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  1. #1
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    frame fit for loaded touring

    hi there,
    i'm brand new to touring, and am in the process of searching for a bike.

    if you had to go with a frame that was slightly too small or slightly too large, which one would be more suited for loaded touring? i understand the ramifications for daily riding (e.g. compensating with stem length, seatpost length, standover height), but was wondering if it made a difference for when you've got a heavy load.

    thanks!

  2. #2
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    Sadly, this is an impossible question to answer as written. How are the frames too large and too small? Some differences will have no noticeable effect, while some could make the bike almost unrideable under weight. Even with the same model bicycle, it's hard to predict how a larger or smaller frame will feel. The only useful metric I can give you is that the added weight will exacerbate every instability.

    For example, if the standover height is too high, you can still get on by leaning an unloaded bike; but not with 60lbs of gear on the back! If you have to use extremely long or short stems, you might feel only a little unsteady riding empty, but fight to stay upright when loaded. If the larger bike has a longer wheelbase, the steering might feel more stable; but that also depends on the fork rake and head tube angle. A small bike might not have as much room in the main triangle for water bottles, pump, anything else, but, then again, this isn't a given. And whichever bike has longer chainstays (which is entirely independent of every other measurement) will be better for avoiding striking rear panniers with your heel. There are just too many factors at play to determine which will be a better tourer.

    What really matters is how it feels for you. If it doesn't feel right, any tour will be painful.

    However: If I had to choose between two fictional bikes that were identical in every way except that one had a slightly-too-low standover height/seat tube, and the other was slightly-too-large, I'd go with the small one. The hardest part of each tour is getting my leg over that top tube on day 2.

  3. #3
    Tweaker-Tinkerer Lotum's Avatar
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    Quote Originally Posted by harryhood
    hi there,
    i'm brand new to touring, and am in the process of searching for a bike.

    if you had to go with a frame that was slightly too small or slightly too large, which one would be more suited for loaded touring? i understand the ramifications for daily riding (e.g. compensating with stem length, seatpost length, standover height), but was wondering if it made a difference for when you've got a heavy load.

    thanks!
    Good bike fit is important for touring because it is likely that you'll be spending many and consecutive long hours on your bike (the same applies for audax). You can withstand and tolerate some discomfort if you ride your bike only for (say) an hour or two at a time. But during longer sessions, even diminutive irritations may grow into major ones. In a way it's analogous to the Chinese water torture.

    So your best bet would be perfect fit. As for whether too large or too small a frame would be better, it depends on who you ask. Grant Petersen would probably recommend the former, while the majority of the rest of us would probably recommend the latter.
    "There is nothing, nothing, nothing wrong with spending money on a bike."--Richard Ballantine

  4. #4
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    With non-custom bikes, and probably also quite a few of those, most bikes are a little small or large. At the moment my current bike is certainly a little large, but as to riding it makes no serious difference that I can tell. Standover is too high, and the only problem I ever had was that I once strained something throwing a leg over, uphill.

    If I was a fit-off-the-rack guy with exactly the proportions from which bikes are built, then I think a little big would be a better bet. But where it gets complicated is if you are short in the torso, or the legs, then you would probably bias slightly in one direction or another in recognition of your smallest dimension.

    Beyond that you need to look at the frame dimensions, because they don't scale up ideal proportions, normally, there is a skew towards short reach in most larger sizes and a skew towards short standover in smaller sizes So the proportions they are building for are normal in the middle, short torso in the larger sizes, and short legs in the smaller sizes, though it varies by manufacturer. Study their frame dimension table, but also recognize it often isn't accurate.

    You also need to look at your posture, are you very upright or rather flat. Upright means shorter top tube, flat with a long reach means long top tube. So push that info through your computer relative to your body bias and the frame's bias. Same thing with how the bike will be ridden, lots of off-road, or mostly highway.

    Pay special attention to BB height. The bike may say the seat tube is X length, but if the BB height is 1.5" higher than norm, you will have some extra stand over challenge. What about whether the top tube slopes?

    You can see why most people probably depend on a test ride...

  5. #5
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    DevLaVaca - thanks for your insight - certainly some things i've never thought about!

    Lotum - a perfect fit of course would be ideal - but i'd have to be pretty lucky to be a perfect fit on a mass-produced frame (as Peterpan1 points out).

    Peterpan1 - thanks for the info on skewed scale proportions - i'm on the short side (5'7") but am rather proportional. my road bike i've had for more than a decade is 52x54 (ST x TT), and i had barely any standover clearance. however, cockpit length seemed to be OK. the bike i'm looking at is being reported as 50x54. unfortunately i'm not going to be able to test ride it (agreed, the best way to try out a bike).

  6. #6
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    The other thing I didn't mention was seat tube angle. It varies, often not that much. Also with a Brooks seat, a lower angle is actually better. But the main point is that if you have a sensible road position (not a triathlon forward one, but a more classic one, then there isn't any reason not to have the same cockpit in the new bike. Or if you need changes one hopes you know what they are.

    So if you know your seat angle, seat position relative to BB, then you probably want to get close to that on the new bike. Often if any change in ST angle, your touring frame will be a degree flater, and as mentioned the Brooks will like that. You may find that puts your seat post back about 1/4". If so, then you just need to be sure your seat is well supported by that new support position. Some saddles have more or less room to move around on the rails. And for a heavy use bike I like to be fairly well centered over the post. Having the post higher above the top tube is not a problem unless TT height was already too low, which it sounds it wasn't. This analysis depends on the cranks being the same length, and you also need to think of BB height, it won't affect your fit, but it may affect how you straddle the bike or how the bike fits the road (ground clearance).

    The only other dimension that actually affects your cockpit is the reach/bar position, and you can measure that on your current bike and check it against this new one as measured by whoever curently has it, but it would sound unlikely that it would be wildly out.

    Your comfort efficency is determined by those four measurements: BB height, ST angle, resulting seat position, relative bar position. The other factors are more related to what kind of frame it is, not how you fit it. If it's a touring bike, the bars aren't likely to be anywhere too kookie, they tend to be pretty much out from the seat. One thing to check would be your current stem length. I'm thinking it shouldn't be a lot longer than 90, that's a guess, I am only up on my own measurements. It only makes sense to work from your current TT measurement if it's correct with the propely proportioned stem
    Last edited by NoReg; 05-02-07 at 06:02 PM.

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