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  1. #1
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    Headtube/seat tube angles - any standard for measuring

    I've been looking at a Seeker or Guardian for my wife. Since I have a Niner EMD I have also considered building one for her. So that has me looking at the geometry numbers between the two bikes. Which apart from chainstay lengths are pretty similar. But one thing I can't quite figure out is if their is any standard for measuring heatube or seat tube angles on the bikes.

    On Airbornes website they specify that the headtube angle is measured with a sagged fork. Can I assume that seat tube angles are also measured with the sagged fork? Also how much sag is that? Finally, is this an industry standard? Can I assume that Niner or other companies also have a sagged fork when taking their measurements. Or do I need to add/subject an extra degree of angle to account for the sagged fork?

  2. #2
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    I don't know if its actually a standard but typically I see geometry posted that would line up as "with a sagged, 100mm fork" or whatever the frame is designed for.

    If it would help, I could probably arrange to post a photo of my Seeker next to a 2012 EMD9 so you have a ... frame... of reference.
    Eric

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    Thanks for the reply. Its encouraging to know that you think they might all be using a sagged fork. As I compare the numbers from Airborne and Niner it seems like they could both be using a sagged fork, but I don't know enough about the impact those numbers would have to know if I am thinking it through correctly or not.

    I have a friend that has a Goblin. So I have seen the bikes together. But I've never compared the angles that close before. Some day I might have to get out my angle finder to check them. But he lives two hours away so that might be awhile. Besides, I'm not sure my angle finder is that accurate. The bikes do ride a little different, but I also have a Manitou Tower Pro which has a longer offset. So that would play a roll as well. Along with the Goblin having longer chainstays. So I don't konw how much is head angle and how much is other things.

    However, I'd still love to see your bikes together.

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    The chainstay length is definitely a variable to consider. I have a small Guardian and Seeker in the garage and even compared to my medium EMD, the front ends take a bit more effort to pop up over obstacles, if that is a concern.

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    Quote Originally Posted by tuskenraider View Post
    The chainstay length is definitely a variable to consider. I have a small Guardian and Seeker in the garage and even compared to my medium EMD, the front ends take a bit more effort to pop up over obstacles, if that is a concern.
    That is part of my concern. Although I don't see it as being a big issue for my wife. I suspect that is due mostly to chainstay length. How does the fork and wheelset on the EMD compare to the Airbornes. I lighter wheel could make a difference too.

  6. #6
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    Quote Originally Posted by Fargo1 View Post
    Thanks for the reply. Its encouraging to know that you think they might all be using a sagged fork. As I compare the numbers from Airborne and Niner it seems like they could both be using a sagged fork, but I don't know enough about the impact those numbers would have to know if I am thinking it through correctly or not.

    I have a friend that has a Goblin. So I have seen the bikes together. But I've never compared the angles that close before. Some day I might have to get out my angle finder to check them. But he lives two hours away so that might be awhile. Besides, I'm not sure my angle finder is that accurate. The bikes do ride a little different, but I also have a Manitou Tower Pro which has a longer offset. So that would play a roll as well. Along with the Goblin having longer chainstays. So I don't konw how much is head angle and how much is other things.

    However, I'd still love to see your bikes together.
    Most angle-finders are just somewhat accurate at best with a variance of a degree or so. Which is also, coincidentally, the difference in angle measurement between a sagged for and an unsagged fork.

    We're starting to measure our angles with a sagged (for XC, is about 20%) fork because that is the true angle of the HT and ST when you are actually riding the bike. Frankly there is no "industry standard" for this measurement, that's why we list it as "sagged" to clarify it. Some manufacturers are starting to do the same thing and generally list it as being sagged.

    In regards to the slightly longer stays, they will slightly affect picking up the front, but also are a benefit in adding some stability when decending in rought stuff.

    Jeremy
    Airborne Dude.

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    Thanks Jeremy. I pretty much expected there was no standard. I agree that measureing with a 20% sag is more accurate as thats where it is at while riding.

    Looking at Niners specs they show the geometry with an 80mm and a 100 mm fork and the angle changes by about 1 degree. So I figured thats about what a sagged fork would change them.

    Thanks also for the comments on the chainstay length. It helps to confirm some of the information I had been learning about them. Although I really like my Niner, I can see where the Seeker might actually have some advantages for my wife who will ride a less aggressively.

    Now knowing there is not hard and fast standard for measuring headtube angles it makes a lot of those conversations about angles look a bit silly. I know there is at least one thread in the forum where someone is screaming that Airborne needs a slacker head. I wonder how his opinion will change once he relizes that the Goblin headtube angle is actually 1 degree more slack than he thinks it is? I think it just goes to show that we don't always feel what we think we feel in a bike. I konw I have a hard time telling the difference in handling between my medium Niner and my friends small Goblin. And the differences I can feel I don't know if they are due to geometry or size and fit differences. I'm sure its a little of both.

  8. #8
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    Quote Originally Posted by Fargo1 View Post
    However, I'd still love to see your bikes together.
    At the ready, here is what I've got, but it doesn't show much. The next time I ride this bike with my riding buddy I'll update the thread. They are both 20" bikes with 100mm RockShox (mine a Recon Gold, his a Reba TL.)



    Eric

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    Yeah, truthfully only the "one percenters" are the ones who can really even notice a difference of 1-2 degrees, or even 5mm of chainstay length difference. I can, but its my job to be a "one percenter".

    Even then I scoff a little at the notion that one train of thought is "better" than the other. Some folks like and need longer stays, and other folks riding style/area lends itself to slacker HT's and shorter stays. I have short stayed and long stayed Airborne bikes in my personal stable, and I like both ways for different things. The short stayed bike is a lot of fun and "tossable" for lack of a better word, but isn't as good as the longer stayed bike on choppy/bouncy downhills. I've got years in the saddle and a higher level of riding experience, so its fine for me. In truth I'm building a 29er for my wife (she's agreed to make the move from her beloved 26inch ti mtb) and I would much rather see her on a Goblin frame with the slightly longer stays.

    Jeremy
    Airborne Dude.

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    skyphix - Thanks for the photos. It surprised me how much I liked the look of the Seeker in that photo. I never really liked it before because I don't care for black bikes. But in that photo I can see better that its actually a dark gray and not black. I still prefer bright bikes, but the Seeker is growing on me. Those two bikes should be a pretty fair comparison since they are both 20". Although the Reba is about a 1/2 ligher and I'll bet he has lighter wheels on his. So that would make some difference in being able to pull up the front wheel as well. But other handling characteristics should be pretty comparable.

    Jeremy - If I built a Goblin, do you think I would notice much difference between a Manitou Tower Pro with a 48 offset versus Seeker with a Recon Gold with a 45 offset?

  11. #11
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    Quote Originally Posted by Fargo1 View Post
    skyphix - Thanks for the photos. It surprised me how much I liked the look of the Seeker in that photo. I never really liked it before because I don't care for black bikes. But in that photo I can see better that its actually a dark gray and not black. I still prefer bright bikes, but the Seeker is growing on me. Those two bikes should be a pretty fair comparison since they are both 20". Although the Reba is about a 1/2 ligher and I'll bet he has lighter wheels on his. So that would make some difference in being able to pull up the front wheel as well. But other handling characteristics should be pretty comparable.
    His bike is definitely way lighter, carbon seat post and bars, Stans Flow EX set up tubeless, and the Reba TL Ti all are where the differences are. I've ridden the EMD9 back to back with my Airborne. I would say the difference in handling is noticeable but not in a negative way. I would say the Niner is a bit easier to find the balance point in a wheelie but not really any easier to manual or in the initial lifting of the wheel. They both clear the same size trail obstructions with equal ease. I tend to find it wandering a bit over babyhead filled fireroads at 20+ mph where my Airborne stays super stable and actually feels like it comes into its own at that point. The niner feels like its probably easier to ride over technical stuff or in really tight non burmed switchbacks vs. the Seeker being more comfortable over a longer ride and more stable at speed. With the Seeker, the faster you go, the better the bike feels. All of that said, I never feel like I am being held back by my bike or "if I had bike XYZ I would've cleared this." He rarely loses me on a trail unless it's technical and I only lose him if it's burmy and smooth... but that says more about our riding styles than the bikes themselves.

    Neither of us are even close to being Advanced riders... just barely entering the intermediate territory on the trails we can easily clear. My observations are mostly because I tend to obsess a little over these things, and riding various road bikes has definitely kept me aware of handling.

    I also like really bright bikes and much preferred the paint on the white Guardian but Airborne had this one as a very rare scratch and dent and it was an upgrade so I took it. That's why you see the orange bars and seat clamp on my bike - I missed some color.
    Eric

  12. #12
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    Quote Originally Posted by Fargo1 View Post
    Jeremy - If I built a Goblin, do you think I would notice much difference between a Manitou Tower Pro with a 48 offset versus Seeker with a Recon Gold with a 45 offset?
    Not long ago I swapped out the Reba on my HobGoblin for a Manitou Tower Pro to do a long-term test. I really didn't notice any change in handling with the offset change, which surprised me because I was expecting to notice it. The one thing I need to look at is the ATC of both forks to compare; if the ATC on the Tower is shorter than the Reba that could explain things.....

    Jeremy
    Airborne Dude.

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    Thanks Jeremy, thats really good to know. I love my TowerPro. I'm starting to think about building a bike based on the Goblin frame now. I think its come down to the Seeker or a custom Goblin build. The Goblin build is very tempting because my buddy "MikeinMN" has done a lot of upgrades to his Goblin, so I may be able to purchase a lot of his used hardware from him. I think it will be more a matter of 'do I want to build a bike over the winter or do I let Airborne store a Seeker for me and buy it in the spring?'

    skyphix - thanks for the detailed comparison for me. That helps me to know better how the 2 bikes will behave. Reading your review its quite possible the Airborne might be a better fit for my wife. She won't be doing anything technical so the Niners advantages may not be of any benefit to her. But oddly enough, Niner gave the Small EMDs more slack in the headtube. So I guess that can change things again too. But unless a deal on a Niner or something used falls into my lap over the winter, I will most likely be building a Goblin or getting the Seeker next summer.

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    Jeremy - I found on SRAMs site (http://www.sram.com/sites/default/fi...0to%20Axle.pdf) the Rebas axle to crown is 506mm (+/-5mm) and offset is 46.

    Manitou (Tower | Manitou) list the Tower Pro as 510mm and offset of 48mm.

    To me that would appear to be a wash, especially since SRAM indicates the ATC measurements have a variable of +/-5mm. So maybe the 2mm in offset is just not enough to really be noticable. Or the slight differences in ATC negate it.

    Am I correct that ATC measures axle centerline to the top of the crown (or bottom of head tube?) So effectively a longer ATC would give (marginally) more slack?

  15. #15
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    Yes, that's correct, a longer ATC would make a HT angle less steep (ie, more "slack").

    Good info, thanks for looking that up on the Manitou fork.

    One thing I want to mention is that we are temporarily sold out of Goblin frames. We have more in the queu to be produced but we probably won't have them for about 2 months or so. Our Goblin frame-only sales went way up in the past two months and out-ran our forecasting. Again more growing pains of being a relatively small company with exponential growth like we've seen this year.

    Jeremy
    Airborne Dude.

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    Thanks for the notice on the frames. As long as you are getting more in, I could wait. I just see a lot of closeout deals right now on various components. So building from scratch is appealing.

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    Quote Originally Posted by BigDaddyFlyer View Post
    Yes, that's correct, a longer ATC would make a HT angle less steep (ie, more "slack").

    Good info, thanks for looking that up on the Manitou fork.

    One thing I want to mention is that we are temporarily sold out of Goblin frames. We have more in the queu to be produced but we probably won't have them for about 2 months or so. Our Goblin frame-only sales went way up in the past two months and out-ran our forecasting. Again more growing pains of being a relatively small company with exponential growth like we've seen this year.

    Jeremy
    Gotta wonder if folks are building up bikes because of some of the crazy bargain basement prices on components lately. When I saw a set of new Sun Ringle Charger Pros for $399 and Manitou Towers for $250, I figured that it was a good time to be a consumer.

  18. #18
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    Quote Originally Posted by MikeinMinn View Post
    Gotta wonder if folks are building up bikes because of some of the crazy bargain basement prices on components lately. When I saw a set of new Sun Ringle Charger Pros for $399 and Manitou Towers for $250, I figured that it was a good time to be a consumer.
    Good time to be a consumer, bad time to be a bike company (generally). Most bike companies are seeing a surplus glut of inventory and are scrambling to get out from under. Its especially bad in the BMX sector this year, where the market is flooded with 2013 and even still 2012 product.

    Thankfully we are the exception rather than the norm.

    Jeremy
    Airborne Dude.

  19. #19
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    Quote Originally Posted by Fargo1 View Post
    That is part of my concern. Although I don't see it as being a big issue for my wife. I suspect that is due mostly to chainstay length. How does the fork and wheelset on the EMD compare to the Airbornes. I lighter wheel could make a difference too.
    Both were on my Guardian first and with a 1x9 setup was pretty light. To make a long story fairly short... the EMD is my fourth bike/frame in a year. My first MTB was medium Giant Talon(added Reba and custom ArchEX/White Industries wheels), small Guardian(went 1x9 along with fork and wheels from the Giant), which was first bought for my wife and convinced me the Giant was too big(pun?). I bought the wife a Seeker with the much better fork over the Guardian, which helps even a novice IMO. The added TT bend in the small helped in clearance for her as well and she's happy with it. Third frame was a small Yelli Screamy(moved all parts over from Guardian, added XT brakes and went 1x10) and now medium EMD(moved the parts over). The medium EMD is perfect for me. It was a fight finding the right size for me at 5'8" between brands. I loved size of the small Guardian because it felt more nimble than the bigger Giant. I loved the maneuverability of the Yelli with the super short chainstays, but a bit too busy maybe partly because it was too small. Liking the shorter chainstays to a degree, I tried the EMD. I decided on a medium after riding an medium Air 9. With the same wheels and fork on every bike, I can say the 450mm chainstays on the Guardian keep the front end down and bike stable if that is the desire, the EMD's at 439mm is noticeably lighter even with the longer ETT of the medium. Maybe it's just the whole geometry package(?). And being captain obvious.........a good fork and (tubeless) wheels shave a ton of weight off any bike, but are pretty much the most expensive components to upgrade. Well, I stop rambling, as like you said, your wife will likely not notice much difference. Good luck choosing!

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