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  1. #1
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    Seat Angles and BB Height?

    What are the pro's and con's of seat angle of 75 vs 72? Is the other benefits to having a higher BB Height other than clearance? I'm guessing a lower BB height lowers your center of gravity, making you more stable? Is a different of a 16mm that big of a different?

    I'm interested in the Kona Honzo and the Norco Torrent or Fluid, just trying to figure out the benefits of different geometry.
    Thanks.

  2. #2
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    Short stays and slack seat tubes can make it a chore to climb steeps. I've heard the Honzo referred to by an owner as a less then stellar climber for that reason. Figured it's worth mentioning...

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    72 STA is good for flat power, but can make the front wander and felt like you're going to loop out on a climb. 75 is better for climbing since to will put more weight on front. Worst case if you don't like it, you can set the seat back. Higher Bottom Bracket is good for clearance, manuals and changing direction back and forth in tight S turns.

  4. #4
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    I have a Honzo. It climbs like a horny monkey.
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  5. #5
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    BB height changes the center of gravity of the bike and lowers your seat in relation to the axles. 16mm is a big deal. As our president would say.... Huge. Pedal strikes are the determining factor in how low you can comfortably go.

    Seat tube angle is mostly meaningless. As long as you can slide your seat to the position that you like, STA is fine. By this I mean that a 78 with the seat slid all the way back and a 72 with the seat slid all the was forward put the seat in an identical place.
    Now if you're tall and ride an Evil you're screwed because you run out of range.

    FYI a seat that can move 3 inches with a 30 inch inseam is 6 degrees of adjustment.

  6. #6
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    Quote Originally Posted by alexbn921 View Post
    Seat tube angle is mostly meaningless.
    I would strongly disagree. Also, most seats/post clamps allow for maybe 2" of adjustment (1" each direction from center). If, like me, you're riding a 72* seat angle and prefer(need) a 78* seat angle - it aint happening.

  7. #7
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    Quote Originally Posted by EatsDirt View Post
    I would strongly disagree. Also, most seats/post clamps allow for maybe 2" of adjustment (1" each direction from center). If, like me, you're riding a 72* seat angle and prefer(need) a 78* seat angle - it aint happening.
    You're outside the range of what you prefer. So in that case you need at least a 74 to get to 78 with seat adjustments. STA doesn't change the handling or fit of a bike for 95% of riders. They simple slide the seat to it's desired location. BB, reach, HTA...change how the bike feels for all riders.

  8. #8
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    Quote Originally Posted by Graveltattoo View Post
    What are the pro's and con's of seat angle of 75 vs 72? Is the other benefits to having a higher BB Height other than clearance? I'm guessing a lower BB height lowers your center of gravity, making you more stable? Is a different of a 16mm that big of a different?

    I'm interested in the Kona Honzo and the Norco Torrent or Fluid, just trying to figure out the benefits of different geometry.
    Thanks.
    You can't really look at 1 number in isolation. Typically a steeper seat angle will correspond with a longer front end and a shorter rear (and a longer wheelbase and more progressive suspension), but it could also be done so the front of the bike stays extra planted on seated climbs. I agree that without looking at the rest of the bike seat angle is mostly meaningless.

    BB height is similar; a designer wants to get the BB as low as possible before it becomes problematic. If you ride smooth forest trails with clipless pedals and a slow cadence you can enjoy a much lower BB than someone riding in rocks with flat pedals. 16mm of drop is quite a lot if you're comparing two otherwise identical bikes, but if one of them is a hardtail it's meaningless.




    You're looking at hardtail VS FS. I would get that question sorted first, then look at the geo.

    Quote Originally Posted by EatsDirt View Post
    prefer(need) a 78* seat angle - it aint happening.
    That doesn't sound right. Have you ridden a bike with the seat that far forward? I had a geometry experiment frame that could; it was a pretty lousy climber set up like that, regardless of how long i made the chainstays or reach. Didn't ride it that way long enough to adapt to it though.

    Why do you want it so steep?
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    Quote Originally Posted by alexbn921 View Post
    You're outside the range of what you prefer.
    Yet somehow seat tube angles don't matter. Just slam the seat forward an inch and add an inch of stem, right? I do agree with post above about looking at geo as a whole though, which is why I mentioned slack seat angle w/ short stays.

  10. #10
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    Quote Originally Posted by scottzg View Post
    That doesn't sound right. Have you ridden a bike with the seat that far forward? I had a geometry experiment frame that could; it was a pretty lousy climber set up like that, regardless of how long i made the chainstays or reach. Didn't ride it that way long enough to adapt to it though.Why do you want it so steep?
    My body type, knee issues, and terrain favor a forward weight bias climbing at the expense of comfortable pedaling in the flats. While I haven't strung a line to find my adjusted seat angle on my current bike, I'm sure it's pushing the norm (excluding recent geo trends). This is nothing new to me, although I bought into massive hype and didn't properly scrutinize geo (seat angle) when purchasing my current bike. Happy to see many manu's stretching bikes with steeper seat tubes.

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    Quote Originally Posted by EatsDirt View Post
    Happy to see many manu's stretching bikes with steeper seat tubes.
    Me, too. While SA may not affect handling per se, it certainly affects body position which does affect handling, at least while climbing. I run 185mm cranks and like to climb steep grades so I prefer a steep SA (mine's 76 degrees and I run my saddle all the way forward). When I'm bombing downhill SA doesn't matter because there is no seat -- it's gone when it's dropped. So I choose this aspect of frame geo based strictly on climbing. What is the SA when the front of the bike is tilted up 10 degrees? It's sure as heck no longer 76 degrees. That's when I want the saddle under me. A steep SA gives me this.
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    Quote Originally Posted by Sparticus View Post
    Me, too. While SA may not affect handling per se, it certainly affects body position which does affect handling, at least while climbing. I run 185mm cranks and like to climb steep grades so I prefer a steep SA (mine's 76 degrees and I run my saddle all the way forward). When I'm bombing downhill SA doesn't matter because there is no seat -- it's gone when it's dropped. So I choose this aspect of frame geo based strictly on climbing. What is the SA when the front of the bike is tilted up 10 degrees? It's sure as heck no longer 76 degrees. That's when I want the saddle under me. A steep SA gives me this.
    =sParty
    If you peddle seated flat, you can slam the seat back. I like steep since your seat doesn't change much if you want to lower it a bit. And like you if you're doing a lot of climbing move it forward.

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    So a SA of 75 is better for climbing than a SA of 72? But you can change the SA by moving your seat. The higher the BB height the less pedal strikes, and lower is better for center of gravity? I used to to be 6'2", I'm now an inch shorter, so a BB height difference of 16mm will almost make me 6'2" on a bike? Which has a better geometry, the Kona Honzo or Norco Torrent for all around riding(climbing, steep decents)?

  14. #14
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    Quote Originally Posted by Graveltattoo View Post
    So a SA of 75 is better for climbing than a SA of 72? But you can change the SA by moving your seat. The higher the BB height the less pedal strikes, and lower is better for center of gravity? I used to to be 6'2", I'm now an inch shorter, so a BB height difference of 16mm will almost make me 6'2" on a bike? Which has a better geometry, the Kona Honzo or Norco Torrent for all around riding(climbing, steep decents)?
    Looking at the geo charts and taking a guess... Ultimately they'll be pretty similar and have a similar 'comfort zone.' They'll climb differently, but have similar capabilities, and the front wheel will get light at about the same grade. The honzo will be livelier and the torrent will be more stable. The kona's geometry is more progressive, the norco will feel more immediately familiar. The kona will respond more to a dynamic riding style. Neither bike has a super low BB; the norco is high-yet-good. Seems like overall someone who likes 29ers is gonna favor the kona, whereas someone who likes the chill-and-straight-line 650+ capabilities will enjoy the norco. Both look good. I haven't ridden either of them.
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    Quote Originally Posted by scottzg View Post
    Looking at the geo charts and taking a guess... Ultimately they'll be pretty similar and have a similar 'comfort zone.' They'll climb differently, but have similar capabilities, and the front wheel will get light at about the same grade. The honzo will be livelier and the torrent will be more stable. The kona's geometry is more progressive, the norco will feel more immediately familiar. The kona will respond more to a dynamic riding style. Neither bike has a super low BB; the norco is high-yet-good. Seems like overall someone who likes 29ers is gonna favor the kona, whereas someone who likes the chill-and-straight-line 650+ capabilities will enjoy the norco. Both look good. I haven't ridden either of them.
    Thanks.
    Now I just need to decide on whether I like a 650+ or 29er.

  16. #16
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    Quote Originally Posted by Graveltattoo View Post
    What are the pro's and con's of seat angle of 75 vs 72? Is the other benefits to having a higher BB Height other than clearance? I'm guessing a lower BB height lowers your center of gravity, making you more stable? Is a different of a 16mm that big of a different?

    I'm interested in the Kona Honzo and the Norco Torrent or Fluid, just trying to figure out the benefits of different geometry.
    Thanks.
    Ideal geometry is different by region & rider, if you live in the east coast. Chances are you'll need a higher BB to clear rocks and obstacles. If you are over in the west, you'll find the advantages to having a lower BB is better cornering. Another commonly missed item is the BB heigh in relationship to the axle line of the bike. BB above that line typically will have you feeling like you are riding ontop of the bike, while under will give you a feeling of ebing in the bike.

    STA is pretty important depending on what you ride as well, as mentioned by a few people..slack STA on steep climbs require you to get into weird positions.

    Hopefully this info helps you pick.

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