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  1. #1
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    Understanding Fat Bike Seat Tube Angle

    Howdy. I'm the new owner of a 2019 Norco Bigfoot 1 https://www.norco.com/bikes/mountain...num/bigfoot-1/ fully-rigid fat bike.

    For the price it largely seems to have pretty good geometry for trail riding and bikepacking. It's got a suspension-corrected fork, 125mm dropper post, long front-centre, and the best part, a 67.7 degree headtube angle. Lots of mounts for bikepacking too.

    However there's one aspect of Norco's geometry choice I don't really understand, namely the 71.7 degree seat tube angle. Overall the geometry keeps pretty well to trail geometry except for the STA and 45mm chainstays. But from what I can see, trail bikes typically sport a 73-74ish degree STA. A 71.7 degree STA seems more along the lines of all-mountain, but combined with a conservative trail HTA.

    I'm a bit confused as to whether this STA is a liability or asset when combined with the rest of the geometry. Any ideas as to Norco's reasoning behind it?

  2. #2
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    Reputation: JackWare's Avatar
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    Isn't this a solution to the issue of keeping the bike compact / a short wheelbase but needing to fit in the 4.8 tires? How does it ride?
    What a perfect waste of time

  3. #3
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    Quote Originally Posted by JackWare View Post
    Isn't this a solution to the issue of keeping the bike compact / a short wheelbase but needing to fit in the 4.8 tires? How does it ride?
    Ah I think you're on to something! Based on reviews of the Bigfoot I think they were in fact going after a long wheelbase so it would be suitable for both trail and touring. And there are other 5" fat bikes that don't have a slack STA but I think they can get away with it because their HTA isn't as slack.

    To explain, the Bigfoot has a pretty slack HTA for a 5" fatbike, putting the handlebars back more. So I think to keep a normal reach between the saddle and head tube they have slackened the STA to set the saddle further back.

    With a HTA that slack, the only alternative if keeping a normal STA is to lengthen the chainstays beyond 45mm to get the tyre out of the way. But as you know that would really hurt agility for trail riding. So I suppose they reason that a slack STA is the lesser of two evils, if indeed a slack STA on this bike is an evil.

    Only been on 1 trail-ride so far but mate it rides amazing! I've never ridden a modern-geometry mtb off-road in earnest so don't have anything to compare it to, but I've never been into a ride as much as that trail ride. I can't wait to get back out there, weather permitting.

    And whoever invented dropper posts deserves a medal, after using one I don't know how they got by without them! And regarding the slack STA, I thought that might help set me back nicely for the downhill action, although may not make for the best pedaller or climber.

  4. #4
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    Reputation: Jayem's Avatar
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    The hardtail is not an FS trail bike, therefore it won't sag back and slacken the seat tube while climbing like an FS trail bike, therefore the effective seat tube angle doesn't need to be as steep.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  5. #5
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    Quote Originally Posted by Jayem View Post
    The hardtail is not an FS trail bike, therefore it won't sag back and slacken the seat tube while climbing like an FS trail bike, therefore the effective seat tube angle doesn't need to be as steep.
    That's something I didn't consider! Thanks Jayem, nice one!

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