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  1. #1
    I'm with stupid
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    How low is too low bottom bracket style?

    I was wondering what peoples thoughts were on how low is too low as far as bottom bracket height goes. Is there a point of that super low and slack feeling is just too much, or has a adverse effect on handling. I just short shocked a 5" bike I own and the BB Height dropped to 12" static and the head angle is now at 66 with a 140mm fork. The travel didnt drop and cause the linkage does not bottom out and the stroke of the shock is the same, the tire just ends up closer to seat tube. I have not had a chance to ride it since my ribs are broken form a DHing crash 2 weeks ago. I was just wondering what your thoughts were on the subject. Plus being bored and broken leads you to think and tinker alot with the bikes you cant ride.

  2. #2
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    I have an el guapo which has 150mm rear travel and a static BB height of about 13.25/13.5. This is about as low as I can go on this bike without constant pedal strikes on normal trail rides. I've gotten pretty well used to timing my pedaling but I still get a pedal strike here and there. Nothing too bad and it's acceptable. If you are regularly deep into your travel when pedaling it could well be an issue. only way to know is to ride it. I'd be quite careful until you put it thru the ringer.

  3. #3
    DBY
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    Quote Originally Posted by hitechredneck View Post
    I was wondering what peoples thoughts were on how low is too low as far as bottom bracket height goes. Is there a point of that super low and slack feeling is just too much, or has a adverse effect on handling. I just short shocked a 5" bike I own and the BB Height dropped to 12" static and the head angle is now at 66 with a 140mm fork. The travel didnt drop and cause the linkage does not bottom out and the stroke of the shock is the same, the tire just ends up closer to seat tube. I have not had a chance to ride it since my ribs are broken form a DHing crash 2 weeks ago. I was just wondering what your thoughts were on the subject. Plus being bored and broken leads you to think and tinker alot with the bikes you cant ride.
    Sucks about the crash, hope ya heal up fast.

    For me, anything below 13" causes problems with more technical climbs.

  4. #4
    on my 3rd wind...
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    I ridden my 6" travel El Guapo V3 at 66 deg HA and 12.7" BBH since last fall. It rails like no others but sure sux at tech climbing. At this setting I am getting constant pedal smack and have to watch my pedal position at all time. Gone down several times from phantom pedal smack on trail object that I have no idea what my pedal hit. Constantly having to watch pedal position, back pedal, ratchet pedal, pause pedal can get tiring and sure is momentum killer when climbing. Having said that I have been tweaking my bike so it is sitting dead even 13" BBH and 67 deg HA. It has helped a lot but still too much pedal smack going on for my taste. Based on my experience sweet spot for low bottom bracket height on 6" travel slacked bike is 13.2-13.5". Anything lower or equal to 13.0", you are just asking for mentally annoying constant low speed peal smack and dangerous high speed pedal smack that will slam your body onto trail with bad outcome.
    sth

  5. #5
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    Under 13.5" on a 6" and I have to be careful with platform pedals. With 38t, some trails only doable w/ bigger 2.5's

  6. #6
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    Op, keep in mind that your bike has an inch less travel. But like I said, only way for you to really know is to ride it. If the bike is still not built and you can change that shock to raise the BB, I would do it.

  7. #7
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    13.5 inch BB minimum for me on all my trail bikes with 4 to 5.5 inch, and 3.7 BB for 6 to 6.3 inch travel. Otherwise pedal strikes are too frequent and can be dangerous.

    For DH park or shuttle only with almost no pedaling, or fire road climb, 13 or 12.5 inch BB with bash guard would be fine.

  8. #8
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    I wouldn't want to go any lower than my Enduro is. I hit the pedals a lot when climbing.
    '11 Specialized Enduro Expert for the trails
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  9. #9
    U $ 4 O?
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    Rocky vs. Groomers

    Quote Originally Posted by derby View Post
    13.5 inch BB minimum for me on all my trail bikes with 4 to 5.5 inch, and 3.7 BB for 6 to 6.3 inch travel. Otherwise pedal strikes are too frequent and can be dangerous. For DH park or shuttle only with almost no pedaling, or fire road climb, 13 or 12.5 inch BB with bash guard would be fine.
    Good points ;^ ) @ 13.7" a good number if you don't want to puszy foot around chunk. Hit a low swingarm, you will knock the piss out of, or KO the frame

  10. #10
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    I ride a Canfield One with a very low bb. It is about 12.8 in. But honestly I don't see why everyone is so worried about it. I rarely hit the pedals after the first ride or two. I don't even think about it now, and it is very rare that I hit anything. I plow rock gardens all day on it, and pedal up through manzanita stumps every time I ride. The low center of mass is definitely appreciated when I'm going fast. I had a 14 in bb height on my old bike, and I would take the 12.8 any day of the week. It handles infinitely better. I won't ever go back.
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  11. #11
    U $ 4 O?
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    Quote Originally Posted by charging_rhinos View Post
    I ride a Canfield One with a very low bb. It is about 12.8 in. But honestly I don't see why everyone is so worried about it. I rarely hit the pedals after the first ride or two. I don't even think about it now, and it is very rare that I hit anything. I plow rock gardens all day on it, and pedal up through manzanita stumps every time I ride. The low center of mass is definitely appreciated when I'm going fast. I had a 14 in bb height on my old bike, and I would take the 12.8 any day of the week. It handles infinitely better. I won't ever go back.
    There's no doubt, low center mass is nice. Would love a frame w/ convertible BB drop to swap from 26" to 27.5" wheels.. need to be massive drop though, something like 1.5".

    13.8" bbh w/ 26" wheels and 12.8" bbh w/ 27.5"

  12. #12
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    Quote Originally Posted by charging_rhinos View Post
    I ride a Canfield One with a very low bb. It is about 12.8 in. But honestly I don't see why everyone is so worried about it. I rarely hit the pedals after the first ride or two. I don't even think about it now, and it is very rare that I hit anything. I plow rock gardens all day on it, and pedal up through manzanita stumps every time I ride. The low center of mass is definitely appreciated when I'm going fast. I had a 14 in bb height on my old bike, and I would take the 12.8 any day of the week. It handles infinitely better. I won't ever go back.
    That is good to hear, I rode a enduro for a while with a low BB just didnt know if it was too low. At 12.8 before sag yours will be at a lower ride height then mine.

  13. #13
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    All of what I was thinking about has been talked about already. It is a very subjective question and will be based on the preference and skill of the rider, tire size (height), suspension travel, terrain you ride, other bike geo, pedals (HUGE platforms or otherwise), crank length, etc....

    What it comes down to for me is I want the BB as low as possible without promoting pedal strikes in the terrain I ride. Its like tire pressure, you want it as low as possible without creating problems. Satisfaction can be had through trial and error based on rules of thumb as a starting point... which there is plenty of in this thread.

  14. #14
    LCW
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    Keep in mind too that crank arm length plays a role too if avoiding pedal strikes... obviously you reduce chance of pedal strikes with say a 165mm crank arm vs a 175mm... if all one is worried about is pedal strikes, could shorten the crank arms on a low BB bike to help avoid them
    2011 Yeti 575 - 2015 Fox Float 36 RC2 160 / Fox Float X - 31.3 lbs

  15. #15
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    I just got a 26' with a 38mm BB drop.. I can zoom back and forth real agile around things on a flat surface, it definitely has control, but with my toes hitting the ground with platforms and having to worry about pedal position when going up small driveway curbs, I just can't see this bike being really safe for the washed out super rooty/rocky local single track.. Maybe 5-7 years ago, but with the roots as exposed as they are now-a-days with all the riding and the tracks all getting older, I can't see this bike being very fun on local single track. I like the bike for suburban commuting and getting around, and the SLX/XT drivetrain shifts as good as I've seen, but too low a BB just doesn't work for me for actual mountain biking. Out in the desert? Maybe. With the roots around here? No thanks.

  16. #16
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    Quote Originally Posted by hitechredneck View Post
    I just short shocked a 5" bike I own and the BB Height dropped to 12" static and the head angle is now at 66 with a 140mm fork.:
    That's too low. I have a hardtail that sits at 11.5in sagged (140mm fork, 25% sag), it's brilliant but everyone who hasn't ridden it before comments on how much they hit the pedals on the ground. It's somewhat mitigated by the being a hardtail, the bb drop through travel is less as it pivots round the rear wheel.

    On your FS bike you'll be around 10.5in once you're sat on it, that gives you about four of crank clearance, which will run out really fast on bumpy ground. Prepare to put a lot of marks in any bashgaurd you're using, or else kiss goodbye to some chainrings and pedal spindles.

  17. #17
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    my 07 db mission was 13.5 or so. that bike carved like a mofo. I think it sounds fun. obviously you got be more careful pedaling and hi centering in rocky stuff. but dam I bet that mofo will kick up some dirt in the turns. sign me up.

  18. #18
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    I prefer a higher bottom bracket. My freeride (7" Gt Ruckus) bike has a 15" bb, but I could stand it to be a bit lower. My Am bike (diamondback Scapegoat) is a little under 14" and that's about perfect. My hardtail has about a 12.75 inch bb, but it has a lot less sag, so that feels about right for most trails.

  19. #19
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    I like it somewhere between 13.2 and 13.8.

    I owned a bike that was 12.8" and technical climbing was a chore. When you start pushing 14" cornering suffers and at slow speeds the bike wants to tip over.

  20. #20
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    My am bike has a 13.3in static and pedal strikes are common on steep rocky climbs, enough to constantly knock me off balance. It would be easy to say "just time your pedals" but on a slow rocky gasping grind that's easier said than done. I somewhat solved the issue scraping over lips on stepdowns by putting on a taco bash guard. But overall it's better stability-wise than the 14.25in bb on the bike it replaced. Somewhere in between would be ideal for the techy stuff around here. I might consider 165mm cranks.
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  21. #21
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    I ride a 13.3" static BB bike and have no problems with it, modern chainrings are smaller and more out of the way. When considering super chunky terrain, downhill trails found at ski resorts (chutes, big obstacles, etc), and everything else I ride-it's interesting that it's the smooth bermed trails where I occasionally drag a pedal on the ground and notice it. On DH trails I'm keeping my pedals level or lowering the outside one, but I never seen to have any problem there (and I got carbon cranks now ). This BB height feels good, especially because it's a 29er with 6" of travel, which means you don't feel like you're riding on a sky-scraper, more riding "in" the bike. I definitely know the benefit of 14" in really rough/rocky terrain, but now I'm starting to doubt that a bit due to smaller chainrings and that I'm not seeming to hit anything in the conditions where I'd expect to.
    "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

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  22. #22
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    Quote Originally Posted by Jayem View Post
    I ride a 13.3" static BB bike and have no problems with it, modern chainrings are smaller and more out of the way. When considering super chunky terrain, downhill trails found at ski resorts (chutes, big obstacles, etc), and everything else I ride-it's interesting that it's the smooth bermed trails where I occasionally drag a pedal on the ground and notice it. On DH trails I'm keeping my pedals level or lowering the outside one, but I never seen to have any problem there (and I got carbon cranks now ). This BB height feels good, especially because it's a 29er with 6" of travel, which means you don't feel like you're riding on a sky-scraper, more riding "in" the bike. I definitely know the benefit of 14" in really rough/rocky terrain, but now I'm starting to doubt that a bit due to smaller chainrings and that I'm not seeming to hit anything in the conditions where I'd expect to.
    The Ventana I rode for years had a high BB, which was made even higher by the big volume tires I was running. For someone riding a small and being 5'4", the BB height feels extremely high. This made steep DH sections particularly scary and cornering really unstable. Never scraped a pedal though.

    Note that your tire choice is also going to affect the BB height too. Manufacturers usually have a tire size in mind when they design the bike with a specific BB height.

    Now that I'm on an Ibis Mojo HD, the BB height is much more realistic, but the Fox CTD blows through its travel too quickly so I'm striking pedals (usually on the climbs) until I get the rear shock replaced with the Monarch Plus.

    In order to deal with pedal strikes (which my guess is why the OP posted this) is to learn to time your pedals and ratchet. Everyone used to do that when hardtail 26" frames was all people had. With suspension and different size wheels, BBs got higher and the need for ratcheting was disappearing. Now that 26"/650B bikes are going with much lower BBs, it looks like there's a need for ratcheting again.

  23. #23
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    My BB is about 12.75" and I do smack my pedals now and then going through rock gardens, and occasionally on root-infested climbs. (Usually the roots are easier to see and plan for.)

    When I first switched from Eggbeaters to Rove DH platforms I noticed I had given up some ground clearance, but I've adapted ok.

    I'd like to try a bike with a 1" higher BB.

  24. #24
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    Striking pedals low speed on climbs can get tiring, but if it's only once in a while and the type of suspension is factored in, the trade off is well worth it.

    Once you get over 10-15 mph and need to pedal in between tech spots is where your calculations could matter a bit more. You don't want to be smacking a crank arm at speed on something you didn't see

    Best to get the bottom bracket drop figure from the manufacturer so you can take the front and rear tire heights out of the equation, you don't always know what tires they used to post BB height on their geometry chart.

  25. #25
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    My 5" travel Spitty is 12.8" static and that's about the lowest you should go (with 175mm cranks). I LOVE it, no strikes but I sure am glad to have my I9 rear hub for instant engagement/ratcheting the pedals for technical climbs!

    Have FUN!

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