29er Head angles....- Mtbr.com
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  1. #1
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    29er Head angles....

    Hi guys, I am new to the concept of 29ers, coming as I do from a 26 inch freeride background. I am interested in getting a 29er though, so that I can explore the ups as well as the downs, plus I like the fact that they are a bit "different".

    I have looked at the specs and Geo of a lot of hardtail examples and I have one question about the headtube angles. I have noticed that most 29ers have head angles between 70 and 72 degrees, and yet a lot of them are still rated by the press as being great all around trail bikes. In my experience 26er trail bikes are a bit slacker than this to help with downhill stability.

    I am not sure If I am just getting the intended use of 29ers mixed up a bit, i.e. they have steeper angles because they are more XC orientated than flat out Trail orientated, or if the larger diameter wheels effect the stability of the bikes to the point where they can/have to run steeper headtube angles to achieve the same general rideability as a 26er.

    I hope that all makes sense, in a nut shell, I guess I would ask, if I was looking for a good 29er trail bike/all rounder (not freeride!!) should I be looking for similar angles to the equivalent 26er, or would I be looking for different angles because of the 29er wheels!

    Thanks for the help guys, I apologies if I have missed the point somehow or if this comes across as ignorant, but I am a 29er newb!!

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  2. #2
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    Seems to be a fairly wide range in head tube angles on 29ers. Some will scoff at something as steep as 70 degrees while others will call it too slack. All depends on a combination of intended use and personal preference. I have a hard tail with a 73 degree head tube and use it for everything from short xc rides to 100-mile races. Of course I'm not one of those riders that can sense TNT changes to a bike like 2 psi in tires or 1 degree in frame geometry.
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  3. #3
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    Quote Originally Posted by Vecsus
    Seems to be a fairly wide range in head tube angles on 29ers. Some will scoff at something as steep as 70 degrees while others will call it too slack. All depends on a combination of intended use and personal preference. I have a hard tail with a 73 degree head tube and use it for everything from short xc rides to 100-mile races. Of course I'm not one of those riders that can sense TNT changes to a bike like 2 psi in tires or 1 degree in frame geometry.

    Thanks for the reply mate, Do you find that a 26er with a 73 degree head angle compares to a 29er with a 73 degree head angle?, do they have the same cockpit feel or do the 29er wheels make the 29er "feel" slacker, or more stable?
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  4. #4
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    I went from a Giant Trance 26er to an Epic 29er. Both have 70.5 HA. I found the 29er more stable but required more leaning/body english to turn. You have to really throw it into a turn but it seems to stick like glue. Doing some long fast downhills it feels very stable. I don't do any really steep drops so can't say there.

  5. #5
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    Quote Originally Posted by BiknBob
    I went from a Giant Trance 26er to an Epic 29er. Both have 70.5 HA. I found the 29er more stable but required more leaning/body english to turn. You have to really throw it into a turn but it seems to stick like glue. Doing some long fast downhills it feels very stable. I don't do any really steep drops so can't say there.
    Thanks, that is interesting, I am not intending to do any drops etc on the bike, I still have a full suspension 26er for all that, I just want a bike that can slay technical singletrack and put a grin on my face, that I can pedal up-hill without having a heard attack :-P
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  6. #6
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    From what I've learned through selling bikes for a living, is that the 29ers require a steeper head tube angle to keep the steering quicker due to the larger wheel size. This is to try and keep it from being too lazy through the turns.

    I noticed a little difference riding my Kona Kikapu Deluxe 26 FS bike, which has a 69.5 degree head tube angle, and my Fuji Tahoe Pro 29er, which has a 72 degree head tube angle with a 100mm fork.

    The Kona was still a tad quicker to turn, and easier through tight switchbacked single track than the 29er, and is a tad more stable on the downhills. But the overall difference isn't huge, IME.

  7. #7
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    I think you'll find, if you prefer slacker angles on a bike...you'll want them on any bike, regardless of wheelsize. My biggest complaint with 29ers for years was the steeper HTA which placed more of my weight on the front of the bike. Now, all my 29ers have 68.5* HTA & I am much happier....it's more about the rider's preference in geometry than it is the wheelsize.


  8. #8
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    Quote Originally Posted by jncarpenter
    I think you'll find, if you prefer slacker angles on a bike...you'll want them on any bike, regardless of wheelsize. My biggest complaint with 29ers for years was the steeper HTA which placed more of my weight on the front of the bike. Now, all my 29ers have 68.5* HTA & I am much happier....it's more about the rider's preference in geometry than it is the wheelsize.

    Also very interesting, thanks for the info, may I ask what 29ers you have found that have slacker angles?

    Cheers.
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  9. #9
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    Sorry to hijack the thread but I am also looking for my first 29er and have a ?

    It appears that most 29ers have a longer effective top tube for a given rider size?
    What's up with that? Or am I wrong?

    I was thinking I should go with a ETT that is about the same as I ride on a 26er.

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  10. #10
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    Quote Originally Posted by bodben
    Also very interesting, thanks for the info, may I ask what 29ers you have found that have slacker angles?

    Cheers.
    They are in my signature. All my hardtails are custom, and I just received my new Turner Sultan this week with the revised geometry. It has a 69.5* HTA with a 120mm fork...I am running it with the 140mm Zocchi which moves the resulting HTA under 69*.



  11. #11
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    Great subject. Lots of different takes will be made, no doubt. Here's mine....

    First off, we need to understand that head angle is only part of the equation. Fork offset, (or "rake" as some will want to call it), is also very important here. For years, those riding 26"ers were stuck with basically one fork offset. Because of this, all the 26 inch rider had to worry aboutwas head angle, and everything was understood from that perspective.

    If you are coming from a 26 inch backround, you are going to be befuddled a bit because of the different offsets you can get with 29 inch rigid forks and the different range of offsets available on the 29 inch forks.

    Essentially, two things happened with 29"ers: Designers steepened head angles to account for the 29"ers increased wheel mass and incresed trail figure due to the larger diameter.So- 72-73 degree head tube angles were common to begin with.

    Then suspension fork crowns got the increased off set with figures running from 44-48mm of offset compared to the old 38-40mm offset which was a hold over from the 26"ers.

    This allowed designers to back off on the head tube angles and still get the lower trail figures needed to give us quicker handling. So- we're seeing a lot of 71 degree angles on XC rigs coming out now. (Sagged angles on suspension bikes)

    The other issue- that of weight in the wheels, has been addressed as well, for XC/Trail, so bikes have become less sluggish since the early 29"er days, even with similar geometry figures. (Offset of the forks can make this even more dramatic)

    AM bikes are going even slacker, which would have been unheard of in 2005. (With the exception of Lenz, which sort of pioneered this geometry for big wheelers) What was found was that with the increase in offset on the forks, the head angle could be relaxed even more on a 29"er, ( back into the upper 60's), and still handle like a 26 inch trail bike does to some degree.
    Of course, this is all generalizations, but I am offering this up as an example for those that are wondering about 29"ers and the weird geometry.

    With all the available variations from what 26 inch riders are used to, its no wonder it is confusing.

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  12. #12
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    Quote Originally Posted by bodben
    Thanks, that is interesting, I am not intending to do any drops etc on the bike, I still have a full suspension 26er for all that, I just want a bike that can slay technical singletrack and put a grin on my face, that I can pedal up-hill without having a heard attack :-P
    The 29er will definitely have you grinning. There's something very "swoopy" about the handling to me. I really like it. I've got an Ellsworth Evolution on order, which has a 72 degree HA. I'm actually looking forward to having quicker steering as my riding is on twisty east coast singletrack. The climbing is something that surprised me. The wheels roll over roots and rocks much more smoothly and you can really keep momentum up. On hour-long climbs up in the Shenandoah's, you can really get a nice rythym going and it makes climbing enjoyable to me.

  13. #13
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    Quote Originally Posted by chas_martel
    Sorry to hijack the thread but I am also looking for my first 29er and have a ?

    It appears that most 29ers have a longer effective top tube for a given rider size?
    What's up with that? Or am I wrong?

    I was thinking I should go with a ETT that is about the same as I ride on a 26er.

    Comments?
    Run a shorter stem to get the same reach.
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  14. #14
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    This geomery explanation from the Niner web site was very helpful to me. It explains the effect the larger wheels have on trail. I tried to find a link from the site but couldn't??? I found the PDF by searching "Niner Trail" on google. If you do that you will get diagrams too.

    >> If you took a glance at the geometry chart, the 72 degree head tube angle might stand out as
    extremely steep and alarm bells might be ringing. Remember, the larger wheels alter the way the
    bike handles as well. By increasing the diameter of the wheel, the “trail” is also increased. The trail is
    determined by drawing a vertical line from the drop out of the fork to the ground, and another line that
    follows the head tube angle all the way to the ground. The distance between where these two points meet
    the ground is called the trail (see trail chart). You can see the difference in trail between the 26” wheel
    (the smaller circle) and the 29” wheel (the larger circle) in the chart. For a 71 degree head tube angle,
    the 26” wheel has a trail of 76mm while the trail for the 29” wheel with the same head tube angle grows
    to 87mm (all other tings being equal like the fork height, etc.). As the trail becomes larger, the steering
    starts to have a flip-flop washed out feeling. One way to compensate for this is to increase the rake of the
    fork. Since we do not currently have enough power to ask the fork manufactures to do this, we took care
    of it the other way, to increase the head angle, thus decreasing the trail. Once again, you can see on the
    trail chart that the trail for the 29” wheel with a 72 degree head tube angle is 80mm, much closer to the
    trail of the 26” wheel with a 71 degree head tube angle. The 72 degree head tube angle on Niner bikes
    gives the perfect balance of control and liveliness to the front end. In addition, the Niner geometry works
    brilliantly with either an 80mm or 100mm fork.
    >> You’ll notice that the SMALL Niner has a slacker head tube angle and a steeper seat tube angle.
    This was to allow for better toe clearance with the front wheel. With the larger tires of the 29” wheel, toe
    overlap is an important factor. We had to make sure that there was ample room for a normal size foot to
    clear the front wheel. If you’re 5’6” and wear a size twelve shoe, you might have some problems here, but
    then again, you should probably be in the circus.

  15. #15
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    Quote Originally Posted by BiknBob
    The 29er will definitely have you grinning. There's something very "swoopy" about the handling to me. I really like it. I've got an Ellsworth Evolution on order, which has a 72 degree HA. I'm actually looking forward to having quicker steering as my riding is on twisty east coast singletrack. The climbing is something that surprised me. The wheels roll over roots and rocks much more smoothly and you can really keep momentum up. On hour-long climbs up in the Shenandoah's, you can really get a nice rythym going and it makes climbing enjoyable to me.
    Where are you located? I have no problems with the tight/ twisty EC singletrack in my neck of the Shenandoah's


  16. #16
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    I think with the increased offsets of the modern 29er forks, that 26 & 29 behave pretty much the same, regarding head angle anyways.
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  17. #17
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    I feel like short chainstays make a significant difference in handling. My Canfield Yelli Screamy is like 3 degrees slacker than my RM Vertex, but the chainstays are .8" or so shorter. I'm definitely faster on the Canfield, also way more comfortable.

  18. #18
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    To follow up on G-Ted's addition to the discussion, now that G2 forks are available to everybody, wouldn't this be an example of a way some people are going: under 70 ht angle, to get off the front end a little, and not feel so endo prone, while quickening the steering with the G2 offset? This would also solve Niners early stated problem of having no forks to to allow less then 72ish angles. I've in fact, been mulling this option over for a custom steel: somewhere around 69, with a G2 fork around with around 100 mm of travel. The front end on my Lenz Behemoth is, by the way, very confidence inspiring when coupled with the 29" wheels. I would be the first to admit that hairpin switchbacks might be a little more of a challenge, but that is such an occasional occurrence as to be a non-factor for me.

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