M
Mark Hickey
Guest
mike anderson <[email protected]> wrote:
>After reading up about ’length of top tube’ at RBT archives on Google,
>I stumbled on this message:
>-----------------------------------------
>For my money, there are only 2 important dimensions: toptube length and
>seattube angle. If you get those right, you can tweak everything else.
>No fit kit can tell you what your ideal saddle to bar drop (or rise)
>should be, that's all personal preference, ditto for bar width. Knowing
>your desired saddle to bar drop, you can avoid buying a frame that
>would require awkward stems or risers to get the bar height you want. A
>wrong toptube length is a disaster. You can fudge around it by sizing
>stem reach & saddle position, but that screws up weight distribution
>and steering response. Seattube angle sets the angle of the hips for a
>given bar drop. Generally, if you want your bars really low, you want a
>steep seattube angle or else you'll be too closed at the hip. The only
>dimension the fit kit needs to really help you with is toptube length,
>that, and your personal preference for bar height determine almost
>everything else.
>---------------------------------------------------
>
>Can somebody tell me what the preferred seat tube angle would be for a
>saddle-to-bar drop of: 0cm (yes I like to have the saddle and handle
>bar leveled)?
Seat tube angle doesn't determine where the saddle ends up... only the
RANGE of fore/aft positioning possible. Most bikes have "average
enough" seat tube angles that you can get the proper position by
choosing the right seat post (with or without setback), and then
adjusting the saddle accordingly.
The seat tube angle DOES affect the "cockpit length" relative to the
listed top tube length. Since the saddle's position is determined by
the rider's position on the bike, it will be in the same place
regardless of seat tube angle. If the bike has a steeper seat tube,
that places the saddle further behind the top tube/seat tube junction,
effectively lengthening the cockpit. If the seat tube is shallower,
the opposite is true.
Neither condition really affects the ability to get the bars up as
high as you need them, however. You just need to be sure that the top
tube horizontal component plus the stem's reach add up to the "cockpit
length" you need.
To get some info on how a stem's rise and length affect the horizontal
and vertical positioning of the bars, check out my infamous stem chart
at: http://www.habcycles.com/fitting.html
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame
>After reading up about ’length of top tube’ at RBT archives on Google,
>I stumbled on this message:
>-----------------------------------------
>For my money, there are only 2 important dimensions: toptube length and
>seattube angle. If you get those right, you can tweak everything else.
>No fit kit can tell you what your ideal saddle to bar drop (or rise)
>should be, that's all personal preference, ditto for bar width. Knowing
>your desired saddle to bar drop, you can avoid buying a frame that
>would require awkward stems or risers to get the bar height you want. A
>wrong toptube length is a disaster. You can fudge around it by sizing
>stem reach & saddle position, but that screws up weight distribution
>and steering response. Seattube angle sets the angle of the hips for a
>given bar drop. Generally, if you want your bars really low, you want a
>steep seattube angle or else you'll be too closed at the hip. The only
>dimension the fit kit needs to really help you with is toptube length,
>that, and your personal preference for bar height determine almost
>everything else.
>---------------------------------------------------
>
>Can somebody tell me what the preferred seat tube angle would be for a
>saddle-to-bar drop of: 0cm (yes I like to have the saddle and handle
>bar leveled)?
Seat tube angle doesn't determine where the saddle ends up... only the
RANGE of fore/aft positioning possible. Most bikes have "average
enough" seat tube angles that you can get the proper position by
choosing the right seat post (with or without setback), and then
adjusting the saddle accordingly.
The seat tube angle DOES affect the "cockpit length" relative to the
listed top tube length. Since the saddle's position is determined by
the rider's position on the bike, it will be in the same place
regardless of seat tube angle. If the bike has a steeper seat tube,
that places the saddle further behind the top tube/seat tube junction,
effectively lengthening the cockpit. If the seat tube is shallower,
the opposite is true.
Neither condition really affects the ability to get the bars up as
high as you need them, however. You just need to be sure that the top
tube horizontal component plus the stem's reach add up to the "cockpit
length" you need.
To get some info on how a stem's rise and length affect the horizontal
and vertical positioning of the bars, check out my infamous stem chart
at: http://www.habcycles.com/fitting.html
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame
