Dreaming Out Loud- Mtbr.com
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  1. #1
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    Dreaming Out Loud

    CK has got me reconsidering something lower than 20.0 gear inches with his ride
    against the wind on the beach. A 20t ring would make for about 16.0".

    It also got me wondering...with 20-27 (20-30?) up front and running two rear wheel
    sets, one with 11-36 (XG 1099) and the other, 11-28 (OG 1090).

    Years ago I tried half-step gearing, liked the steps between gears but hated all the
    shifting. Thinking that fat might make small steps between gears worthwhile. I
    would not be using a fd.

    My thought is to use the 20 x 11-36 as a lower range and the 27 or 30 as an upper.
    Both rears would be on 170 hubs, so a wider fork would be required.

    Anyone have any experence with a road cassette and running fat? Or have tried this
    idea?

  2. #2
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    Oh yeah, a DUO spyder in 64 bcd might help;...HBC? Does not seem like it would
    be that hard for them to do, if they are willing.

  3. #3
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    Lets see if I can save face here; chalk it up to...One of those dreams that don't make sense?

    I enjoy thinking about ideas concerning things that interest me, if I actually had a fat bike to ride
    my thoughts would hopefully be less woundering.

    When I started this thread my thoughts did not extend beyond finding an ideal gearing arangement
    for myself. It was my thought that close steps between gears in an upper range might be easier to hold.
    And so the above idea came to be. Perhaps you are thinking, who would want to do such a thing? Out
    of the box is one thing...I am beginning to amble.

    Shortly after my second post I began to think about actually running a 170 dropout fork and what that might mean.

    Make the steering feel...heavier? True or false; the point of leverage upon the wheel is at dropouts,
    not at the axle center point; which means a wider hub wants a longer lever (handlebar)? Might be usefull if all one did is downhill racing?

    So, there goes that approach. Which leaves me with the idea of a double ring spyder with a 64bcd.
    For my style of riding, a 30 x 11 gear seems high enough for 98%, anything else...getting too old
    for this!

    My thought is to come up with a 'design' that is quick in its ability to change directions in a short distance. True or false; a short wheelbase is required? Meaning short chainstays and a short front center. Jeff Jones's 2Fat bike (see April 2009 blog, his site) shows very short chainstays and a shortened front center using a setback seatpost. The largest setback I have found is 32.5mm. from
    FSA.

    Using my 26"er MTB as a reference, a 42" or maybe less, wheelbase 'seems' workable without
    any toe overlap. Sticking with Jeff's 70* HA and 55mm offset around a 435 - 450 AC fork.

    While I go by Sand Rat, most of my riding would not be on the nearby dunes, (1.5 - 2 hr away)
    but as a trail bike. Therefore my preference for a short wheelbase, at the expense of float on the
    dunes, if there be much.

    By the way, I spoke with Jeff a little on the phone, no production 2Fat bikes. One and only.

    Getting back to the thought about wide dropouts, if two bikes were built the same, save that one had an 135 offset rear, would it not therefore have a slight edge over the other in terms of changeing
    directions?

    Could this be a least part of the reason not many invest in a 29er wheelset for a fatbike? Because of the wider dropouts over a standard 29er, a 29er wheelset in a fat bike is just a lighter wheelset, you
    can't make a fatbike perform the same?

    Am I beginning to grasp an understanding of how things work? All I know is that as time has progressed I find myself returning to tried and true. But still...

    Well, hope your time was not a waste.

  4. #4
    That Unicycle Guy
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    Quote Originally Posted by Sand Rat View Post
    True or false; the point of leverage upon the wheel is at dropouts,
    not at the axle center point; which means a wider hub wants a longer lever (handlebar)?
    False. In terms of steering your pivot point is the axis of your steerer tube. You can think of the wheel and fork as a single piece with the width of the axle having nothing to do with steering input. Where the width of the hub makes a difference is in torsional rigidity. In theory a fork with 170mm dropouts will be 70% more resistant to the wheel twisting than a equal fork with 100mm dropouts. (if the fork flexes 1mm on each leg with 100mm dropouts the wheel will twist 1.15˚ in relation to your handlebars, now if the fork flexes 1mm on each side on a 170mm dropout fork you only get 0.67˚ of twist.)

  5. #5
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    The fork twist angle is interesting.

    I reckon my 135mm OLD forks feel more flexy than the 100mm OLD versions.

    I've got 4 sets of forks. I'll list them in order of feel:
    homemade 100mm - best feel
    Surly 100mm
    Surly 135mm offset
    Salsa Enabler 135mm - squirms under heavy braking
    As little bike as possible, as silent as possible.
    Any bike, anywhere, anytime.
    Latitude: 5736' Highlands, Scotland

  6. #6
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    Thanks guys!

    Now this is interesting!

    Eric and Velo seem to be at odds. But wait...

    Eric, when you speak about a 1mm twist at the dropout and the amount of movement difference
    at the handlebar, I follow and 100% agree, was my thinking also. So why the disagreement?

    Do I see what is a general problem when talking about things of this nature, ie no black and white
    adhearence to terms? one mans 'twitchy' is anothers fast or light? Things get twisted up and in the
    head of someone like me...mush!

    Not looking to start a personal argument anywhere, but I do find this appearent conflict interesting
    and fun to engage in. Which is why some shy away? A source of trouble to me in the past.

    If no one is willing to engage in such matters how is anything resolved, and progress made?

    Any more brave or foolish souls? Being thought a fool is not the same as being one, nor
    the prospect of either...desireable.

  7. #7
    aka bOb
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    Sand Rat you sure are an interesting one. I think my head has bounced off a one to many of rock to even try to get in a conversation with you. I do enjoy reading your posts though, even if it takes me a day to figure them out. It's fun having you here

  8. #8
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    Thanks; makes my day!

    Even my wife says I am 'weird', (so; what does that say about...her?) I do not want to be like anyone else, I want to be me, whom ever that may be, you decide.

    Enjoy life, be a source of joy unto others, dare to be whom you were designed to be.

    This life/fourm is just a means for that expression. Happy to see you see things that way.
    Along the way everyone does in some way or another, it is truly sad when someone misses
    the point.

    Got to figure out how to lessen your time in understanding my aim on this forum though!

    Thumbs Up!

  9. #9
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    My opinion is that a 135mm OLD front fork probably would be better with bolted in axles or a through axle so that the stiffness was optimised.

    However I did use bolted axles in my Salsa fork and still felt it squirm under heavy braking.
    As little bike as possible, as silent as possible.
    Any bike, anywhere, anytime.
    Latitude: 5736' Highlands, Scotland

  10. #10
    Dr Gadget is IN
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    Quote Originally Posted by Sand Rat View Post
    Thanks guys!

    Now this is interesting!

    Eric and Velo seem to be at odds. But wait...
    Simple. One is talking ideal (all forks being of equal strength), and the other is talking real world parts in hand.

    But on your original topic: I'm running 20/32/44 front and 12x36 on the back (12 - 14 - 16 - 18 - 21 - 24 - 28 - 32 - 36). The outstanding traction and slow speed control of fatties allows that 20/36 combo to work very nicely. Climbs that required momentum with a "plump" tire bike, because you would just spin out due to lack of traction, become no problem to creep up fully in control.

    As far as close spacing the gears - in a trail environment, I've never wished for an intermediate ratio between what I've got. That becomes more important for setting the perfect power level for long sustained efforts. I've always been willing to pick the best compromise of a wide range cassette - knowing that even the close ratio version won't necessarily deliver perfection. YMMV. If I'm going to do something other than a joyride on the road, I'll be on my recumbent anyways.
    This isn't a "you're doing it wrong" topic.

    WSS/OSS: Open Source Sealant

  11. #11
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    OK: girl's point of view (bike nerd, here, not necessarily techno-wizzo-nerd).

    Design, design, design (with some engineering thrown in)...it isn't just aesthetic. Design, materials, thicknesses, year built, angles, spaces -- all of these will have something to do with fork (or any component) feel. Technology continually advances and changes, and all of those incremental changes add up to difference in feel. Width is but one attribute. I don't think it can be held to an absolute.

    Although Eric did say: "In theory a fork with 170mm dropouts will be 70% more resistant to the wheel twisting than a equal fork with 100mm dropouts," covering the all-other-things-being-equal argument.

    I don't know about you, but when things get nitpicky, I always fall back on red...anything red will be stiffer and faster

  12. #12
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    Quote Originally Posted by wadester View Post
    Simple. One is talking ideal (all forks being of equal strength), and the other is talking real world parts in hand...
    Bear in mind I'm talking about my impression of using those parts. I haven't tried any sort of measurement of deflection.

    Old Bag may have the best idea. I'm off to the shed to paint my Salsa forks red.
    As little bike as possible, as silent as possible.
    Any bike, anywhere, anytime.
    Latitude: 5736' Highlands, Scotland

  13. #13
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    I don't know, VB, it might clash with the red of your fenders!

  14. #14
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    Eric; Ok, lets see if I understand things better now.

    For the purpose of illustration, lets say the handlebar is fastened directly over the headtube.
    The longer the bar, the slower the steering due to the greater arc distance required to turn
    the wheel the same amount of degrees. This is true for the stem length or the width of the hub.
    Increasing the length of either does the same. Decreasing the length of either speeds the
    steering up.

    A concern comes into play when hub width is increased. The width of the hub acts as a lever
    upon the fork ends when twisting forces are applied, such as Velobike noted. He rated the
    Surly 135 offset better than a 135 non offset hub, because each leg of the fork were not operating
    in the same plane, thus providing greater resistance to twisting forces.

    My thought of using a 170 fork in order to park one rear wheel with a close ratio road cassette
    when not in use on my large 27 or 30 tooth ring, in an effort to create an ideal gearing set up
    is not worth the expense nor the increase of twisting forces upon the forks. Sure, they could be
    made stiffer, but ride quality would suffer.

    My experment with half-step gearing was tossed becuse I hated all the shifting with the fd, it was cheap, and a small outlay in cost, but this...I would be looking at no small sum to undo if it proved otherwise.

    Do I have all of this correct?

    Bdundee, I hope my writting style has improved. Maybe I just need to be more focused.
    I take it you might equate my posts to not unlike the pic reports that Velobike does; taking
    the road less traveled, getting tangled up in a fence like a steer... Is that not the whole point
    of fat bikes...to be able to go where none have gone before?

    Wadester, I shall keep in mind of the added traction of fat tires in my gear selection, and
    chainrings are not expensive to try one over another.

    Old Bag, thanks for adding a little color to this ride along the way, keeping the scenery
    interesting and unexpected, completely in the spirit of fat biking!

    Thanks all!

  15. #15
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    Quote Originally Posted by Sand Rat View Post
    Eric; Ok, lets see if I understand things better now.

    For the purpose of illustration, lets say the handlebar is fastened directly over the headtube.
    The longer the bar, the slower the steering due to the greater arc distance required to turn
    the wheel the same amount of degrees. This is true for the stem length or the width of the hub.
    Increasing the length of either does the same. Decreasing the length of either speeds the
    steering up.
    As long as the bar is what you are holding on to and as long as it's rigidly connected to the fork then hub length has nothing to do with steering quickness. Turn the bar one degree wheel turns one degree regardless of hub length. Increasing stem length can effectivly increase bar length, and slow down steering, as it moves the bar ends farther from the steering axis. Like you Sand Rat I wish I could say what I mean more clearly sometimes but I hope I got it this time.

  16. #16
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    Thanks for the correction Sryanak!

    And to think that I chose that example to keep things simple, and to put the hub
    and the bars in the same line. Now you all see what my wife sees and has a laugh.
    I can only reply that I am glad I exist to bring laughter into her life, and I remind her
    that I am the best husband she has ever had. (She was married before.

    As my idea of a fatbike centers around an ultra short wheelbase, and with something
    telling me in so doing, there is less margin for error with other things, better get it right!

    So thanks everyone for helping me along in that direction.

    I shall shut up and go ride what I got...untill next time?

  17. #17
    That Unicycle Guy
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    Quote Originally Posted by Velobike View Post
    The fork twist angle is interesting.

    I reckon my 135mm OLD forks feel more flexy than the 100mm OLD versions.

    I've got 4 sets of forks. I'll list them in order of feel:
    homemade 100mm - best feel
    Surly 100mm
    Surly 135mm offset
    Salsa Enabler 135mm - squirms under heavy braking
    hmmm never thought about twisting forces from a disk brake. Tried to figure that one out on paper and it is a bit more complicated. Looks like the hub/fork connection is the most important factor, with skinny stiff hubs helping the equation.

    I have no real-world wide hub fork experience so I would take others real-world experiences over my pen and paper speculations. It's too easy to miss things like braking squirm unless you experience it.

  18. #18
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    I recognised the feeling from my days on early disk brake motorbikes
    As little bike as possible, as silent as possible.
    Any bike, anywhere, anytime.
    Latitude: 5736' Highlands, Scotland

  19. #19
    Tigard, Oregon
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    Quote Originally Posted by bdundee View Post
    Sand Rat you sure are an interesting one. I think my head has bounced off a one to many of rock to even try to get in a conversation with you. I do enjoy reading your posts though, even if it takes me a day to figure them out. It's fun having you here
    I was thinking the same thing! lol...
    2011 Salsa Mukluk / 2006 KTM 400 EXC

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