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  1. #1
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    Examples of "old" 29er geo?

    I have been watching discussion about how bike geometry has changed over the years. It's incremental and hard to see over time. Anyone have some good examples of the first production 29ers (especially hardtails) geometry? What have been the biggest changes that make a modern xc/ trail 29er more capable?

    I hear people complain about how lousy 29ers handle/ used to handle. my first 29er was an early Karate Monkey, which was progressive at the time, so I have nothing to compare.
    Last edited by mack_turtle; 10-04-2018 at 10:41 AM.

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    71* headtube angle, 73* seattube angle. This was pretty standard 29er angles at the onset. Over the years, the head angle has slackened out, considerably when you look at the class of All Mountain HT 29ers.

    Also, 80mm suspension forks/468mm A-C rigid forks. Again, standard at the time, but you really can't find an 80mm fork these days. Seems like everything is 120mm or more.
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    curious about BB drop and CS length too.

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    Quote Originally Posted by LBIkid View Post
    Also, 80mm suspension forks/468mm A-C rigid forks. Again, standard at the time, but you really can't find an 80mm fork these days. Seems like everything is 120mm or more.
    I believe most manufacturers still equip their XC 29ers with 100mm forks like the Specialized/S-Works Epic/FSR and Cannondale’s F-Si and Scalpel-Si, for example.


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  5. #5
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    Long chainstays 450mm and more.
    Short reach 420mm on a large is an example.
    Steep head tube angle 70 or 71*.
    Fork offset of 44 or less.

  6. #6
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    Quote Originally Posted by mack_turtle View Post
    curious about BB drop and CS length too.
    My L Niner EMD9 had a 60mm BB drop and 444mm chainstays. It came with a Reba at either 80 or 100mm. The Reba has 38mm offset, as far as I can tell.


  7. #7
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    Quote Originally Posted by mack_turtle View Post
    I have been watching discussion about how bike geometry has changed over the years. It's incremental and hard to see over time. Anyone have some good examples of the first production 29ers (especially hardtails) geometry? What have been the biggest changes that make a modern xc/ trail 29er more capable?
    What they did on the first few generations of 29ers, especially the FS bikes, was simply extend the chainstays to fit the front derailleur in there. So you ended up with goofy 18"+ long chainstays, on a bike that was ALREADY more stable because of the bigger wheels with more gyroscopic stability, so by doing this, they handled more like a truck. I'm not kidding, some were 18.5"! IMO, it was lazy engineering waiting to see if the "bubble" caught on.

    The Karate Monkey was one of the early "normal geometry" bikes that had what I consider to be "normal" sized chainstays. Anything around 17" + or - .25" or so is fairly normal IME and will handle decent in this respect. Specialized eventually came up with the solution on the E-29 with a special derailleur mount, but at the same time 1x drivetrains took over and the problem went away. It took a LONG LONG time though for these manufacturers to make 29ers with what I consider to be "normal" geometry.

    Although there is more that defined them than just the chainstays, I felt like this was the biggest factor and avoided the FS 29ers for years until they did something about it.

    What I don't see is a need to go very slack on a 29er, the wheel naturally resists wheel-catchers and drops better and going too slack also turns it into a truck IME. If you are endoing a 29er, you need to buy some skills. Making the wheels heavy also gets out of hand fast, due to how far that weight is from the hub. That was the primary reason I dropped the E-29, too lethargic with rubber and build worthy of DH, but go to the other extreme, my 29er XC Race bike and it's a hoot where you can pop off all sorts of stuff that's just not possible with bigger heavy wheels. I think this is one area where we have gone a little too far in some respects. I can ride a 66-65.5° bike uphill as long as the suspension does not squat a bunch on the uphill, but from that HTA, things get bad much faster when you go slacker and the 29er can get away being 1.5° or so steeper than the equivalent 27.5 bike without giving up anything in terms of it's DH-ability.

    If I could only have one bike it would still be a 29er with a bit more travel than my XC rig, but since I have two FS bikes my 29er is for XC and I go slightly smaller wheels for more aggressive stuff. Not to say you can't ride something like an E-29er on aggressive stuff, it loves it, make sure you have some nice big downhills for it, lots of vertical.
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    On my 05 Fisher Sugar 29er the chainstays are 467mm with a HT angle of 71* and a seat tube angle of 73.4*. It honestly doesn't handle bad at all, but it does feel very awkward to ride after getting off my Remedy 9.8 29er. The Fisher is more agile and easier to wheelie, manual, and bunny hop on though, as well as being generally more playful feeling. It's not as fast or confidence inspiring as my Trek, but it's certainly easier to toss around.
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    Giant Trance X from yesteryear

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    Quote Originally Posted by eb1888 View Post
    Long chainstays 450mm and more.
    Short reach 420mm on a large is an example.
    Steep head tube angle 70 or 71*.
    Fork offset of 44 or less.
    and the Top Tube is Way Up There

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  11. #11
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    The geometry for all wheel sizes changed with shorter stems and wider handlebars on most MTN bikes. The longer top tubes and increased "reach" along with slack head tube angles has not been universally adopted among the brands but is considered "progressive " now. Fischer pushed the 51mm offset back when 29er forks had only a 80-100mm of travel and stems were four inches long. It was claimed to "quicken"the supposedly slower handling and increase toe overlap which was a problem for people with big feet on the new 29ers. This is now considered"old" geometry as manufactures are returning to 44mm offset forks with longer travel and slack 67-65 degree headtubes.
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    It seems to me that except perhaps for fork offset, it's difficult to deconvolve 29er specific changes from the general evolution of geo toward more descending prowess; longer f-c, lower BB, slacker HT angle. Even XC bikes have crept in this direction.
    Do the math.

  13. #13
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    Quote Originally Posted by Lone Rager View Post
    It seems to me that except perhaps for fork offset, it's difficult to deconvolve 29er specific changes from the general evolution of geo toward more descending prowess; longer f-c, lower BB, slacker HT angle. Even XC bikes have crept in this direction.
    This is definitely true, but at the same time it’s true that many early 29ers were gawky. Compared to a similarly XC-oriented 26” wheeled bike, the CS were longer and the HTA was steeper.

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    Geo chart from my 2009 GT Peace 9r, I could get the CS to 17.25" using half-link chain but that was it from spec'd 17.5+. 45mm fork offset, couldn't get many sus forks on due to the DT/HT interface. 71/74 HT/ST angles make me nervous now a days after riding ROSs

    Examples of "old" 29er geo?-gtp9rgeo.jpg
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    Quote Originally Posted by mack_turtle View Post
    I have been watching discussion about how bike geometry has changed over the years. It's incremental and hard to see over time. Anyone have some good examples of the first production 29ers (especially hardtails) geometry? What have been the biggest changes that make a modern xc/ trail 29er more capable?
    My impression is that the first mountainbikes were road bikes that people took up into the mountains and rode. In fact, I saw a documentary somewhere. It was a citybike taken over boulders, it broke down, and there it remained. Meanwhile, the bike design was beefed up, but the geometery didn't change. The overall slacker angles and semi-upright position is what I consider the most substantial change. Bikes were originally designed for road and light trail riding. It took a long time for people to realize and design bikes that handled better offroad. If you look at mountainbikes from the 90's, they look an awful lot like hybrid city bikes with big tires. Right down to the level top tube.
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    Quote Originally Posted by Muirenn View Post
    My impression is that the first mountainbikes were road bikes that people took up into the mountains and rode.
    I get that, but my question was about how 29ers specifically changed over the years. people said they inherently sucked at first and I am wondering how 29ers evolved to leave that reputation behind.

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    Quote Originally Posted by mack_turtle View Post
    I get that, but my question was about how 29ers specifically changed over the years. people said they inherently sucked at first and I am wondering how 29ers evolved to leave that reputation behind.
    Yeah, I just realized that after I answered. I still think it has to do with HTA and STA. And forward geometry.
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  18. #18
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    Here's the specs from the Felt 9 Race, 2009 models:
    Attached Thumbnails Attached Thumbnails Examples of "old" 29er geo?-felt-geo.png  


  19. #19
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    Quote Originally Posted by LBIkid View Post
    71* headtube angle, 73* seattube angle. This was pretty standard 29er angles at the onset. Over the years, the head angle has slackened out, considerably when you look at the class of All Mountain HT 29ers.

    Also, 80mm suspension forks/468mm A-C rigid forks. Again, standard at the time, but you really can't find an 80mm fork these days. Seems like everything is 120mm or more.
    Crap! I guess I'm gonna have to just take my 429SL XC bike (with its 100mm fork, 70.5* HA, and 73* seat tube angle) out behind the garage and shoot it since it's not worthy of riding anymore. Sad, I kinda liked it.
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  20. #20
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    I dug this up, 2004 Gary Fisher 292: http://www.vintage-trek.com/Trek-Fis...nualFisher.pdf

    This is what I'm talking about:

    Head tube angle 71.0 71.5 71.5 71.5
    Fork offset 42.0 42.0 42.0
    Trail 87 83 83 83
    Seat tube angle 73.5 73.5 73.5 73.5
    Effective top tube 590 608 628 647
    Seat tube 394 446 484 535
    Standover 714 737 754 772
    Wheelbase 1100 1118 1132 1152
    Bottom bracket height 322 322 322 322
    Chainstay 467 467 467 467
    Head tube 105 105 105 105
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  21. #21
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    Quote Originally Posted by BmanInTheD View Post
    Crap! I guess I'm gonna have to just take my 429SL XC bike (with its 100mm fork, 70.5* HA, and 73* seat tube angle) out behind the garage and shoot it since it's not worthy of riding anymore. Sad, I kinda liked it.
    Similar geo #'s on my Jet 9 RDO also. Bike does everything I've ever asked but according to the numbers it's not even fit enough for a dumpster, oh well.
    Change for the sake of change does not equal improvement.
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  22. #22
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    Quote Originally Posted by upstateSC-rider View Post
    Similar geo #'s on my Jet 9 RDO also. Bike does everything I've ever asked but according to the numbers it's not even fit enough for a dumpster, oh well.
    Change for the sake of change does not equal improvement.
    Add a dropper post and I'm not too worried about steep.
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  23. #23
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    Quote Originally Posted by chazpat View Post
    Add a dropper post and I'm not too worried about steep.
    Granted I'm fairly late into the 29er game but my jet 9 rdo is the end all, be all as far as I'm concerned...I was running an 04 Stumpjumper FSR 26" for a long time then traded a set of road carbon wheels for a (2009ish?) 29er Gary Fisher Xcaliber, I was so stoked. Took it for a maiden voyage on my favorite gnarliest trail and quickly realized 29er's were not for me, the thing handled like a garbage truck on 3 flat tires. Maybe it was that G2 geometry, maybe GF, maybe only that bike handled that awful but it turned me away from 29ers for about 7 years.
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