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  1. #1
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    "Modern Geometry" vs. old school 26"

    I'm in the market for a new bike after 18 years with old 26" 4x4. I come from XC heritage, but where I ride now there is much more trial and all-mountain.

    Can someone, ideally someone who rode in the 90's and early 2000's explain to me the true benefits of today's "modern" geometry.

    Slack head angles - OK so you can roll DH with more ease..
    Longer wheelbases - OK so more stability at high speed
    Lower BB - OK - lower center of gravity, but is this true with 27.5 and 29 being the new standard if you compare back to 26??

    Hasn't the above made sacrifices in handling, cornering, and climbing abilities?

    To me it seems we have just made downhill bikes lighter...

    Please explain to this old-schooler....

  2. #2
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    Short answer: Just buy a 29er XC/Trail bike - it will do everything better.

    Long answer: I think the some of the issue is making big wheel bikes behave like 26ers. It's been so long since I rode a 26" bike, but I still feel like I can remember, and I still feel like 29" feels way different.

    OK - big thing is rollover. Next is traction. This makes climbing incredibly easier in more technical stuff. The big wheels just eat that stuff up and you have way more traction. I'm climbing stuff I never even dreamed I could with my 26" bike.

    I think in most XC focused bikes, the BB is pretty close to where it would be with a 26", if not a little higher. Don't know though... I don't recall having many pedal strikes in my 26" days and I have a few here and there now. Was worse at first. I never measured, but eyeballing it, they look about the same.

    Slack head angles do a lot of things like increase the wheelbase, so all that stuff is related. The big thing is biasing the weight of the bike more rearward so at speed it naturally wants to roll over things rather than stall the front tire and throw you over the bars. That's not to say you don't have to work the bike over obstacles, but it's easier to do with more speed. Plow ability is increased but I try to avoid that except in really rough descents where I can't react fast enough to work the bike over stuff. That's just my technique though... it's not a bad one to remember if you are good at it. It works on all wheel sized and geos. The tradeoff is really low speed handling. Longer wheelbases and slack front ends are bears to handle in really tight twisties where you are moving at little over walking speeds. I can best describe it as the front doesn't turn, then goes way off line and you need to turn overly exaggerated and then pull the rear end around. This can be particularly tricky on tight, uphill switchbacks with obstacles like roots. Many of the more XC focused bikes will be a bit shorter and do this better.

    So with this rear weight bias, you need to consciously add weight to the front of the bike when necessary to make it grip where you want. Too much with too much steering angle it will dig in and plow, too little and it may feel like it wants to wash or just go straight. There's still a wide range of values here, so less slack generally will be a little easier to adapt to be better at more moderate terrain.

    Longer wheelbases not only have more stability at high speed but handle things like berms and flowy terrain better. They climb pretty well once you adapt to the technique of getting weight on the bars while climbing. It's not hard to figure out.

    DH bikes lighter? Not really. Adapted more DH ability into the average XC bike? Yes.
    Life is too short to ride a bike you don't love.

  3. #3
    wanna ride bikes?
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    Quote Originally Posted by smoothmoose View Post
    Can someone, ideally someone who rode in the 90's and early 2000's explain to me the true benefits of today's "modern" geometry.
    You need to do some reading, this question was answered years ago. Or better yet, just go rent/demo a bike and make up your own mind.

    Otherwise, L'oiseau gave you the best answer your going to get in his first line.
    Rigid SS 29er
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    "Fully rigid" isn't a thing.

  4. #4
    meatier showers
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    Got my first mountain bike in '85 so I've been through it all. My current fav bike is a 2017 Guerrilla Gravity Trail Pistol with 160mm fork and 130mm rear travel. Slack front, short stem, wide bars, steep seat angle, long top tube, short chainstays, low-ish bottom bracket. In other words I've swallowed the "new geo" pill. (But I did that 4 years ago when I bought a Kona Honzo.)

    Anyway I. Love. It.

    In my opinion, yeah, if you're not into going fast, don't bother with new geo. But if you do like thrills, then new geo (along with a dropper seatpost) will allow you to progress from mere bike riding to low elevation flying. With more safety and confidence.

    LOTS more.

    Climbing? My rides never include less than 1000' of elevation change and often include 3-4000'. I love to earn my turns and yeah, the slacker front tends to wander a bit more. But not much. It's not bad. Any minor trade off is well worth the benefits on the other side, IMO.

    I'm not sure you'll get it with a demo ride. I didn't really exploit the benefits of new geo until I'd gotten used to the new feel. And if you're moving from 26" wheels to larger wheels at the same time, you may not be able to tell what's coming or going. Do some research. Ask opinions. Then make the leap. Buy a new bike -- there are lots of good ones out there -- and enjoy getting used to it. In a few months time you'll wonder how you were ever able to ride that old sled.
    =sParty
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    We don't quit riding because we get old.
    We get old because we quit riding.

  5. #5
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    Good question. I'm in the same boat, 19 years with my current bike. Bought it brand-new in 1998. It still rides, nothing wrong with it. But maybe time to see what all the new hype is about.... things like:

    -disc brakes
    -27.5/29 wheels
    -fat tires
    -more than 60mm of fork travel.

    I just don't know if all the hype is worth sandbagging a perfectly good bike. I think the answer is to go rent a demo. The devil on my shoulder holding the debit card says a whole new exciting world of mountain biking is out there. And the frugal old grouch in me says my 19 year old bike is fine, ride the wheels off.

  6. #6
    Trail Gnome Moderator
    Reputation: griz's Avatar
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    Quote Originally Posted by smoothmoose View Post
    I'm in the market for a new bike after 18 years with old 26" 4x4. I come from XC heritage, but where I ride now there is much more trial and all-mountain.

    Can someone, ideally someone who rode in the 90's and early 2000's explain to me the true benefits of today's "modern" geometry.

    Slack head angles - OK so you can roll DH with more ease..
    Longer wheelbases - OK so more stability at high speed
    Lower BB - OK - lower center of gravity, but is this true with 27.5 and 29 being the new standard if you compare back to 26??

    Hasn't the above made sacrifices in handling, cornering, and climbing abilities?

    To me it seems we have just made downhill bikes lighter...

    Please explain to this old-schooler....
    What is your current bike? You're going to be in for a shock...lots of advances have been made, some good some bad. Test ride as many bikes as you can...on actual trails you ride/know. I'm not going to lie...I'm not a huge fan of the newest trend in geometry. Talk with locals...ride their bikes, if they'll let you. I'm in the market myself but, I'm coming off a 3 year old 27.5" bike...pretty sure I'm going to stay with 27.5" for now.

  7. #7
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    Its pretty serious diminishing gains. The first few steps away from the oldschool are pretty huge! The improvements in the last few years hasnt been a big deal.

    Im on a 2010 giant reign. It pedals great, its fun to ride, it fits well. Its geometry is appropriate enough to run a short stem and wide bars. I demo'd the new 2016 trance, and... it felt like my bike. A lot like my bike. Even on paper it shared a lot of similarities.

    Ill happily admit the new trance had some characteristics that were a really nice upgrade, and I do prefer the newer bike, but again, just not that different. I left without much bike lust, happy with what ive got. Checking out the new 17 and 18 trance, I see some changes, but nothing that makes those bikes wildly different than my 8 year old bike.

    Ive had oldschool late 90's bikes, and the gap between my old steel GT and my newer reign is MASSIVE. The capability is incomparable. It might as well be a different sport, riding the two bikes. In some ways it is. Thats no small changes, no hype, and worth every penny to get into something more modern.

    Imo, somewhere closing in on 2010 we sorta figured it out. The changes since then have been minor improvements.

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