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"Carbonfest"

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  1. Smudge
    Member

    I was teasing in an earlier thread about “Carbon Fibrefest”, but it got me thinking a little. Now I’m not averse to a bit of the black matted bling, if you want the lightest, stiffest component then a well made and designed bit of carbon fibre is probably best, and if not, then it is likely to be amongst the best materiel.
    However now the initial exotic gleam has faded just a little, I wonder if it is still seen as the ultimate material to aspire to?
    I have been told on numerous occasions that a carbon fork can/should be fitted “for comfort, or that a carbon seatpost can make a (presumably uncomfortable) seat more comfortable, yet we also see adverts for carbon frames with various whizzy bits added to make them more comfortable and flexy… we also, for instance see titanium framesets advertised as having the weight advantage of carbon but the comfort giving flex of steel (allegedly), according to the journalists/advertisers because (some?) carbon bikes can be too harsh for the road? The same accusation is now being levelled against alloy frames by some.

    Now as I say I am not against cf, indeed I find it fascinating to watch the trickle down from race technology and do not rule out getting a carbon wonderbike in the future (possibly sooner than that if the lottery numbers come up!), but I do wonder if it’s the ideal for riders who are not racing?

    imho where absolute speed is the requirement and all other considerations secondary, then cf appears to be the answer, alloy frames appear to confer similar advantages/disadvantages with more weight and lower cost, steel is cheap, (relatively, and dependent on the type and builder) and more flexible (good or bad? Hmmm?) and a little heavier. Titanium somewhere in between depending on the design (but generally ***** expensive!)

    In an area (I’m thinking of frames/framesets here) where the differences/advantages/disadvantages can be slight and often open to argument, do we place too much emphasis on frame materials?

    S (with a mediumweight steel folder, a heavy steel tourer, an light(ish) alloy road/audax bike and a light(ish) steel mtb… )

    PS It really doesn't matter, as long as people ride, and ideally ride a wide range of interesting machines in my ideal world :-)

    Posted 12 years ago #

  2. Wilmington's Cow
    Member

    In frames, possibly... I happen to like steel because I think it has that perfect balance between weight, durability and comfort (alu frames definitely are stiffer and ride more harshly, but lighter and ergo faster - though remember, it's not about the bike).

    Carbon fibre for a town bike would be a bit of overkill, but weight is a consideration - I reckon a lot of people are put off cycling by buying a hefty full-sus Halfords mountain bike, thinking that makes it comfortable, then find cycling 'hard'.

    Anyway, I just had arrive in the post today a new rigid carbon fork for the MTB to become a bit more of an urban machine, and I'm looking forward to losing the heavy (though good) suspension fork in its place. Price of that compared to the alloy fork I was looking at was similar - supposed additional comfort, on top of the weight saving, was a factor.

    Must compare the rides of the Kaff (steel fork) and the X (carbon fork) and come back more informed!

    Posted 12 years ago #

  3. Dave
    Member

    I went for alu on my PY/Strava machine because the weight penalty versus carbon is modest yet the cost saving is still significant. In the same size, 350g heavier than the equivalent carbon frame (and £125 instead of £300).

    I ran the numbers and at a given power I'll be climbing at 10mph, not 10.04mph, or 1 metre / minute slower - hardly an issue.

    The most important thing from a go-fast frame is stiffness and I didn't see any reason to expect the carbon frame to be stiffer - it might easily be more noodly, giving the alu frame more than 0.04mph in extra efficiency.

    I do have a full-carbon fork mind you.

    Finally, it looks great. Carbon weave seems bling, but it looks a bit boring!

    Posted 12 years ago #

  4. wingpig
    Member

    Presumably someone somewhere has already tried building a bicycle frame out of discarded animal bones as the logical progression from early cycles built from discarded plant structural elements, possibly even attempting to use the flexible joints in some way (though the tendons and cartilage would have been a maintenance nightmare without a biological support mechanism). Seatposts built to resemble the vertebral column with a series of bouncy discs held between articulated pseudobones would offer excellent suspension for the real backbone. Maybe H R Giger has already sketched vaguely biomechanical bicycles, though I shutter to think what the saddle might look like. Maybe someone's already attempting to biologically grow a bicycle frame, perhaps by encouraging structure-forming or structural-protein-secreting modified organisms to colonise and build around a frame-shaped armature. Bone might not weather too well but perhaps a shiny chitin coating (in a range of colours) could be grown around a frame-shaped artificially-grown bone.

    Posted 12 years ago #

  5. Roibeard
    Member

    I think the material discussions are very easily obscured by design considerations - if a design optimised for one material is used for another, the second material may not perform as expected.

    For example aluminium frames requiring larger external diameters compared to steel.

    The new material may be x% less dense than the old, but actually required more of it for the same rigidity, hence the construct doesn't weigh x% less, or ends up being insufficiently rigid...

    When test riding candidate bikes for the commuter, I quickly developed a preference against aluminium forks as installed on the candidates, as they were harsher than the old commuter over potholes and cobbles. Of course, this could be because they were straight rather than curved, or a different diameter, or had a different geometry, or...

    And the one carbon forked bike I tried also felt harsh - I seem to think carbon fibre can be too flexible, so possible additional material had been added, thus making it too rigid again.

    In any case, the steel forked bikes felt subjectively better, whilst attempting as similar a test as possible, without going double blind!

    Design is much more complex than simply material choice, and optimum design definitely means designing closely in concert with the chosen materials. I'm pretty certain brilliant frames could be made in almost any material, by a brilliant framemaker, experienced in that material!

    Robert

    Posted 12 years ago #

  6. Dave
    Member

    The most important thing would be to try using identical tyres, especially if interested in the comfort of the ride (admittedly this wasn't a consideration for me).

    It was difficult to test SWMBO's Croix-de-Fer because it came with daft knobbly actual cyclocross tyres, so on the streets around the bike shop, we were both left wondering what it would actually be like to ride.

    Personally I think the wider handlebars won it (such a simple thing).

    Posted 12 years ago #

  7. Bhachgen
    Member

    Dave is right to point out that tyres make a big difference when comparing how different bikes feel.

    I've got a Revolution Cross which came with some nice but knobbly Maxxis CX tyres. They had very poor puncture protection so I switched them out for Schwalbe Sammy Slicks which have a kevlar belt, faster on the road, but still have some grippiness for the rougher parts of my commute.

    Neither of those options were all that fast, but they rolled Ok and they did cushion out the potholes, cobbles etc fairly well.

    As I discovered when I put some 25mm Vittoria road tyres on it. Stiff alu frame and fork on skinny tyres = very unforgiving ride. I'm thinking a future upgrade might be a carbon fork which could help that to some extent (but probably after a new set of wheels for the "road" incarnation so I don't have to keep swapping the tyres over every time I go off-roading!)

    My other bike is an old 531 steel frame with a slim, curved, steel fork. Tyres on this probably even less rubber than the Vittorias but in comparison with the cross in road mode the ride almost feels like it has suspension.

    The steel frame is definitely heavier than carbon or a mid-priced aluminium frame, but I find that the forgiving ride helps to carry momentum. I often find on club runs where the road starts to ramp up that I'm carrying more speed through the lower part of the climb and finding myself at the front of the group without even really trying. Then if it's more than just a short kick up, gravity kicks in and I find myself working my behind off to try and stop them all coming back past me!

    Posted 12 years ago #

  8. Smudge
    Member

    @Dave, interesting observations, I have wiiiide drops on the Surly to give me leverage off road, but on my roady bike I have narrow to suit my shoulder width (380mm bars? From memory)
    @Bachgen, I'm no racer but have wondered about swapping my Giant OCR frame for a Surly Pacer, slightly heavier but allegedly more comfortable.. I've already got a B17 fitted as "race" saddles take all the enjoyment out of riding for me after a couple of hours.

    Posted 12 years ago #

  9. Wilmington's Cow
    Member

    "The most important thing would be to try using identical tyres"

    Yip, both my Kaff and X (currently) have the same tyres.

    Posted 12 years ago #

  10. Tom
    Member

    I think carbon is the ultimate frame building material. But, it has to be done well. My road bike has had three different carbon forks. One cost £80, visibly flexed and caused speed wobbles. Its replacement cost £200 and doesn't.

    Posted 12 years ago #

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