Tangible difference in frame material

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  • Tangible difference in frame material
  • steve_b77
    Member

    Now I always knew there was a difference between frame material in terms of feel, stiffness, compliance and other marketing buzz words etc, probably less noticeable on a MTB hardtail than a CX bike due to tyre size etc.

    But at the weekend our CX course had quite a stony layer underneath, so noticeable changes in surface texture. I’ve got one carbon framed bike and one alloy framed bike, they both have 27.2mm carbon seatposts, different brand but both Ti railed saddles and they’re equally comfortable, full carbon forks, the same wheel sets and the same tyres set up tubeless at the same pressures and checked with a digi pressure gauge.

    But while on the smooth bits – where there were no stones poking through – there’s little to tell between them (at race pace anyway) in terms of compliance, but during the race when on the alloy bike I recall feeling the rear rim bottoming out 3 or 4 times per lap (in the same place each time) whereas the carbon bike didn’t suffer from that.

    It’s a bit of an eye opener for me, but not that important, other than longevity of the wheels.

    hols2
    Member

    the same wheel sets and the same tyres set up tubeless at the same pressures and checked with a digi pressure gauge.

    during the race when on the alloy bike I recall feeling the rear rim bottoming out 3 or 4 times per lap (in the same place each time) whereas the carbon bike didn’t suffer from that.

    Are you saying that one frame caused the rims to bottom out, but the other didn’t, or that they both bottomed out but you could only feel it on one bike? Surely, if you’re running same wheels and tyres at the same pressure but it only bottoms out on one bike, then you must be going faster and hitting stuff harder on that bike. Or your gauge is giving inconsistent readings.

    steve_b77
    Member

    What I’m saying is, that the alloy framed bike isn’t / can’t be as forgiving as the carbon one, hence the bottoming out, speeds are pretty consistent and certainly not appreciably faster on one. Certainly didn’t feel it on the carbon one.

    Gauge is consistent as I take them and check again, just to make sure you know.

    Premier Icon timbog160
    Subscriber

    That seems a little counter intuitive to me – I would have expected the carbon framed one to be a bit stiffer if anything…

    Premier Icon molgrips
    Subscriber

    The supposed benefit of carbon is with high frequency buzz absorption, not flexing to soak up actual hits. I think there’s something else going on – you took a slightly different line, ran over slightly different stuff.

    philjunior
    Member

    Maybe it’s just the carbon framed one is lighter so doesn’t slam the wheels into stuff as hard/allows you to tweak it over things more easily.

    Premier Icon thisisnotaspoon
    Subscriber

    Yea, I dont think any frame flexes enough to stop the the rear wheel from gettting dinged.

    Could be down to the frame but in a different way, a stiff but confident not in a shakey on the edge kinda feeling frame might encourage you to ride faster?

    Or more likely, slow puncture or tyre burped.

    Or even more likely, a possion distribution of a small number of events and conformational bias. Next week you will get a puncture on the carbon bike and attribute it to carbon splinters.

    steve_b77
    Member

    Or more likely, slow puncture or tyre burped.
    Or even more likely, a possion distribution of a small number of events and conformational bias. Next week you will get a puncture on the carbon bike and attribute it to carbon splinters.

    Negative on the first as the tyre pressure was the same at the end as the start (on both bikes).

    Nah, I’m not that kind of person, it’ll be the fault of the aliens.

    philjunior
    Member

    conformational bias

    This is a very real option.

    mashr
    Member

    timbog160

    Subscriber

    That seems a little counter intuitive to me – I would have expected the carbon framed one to be a bit stiffer if anything…

    Laterally stiff, vertically compliant – its the “playful yet stable” of road/CX bikes

    steve_b77
    Member

    Laterally stiff, vertically compliant – its the “playful yet stable” of road/CX bikes

    Many lols

    Premier Icon ampthill
    Subscriber

    I thought that in blind trials most people couldn’t pick up the alleged differences between stiff add non stiff frames.

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