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Question about stem angle

BG2000BG2000 Posts: 517
edited May 2010 in MTB workshop & tech
Does anyone know how stem angle affects bike handling ?

I've not got any other stems to try out, but before splashing out on something nice I'd like to know if there's any general rule.

I'm currently running a -6º stem (6º flipped over), and this feels pretty good. But I'm probably going to get a 0º rise stem just to raise the bars a bit.

I know people are going to say "it depends on your head angle and forks", but for a given bike, is there a rule ?

Perhaps it's more dependant on stem length ?

So for XC/trail riding, what would be the ideal stem length/angle ? I'm guessing 100mm x oº rise.

Posts

  • supersonicsupersonic Posts: 82,708 Lives Here
    The steeper the angle, the more weight is taken off your hands and the shorter the effective stem length becomes.

    See FAQ for a stem comparison utility.
  • BG2000BG2000 Posts: 517
    I already read the FAQs - I don't need to know what the position change will be, only how it affects the bike's handling.

    With a steep stem, say +10º rise, when you steer to the right, you left hand rises a bit, and your right hand drops down a bit (as well as forwards and backwards). Compare this to a road bike where the stem is at 0º relative to the ground, as you steer to the right, your left hand moves away from you a bit, and your right hand moves towards you a bit (with a bit of upwards and downwards movement too).

    My guess it that a stem set horizontally like a road bike is better for higher speed, and a steeper stem is better for lower speeds, and more technical riding.

    But I've never seen anything that explains this, despite all the different stem angles available.

    Anyone who's noticed a difference when changing stem rise, please let me know.
  • supersonicsupersonic Posts: 82,708 Lives Here
    What I am saying is you can have two stems with different angles and lengths but they can put your hands in EXACTLY the same position. Also consider bar width, rise, sweep and spacers.

    But for all being equal, the shorter effective length and more rearward weight bias will quicken the steering by reducing leverage to the steerer axis, plus the slightly lighter front end. The shorter effective length also means that there is less lateral movement [ie imagine a 2 foot stem - the bars will move left or right much more as you turn]. This makes the steering feel more direct.

    Lower stems are better for speed in many cases as you are in a more aero position, and can help climbing too.

    Upwards/downwards movement is accentuated by the head angle.
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