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  1. #1
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    Head Tube Angles...

    Those who have ridden lots of miles and lots different bikes, I'm wondering what your opinions on head tube angles are. I've been going over my bars more with my recent bike than any before and wondering how much of a role head tube angle plays...

    I'm curious what people's favorite angles are for XC/AM riding as well.

  2. #2
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    Start out by posting a pick of you bike with a head-tube angle.
    Only if I got paid to hang out in my garage and tweak on my bikes...

  3. #3
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    It's 70 degrees (just a Cannondale F5)... Not sure what my former head tube angle was...

  4. #4
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    My favorite XC/AM bike has a 68 head angle with a 29er wheel. The only time would want it steeper would be for racing.

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    Sometimes it just happens, but going over the bars is more of a riding/bike handling issue. How often do you crash and under what circumstances?

  6. #6
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    Head tube angle influences steering. Slack angles provide slower handling, more stable on downhills, holds a line better. Steeper angles provide faster handling, better for the twisty stuff but can feel twitchy.

    What do you feel caused your OTB - what's the complaint with steering?

  7. #7
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    When I switched to a bike with significantly more front suspension than I was used to, but with a similar head angle, I found myself going over the bars a lot until I adjusted my riding style.

    -Pete
    I can barely get my mouth around it.

  8. #8
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    Quote Originally Posted by danhasdrums View Post
    Those who have ridden lots of miles and lots different bikes, I'm wondering what your opinions on head tube angles are. I've been going over my bars more with my recent bike than any before and wondering how much of a role head tube angle plays...

    I'm curious what people's favorite angles are for XC/AM riding as well.
    I have an old 96 GT avalanche and a 99 Wildhare both of which have a 71 degree HA I believe. I had them built up for XC but found that when started riding out here in AZ with what I consider to be more AM terrain I was going over the bars too much.

    I purchased a RM Slayer and it has a 66.5 degree HA with 160mm fork. The difference was huge. I have never had the feeling of going over the bars on my Slayer and Im talking about riding on trails like National on South Mountain AZ. It drastically improved my confidence and have become a much better descender. That being said it did take awhile to learn how to climb on it. While I can climb pretty much everything that I can on my other bikes it is more difficult on the Slayer. Its also heavier and has 165mm rear wheel travel so its not just the HA that is making things more difficult.

    I currently have my eye on the Transition Trans AM 29'er which has the 68 degree HA someone else mentioned.
    Last edited by Douger-1; 05-01-2012 at 11:41 AM.
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  9. #9
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    Quote Originally Posted by danhasdrums View Post
    Those who have ridden lots of miles and lots different bikes, I'm wondering what your opinions on head tube angles are. I've been going over my bars more with my recent bike than any before and wondering how much of a role head tube angle plays...

    I'm curious what people's favorite angles are for XC/AM riding as well.
    It is the whole of the frame geometry and bike setup that matters. The HTA is just one part of it and can not be blamed or credited for the handling traits by itself.
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  10. #10
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    The reason I see for going over the handlebars has to do with the force of the center of gravity of the rider in relation to the opposing force of the tires contact with the Earth. The greater distance between the center of gravity of the rider and the contact point of the front tire, the more force is needed to make the rider go over the handle bars. Head tube angle would play a large role in determining the distance of the center of gravity of the rider and the front tire contact point. Sure, there are other factors, but that is a very large one. Stretching out the wheel base will also make your bike go over obstacles at a less steep angle giving less chance of you reaching the tipping point.

    Got a couple good responses here, so thanks!

  11. #11
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    my older "race bike" had a steep 71 head angle. i felt totally sketched on downhills, and i felt like i rode worse on technical stuff.

    however, for cornering and climbing it was great. I just "care" more about technical riding and stability, so i ended up selling that bike. My current bike is at 68. i love it, and still climbs well enough.

  12. #12
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    ....Also, you and i live fairly close, so i know what kind of riding you're probably doing. Rocky XC. (at least thats what i'm doing). my current bike is a "trail bike" with 120mm of travel, but recently i swapped over to a 140mm front fork, and that obviously raises and slackens the front even more. However, it works great for me because i have such short arms and torso, so it helps me get further back on the saddle.

  13. #13
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    Quote Originally Posted by NicoleB28 View Post
    ....Also, you and i live fairly close, so i know what kind of riding you're probably doing. Rocky XC. (at least thats what i'm doing). my current bike is a "trail bike" with 120mm of travel, but recently i swapped over to a 140mm front fork, and that obviously raises and slackens the front even more. However, it works great for me because i have such short arms and torso, so it helps me get further back on the saddle.
    Thanks. Where do you ride? Fells, Landlocked Forest, Great Brook, Harold Parker, Wompatuck? Wompatuck is definitely rocky, and my little experience in HP I saw some really rocky inclines and declines, but then other areas of the park that were less so.

  14. #14
    see me rollin, they hatin
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    i dont make it down in MA much, i tend to hang around NH, but i havent been to Harold Parker yet (on my list) but i have ridden Russell Mills in Chelmsford, and Lowell-Dracut town forest. those are two of my favorites. i dont do AM riding, (i can barely wheelie, its sad).

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    Quote Originally Posted by danhasdrums View Post
    Those who have ridden lots of miles and lots different bikes, I'm wondering what your opinions on head tube angles are.
    Since switching from 71' to 69' it has 100% eliminated OTB (the rest of the geometry is almost the same). I ride aggressive XC (26er) and will never own anything 70 or above again.

    Having said that, make certain your stem and seat are properly adjusted. If you don't want to change bikes/frames, you could try using a shorted stem and move seat back.

  16. #16
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    Quote Originally Posted by RaveOn View Post
    Since switching from 71' to 69' it has 100% eliminated OTB (the rest of the geometry is almost the same). I ride aggressive XC (26er) and will never own anything 70 or above again.

    Having said that, make certain your stem and seat are properly adjusted. If you don't want to change bikes/frames, you could try using a shorted stem and move seat back.
    Thanks. Interesting to hear just a couple degrees can make such a difference. I'm going to be getting a new bike this year and just trying to narrow down the angles that I want to try out when searching for an appropriate frame. I compensate on steep downhills by putting my butt way behind my seat and almost dragging my butthole on my tire, but I don't want to have to work that hard on downhills. Sometimes I'll hit a rock that I used to just roll right over and to my surprise, I'll end up over the bars. Maybe three times in the last year I had incidents that I was quite surprised with... It looks like a range of 67-69 would be a step in a good direction from what I'm getting back from those here...

  17. #17
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    Quote Originally Posted by NicoleB28 View Post
    i dont make it down in MA much, i tend to hang around NH, but i havent been to Harold Parker yet (on my list) but i have ridden Russell Mills in Chelmsford, and Lowell-Dracut town forest. those are two of my favorites. i dont do AM riding, (i can barely wheelie, its sad).
    I don't do AM either (I'm pretty sure I don't anyway), but I'm leaving the option open. I would do bigger drops now if I had a full suspension, but my body is old and has been hacked open by too many surgeon's to put it through too much more.

    I haven't been to either of those places yet, but they're on my bucket list...

  18. #18
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    Quote Originally Posted by danhasdrums View Post
    I don't do AM either (I'm pretty sure I don't anyway), but I'm leaving the option open. I would do bigger drops now if I had a full suspension, but my body is old and has been hacked open by too many surgeon's to put it through too much more.

    I haven't been to either of those places yet, but they're on my bucket list...
    Good luck with your 68ish endeavors. I had a Jamis Dakar with 68 degs. and loved it! I'm a trail rider...not a huckster. IMO, if you've spent that much time with your surgeon, you'de probably prefer a more confident down than a more efficient up. On my bikes that have a 70deg h.a. I'de like to experiment with longer travel forks to get me closer to 68 degs. It ain't easy gett'n old, slow, and scairt!!
    Only if I got paid to hang out in my garage and tweak on my bikes...

  19. #19
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    So if you have a steep angle frame, 70+ degrees HTA, to what extent will adding a longer fork improve stability? I've been somewhat hesitant to do so, since I know that handling traits are not solely based on effective HTA. What else is going to change in the handling by going, say from 60 mm to 80mm of travel (and assuming that adds 20mm o~f fork length?)

  20. #20
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    Quote Originally Posted by Jamespio View Post
    So if you have a steep angle frame, 70+ degrees HTA, to what extent will adding a longer fork improve stability? I've been somewhat hesitant to do so, since I know that handling traits are not solely based on effective HTA. What else is going to change in the handling by going, say from 60 mm to 80mm of travel (and assuming that adds 20mm o~f fork length?)
    An extra 2 cm of length on the hypotenuse of a 70 degree/90 degree/20 degree triangle isn't going to change much. If my old days of trig serve me right, sin (20) = .342 which means that when you add 2 cm of length to the hypotenuse you'll add approximately .68 cm in wheelbase. This is approximate because you'd really need calculus to calculate exactly, which I don't feel like trying to remember.
    Last edited by dirtdan; 05-01-2012 at 09:57 AM.

  21. #21
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    Yes math has it's place in figuring how a bike's gonna handle of coarse, but like "Shiggy" said, all of the bikes geo plays a part. It's not just the HTA but how the rest of the bike positions your weight, and a bike's "feel" and feedback is gonna change how you react with it. Tire/rim size, bar / stem length, saddle and pedal/BB position, wheel base, how much rebound/dampening and amount of travel on fork, and even how much flex the frame has all play a roll. Someone can try and explain to you why they like a certain flavor ice cream, but until you try it for yourself? So test as many as you can, for as long as you can would be my advice. HTA is a good measure in general for narrowing your search, but definitely the not the tell all be all so don't let it put the blinders on your search for a great/better bike. Some things look great on paper ?, like some cars, 29er, whatnot but in reality, and with different terrain, and personal preference?

    FWIW, think yeah, it's great to have even a little bit more of the latest and greatest, to go a little bigger and faster, I know I do, but find the most fun, and challenge, in improving my ability so it's sort of a catch 22 for me. SS and/or rigid, or a 3x10 fs, Hmmm
    Last edited by theMeat; 05-01-2012 at 11:53 AM.
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  22. #22
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    Is the stem any longer on the new bike? It dosen't take much of an increase in stem length to make a big difference in center of gravity.

  23. #23
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    Quote Originally Posted by Jamespio View Post
    So if you have a steep angle frame, 70+ degrees HTA, to what extent will adding a longer fork improve stability? I've been somewhat hesitant to do so, since I know that handling traits are not solely based on effective HTA. What else is going to change in the handling by going, say from 60 mm to 80mm of travel (and assuming that adds 20mm o~f fork length?)
    Im not sure I can answer your direct question of "how will it improve stability". What I can tell you is it will change your bikes ride characteristics. Some for the better and some for the worse. Like all things in life there is no free lunch. I currently have a 140mm fork on my GT hardtail that came with a 80mm Judy fork on it back in 1996. I have gotten much more aggressive as my skills have improved and I like to charge the tech/chuncky stuff now. I can adjust my current fork from 100mm to 120mm to 140mm. When I was in 100mm mode I found I got the sensation of going OTB on any little tech section I rode. It climbed like a goat but I wanted a little more DH performance so I tried 120mm and now finally 140mm. It didnt climb bad in the 120mm mode but when I went to 140mm I did feel a handling change. The bike gets squirrely on the climbs now and requires me to shift my weight differently. I do like the feel going down now and havent felt any OTB yet. Its a give and take.
    “Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did." Mark Twain

  24. #24
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    Quote Originally Posted by RaveOn View Post
    Since switching from 71' to 69' it has 100% eliminated OTB (the rest of the geometry is almost the same). I ride aggressive XC (26er) and will never own anything 70 or above again.

    Having said that, make certain your stem and seat are properly adjusted. If you don't want to change bikes/frames, you could try using a shorted stem and move seat back.
    I am planning on changing frame/bike this year so I'm doing the research and getting different opinions before I demo any more bikes. I hadn't really thought about the difference in climbing, so that's good to keep in mind. Hopefully I'll find some demo days where I can really take them on some trails, but in deciding between the 67.5 of a Pivot Mach 5.7 and an Ibis Mojo of 69, if they feel equal on a wimpy demo where I don't get to really try the bike on some tougher trails, I'd probably go with the 69 with all other elements being almost equal to keep with the better edge in climbing and handling.

    I could also see possibly trying a shorter stem to shift the center of gravity back a tiny bit as well, but it's not that important and with some minor adjustments in riding style, I can prevent the over the handle bar issue easily using pedal wheelies and/or including a larger range of declines in the ones that I need to get my butt behind the seat for. My position is comfortable and I can ride for hours and hours comfortably. Technique is an easy fix and needs to be adjusted slightly depending on what bike you're on. It's more about finding a frame that fits where my natural style is and find my personal happy spot where I sacrifice a little bit of the handling/climbing I currently have and give myself a little more ability to tackle some difficult declines in a slightly more upright position. The climbing and handling of my current bike is really solid once an acceptable wheelset was added (although the thru-axle to quick release conversion isn't going well and I have some play in the wheel and that probably played a small part in my last over the bars). I'd be willing to give a little bit of that up in favor of more stable downhill properties...

  25. #25
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    Quote Originally Posted by danhasdrums View Post
    Sometimes I'll hit a rock that I used to just roll right over and to my surprise, I'll end up over the bars.
    Try to push the handlebar forward when your front wheel hits the obstacle. You will feel the difference. You can do it even when you are in the behind the saddle position.
    Getting a longer fork will make your BB higher, ~4 mm for every 1 cm of added A2C length. You will feel it, particularly in the beginning, when cornering. A good idea is to get thinner pedals to compensate for additional BB height.

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