it feels to ride, fortunately for us, the owner of Twmpa Cycles has delivered the bike in person. I'm going to go grill him now and find out just what this is all about. Andy, you're a lifelong cyclist, engineer by trade, furniture maker of 20 years, if I'm correct. Andy: That's right. Si: As qualified as anyone to make a wooden
bike. I guess, the question is why? Andy: Why wood? It's not the obvious choice for a bike frame is it. I'm a woodworker and an engineer and a lifelong bike enthusiast. An opportunity arose, I had a conversation with a potential furniture customer. He previously had written a book about bikes, It's All About The Bike, I think was the name of that book. I thought maybe we should build an ash bike. In the end, his publishers didn't agree, the publishing deadline was looming. We'd never built a bike before and we built a piece of furniture. In my mind there was the idea for building a bike out of ash. Once an idea is in your mind, if you're a maker then it tends to stay there. It happened over a period of about two years, I built myself an ash bike. It was a purely personal project. It was never intended as a business or as something for anyone else until I started riding it. Then
I become slightly some people would so overly evangelical about it. Si: How does it compare to another material like steel or a carbon fiber in terms of the strength of it and the density of it? Andy: It does offer different properties. A lot of the properties of a frame as you will know are in the design of the frame itself, in the geometry of the frame, not necessarily in the material. Wood has unique properties at a micro-structural cellular level. The cellular structure of wood is essentially a vast complex of spring-damper combinations. This frame is made up of a large complex of micro-suspension systems. That has the effect of damping the vibrations which come through
the road and into the frame. [music] Si: Going in at first impressions, well, my very first impression is actually, it feels normal. In the sense that, having spoken to Andy at length about this bike, I still have this preconceived idea that it would feel like a wooden bike, but yet it doesn't. If I couldn't see where I was on, it would be a normal bike. Now, to give you a visual illustration of it, one of the first things I do when I get on a new bike is the shakedown test, which is completely unscientific, not even very objective. I give the handlebars a little
shimmy just to see what kind of torsional stiffness is in the front end of the bike and this one is totally within the realms of a metal bike or a lightweight carbon bike. On a stiffness perspective, it definitely doesn't feel weird. Okay, ready? Three, two, one, go. [music] Si: That must be at least 600 watts. What about the stiffness and the density of it compared to steel? 1800 grams for a frame. Andy: Yes, absolutely. Si: Is comparable to a top-end steel frame. Andy: Yes, it is. Si: How strong is it in comparison? Andy: Well, obviously the density is a lot lower than steel and that means that you can use a lot more of it without exceeding the
weight of a piece of steel. The wall thickness on these tubes varies between five and six mil, depending on whereabouts it is. Obviously with steel frames, you're looking at 0.5, 0.8, that kind of thicknesses. If you have a steel tube and a wooden tube, you can have a lot more wood in other words, your wall thickness can be a lot thicker. The diameter can be a lot thicker for the same weight, for the same massive material. It has a greater strength to weight ratio and when you combine that with turning it into a tube, that magnifies that effect again. It's a very suitable material for building a bike for instance which are essentially tubes. Si: What then about these feign vibration damping qualities? We've got a perfect caveat here and say, these are completely my first impressions. I'm also using gravel tires on here, but admittedly, I got 60 PSI in them, but it definitely feels very quiet, like orderly
quiet, but also in terms of vibrations coming up through the bike. Now, one way though that it does differ quite significantly from carbon fiber is what you'd call compliance, which is different to vibration damping, it is a more pronounced flex. I guess that's one thing you can't engineer into a wooden frame, or at least not at this stage. Whereas with carbon fiber, you stick a D-shaped seed post on there, and you can actually visibly see a flex. Some frames having designed in the C tube and the C state even up to 20 millimeters of movement. Whilst you've got this whisper-like vibration damping, it is perhaps more in line with a metal bike, like an aluminum bike or titanium bike in terms of their compliance, which is not a good thing or a bad thing. It's just what it is, I guess.
If you go crashing through potholes, you feel it, but the finer vibrations that come up from rough surfaces like gravel or uneven tarmac, they're just not there as much. Nice bonkers, I'm riding a wooden bike. How has it actually made then, the fact that it's hollow, I probably should have guessed, but I can see joints, is it built in a modular system? Andy: These don't start as tubes and surprisingly, they don't grow as tubes. The front triangle of this bike starts off as two triangles of jointed planks jointed together with this jigsaw joint here, which locks those very firmly securely. The end to end, those are bonded with a poxy. The planks are also laminated
so that the joints are staggered, so they effectively reinforce each other. Most of the machining is done on a CNC router. The front triangle starts off, and then it becomes two machined half shells which are then bonded together along the center line. Then after that the rear triangle the seat stays and the chainstays are bonded on. Chainstays are laminated out of six pieces of ash which is form on a former to give us the curves that we need. They come together then at this end in a non-wood component which has been one of the most challenging aspects actually of building a wooden bike which are the dropouts. Si: Is the design of the bike, the shape of the bike a product of the properties of the wood? Or have you got a bit of flexibility in terms of the look. Could you for example make an aero-wooden bike by tailoring the tubes making them into aerofoils?
Andy: You could do. There's no reason that the tubes need to be round. They will lose some strength if you change the profiles because you start to introduce stress concentrations. A circular profile has no point on it that wants to act as a stress concentrator. If you start to focus into pointed sections, then you do start to create slight stress concentrations, but these are over designed. It's very easy to over design it to make sure that's not a problem. This is intended as a gravel bike and as such I anticipate heavier loads, greater impacts and things on the frame. If I was designing an aero bike I would be able to reduce the sections slightly of some of these members and change the profile. They don't need to be circular section. Si: That's pretty cool. Actually you've got almost the same degree of flexibility as carbon fiber, potentially in terms of shaping and-- Andy: Yes you do. There really is very little limitation in the shape. As long as you're
putting enough material in the right places and you're joining the different components, the different elements of timber in the correct way, the shapes are hugely variable. What you are always going to be left with is the need to sweep these radiuses here. Again the same about avoiding sharp changes of direction which cause stress concentrations. Here we've got these smooth curves which are avoiding those stress concentrators. That's a detail that I would personally always want to maintain on a design. [music] Si: Sorry I couldn't help myself. It's a gravel bike after all. I had to venture onto some gravel. Actually I'm really glad I did. Definitely
it adds a whole new dimension into that vibration damping quality. It's best illustrated by the fact that the front and the back of this bike feel quite different in that the back of the bike is really forgiving and it does absorb the gravel. The bumps coming up from the trail. Whereas this form which is an MV carbon form, it's absolutely top quality form, definitely still feels like it's translating more vibration. That's partly because I've got the tires pumped up to 60 psi because I've been riding around the road, but the back doesn't feel like I've got 60 psi. It feels like I'm running about 35 which is a pretty significant difference. Testament to the wood I guess. What more can you say. Unlike carbon fiber, if you change the grain of the wood or the direction-- Can you change the properties of the bike or you're fairly fixed in terms of wood is obviously super strong in one direction and [inaudible 00:13:53]? Andy: You're absolutely right. One of the biggest challenges designing with wood is
that wood has great strength and tension along the grain. It's great bending, as long as the grain runs that way it will bend, it's very stiff that way. As soon as you start to go across the grain, that's when you get split. So designing with grain in the right orientation is absolutely crucial. Si: Have you got the lateral stiffness then? If you've got the grain going down the down tube like that to mean that it's strong enough, how do you resist torsional? Andy: That's where the oversizing comes in and the wall thickness. You're right, picking up on that is something that very few people have done actually. That twist is something which other manufacturers of wooden bikes have used a layer of carbon internally to-- Si: Really, that's cheating. Andy: Which does seem like cheating to me. Well it's not cheating, every way of building
a bike is legitimate. Si: But you didn't point out [unintelligible 00:15:02]. Andy: I wanted to build a wooden bike and I don't think there's any need for carbon in there. Si: No. Andy: So far I think I'm born out in that belief. Si: What about the toughness of the material? How resistant is it to knocks and damage? Could you put a dent in it for example? Andy: You could dent it. I'd rather you didn't. That's all right. Si: No, I'll try my best. Andy: There's been a lot of product testing. There's been a lot of hard riding. Although, of course most dents don't tend to come when we're riding our bikes, most dents come when we're taking them in and out of cars and things like that. Si: That's it, or if you lay it down on some particular pointy rough rocks. Andy: Yes, exactly. The ability to absorb shocks which we've discussed before also means that it makes it more resistant to denting. Whilst of course, yes you could damage it. You could bang it. It is more resilient to knocks than probably other frame materials. Si: Now I'll confess, until today I had never
thought of wood as a performance material. I know humanity has made and continues to make incredible structures from it. To my mind in a sporting context, wood has always meant blunt instruments like bats and clubs and sticks, but here firstly the scales don't lie, 1,800 grams for frame is 1,800 grams for a frame and it's not nudely. Maybe my prejudice about wooden bikes stems the fact that there just haven't really been any. Perhaps more to the point there haven't been any in pro racing which for me and I suspect a lot of you too often serves like the barometer of success and credibility. I've got no romantic visions of a pro cyclist dancing Mont Ventoux astride a wooden bike. That's not actually what bike riding is, well probably virtually all of it, yet performance really matters. Owning a bike is an emotional thing. That
emotion might come from knowing that you have the fastest or the lightest bike. It's also about the look of it, the feel of it, and the craftsmanship and the ethos behind it. Perhaps even the fact that it treads a little lighter on the planet. Certainly from talking to Andy, that side of things is really interesting. He was explaining how a ton of processed wood contains within it about five or half a ton rather of carbon. Whereas to make a ton of titanium releases about four and a half tons of carbon into the atmosphere. While it's small-scale stuff that can really matter to an individual and increasingly I think it should matter to an individual. What's the future for Twmpa Cycles then? Andy said, at the minute production is limited to about 30 frames a year. He's confident
that it's scalable until they can and hope to make more than that both stock sizes and also completely bespoke frames as well. It's a premium product at the minute. It's about £3, 000 or €3,000 for the frame. You can certainly see the time and the effort that goes into making them. Can't stop looking at it. [music] Si: Hopefully Andy is not going to mind if I don't bring his bike back for another hour. Quite frankly I want to spend a bit more time on it before I hand it back. I'll be very interested to know what you think though. Take part in our poll over on the GCN App wooden bikes hot or not? Would you ride one, would you buy one? Please make sure if you enjoyed this video as well that you give it a big thumbs up. I'm going to do a little bit more.
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