hardtail BB height

Ferrals
Ferrals Posts: 785
edited April 2015 in MTB general
How low is too low when it comes to hard-tail bottom bracket height? and is bb height measured sagged or unsagged?

My current bike had a 305mm bb height and 130mm travel forks.

I am planning/thinking of reducing these to 120mm which will knock 4mm off the bb height if my calculations (or rather an online geo calculators) are correct. Is 301mm too low? I run xc tyres (schwalbe rocket ron 2.25 front and racing ralph 2.1 rear) so don't have high volume tyres lifting things up.

I guess fully bottomed out the bb height will be the same. probably the only option will be to see what happens.

Comments

  • robertpb
    robertpb Posts: 1,866
    BB are measured unsagged, Because sagged would have too many variables.

    Most bikes will end up between 300 and 320 with sag, but that has lots of variables.
    Now where's that "Get Out of Crash Free Card"
  • The Rookie
    The Rookie Posts: 27,812
    Many HT's run BB's with a drop below the wheel centreline, yours is pretty much on it, 301mm is certainly not 'low' and I rather doubt you'll notice 4mm reduced clearance to the cranks/pedals as I doubt you can ride with them level enough (when it may be critical) to make that much difference!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Ferrals
    Ferrals Posts: 785
    Haha valid point!

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