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  1. #1
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    How much slack is too much?

    At what point is your head tube gonna mess with your handling? Bikes seem to be getting more and more slack, especially in the AM/Trail category. What is considered "steep" now and what is consdered lots of "slack"?

  2. #2
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    Not just in the trail/AM category. The new Scott Gambler DH frame has a HTA as low as 62*.

    I wouldn't say that a slacker front end messes with handling so much as it takes a different style. I switched hardtail frames a couple years ago, and my Yelli Screamy absolutely requires a different riding style than my EMD9 did. BUT - the front end is only one variable in what is a very different package. The rear end is pretty different too, and that also affects the handling. I have a few friends who are like many people posting here who go on and on about the HTA as the single determinant for how a bike rides, when it's just one (important, sure) variable out of many.

    edit- and I should probably add that the required riding style may not work for every rider and every terrain. If I ever buy a DH bike, for example, it probably won't be a Gambler, in large part because of the super aggressive front end.
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    Quote Originally Posted by GnarBrahWyo View Post
    At what point is your head tube gonna mess with your handling? Bikes seem to be getting more and more slack, especially in the AM/Trail category. What is considered "steep" now and what is consdered lots of "slack"?
    I am at the point where anything but an "XC Race" bike is too slack for me, and even some of those will not work. Many other factors come into play, but I see few, if any, production frames in my future.
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    Quote Originally Posted by evasive View Post
    Not just in the trail/AM category. The new Scott Gambler DH frame has a HTA as low as 62*.

    I wouldn't say that a slacker front end messes with handling so much as it takes a different style. I switched hardtail frames a couple years ago, and my Yelli Screamy absolutely requires a different riding style than my EMD9 did. BUT - the front end is only one variable in what is a very different package. The rear end is pretty different too, and that also affects the handling. I have a few friends who are like many people posting here who go on and on about the HTA as the single determinant for how a bike rides, when it's just one (important, sure) variable out of many.

    edit- and I should probably add that the required riding style may not work for every rider and every terrain. If I ever buy a DH bike, for example, it probably won't be a Gambler, in large part because of the super aggressive front end.
    It was not that long ago when a slack angles were called "relaxed" and the steep angled bikes were "aggressive".

    I am still there.
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  5. #5
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    Quote Originally Posted by shiggy View Post
    It was not that long ago when a slack angles were called "relaxed" and the steep angled bikes were "aggressive".

    I am still there.
    I know- I still see both. Obviously you see the usage I've settled on. I guess I adopted what builttoride posted in the Banshee forum about 'aggressive' geometry meaning to him a design that requires a forward position (akin to a skiing 'attack' stance) on the bike.
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    When downhill bikes start looking like this.............

    They've went to far.

    I'm no longer aggresive enough to seek anything far away from the old standard angles ... But I would consider a 68 degree angle heading toward a chopper style, and kind of slow responding.

    Might be good at +40mph, but what do I know.

  7. #7
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    Quote Originally Posted by shiggy View Post
    I am at the point where anything but an "XC Race" bike is too slack for me, and even some of those will not work. Many other factors come into play, but I see few, if any, production frames in my future.
    shiggy & I "grew up" riding off-road together and I learned a lot about what I, er, "know" {ahem} from him. (Truth is he knows 100x more than I ever will.) Maybe because of my lack of knowledge, I'm willing to experiment with HAs whenever I lay my money down on a new frame. Between my production & custom frames I've got everything from 72 to 67 HAs.

    For years I thought steep was better. "Responsive." But that was when I was a younger man... and climbing was somehow more important to me than descending... or something like that. Then in '11 I bought a Turner Sultan (slacker) and put a longish fork on it and discovered how fast I could really go downhill -- fast -- and in control.

    Call me Mr. HA Dejour but I just picked up a Kona Honzo (that's my 67 HA bike) and discovered it doesn't give anything up when it comes to climbing but it still rips the epic descents, which we have in abundance here in the Cascades foothills. I feared the dreaded slow speed wheel flop while climbing but there's none. Nada.

    So I'm a convert. Slack for me. For now, anyway.

    shiggy's not wrong. Neither am I. People seek different handling characteristics which is the point of this rambling. Only you can figure out what you like. My buddy Brock hucks 30' gaps on his 65 HA hardtail. That sounds maybe a little toooo slack for me, but... who can say?

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    Interesting question...I wouldn't have thought that bikes set up as designed would have "messed up" handling, I would expect that to happen if someone took a nice little XC bike, designed around say an 80mm fork and then slapped a 140mm fork with a much longer A-C length on there to slacken it out. Well, it'd have messed up chopper handling until the head tube snapped (which would probably be sooner rather than later) :P

    I also agree that HA is only part of what makes a bike handle, there's also wheelbase, fork rake/trail, chainstay length etc. I'd say that slack and steep are relative to the class of bike.

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    I demo'd a Jamis Dragon 650B, with a 68* HA, and didn't enjoy the way that bike climbed at all. Elsewhere, it was just OK. Nothing special on the downhills to reward me for the floppiness going up.

    The finest handling bike I've had was my OS Blackbuck with the medium fork: 73*, 51mm rake fork--confident, yet still pinpoint accurate on most single track. Then again, what I usually ride is pretty flat and twisting.

    I rode my Rawland Sogn off road: 650B, flat bars, a 73* HA and (I think) a 65mm fork rake. Something like 35mm of trail. It was very precise, but if I didn't pay attention for an instant, I was off my line. Not confidence inspiring. So I guess a bike can be too quick.

    I'm thinking of putting a 440mm rigid fork on my 72* HA Karate Monkey. That might be nice.
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    Quote Originally Posted by bikeabuser View Post
    When downhill bikes start looking like this.............

    They've went to far.

    I'm no longer aggresive enough to seek anything far away from the old standard angles ... But I would consider a 68 degree angle heading toward a chopper style, and kind of slow responding.

    Might be good at +40mph, but what do I know.
    Obv nothing since this is a 29er forum and a DH bike is 2 different worlds .

  11. #11
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    Quote Originally Posted by evasive View Post
    I know- I still see both. Obviously you see the usage I've settled on. I guess I adopted what builttoride posted in the Banshee forum about 'aggressive' geometry meaning to him a design that requires a forward position (akin to a skiing 'attack' stance) on the bike.
    That is my riding position, and the current "slack" geometry bikes handle like a wheelbarrow in a sand pit.

    On another forum I said the only way I could call the current trend "aggressive" is because it requires very aggressive input from the rider to get the bike to do anything.
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  12. #12
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    Quote Originally Posted by shiggy View Post
    I am at the point where anything but an "XC Race" bike is too slack for me, and even some of those will not work. Many other factors come into play, but I see few, if any, production frames in my future.


    this......!!!!




    i have made the complete loop two and a half times. started with a karate monkey, left it for a lighter frame that had long chainstays and slack head tube. didn't like it. went to a long chainstay/steep headtube, better, but not as fun as the KM.

    back to the karate monkey. then came the super light carbon frames. not really steep and medium chainstays. good at everything, great at nothing.
    the jet9 came out and i really liked it, but way too long chainstays. got a vassago on a really short fork and it was ok, great top tube length, except for standup climbing sucked. too long chainstays. tall boy, superfly and scott frames came and went, not happy
    got a new scalpel 29er, bobbed to much or was too stiff, no setting for fast active and great hard pedaling like the jet9. canfield and kona short chainstays, slack head tube disasters. hated it. many other bikes in between and demo'ed.


    i finally went back and through all the different frames and geometries to figure out what i wanted.

    the answer is the impossible bike.

    16" chainstays, 72 degree headtube angle, 73 degree seatube angle, long top tube, trail number that makes for quick steering, medium height BB, carbon fiber(uber light weight), 1 1/2" headtube to fit a lefty fork, BB30, paragon sliders that i can run it SS or geared and a slightly curved(down) top tube for my short leg/long torso body.

    yes i know short chainstays and a front derailleur is a paradox.




    soooo where does that leave us? a custom waltworks at 4 1/2 lbs? waiting indefinitely for a chinese honfu type to magically show up? perhaps cannodale might grow some balls and become grassroots again, take a chance at making bikes that are great at something instead of just OK at everything.


    some how all the recent 26" converts sneaked over to 29ers and demanded slow slack bikes with more travel like they were used to. great, i am all for that, but why ignore the race or faster handling people that like excitement and know how to ride. why stop making quick handling bikes. a bike geo watered down to fit every bodies needs, makes nobody happy.

  13. #13
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    My stumpjumper has a 69 degree HTA, I think. I like it a little steep for the gnar drops and downhill. I guess I will see how it climbs when all this snow melts.

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    Mountain bikes started out around 69 degrees or so. Then it seems they went steeper, appproximating road bike geo for the XC boom. Trends are always cyclical and tend to swing to extremes before settling back down. 65 degree headtube angles for a general all around bike seem a little ridiculous. My bet is things will swing back to center and 69 -70 degrees will be the norm (for 100-120 mm fork bikes.)

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    Yeah, the 69 deg HTA seems managable compared to other bikes I have ridden I guess.

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    Tradeoffs

    Like anything else with bike geometry, you're trading one thing for another, and how much you value A vs. B will strongly affect your opinion on what's "too much".

    Assuming everything else is held constant (except trail and HTA) the slacker the bike, the better it will do on very rough and/or very fast stuff where you want to run over things and not pick your way through. But that same bike will do worse and worse at slow speeds (wheel flop, general sluggishness) which means if you value being able to pick your way through things at lower speeds, you'll want something steeper.

    It's not that slack bikes don't climb well - it's that none of us are strong enough to climb at 20mph! If you could put out, say, 2000W on the climbs, you'd want slack a slack bike on most types of terrain, because you'd be going just as fast up as down.

    So if you live in, say, New England, you probably won't get much benefit from a slack setup and you'll give up in the lower speed handling department since many of your rides will average 6mph and you'll seldom go faster than 10. The opposite is the case if you live in, say, the mountain west somewhere.

    Keep in mind that I'm leaving out everything else that goes into choosing an appropriate frame geometry. The HTA is not the end of the story.

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  17. #17
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    I'm going to throw in my .02. My FS 29er is currently at 67.2, carefully measured and averaged over both directions with a digital level. Going from 69 to 67 hasn't had any negative effects on steering other than increased wheel flop, which is to be expected since the trail is very high with a 44mm fork offset and a 2.35 Hans Dampf. Other than wheel flop, which is not a big deal to me, I'm not experiencing poor steering or problems on slow climbs. I even set up a tight course in my back yard, rode it, then swapped out my 7.5" rear shock for a 6.5". I can't say I liked it that slack, but I still made it through the course and it didn't seem any more difficult. Granted the BB was lower so it's far from a perfect test.

    I've also run entire trails with my rear shock sagged excessively, and my front at almost no sag. In the end I concluded that slack works fine for me and doesn't cause any significant steering issues. YMMV. I'm sticking with 67 HTA for now as I like the bike overall much better vs. 69. I am planning on upgrading to a 51mm offset fork, which should get the trail numbers closer to stock. I noticed that the new Lefty Supermax has a 53mm offset. That's a sign that fork builders are moving the offsets on the trail-oriented forks to better match the slacker HTAs and bigger tires that have popped up in the last few years.

    I do wonder how center of gravity relates to HTA. I'm 6'2", weigh 225, and have a large upper body and a significant gut. All of this weight is high above the axle centerline. I've noticed that my shorter and skinnier friends can ride certain steep bumpy sections without even shifting their weight back, while I've got to extend my arms extended and get my butt back on the same section.

  18. #18
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    Quote Originally Posted by JACKL View Post
    I'm going to throw in my .02. My FS 29er is currently at 67.2, carefully measured and averaged over both directions with a digital level. Going from 69 to 67 hasn't had any negative effects on steering other than increased wheel flop, which is to be expected since the trail is very high with a 44mm fork offset and a 2.35 Hans Dampf. Other than wheel flop, which is not a big deal to me, I'm not experiencing poor steering or problems on slow climbs. I even set up a tight course in my back yard, rode it, then swapped out my 7.5" rear shock for a 6.5". I can't say I liked it that slack, but I still made it through the course and it didn't seem any more difficult. Granted the BB was lower so it's far from a perfect test.

    I've also run entire trails with my rear shock sagged excessively, and my front at almost no sag. In the end I concluded that slack works fine for me and doesn't cause any significant steering issues. YMMV. I'm sticking with 67 HTA for now as I like the bike overall much better vs. 69. I am planning on upgrading to a 51mm offset fork, which should get the trail numbers closer to stock. I noticed that the new Lefty Supermax has a 53mm offset. That's a sign that fork builders are moving the offsets on the trail-oriented forks to better match the slacker HTAs and bigger tires that have popped up in the last few years.

    I do wonder how center of gravity relates to HTA. I'm 6'2", weigh 225, and have a large upper body and a significant gut. All of this weight is high above the axle centerline. I've noticed that my shorter and skinnier friends can ride certain steep bumpy sections without even shifting their weight back, while I've got to extend my arms extended and get my butt back on the same section.
    How do you slacken your fork/head tube without modifying the frame?

  19. #19
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    In my case, I installed a larger front tire, removed a spacer from my Marzocchi 44 TST2 fork to increase the travel (and axle to crown distance) by 20mm, and installed a set of Burgtec offset rear shock bushings. Anything you do to raise the front-end or lower the back-end will make the bike slacker. It will also change your bottom bracket height (among other things), so you need to be aware of that.

    Usually the best way to significantly change the HTA is to install angled headcups, which is probably a better and more direct way of doing it.

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  20. #20
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    Quote Originally Posted by JACKL View Post
    Going from 69 to 67 hasn't had any negative effects on steering other than increased wheel flop..
    Wheel flop is a major handling flaw for me.
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    We will see how my 69 deg head angle in my new Stumpy will handle. I couldn't find the geometry stats for my 2008 Stumpy FSR Comp 26er but it doesn't seem different.

  22. #22
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    Quote Originally Posted by shiggy View Post
    Wheel flop is a major handling flaw for me.
    This! Been there, done that, somewhere around 68.

    The 26er is 70* (perfect) and the 29er is 73* (also perfect)

    Two people I know who had Chromag Surfaces sold them. Gorgeous bikes that don't work all that well on tight single track.

    Tight single track is all there is around here.

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  23. #23
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    Quote Originally Posted by GnarBrahWyo View Post
    We will see how my 69 deg head angle in my new Stumpy will handle. I couldn't find the geometry stats for my 2008 Stumpy FSR Comp 26er but it doesn't seem different.
    It is more than the HTA that makes the difference. If a 26" wheel bike and 29" wheel bike have that same HTA and fork offset the 29er's steering will be less responsive and more likely to have wheel flop.
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  24. #24
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    While I agree in general, I've changed up a 26" bike (Fango) from its recommended 80mm travel fork to 100mm and later added a front 650b wheel to the mix (as a stopgap for my stolen Waltworks SS - thanks Walt, I never told you, but every time I rode that bike, I enjoyed it even more). I haven't bothered to try to make an accurate measurement of HTA, but my angle-finder said ~68 one time when I got curious about how I'd changed things.

    While it's sometimes a bit vague feeling at *really* low speed, I'd say the overall effect is positive. Maybe it's the intermediate sized wheel. Maybe PA riding is faster overall than NE riding...

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