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Bianchi & cannondale geometry ?

s1mons1mon Posts: 618
edited April 2008 in Road beginners

Can someone explain to me what the difference is between A1 & AS and B1 & BS on the geometry pictures on the Bianchi site ? I had a bike fitting and I should be looking for a top tube length centre to centre of 539mm and I can't figure out Bianchi's figures :?



  • redddraggonredddraggon Posts: 10,862
    b1 = horizontal (virtual) top tube length
    bs= sloping top tube length

    a1= (virtual) seat tube length (if tt is horizontal)
    as= actual seat tube length.
    I like bikes...

  • Steve928Steve928 Posts: 314
    Yep, so B1 in column 3 is the measurement that you want to match your desired 539mm., and then A1 in column 1 gives the Bianchi frame size e.g. 610 is the 61cm size frame etc.
  • s1mons1mon Posts: 618
    Ok thanks,

    I was looking at the Via Nirone alu/Carbon and 1885. Both of them in a 53cm (A1) are actually 50cm (AS) frames and both have a top tube length (B1) of 535. This would be the size I should be looking at ?

    The other thing bugging me was I tried a Cannondale in a 51 which on their site says is actually a 47cm with a top tube length of 530. So this actually is a good fit regarding top tube length but how come it's only a 47cm frame ?

  • Steve928Steve928 Posts: 314
    This would be the size I should be looking at ?
    I would say so.

    but how come it's only a 47cm frame ?
    Don't fret - you're going about it the right way. Select your frame using the desired horizontal top tube length, then just check that the seat tube centre-to-top measurement (A1 in Bianchi's case) works for you also i.e. that you will be able to set your saddle to the required height too. Also look at head tube length and check that you're going to be able to get the bars either as low as you want, or as high as you want without too many stem stackers.

    Whether you end up with one manufacturer's 52 or another manufacturer's 49 etc.. doesn't matter as long as it fits..
  • s1mons1mon Posts: 618

    I have ridden the 51 cannondale but haven't tried the 54 looking at the geometry it might fit ? I am test riding some Bianchi's this week in a 53cm but a 50cm would fit as well. Can someone have a look at these geometrys and compare them to some of my recommended bike size's ?

    I do like the ride/fit of the 51 Cannondale alot but I need to ride the Bianchi's first.

    My recommended size's are,

    539 top tube
    514 seat post
    73.5 seat post angle
    987 centre to centre of each wheel
    700 centre of BB to top of saddle

    Let me know if you need any other measurments.

    Geometry of the Cannondale and Bianchi's,





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