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  1. #1
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    Frame size control question

    I just started riding singletrack and really enjoy it, however I am a 60 yr old newbie tiding a GF HT 29 er. The bike is a 21 inch frame and I have the 1 to 2 inch standover so the bike is very comfortable and great on the rail trails, fire roads and general riding.

    On singletrack runs, it seems almost impossible to get good lift on the front tire when trying to hop over obstacles and I have noticed that almost all of the mountain rides have a minimum of 12 inches of seatpost ( smaller frame ) compared to my 3 or 4.

    I am thinking I should consider a smaller framed bike, FS or a HT if I am serious about spending more time on the singletrack trails ?

  2. #2
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    Try a shorter stem. Nothing DH short but you will be amazed at what a 20mm shorter stem can do for you.

  3. #3
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    29ers are taller bikes which is going to make the front harder to lift. The question may be easier to answer if we new how tall you are? If your riding a 21" 29er I hope your 6'3 or taller.

  4. #4
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    Quote Originally Posted by Drth Vadr View Post
    29ers are taller bikes which is going to make the front harder to lift. The question may be easier to answer if we new how tall you are? If your riding a 21" 29er I hope your 6'3 or taller.
    You are close my friend, I am 6-1 1/2 inches. I did test ride a 19 & 21 inch frame in a parking lot and the larger frame, which is what I bought, was a whole lot more comfortable. Difficult to explain but is was a no brainer.

    Maybe too big for single tracking ??

  5. #5
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    Shorter stem, lighter forks, lighter wheelset... each would help.

    Also, what are the widths of your shoulders and bars?

    You also need to know that 29ers are slightly more difficult to lift and hop.

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    dunno if it helps but those 21'' bikes can look real big sometimes. i'm 6'3 and am a little scared of them at times. i ride a 20'' 26er and love it, but if yours rides comfortably and its just not being able to lift the front wheel appropriately, maybe not
    Last edited by pwalt; 09-08-2011 at 04:41 PM.

  7. #7
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    Try riding a 26 inch bike so you can feel the difference.

    Maybe you'd be a good candidate for the in-between size 650B.
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  8. #8
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    I was always told that you have better control of a bike if it has a smaller frame however the proper sizing is the standover rule.


    So why do I see all the serious mountain bikers with 12 to 16 inches of seat post exposed ?
    They have to have way more than 2 inches of stand over clearance!
    Last edited by rickcin; 09-09-2011 at 04:36 AM.

  9. #9
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    You could get the front end of the bike off the ground if you are shifting your weight properly. All the suggestions you have received are all well and good but you could spend all the money in the world on smaller frames and lighter parts (lighter parts, really? You people honestly believe that's what's going to make the biggest difference?) but in the end you're eventually going to have to learn and practice the same weight shift on your new bike too.

    Put your saddle all the way down, get out some platform pedals, put your helmet on, and go play on your bike. Try and learn wheelies, manuals, and bunny hops. All three require a weight shift backward in order to successfully do it, which is what you're lacking.

    Would a smaller framed bike make a difference? It would make the learning curve a little shorter. Honestly, no one can sit there in their chair in front of the computer and say that your bike does or does not fit you. None of us know what your body proportions are and probably your best fit might have been the one you choose. Suggesting a smaller frame might cause other fit issues that we can't predict but the smaller frame will allow you to move your body around the bike a bit more and have more control of how your weight affects the way the bike handles. Of course, it's entirely possible that you choose the larger frame because you're used to larger bikes in the past.

    Would a shorter stem make a difference? Absolutely, but it also changes your riding position which seems to be exactly why you choose the 21" in the first place. If you do want to make a modification to your bike, a stem change is cheap and effective (pair it with a wide bar and you'll negate some of the reach change you'll face, plus all those other good aspects of having a wide bar/short stem).

    My advice is to go out and practice. You're almost certainly simply not getting your weight far enough backward and you're just trying to yank up on the bars to pull the front wheel up. Take a video of yourself trying to ride over something or up onto a curb and post it if you can. If you're absolutely set on spending money, buy a dirt jump bike and ride that around practicing the skills you want to learn.
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    There is no standover rule. Maybe back in the olden days when mountain bikes looks like road bikes and had 140mm stems and straight top tubes, but those bikes weren't good for anything other than causing some hilarious otb crashes. Any bike fitter who knows what they are doing will size a bike primarily by top tube length. Can you post a pic of your bike? 3-4" of seat post sound really short.
    Zebrahum nailed it as far as lofting the front wheel. It's really about shifting your weight back more than pulling up on the bars. I see 12 year old kids at races all the time doing balance point wheelies on bikes that are two sizes to large for them.

  11. #11
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    Quote Originally Posted by rickcin View Post
    On singletrack runs, it seems almost impossible to get good lift on the front tire when trying to hop over obstacles
    Most 29ers are very bad for this particular maneuver, it's a compromise that has to be made for mass production frames.

    The problem is that the stays on your frame are very long, so the centre of gravity is much further forward than it would be on the equivalent 26er. Getting a similar frame in a smaller size won't really fix this, you'll just end of feeling squashed, uncomfortable and you will still have a hard time lifting the front.

    But all is not lost.

    The cheapest fix is to just practice lifting the front until you can do it frame be damned.

    The other alternative is get a short stay 29er hardtail, where the seat tube is curved or cranked over so the wheel can sit much closer to the frame and give you a shorter back end, making the bike much more nimble whilst keeping the plus points of a 29er.
    The upshot is that takes a lot of fabrication to do, so you're looking at small brand frames or fully custom, neither of which is very cheap.
    If you decide you really, really want a new frame, a Canfield Nimble 9 pretty much embodies what you are looking for. Very 'normal' geometry but a good short back end so it will turn and hop much better than your GF.


    RE: the seat posts
    I would pay no attention to that, most of the bikes like that are sized differently than a 'normal' bike to have much lower seat and top tubes. It makes the frame very good for hurling down steeps and off drops, but in all other areas is more or less irrelevant.

  12. #12
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    One thing for certain that I have learned from reading all of the responses to my thread is that many of you are super knowledgeable and throughly understand almost every aspect of a bike and the inter relationship with the rider, you guys are amazing!

    My initial thought regarding difficulties passing over obstacles on a singletrack was totally due to others telling me a smaller frame is easier to control as well as looking at other serious riders and noticing they all had a ton of exposed seat post. This is where my original skepticism began and I can now visualize that if my bike frame were smaller and the seat post longer, the center of gravity would be exactly the same.

    Perhaps the other variable would be the cockpit length, if I were stretched out further or less, would that effect my ability to raise the front wheel ? I am thinking it is a factor?

    As previously stated, shifting my weight and weight distribution in general may be the single largest factor in passing over obstacles. Common sense, the further the weight is to the rear will lessen the downward weight on the front wheel, but at that point my body position would be further extended, stretched out so more difficult to lift up ?

    At any rate, I realize my frame size is correct, it is the most comfortable and I need to stop looking at or just ignore seat post length. The wider handlebars, wow, a whole nether
    topic. My GF has the big sweep bars, which I hated the appearance of at first but the feel is really good. Should I change, how would I know?? If I installed a straight bar the cockpit would be slightly longer ( maybe microscopically) if the bar was longer, I would probably be okay with that since I have a wide body frame.

    Like how would someone know these answers prior to just making changes ??

    All of these discussions are always a learning experience to some degree and always remind me of how little I really know!!!

  13. #13
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    Quote Originally Posted by rickcin View Post
    I was always told that you have better control of a bike if it has a smaller frame however the proper sizing is the standover rule.


    So why do I see all the serious mountain bikers with 12 to 16 inches of seat post exposed ?
    They have to have way more than 2 inches of stand over clearance!
    I am going to guess the people you see are racer types? A small frame is easier to "throw around" when riding.

    But, some bikes just don't like to come off the ground off for any reason. Though, I agree with others that a shorter stem will help - a good shop should have some around you can borrow to determine what length is best for you.
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  14. #14
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    I don't think a shorter stem is going to do very much for a GF. GF have very long frames which compound the matter. I'd ditch the bike and start again using the info. you have learned. No matter what you change it will probably not going to feel like the bike you want it to be. I would dare to guess that you walk into you LBS and they talked you into a 29er because your 6'1 and didn't explain different categories of MTBs and what are their ride characteristics.

  15. #15
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    Vadr,
    I talked myself into the GF 29 er after trying a few at a bike shop that was 1 1/2 hrs away in NJ. My LBS did not understand the big fuss over the 29 ers however he ordered me one and I waited a long time. I do LOVE the bike and I just discovered singletrack. Perhaps I could pick up a good used FS, perhaps with a 19 frame so I could, as they say, "throw it around"!
    Hard to justify the cost for just a weekend warrior.

    Currently the singletracks are throwing me around!

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    Quote Originally Posted by rickcin View Post
    Currently the singletracks are throwing me around!
    Just out of curiosity, what tire pressures are you running?

  17. #17
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    Quote Originally Posted by rickcin View Post

    At any rate, I realize my frame size is correct, it is the most comfortable and I need to stop looking at or just ignore seat post length. The wider handlebars, wow, a whole nether
    topic. My GF has the big sweep bars, which I hated the appearance of at first but the feel is really good. Should I change, how would I know?? If I installed a straight bar the cockpit would be slightly longer ( maybe microscopically) if the bar was longer, I would probably be okay with that since I have a wide body frame.

    Like how would someone know these answers prior to just making changes ??
    The wider handlebars have the advantage of slowing down your steering response a little bit. It makes it more stable when going faster, makes the bike track a little better, and also gives you a lot more leverage over the bike when you're standing up and cranking.

    But you'll never know if that's good or bad for you until you try. Much like other changes like tires or saddles or grips, you can't be sure they're the right choice until you actually ride them for a while.
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  18. #18
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    Quote Originally Posted by paleh0rse View Post
    Just out of curiosity, what tire pressures are you running?
    Only about 40 pounds.

  19. #19
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    Quote Originally Posted by rickcin View Post
    One thing for certain that I have learned from reading all of the responses to my thread is that many of you are super knowledgeable and throughly understand almost every aspect of a bike and the inter relationship with the rider, you guys are amazing!

    My initial thought regarding difficulties passing over obstacles on a singletrack was totally due to others telling me a smaller frame is easier to control as well as looking at other serious riders and noticing they all had a ton of exposed seat post. This is where my original skepticism began and I can now visualize that if my bike frame were smaller and the seat post longer, the center of gravity would be exactly the same.

    Perhaps the other variable would be the cockpit length, if I were stretched out further or less, would that effect my ability to raise the front wheel ? I am thinking it is a factor?

    As previously stated, shifting my weight and weight distribution in general may be the single largest factor in passing over obstacles. Common sense, the further the weight is to the rear will lessen the downward weight on the front wheel, but at that point my body position would be further extended, stretched out so more difficult to lift up ?

    At any rate, I realize my frame size is correct, it is the most comfortable and I need to stop looking at or just ignore seat post length. The wider handlebars, wow, a whole nether
    topic. My GF has the big sweep bars, which I hated the appearance of at first but the feel is really good. Should I change, how would I know?? If I installed a straight bar the cockpit would be slightly longer ( maybe microscopically) if the bar was longer, I would probably be okay with that since I have a wide body frame.

    Like how would someone know these answers prior to just making changes ??

    All of these discussions are always a learning experience to some degree and always remind me of how little I really know!!!
    You are starting to understand bike sizing.

    It is ALL about the cockpit length and weight distribution.

    Sizing by stand over was a road bike rule of thumb 30 years ago, and even then a poor way to fit a bike.

    For off road riding you should be on the smallest frame that is comfortable for you. This will likely feel small in the parking lot, especially if you are a novice trail rider.
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  20. #20
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    Quote Originally Posted by rickcin View Post
    Only about 40 pounds.
    Ok, that's too high. The goal is to run them as low as possible without resulting in pinch flats (tubes), or burping (tubeless). Running them at 40 is going to make you feel like a pinball on the rocks and roots, and it's almost certainly contributing to your problems.

    Try to get both front and back as close to 30psi, or below. Start with front at 30 and rear at 33, then go down in 1 psi increments on future rides to the point you think might be the breaking point. This is, of course, a guessing game, so you might end up with a flat at one point. When you do, just go back up 1 psi with a new tube, and consider that your ride setting with your specific tubes, tires, and rims.

    But yeah, 40 is too high. With my riding weight of roughly 175 lbs, and my current tires/rims/tubes, I've managed to get mine down to 27 front, 29 rear; and both my traction and bump absorption are fantastic now. I hope to go even lower when I convert to tubeless...
    Last edited by paleh0rse; 09-10-2011 at 10:26 AM.

  21. #21
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    Quote Originally Posted by shiggy View Post
    You are starting to understand bike sizing.

    It is ALL about the cockpit length and weight distribution.

    Sizing by stand over was a road bike rule of thumb 30 years ago, and even then a poor way to fit a bike.

    For off road riding you should be on the smallest frame that is comfortable for you. This will likely feel small in the parking lot, especially if you are a novice trail rider.
    It does stand to reason that a smaller frame would be easier to maneuver on singletrack and over obstacles. Most of my riding is on unpaved rail trails so if I wanted to spend more time on singltrack trails I think a smaller FS bike would be the best.

    Might just keep an eye out for a used one since I cannot justify spending $2500 for another bike that would be used less than 50% of the time since the NY winters really shorten the biking season.

    Thanks for the info, very helpful!

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