Head angle or BB height for cornering?- Mtbr.com
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  1. #1
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    Head angle or BB height for cornering?

    What would be a bigger factor in how a bike corners, head tube angle or bottom bracket height? As a follow up, would a .5" raise in BB height have a noticeable adverse affect on a bikes cornering ability if the head tube remained a slack 67 degrees (i say "slack" as this is on a 130mm trail bike)?

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    I would assume bb height is more important, I say this because dual slalom bikes (lots of cornering) dont have overally slack headtubes, around 68 degrees. This is just a guess however I'm sure someone knows better than I.

  3. #3
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    Lower center of gravity = increased all around stability.

    Slacker head angle = slower steering + additional high speed stability as the WB lengthens.

    A half inch increase in bottom bracket height will definitely have an adverse affect on cornering stability.

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    Higher BB will raise the centre of gravity and make cornering "twitchier." This is not really a bad thing for a bike that will be used on really tight trails or a lower speeds. Only gets sketchy at high speed.
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  5. #5
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    cskolnick: So are you asking if you change the your from whatever HA it was before to a 67* HA and as a result that increases the BB height .5" will the bike corner better or worse? What's the bottom bracket before the .5" and HA before it's 67*?
    "The future belongs to those that believe in the beauty of their dreams."

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    Quote Originally Posted by captain spaulding
    cskolnick: So are you asking if you change the your from whatever HA it was before to a 67* HA and as a result that increases the BB height .5" will the bike corner better or worse? What's the bottom bracket before the .5" and HA before it's 67*?
    Hey,

    At the moment the HA is 67 and BB height sits at 13". This is a 130mm bike with a longish 17.3" chainstay.
    If i used the alternate shock position in would steepen the bike up to about 68 HA / 13.4 BB/ 17" CS.
    My thinking is if i did that i would go with an angleset (it is a tapered headtube) and get the HA back to 67 (or a bit slacker if needed).
    the reason i am considering this is because the "slack" position on my frame gives the shock a falling rate and i am not so sure i am digging that at the moment. The steeper setting is supposedly much better in that regard. I am considering using that as my main set-up but do not want to give up too much in the cornering department. That is one of the reasons i went with the frame.
    With that said, i know these are small numbers but you know how it goes..

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    Considering the numbers I checked the Banshee forum and got confirmation that we actually talk about a spitty.

    I would only regard running the steep/tall setting an option if running 1x9/1x10. If running a granny - you don't want the high/steep setting. Kickback due to chaingrowth..

    Push your shock? Get another shock? Lots of options both coil and air. Regarding geometry and BB height - the spity needs at least 140m up front, better 150mm. Running a Rev 150 Team myself, the blackbox motion control actually make a difference. I find the fork well matched for the frame. Running a 130mm fork in the low/slack setting would give you a very low BB.

    Regarding harsh feeling; have you considered RWS needle bearing for the rear end of the shock? Doesn't really do much in front, so you only "need" it for the rear of the shock really. Everything properly greased? Not overly tightened? The frame dosn't require it to be very tight, just tight enough not to be any play.

  8. #8
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    Quote Originally Posted by cskolnick
    Hey,

    At the moment the HA is 67 and BB height sits at 13". This is a 130mm bike with a longish 17.3" chainstay.
    If i used the alternate shock position in would steepen the bike up to about 68 HA / 13.4 BB/ 17" CS.
    My thinking is if i did that i would go with an angleset (it is a tapered headtube) and get the HA back to 67 (or a bit slacker if needed).
    the reason i am considering this is because the "slack" position on my frame gives the shock a falling rate and i am not so sure i am digging that at the moment. The steeper setting is supposedly much better in that regard. I am considering using that as my main set-up but do not want to give up too much in the cornering department. That is one of the reasons i went with the frame.
    With that said, i know these are small numbers but you know how it goes..
    13.4" is pretty low as is, it should still feel ok at that height. However, if you slack it back out using the angleset your BB height will drop again anyways.

  9. #9
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    Quote Originally Posted by Intrepidity
    Considering the numbers I checked the Banshee forum and got confirmation that we actually talk about a spitty.

    I would only regard running the steep/tall setting an option if running 1x9/1x10. If running a granny - you don't want the high/steep setting. Kickback due to chaingrowth..

    Push your shock? Get another shock? Lots of options both coil and air. Regarding geometry and BB height - the spity needs at least 140m up front, better 150mm. Running a Rev 150 Team myself, the blackbox motion control actually make a difference. I find the fork well matched for the frame. Running a 130mm fork in the low/slack setting would give you a very low BB.

    Regarding harsh feeling; have you considered RWS needle bearing for the rear end of the shock? Doesn't really do much in front, so you only "need" it for the rear of the shock really. Everything properly greased? Not overly tightened? The frame dosn't require it to be very tight, just tight enough not to be any play.
    Yup, it is a Spitty. .Figured the DH forum would be a good place to talk about cornering geometry.
    I actually just picked up a 1x10 (32/11-36) to simplify things and keep the chain under control. I am actually tempted to try the granny in the steep position as it currently does not feel that bad when seated. The bike def has a "feel" to it when pedaling but i actually like it.
    As for the fork, i am running a 130mm. Wanted to keep it a bit more "XC" (will leave it at that considering the forum i am in). I also just upgraded to a BB MoCO cart and oh man , much nicer, Trying to see if there is a floodgate mod i can to as well (i never use lockout really).
    I will eventually get the RWS reducers once i get the rear shock figured out. Seems like there was either something wrong with my RT3 (SRAM is sorting me out..They are the best) or they are just providing waaay to much platform on the new shocks and, personal preferences aside, it may not be a good match with this suspension design soooo spoke on the phone with PUSH today and just ordered a RT-AM shock and sent the leverage schematics to Darren for tuning. Very excited.
    Thanks guys

  10. #10
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    Quote Originally Posted by cskolnick
    Yup, it is a Spitty. .Figured the DH forum would be a good place to talk about cornering geometry.
    I actually just picked up a 1x10 (32/11-36) to simplify things and keep the chain under control. I am actually tempted to try the granny in the steep position as it currently does not feel that bad when seated. The bike def has a "feel" to it when pedaling but i actually like it.
    As for the fork, i am running a 130mm. Wanted to keep it a bit more "XC" (will leave it at that considering the forum i am in). I also just upgraded to a BB MoCO cart and oh man , much nicer, Trying to see if there is a floodgate mod i can to as well (i never use lockout really).
    I will eventually get the RWS reducers once i get the rear shock figured out. Seems like there was either something wrong with my RT3 (SRAM is sorting me out..They are the best) or they are just providing waaay to much platform on the new shocks and, personal preferences aside, it may not be a good match with this suspension design soooo spoke on the phone with PUSH today and just ordered a RT-AM shock and sent the leverage schematics to Darren for tuning. Very excited.
    Thanks guys
    Damn, those are some sweet GEO numbers for a trail bike..

    Looks like you're mostly sorted out.. Only thing I'd keep in mind if you end up liking the steeper position and want to slacken the HA out a bit, running an angleset in like -.5* to -1.5* will also lower your BB height a bit, so it'll be less than the advertised 13.4".
    "The future belongs to those that believe in the beauty of their dreams."

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