Cycling UK Forum

pigman wrote:1. the aeroplane thingy. Parts on planes can get replaced. so while the plane might last 50 years, the carbot bit doesnt necessarily have to. imagine carbon shockers on a car and expecting them to last the life of a car!

The Boeing and Airbus use carbon structures in parts that would be uneconomical to replace. They are on there for the life of the plane. I've used this application as an example as it is at the forefront of examples of the use of Carbon Composites in a manufacturing environment. There are higher performance carbon composites and filled carbon composite structures in development. Things tend to make it on to aircraft or race cars first, then filter through to Cars, and bikes as the R&D costs have been reduced.

Yup, that makes sense!

I think there are improvements int toughness around the corner, I think I've heard something about Kevlar being used in the that composite as well as carbon fibre, and of course improvements in the binding material. Either way it will take a while, probably five years or so till the materials that are being use on for instance the worlds circuit bikes will be affordable to the people spending £1500+ on their Sunday/best bikes now.

How are the rides and club level races organised at the moment? If I sight motor racing as an example this has a tiered system from entry level where you can race if you have a spare £15-20k ( ), through to F1 where you need millions to last a season. With bike racing I haven't seen budget groups, or indeed classic bike groups. Is this a lack of numbers thing or have I got it all wrong?

Granted some of the frame out at the moment don't really seem to offer huge savings in weight over there metallic alloy counterparts. However when a basic carbon fibre composite is compared directly to a standard steel the gains in specific strength (strength / weight) is over ten fold.

From: Web Link



A table bellow this graph seems to suggest that the carbon fibre materials being used for cycles at the moment are not particularly advanced when compaired to the state of the art from carbon composites research.

Carbon fibre composites have only really been around since the 1970s, compare this to the discovery of steel alloys in the 11 century, and aluminium which was discovered 1808 (electrolysis of aluminium developed in 1886). The fact that after 40 years of use it is already lower weight for specific applications such as a bike frame is quite amazing.

This short development period and the large range of properties, composition, and weave parameters that can be changed inevitably lead to high research costs, which have to be recovered from the end user.

I still think the visual appearance of some of the time trial bikes are quite something to behold, and in themselves an accidental work of art. By accidental I mean that the design is not pure aesthetics, the structure is designed for purpose, which results in a structural beauty.

Unfortunately currently there is not a mass market for carbon bikes at anything other than top level, and from those with deep pockets. This leads to the research cost is being bared by a few customers. To create a light weight high performance carbon composite structure is in itself a costly venture, and those persuing the material just want as light as possible, with best performance. Durability would be wasted R&D money for them. Add to this that UCI regs have a specified minimum bike weight for there competitions, so reducing the need to reduce weight as far as possible. Again doing so beyond current levels would be a waste of R&D money.

All that said I would be very careful if I where to chose a carbon frame at the moment as I need a frame I don't have to replace every year. So with this in mind I guess I will also be waiting before buying one, but I'd still love to be able to afford own one and experience it for myself. I don't think we'll be waiting long to loose the durability issues, in a similar way to how aluminum alloys have largely lost theirs. As I mentioned in my last post, if there where worries about fatigue performance they would not be used in a vehicle that has large temperature cycles, and is subjected to the shock of landings and turbulence.

...any one been in a plane before?!! Suffered turbulence and heavy landings? Do you really think they'd use carbon fibre on the new Boeing Dreamliner and in significant quantities on the A380 if thee where any concerns about it's lifespan? I think these planes are designed to last around 20 years, and all materials that get into aviation have to conform to a massive amount of testing - myself and some of my colleagues are currently trying to do just that.

This is a relatively new material and and to get the best out of it will require a good few years research specific to cycling. It wasn't till the recent past that Aluminium bikes came with 3yr + warrenties. I would guess carbon fibre will catch up very soon.

Lawrie9 wrote:If carbon was any good weed all be driving around in carbon cars. I say lets make carbon history..

The most technologically advanced cars (F1) and some of the most fuel economic vehicles on this planet use carbon fibre. Alas costs are high as it's still a reasonably active research area with new developments still filtering through. Although it's easier to create shapes that would be impossible in single piece pressed metal sheets it's a messier and trickier process to automate to the same level as a press panel works, and so will cost more.

There's already a fair bit of work going on around this area already. Air bags are one option, and bonnets that are risen when a impact with a pedestrian is detected and 'collects' the airborne human and cushions the landing.

I bet there was some funny clips of the latter one during the setup tests! I have mental images of crash test dummies being catapulted across rooms pin ball machine style!

As you say though there is good potential for saving lives. Incidentally did you know that it was far better for a adult to be hit by a 4X4? Saloons tend to through the person into the air, 4X4s tend to collect and carry more. Unfortunately the little folk get knocked down.

Katie's rather large bunny! French Lop, Misty;



As per usual fast asleep as soon as it's picked up. She's got another that has caused a few frights as they like relaxing in the hutch just like that too. ...and well, you can be mistaken for thinking they're not in a particually healthy state when they're doing it!

I have nothing against of the peg frames, or for that matter whole bikes. There are some very nice ones around that would no doubt suit me fine and be a pleasure to ride.

The enjoyment of going out on rides on my bike, although a significant part of my enjoyment of cycling as a whole it isn't the only bit I enjoy. There's also the maintenance, where if current funds allow I'd be doing as much of it as possible by myself (with the exception of welding and painting), and fiddling around with ideas, and perhaps trying out things that are not readily accepted by the mainstream.

For instance while I was involved in the VW scene a while ago my engine tuning was going down the route of extracting as much power as possible from a 1584cc engine with additional aims of improving the original efficiency of the engine and retaining a reasonable degree of reliability through using fuel injection and a proportion of machining (not by myself I hasten to add). This was in contrary to the standard (but also fun) method of raising capacity to 2.1l, fitting very large carbs and enjoying 160-200bhp in a 800kg rear wheel drive vehicle.

My aims here are to end up with what I'd consider my ideal road bike, not necessarily one that would conform to UCI regs. I want hydraulic discs, but I want a ride thats comfortable and fast for sustained high energy efforts. The only bike that looks like a Road Bike with discs that I've seen is the Kona Sutra, but this models target audience seems to be tourers, with a more robust frame and relaxed riding position than I'm thinking of.

I think it was on this forum that I was enjoying a "what if?" post about what state road bikes would be in if they where unregulated. Opinion was clearly split between those who think they have it as good as they are going to get it now and it won't get significantly better and those who are keen to discuss new ideas.

I won't be jumping straight to this bike, I'd be looking to find a second hand road bike in the later stages of this year to spruce up to a usable condition and experience the Road Bike posture, speed, and style for myself. I would be looking for something simple, cheap, with indexed gears (at best STI levers which I could scavenge parts from), and made of steel for this so I can weld bits on here and there and try things out. Something along the lines of a 58-62cm road bike geometry but with extra clearances for guards etc would be ideal.

As I understand the various geometries;

Road Race Bike; As light as possible (to the regs of course), the most twitchy to ride, but very responsive to out of the saddle efforts. Low rider angle.
Audax Bike; More robust than the road bike and a little less twitchy. Designed with light loading in mind. Designed for long rides with efficency in mind, so a little lower rider angle than the tourer.
Touring Bike; Build to be very durable and can withstand full touring loads in addition to the rider. Frames are typically the thickest gauge material of the three. Very stable and relaxed to ride.

All three generally use drop bars, but the touring bikes can come with the butterfly and flat bars.

Bob S wrote:15-18 mph -50 -60 miles with a ruck sack, your fitness is all right now.

That was my best speeds last year. I've only managed about 8 commute runs this year because of bad winds, working of site, and a lingering cold in March, and I didn't enjoy my route during the night rides, so didn't do it. My speeds at the moment are that range but over a 14 mile each way commute, so 55 - 47 minutes ride time only, rather than 3hrs + rides. Really looking forward to joining them though, perhaps late May.

Thanks for the notes on prices and the materials I shall go away and have a little think. I also need to figure out how to convince my partner that I "need" to get a second hand racer / audax bike to try out the basic geometry to see how I get along then swap over to the custom a year or so after!

Regarding the Steel or Aluminium alloy, the Aluminium alloy was just the first to come to mind due to it's light and stiff properties. The last Chromoly bike I had was a Dawes Chilliwack MTB (model before they introduced oval tubes) from about 11 or 12 years ago. That felt like riding on a spring, the bottom bracket would wave all over when out of the saddle and the front wheel would tuck (forks or frame flexing) noticeably into the chassis under heavy braking and then would spring back when stopped. My current MTB ('05 Rockhopper) feels much more rigid, I'm guessing this has a lot to do with more advanced design, rather than material. I'd be happy to go with steel alloy so long as it is rigid under braking. - As recommended I'll google it.

I also hadn't realised (although it makes complete sense) that the builder would want to discuss the rest of the bike, such as a groupset. I guess they wouldn't be too happy about me wanting to start with a kinder-to-the-pocket middle of the range groupset I'll put it back a little further till I can afford a decent groupset too. I was thinking of the roadies equivalent groupset to a MTB's LX or XT, but of course I'd look at all manufacturers.

Are groupsets like computers? In some research areas it's said your best leaving buying the mega computer for simulations till the very last minute in a project because the increase in power of the machine will allow you to get so much more done! Is the advance in groupset design similar paced, or is the developments much more incremental than only really give phycological (argh spellings gone to pot today!) advantages? I love the idea of the electric shifters, perhaps by the time I order this bike they'd have dropped through some of the lower than top end groups!

Cyclenut wrote:Dearie me, that would be awful. Rhymes with boring don't you know.

It was not a knock on touring bikes - on this forum, or indeed in this organisation that would be foolish. But thankfully the CTC is a group and a single voice for all cycling disciplines. I do catch odd ends of conversations from people who don't seem happy about CTC catering for other that touring. That broken up system is what is in existence for engineers, and there is a constant campaign to unite these groups with one aim being for engineering to gain more power to be noticed in this country and government.

I was merely pointing out that I was aiming for the Race / Audax geometries rather than a touring. That aside I don't need a bike designed to take heavy loads apart from myself with a full ruck sack. I'm more than happy doing mini touring like rides at a pace of between 15 and 18mph on my MTB, ok only 50 - 60 mile rides so far hopefully more sunday CTC rides with the Merseyside/St Helens group this year when my fitness is back up.

Thanks again for all your feedback, it's helping me sort out some jumbled thoughts!

Looking at it from a different angle, if I found a steel frame I like would it be a relatively straight forward mod for an experienced frame builder to put the mounting points on for a rear disc brake? Can most frames be modded to take the width of MTB hubs? I'm guessing the extra forces aren't huge for the rear brake but the chain stay may want an additional tube welding on to brace it to the seat stay to stiffen it up a little and carefully considered welding of the mount points, perhaps with an additional plate on the tube to spread the force?

The front end is easier to deal with, just find a disc specific fork. The forces on the head set should be similar?

Are custom frame builders generally a steel only thing then? Would that make it near impossible to get sub 10kg?

After A little hunt I've found that a few Hybrids are close to the mark component spec wise, not sure about the geometry. They also have flat bars rather than drops. Would the drops be too low if they where put on a frame designed for flat bars?

Excuse the ignorance but what's the deal with riding on the drops? I thought it was supposed to reduce air resistance? Not sure how true to real life the Flying Scotsman film is but in one bit he's turning the handlebars upside down to reduce air resistance?

What is the sort of cost involved in getting a custom frame built? I'd obviously be trying out a similar geometry on a cheap second hand bike, or perhaps parts donor first but this is what I'd ultimately be looking for;

Audax like geometry for a 190cm / 84kg (6"3 / 184lbs) rider with 86cm (34") inside leg ...or at least that's my jeans size! Aluminium alloy frame spaced to take standard 32 hole MTB hub wheels with 700c rims stiffened and strengthened appropriately for Disc Brakes - either mechainical, or preferably hydrualic if I could find appropriate levers for the drop handlebars.

I'm looking to build up a spec (this is long term dreaming, not something I'm doing this year - perhaps I may stretch to the second hand audax later this year!) for a fast, all weather commute which I could use for long rides (< 100 miles) that is tough enough to take a rough road but lighter than my XC MTB (approx 12kg), is 10kg or less achievable without spending a fortune?

...is there other bikes already available close to that spec? I've seen the Kona Sultra but that seems to be a tad on the heavy side at 11.5kg, and a touring geometry. Not enough of a difference to coax me off my XC MTB!

Looks like it's not really a way forward for a cheap experience of a Race / Audax 700c geometry then. Cheers for the help, I'll leave it there to rot into the ground. It's been there for over a couple of months already so far, and is similar to the one in the picture.