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  1. #1
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    Does BB height matter to you?

    It seems that BB height trends dictate that a lower bottom bracket is ideal. But my 5.5"-travel trailbike's 13.2 inches BB height seems to be too low for me because I keep on hitting my pedals. But I'm building another bike (old 6"-travel frame) which has 14.5 inches of BB height. I'm anticipating that there is quite a huge difference. Will it be drastic? How would it feel? Or is it just a matter of getting used to?

    Whadya say? What could be an ideal BB height for the current AM bikes that are supposed to be the best balance of various compromises?

  2. #2
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    bb height is so user and terrain specific that it's hard to take one person's experiences and apply that to yourself. Sure, a low bb height is really nice when you coast through the rough and there isn't much rough to slog through, but if you're a pedaller, run flats, and have rough trails, a higher bb is going to serve you better.

    For my part, my long travel hardtail has an 11.5 inch bb height before sag, which is super super super fkn low, and it's awesome 80% of the time. When it sucks it's super obvious,and whether you're willing to tolerate it depends on you and your trails.

    A small change in bb height is pretty obvious to the rider, but what works out to be the best compromise is a pretty user-specific deal. Sorry i don't have a number that is the best, but this is totally a riding-style speciic number.
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  3. #3
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    It does to me but depends on bike travel.
    I prefer 13.0"-13.5" for 4" FS bike. Inch lower on HT.
    For 13.5-13.75" for 5"-5.5" FS bike.
    And 13.75"-14.0" for 6" FS bike.

    13.2" to 14.5" BB height will be a huge difference. Less pedal smash on rocks but you won't corner as well and will feel little tipsy during slow technical moves.
    sth

  4. #4
    TNC
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    BB height is always an interesting discussion. scott is so correct about some of this being preferential. I absolutely hate serious pedal smack, and some bikes have it in spades...others don't. There are so many factors. On the handling issue with some tall bikes and many riders, there is often a problem with a decently tall BB. I had an '03 Bullit with a very tall BB...forget the number at this point...but I had installed a longer shock and fork. Though it didn't quite carve like my Nomad, I had no problem with fast cornering. I've ridden some other tall BB bikes and didn't have much cornering issue with them either.

    I got to thinking that perhaps it was because I was used to riding very tall long travel dirt motors. While not a 100% comparison, you have to be very conscious of where the CG of the dirt motor is when you lean it into a corner aggressively. The height of the bike is less of an issue when you have the CG planted directly over the tires and into the bike's footprint...if you get my drift. I basically do the same thing with my mountainbikes, right or wrong. I think lots of people are more into steering and remaining as upright as possible. Of course you have to lean to some degree regardless of skill or fear factor, but leaning into the corner right at the point of the bike's CG and tire contact point being in line diminishes the impact of the BB height. It's a little bit of balancing act, and it can bite you once in awhile, but you can get used to it.

    Funny thing...that Bullit didn't pedal all that efficiently, but you could pedal that sucker through some pretty nasty rock gardens without pedal smack. On the last trip to Moab with a riding buddy, his frame broke on his Spec Enduro the second day out on a 10-day trip. I bring the Bullit as a backup bike, and even with a 170mm single crown fork and the OEM sized 8.5 X 2.5 shock, the Bullit is known for a tall BB. My buddy rode that bike the rest of the trip, noticed the serious lack of pedal smack in many of the technical, rocky trails there, and absolutely loved it. As already stated...people are different.

  5. #5
    wuss
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    Quote Originally Posted by titaniumgearsolid
    It seems that BB height trends dictate that a lower bottom bracket is ideal. But my 5.5"-travel trailbike's 13.2 inches BB height seems to be too low for me because I keep on hitting my pedals. But I'm building another bike (old 6"-travel frame) which has 14.5 inches of BB height. I'm anticipating that there is quite a huge difference. Will it be drastic? How would it feel? Or is it just a matter of getting used to?

    Whadya say? What could be an ideal BB height for the current AM bikes that are supposed to be the best balance of various compromises?
    Don't take anyones word regarding BB height too seriously unless you know they are riding similar trails. The lower ones will feel better when carving along, but if your trails are very rocky you'll just end up banging your pedals all the time and losing your flow.

    My trails are very rocky, and low bikes just don't work very well here. Luckily I have adjustable drop outs (which I generally have to keep on their highest setting for most trails around here). However I've been riding some places where the trails are smooth enough that banging pedals would never be an issue, there the lower BB would work great.

    You can learn to smack pedals less, but it's not just about skill.

    Also, when you look at the listed BB heights remember that it's an unsagged value. My previous bike had a higher BB on paper, but the increased travel and the way the suspension is set up results in the new one having a lower BB when sagged and with compressed suspension. I don't think the different drop out settings on my bike make more then a 3-5mm differnce in BB height, but it feels like a huge difference on the trail.

  6. #6
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    Thanks for the responses so far.

    I did some back-reading on my old MTB magazines, and I noticed that my 2005 6"-travel frame's "batchmates" had pretty much the same lofty BBs. Mine is a 2005 Giant Reign and the others from the same magazine article were a Cannondale Prophet, Gary Fisher Cake, Kona Dawg and Marin Quad TARA. All their BB heights hovered at around 14 inches, considering most of them were 5"-travel trailbikes. I guess that was the trend during that time, to have that much ground clearance on their BBs.

    So, now I'm thinking that if ever the Reign's BB feels a tad too high, I could just try compensating by dialling more suspension sag. Which leads me to this question: how much sag is too much? (Just for a point of reference, I've always found 28-29% of sag on my 5.5"-travel DW-Link bike to be its sweet spot.)

  7. #7
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    Suspension design can affect how much sag you should have (and usually does). Also the shock you have can make a difference on what works. If you have something that blows through it's travel easily (RP23 with too low compression tune or high volume casing for example) increasing sag could result in quite compromised suspension performance.

    But it's definitely something worth trying. I used to have an air cartridge in my fork and switched to coil. It travels far higher in travel resulting in a higher BB. This will probably allow me to use one step slacker setting my my drop outs keeping the BB at the same height as before (it's winter now so hard to judge, snow evens out all the rocks). On the opposite note I tested having a softer spring on my shock last autumn and it caused me to bash my pedals quite a bit more.

  8. #8
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    i look a tt length, ha, and sa before i check bb height. to me it is not a huge deal, i assume, maybe naively, that the bike manufactor will get it right. it has never detered me from buying a bike.

  9. #9
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    Quote Originally Posted by titaniumgearsolid
    It seems that BB height trends dictate that a lower bottom bracket is ideal. But my 5.5"-travel trailbike's 13.2 inches BB height seems to be too low for me because I keep on hitting my pedals. But I'm building another bike (old 6"-travel frame) which has 14.5 inches of BB height. I'm anticipating that there is quite a huge difference. Will it be drastic? How would it feel? Or is it just a matter of getting used to?

    Whadya say? What could be an ideal BB height for the current AM bikes that are supposed to be the best balance of various compromises?
    Going to a 1.3 inch higher BB before sag with hardly any more travel is a huge difference. Some of the change in handling and balance can be reduced by using much deeper sag, softer springs, and tune a little firmer damping to prevent too much wallow from the higher weight center and softer suspension.

    There is no ideal BB height. Rock crawlers like higher BB for pedaling clearance to avoid dangerous pedal strikes. Downhill riders with mostly smooth climbing prefer lower BB where pedal clearance is a rare problem. Longer travel bikes with softer suspension need higher BB to maintain some pedal clearance when sagged and compressed further in turns and while pedaling through bumps.

  10. #10
    TNC
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    I don't think I'd put a lot of sag into the Reign to achieve a lower BB. Most bikes get mushy and harder to handle in many types of terrain. Even with carefully tuned compression and rebound, excessive sag usually has more negatives than positives in the resulting ride. Some examples are where the sagged bike tries to stop in slower, technical terrain...the geometry and feel of the bike changes in hard cornering at just the wrong point...and pedaling efficiency is almost always affected negatively. It's not a good bandaid. As dropadrop suggested, strictly going by BB numbers is not the whole picture.

  11. #11
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    If your pedals hit the ground or rocks, then some work on your technique is required. If your BB hits the ground or rocks, then a higher BB is the solution.
    Check out my SportTracks plugins for some training aid software.

  12. #12
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    Quote Originally Posted by PissedOffCil
    If your pedals hit the ground or rocks, then some work on your technique is required. If your BB hits the ground or rocks, then a higher BB is the solution.
    I don't know about that statement. I don't think there's one blanket that can be thrown over this whole issue. There's some truth there in many situations, but it's not absolute depending on terrain and the bike...even a bike in perfect setup. The myriad of bike designs and suspension designs alone just about make that impossible.

  13. #13
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    Quote Originally Posted by TNC
    I don't know about that statement. I don't think there's one blanket that can be thrown over this whole issue. There's some truth there in many situations, but it's not absolute depending on terrain and the bike...even a bike in perfect setup. The myriad of bike designs and suspension designs alone just about make that impossible.
    Yes, it's to be taken lightly. My point was that everybody talks about pedals hitting the ground, yet you have control over that in many cases. It can be annoying, I agree, but it's something to keep in mind.
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  14. #14
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    Ratcheting won't get you there all the time. A lot of times you just can't get enough power to get over some big rocks without at least full revolution. It's also dependent to some degree on your rear hub engagement. There's one super rocky trail I hit my pedals at least 5-6 times per ride. The more I focus on avoiding pedal strikes, the more problems I have with not cleaning sections I've cleaned successfully before.
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  15. #15
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    High BB in Michigan for that rocky/rooty crap.

  16. #16
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    As people have said, it's a ton of personal preference. I ride a ton of rocky stuff and yet prefer a low BB for handling traits. I don't mind having an occasional pedal strike and have gotten quite good at timing pedaling to avoid them.

    FWIW the two bikes I ride the most are a 5/6" FS AM bike with a 13" static BB height and an 8" FS DH bike with a 12.9" static BB.

  17. #17
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    adjustible seatpostto lower CG

    Don't worry too much about the BB height as per these posts!
    Put an adjustible seatpost on your bike and lower your CG by alot when needed.
    I'm rocking a 14.65 in. BB with a 4in drop seatpost! No problem what so ever!

  18. #18
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    I have ridden FS bikes anywhere from 13" to 15". As mentioned very terrain specific. Some of my worst pedal smackers were 5" trail bikes equipped w/ air shocks - they just ate travel making the pedals magnetize to the ground. Anytime I went into rocks I felt like I was driving a lowered car approaching a speed bump.

  19. #19
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    Quote Originally Posted by Hardtails Are Better
    8" FS DH bike with a 12.9" static BB.
    Holy cripes!! You probably can't even pedal that thing out of turns
    On my 7" bike with a 14.1" BB and 36% sag i reeeally have to be careful.

    I can now see the future of DH. Bike parks with tracks that require no pedaling.. hence bikes with no drivetrain and uber low BB's.
    Last edited by PsyCro; 01-26-2011 at 02:29 AM.

  20. #20
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    Quote Originally Posted by PsyCro
    Holy cripes!! You probably can't even pedal that thing out of turns
    On my 7" bike with 36% sag i reeeally have to be careful.

    I can now see the future of DH. Bike parks with tracks that require no pedaling.. hence bikes with no drivetrain and uber low BB's.
    You'd be surprised. I've learned to ride it, and it works pretty damn well. Is it too low? Honestly, yes. Is it a lot to low? Nope.

  21. #21
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    Quote Originally Posted by PissedOffCil
    If your pedals hit the ground or rocks, then some work on your technique is required. If your BB hits the ground or rocks, then a higher BB is the solution.
    So basically you are saying that pedals can never be too low. I have to assume we are riding very different trails.

  22. #22
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    Quote Originally Posted by dropadrop
    So basically you are saying that pedals can never be too low. I have to assume we are riding very different trails.
    I'm saying that a higher BB is the easy solution. Working on timing your pedals is also a solution until the BB hits the ground or rocks.

    East coast root & rocks are as bad as it gets to smash your pedals. But we learn to deal with it here. Not to mention that riding trials has improved my handling a lot.
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  23. #23
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    Shouldnt BB height be dictated by your terrain and style. Having ridden several places in the east coast and now living in texas, for smoother faster and/or twisty trails I can see a low bb height being a good thing. I have also ridden some place where the number of logs, tombstone rocks and other crap requires where you ride slower a higher bb is the way to go..

  24. #24
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    Quote Originally Posted by titaniumgearsolid
    Thanks for the responses so far.

    I did some back-reading on my old MTB magazines, and I noticed that my 2005 6"-travel frame's "batchmates" had pretty much the same lofty BBs. Mine is a 2005 Giant Reign and the others from the same magazine article were a Cannondale Prophet, Gary Fisher Cake, Kona Dawg and Marin Quad TARA. All their BB heights hovered at around 14 inches, considering most of them were 5"-travel trailbikes. I guess that was the trend during that time, to have that much ground clearance on their BBs.

    So, now I'm thinking that if ever the Reign's BB feels a tad too high, I could just try compensating by dialling more suspension sag. Which leads me to this question: how much sag is too much? (Just for a point of reference, I've always found 28-29% of sag on my 5.5"-travel DW-Link bike to be its sweet spot.)
    If you have an air shock, try more sag and see how it rides.
    I had a Reign X1 with too stiff a spring (15-20% sag), then I swapped to too soft a spring (30-35% sag) and it rode better in some ways, and felt really smooth pedaling, but I banged my pedals more.

  25. #25
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    I don't think it's a good idea to play with sag to get the ideal BB height IMHO. Getting the correct sag, hence getting the best shock absorption is the main idea, and getting the BB low as a result.

    The pedal smacks only occurs on gnarly stuffs and by running too high a pressure to raise the otherwise low BB, the bike will be bouncing all over the place. And to run a lower pressure to bring an overly high BB down, you'll risk bottoming out and bike wallowing too.

  26. #26
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    Quote Originally Posted by Kaizer
    I don't think it's a good idea to play with sag to get the ideal BB height IMHO. Getting the correct sag, hence getting the best shock absorption is the main idea, and getting the BB low as a result.
    i concure. you may get your bb to the perfect height but if your shock works like poo who cares?

  27. #27
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    Quote Originally Posted by PissedOffCil
    If your pedals hit the ground or rocks, then some work on your technique is required. If your BB hits the ground or rocks, then a higher BB is the solution.
    I am a trail rider that rides for fun - I don't care to increase my skills by focusing on an absolute pedal position technique.

  28. #28
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    Quote Originally Posted by keen
    I am a trail rider that rides for fun - I don't care to increase my skills by focusing on an absolute pedal position technique.
    Getting better is kind of fun! Try it.

    Let me recount this story that occured at the start of last season. I was with a bunch of folks of a local club. We we're probably around 15 riders of all levels with a bunch of different bikes. We were in Bromont. I had my XC hardtail, 11.5 inch BB height. Since it's the start of the season, not all trails we're all cleaned up so we stumble upon a fallen tree. The tree was about 1.5 foot high so of course everybody stops, dismounts, passes the bike and resumes on the other side. Well I had been riding the trials bike for a little while and was confident I could pass the tree. So I stopped 10-15 feet away from the tree, trackstand and wait for those in front of me to pass the tree. Once they cleared the way I take a couple of pedal strokes to gain speed, quickly rose my front wheel as I reached the tree, bunny hoped about 1 feet high. I didn't clear the tree with the hop, but had just enough height for my big ring to dig in the trunk. With proper pedal placement I gave it a good stroke, passed the tree and landed on the other side, without ever putting my feet on the ground.

    It was fun and no amount of "bike" would have helped me pass that tree. I believe the same applies for rock gardens, you can do it the easy way and blame the equipment/trail or you can try the hard way and improve, pushing your limits.

    It's your choice, my mind is made.

    Bye bye.
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  29. #29
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    Lower is better for CG and balance, however in rocky CT i always look for a bike that has at least 13.75" of clearance, and go double ring/bash setup. I have a blur that i do not like because of the low bb, and i run 170mm cranks on it.
    All the skill in the world, may help, but doesn't change the fact a higher bb is a better idea for certain riding locations.

  30. #30
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    When I went from the old style 575 frame (pre '08) to a newer style '08 model the very very first thing I noticed when I got it out to a familiar trail was that I was hitting my pedals much more than on my old bike. I knew they lowered the BB a bit but I didn't expect it to make that much difference. I quickly put a longer travel fork on it to help out a bit, and sent the shock to PUSH as it wallowed too much exasperating the problem.

    Sure, I have adapted as much as possible but I'll take a high BB any day for chunky Phoenix riding thanks. +14'' would be great but I think I'm at 13.75 or so now.

  31. #31
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    I've measured about 3mm bb height difference between the steepest and middle drop out setting on my uzzi. The middle setting causes way more pedal strikes which seems surprising. I tried the slacker setting for about 2 months but had to go back. Now I changed to a coil cartridge in my fork and will try the middle setting again.

  32. #32
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    I agree, the height matters. On my Fat Possium I had almost no pedal hits, on my Anthem X3 I clip them at least 2 to 3 times a ride. Like both bikes for different reasons though.

  33. #33
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    Quote Originally Posted by titaniumgearsolid
    It seems that BB height trends dictate that a lower bottom bracket is ideal. But my 5.5"-travel trailbike's 13.2 inches BB height seems to be too low for me because I keep on hitting my pedals. But I'm building another bike (old 6"-travel frame) which has 14.5 inches of BB height. I'm anticipating that there is quite a huge difference. Will it be drastic? How would it feel? Or is it just a matter of getting used to?

    Whadya say? What could be an ideal BB height for the current AM bikes that are supposed to be the best balance of various compromises?
    I have found that pedals hitting the ground and other stuff is something I can learn to avoid doing once I get used to the bike, though it will take a number of pedal strikes for that to happen. My last bike had a pretty high bb, and even though I did not care for it, it still took me a little while to get used to the lower bb of my current ride (by get use to I mean learn to not smack the pedals). However, I did adjust, and I do prefer it.

    I have yet to ride terrain that makes me want a high-ish bb. I have always preferred the lower bb's. Yes, certain challenging rock gardens that I've never done before will take a little more care, but for just about every other situation (steep climbs, steep descents, cornering, most rough sections at speed, most slow technical maneuvers, and anything with an OTB risk) I prefer a lower bb. The balance and control over the bike feels better to me. So even on terrain that have had places that favor a higher bb, with that also comes more features that (for me) favor a lower one.

    Of course everything is relative, I would not want a 5" bike with a 12" bb. But within the range that frame designers have settled into, I find the lower ones work best for me.

    As someone else mentioned, as you increase travel, you also nee to increase the bb height to account for the extra compression. This is one reason I have gravitated back to 5" bikes from 6" ones.
    15mm is a second-best solution to a problem that was already solved.

  34. #34
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    Quote Originally Posted by kapusta
    Of course everything is relative, I would not want a 5" bike with a 12" bb.
    I actually tried something close to that, it was about 12.2" with 4.6" of travel or something. It was on my old Bottle Rocket with a shortened shock and lowered fork. It had -1.5 degree headset cups in it too, so it had a HTA in the 65 degree range. It was stupid fun on smoother, flowy bermed stuff, and jumped very well, but was damn near unrideable in a lot of other situations.

  35. #35
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    While we're talking about extremes- my 5" hardtail has a 11.5" static bb height, just for laughs. It works pretty well, you have to take chunk/logovers/etc with speed, but it feels more stable when you do it. Too low, for sure, but a lot of the time i like it.
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  36. #36
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    My enduro (6" bike) has a 13.7 BB height and my Rize has a 13.0 (5" bike). I bang the crap out of my rize in colorado rocks. Still hit the enduro but not as much. As far as on way down they are two total different bikes that i do not think has much to do with BB height. But for climbing that little bit makes a big difference. I say to each there own.

  37. #37
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    My Ibis Mojo SL has a 13.2" bottom bracket. I bang pedals much more often than on my 2002 Ellsworth Truth and more than on my hardtail Voodoo Bizango with a 12" bottom bracket height; however, I am more likely to pedal through technical stuff with the Mojo than with the Voodoo because you can just sit and pedal the Mojo and it goes.

    I'll take the pedal hits and wouldn't change a thing about the Mojo. As I get used to the bike, I'm banging the pedals less. And the pedal hits gave me a really good excuse as to why I 'NEED' new wheels with hubs that have almost instant engagement! I had wanted to upgrade the wheels anyway, but having a really good rationale is bonus!

  38. #38
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    13.2 is pretty hight! My FS right now is at 12.5"... Wanting to raise it up to about that...

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    oooold thread resurrection....

    I'll play, I do notice lower BB heights. I can adjust my technique to accommodate for it, I enjoy that part of it. I'm always trying to be a better rider, the first ride out on my new bike that got pedal strikes I just took the mindset "oh, ok, gotta figure out my pedal strokes better"
    Deflated - buy parts to sell parts to buy more parts.. bikes are my drug of choice

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  40. #40
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    BB height matters a ton to me, as all I do is seek rocks to play in.

    luckily, I got a new AM bike with a nice tall BB, so...no worries

    13.3 inches/338mm

    338 is actually the -average- height of 2016 production 27.5 FS 'trail' bikes

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  41. #41
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    13.3 is high?! My last bike was 14.6. 13.3 is pedal banging low.

  42. #42
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    Just went to 165mm cranks. No more BB issues.

  43. #43
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    Only to the extent that I have pedal strikes that aren't my fault.

  44. #44
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    Quote Originally Posted by Dr Evil View Post
    Just went to 165mm cranks. No more BB issues.
    what is your inseam measurement? not pointing fingers, i just have the preconceived notion that shorter crank arms work better for riders with relatively shorter legs but I could be wrong.

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    Quote Originally Posted by TheBaldBlur View Post
    what is your inseam measurement? not pointing fingers, i just have the preconceived notion that shorter crank arms work better for riders with relatively shorter legs but I could be wrong.
    36" and they work fine for me. I need a slightly lower gear, like one, two cog difference to feel right at home.

    I'm not currently running any, but i would if i already had them.
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    Quote Originally Posted by TheBaldBlur View Post
    what is your inseam measurement? not pointing fingers, i just have the preconceived notion that shorter crank arms work better for riders with relatively shorter legs but I could be wrong.
    29".

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    Quote Originally Posted by Dr Evil View Post
    29".
    is twentynine still gay
    or is that old false word
    oops I wasn't clipped in

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    Quote Originally Posted by scottzg View Post
    36" and they work fine for me. I need a slightly lower gear, like one, two cog difference to feel right at home.

    I'm not currently running any, but i would if i already had them.
    ah, same here - so my notion is wrong, good to know! I suppose you have to insert the seat post a little to compensate, but that's no biggie. Thanks!

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    I think raising or lowering the five-pass height has little effect on the stability of the bike.

  50. #50
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    BB height absolutely matters to me. Coming from a bike with roughly a 12.75" bottom bracket height to an Intense Recluse with a 13.5 and its a HUGE difference in clearance. Ill take the slightly "higher" BB any day of the week in the Midwest. Or anywhere that you have to pedal.

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    Higher BB is going to be one of the priorities on my next bike. I'm recovering from another tumble resulting from a pedal strike. Apparently the geo specs (at least from Specialized) do not include suspension sag. Although my hard tail Fuse is supposed to be lower than my SJ I have much better clearance riding the Fuse. The higher BB doesn't hurt my handling or stability, so I don't know the point of the low BB. Since I have had my SJ I stay worried about pedaling because I've had so many strikes, and it takes away from the fun and makes me slower. I keep the shock pumped up to max pressure to hold me higher, so the travel doesn't even get utilized.
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    Quote Originally Posted by TNTall View Post
    Higher BB is going to be one of the priorities on my next bike. I'm recovering from another tumble resulting from a pedal strike. Apparently the geo specs (at least from Specialized) do not include suspension sag. Although my hard tail Fuse is supposed to be lower than my SJ I have much better clearance riding the Fuse. The higher BB doesn't hurt my handling or stability, so I don't know the point of the low BB. Since I have had my SJ I stay worried about pedaling because I've had so many strikes, and it takes away from the fun and makes me slower. I keep the shock pumped up to max pressure to hold me higher, so the travel doesn't even get utilized.
    All FS bikes are measured static for future reference. None of them account for sag percentage when giving a BB height.

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    BB bracket height preference seems to be pretty dependant on terrain, riding style etc. That being said there does seem to be an emerging range (given current geo tends anyways) that is believed to maximize overall performance.

    I've been toying with throwing 29er wheels/fork and shorter stroke shock on my current 650b bike. It would bump the bb to 13.7 and 14.3 in the two modes. Trying to get my head around that bb height for a 29er (which I've never owned).
    "Slow is smooth, and smooth is fast."

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  54. #54
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    Yes, it does matter. In my bike's low bb gravity mode, I mashed a pedal into a large boulder at Whistler and got launched into a pile of rocks. On another black diamond trail I couldn't clear any of the roots and boulders until I put my bike into the high bb trail mode. We don't have very much for high-speed corners here in the PNW and so a low bb really hinders riding over the piles of boulders, logs, and roots. Ratcheting the pedals up a 20' section of roots on a steep climb doesn't work.
    Riding Washington State singletrack since 1986

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    Quote Originally Posted by Curveball View Post
    Yes, it does matter. In my bike's low bb gravity mode, I mashed a pedal into a large boulder at Whistler and got launched into a pile of rocks. On another black diamond trail I couldn't clear any of the roots and boulders until I put my bike into the high bb trail mode. We don't have very much for high-speed corners here in the PNW and so a low bb really hinders riding over the piles of boulders, logs, and roots. Ratcheting the pedals up a 20' section of roots on a steep climb doesn't work.
    Boom. My man.

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    Quote Originally Posted by Curveball View Post
    Yes, it does matter. In my bike's low bb gravity mode, I mashed a pedal into a large boulder at Whistler and got launched into a pile of rocks. On another black diamond trail I couldn't clear any of the roots and boulders until I put my bike into the high bb trail mode. We don't have very much for high-speed corners here in the PNW and so a low bb really hinders riding over the piles of boulders, logs, and roots. Ratcheting the pedals up a 20' section of roots on a steep climb doesn't work.

    So, what BB height range is to low for you, and what range do you find to allow you to peddle/ride through rocks and roots, but not be too high to negatively effect stability and handling?

    Opinions on what is low /too low or high/too high seem to have changed a lot around when I started riding, and is area dependent. I'm interested in actual numbers that people like.
    "Slow is smooth, and smooth is fast."

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    Quote Originally Posted by SingleTrackHound View Post
    It does to me but depends on bike travel.
    I prefer 13.0"-13.5" for 4" FS bike. Inch lower on HT.
    For 13.5-13.75" for 5"-5.5" FS bike.
    And 13.75"-14.0" for 6" FS bike.

    13.2" to 14.5" BB height will be a huge difference. Less pedal smash on rocks but you won't corner as well and will feel little tipsy during slow technical moves.

    Is this universal across wheel sizes for you? Or would these be slightly different for 29er vs 27.5?

    My current bike 13" in gravity mode and 13.4" in trail mode (165mm vs 150mm rear travel). At this point I don't get peddle strikes anymore, but I went from 175mm cranks to 170mm to help, and then of course adjusting to the bike.

    I live in rocky AZ and I think I would enjoy a slightly higher BB. I find it pretty interesting what people like.
    Last edited by kmj831; 09-05-2018 at 06:59 PM.
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  58. #58
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    Quote Originally Posted by kmj831 View Post
    So, what BB height range is to low for you, and what range do you find to allow you to peddle/ride through rocks and roots, but not be too high to negatively effect stability and handling?

    Opinions on what is low /too low or high/too high seem to have changed a lot around when I started riding, and is area dependent. I'm interested in actual numbers that people like.
    The mfg. lists it as 329 mm in gravity mode and 334 mm in trail mode. I'm surprised at what a difference 5 mm makes. I wouldn't mind another 5 mm on it.
    Riding Washington State singletrack since 1986

  59. #59
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    I just checked and if I convert my bike to the enduro version I'll be at 330 and 340.

    I really need to do a service on the fork anyway and so I think I'll go this way. It might be an interesting ride with more travel.
    Riding Washington State singletrack since 1986

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    Quote Originally Posted by Curveball View Post
    Yes, it does matter. In my bike's low bb gravity mode, I mashed a pedal into a large boulder at Whistler and got launched into a pile of rocks. On another black diamond trail I couldn't clear any of the roots and boulders until I put my bike into the high bb trail mode. We don't have very much for high-speed corners here in the PNW and so a low bb really hinders riding over the piles of boulders, logs, and roots. Ratcheting the pedals up a 20' section of roots on a steep climb doesn't work.
    Agreed......the trend towards lower BB is not working well for me on my PNW tecnical climbing trails as well. Judging by the number of rocks being removed and roots actually being cut out or shaved off I see it isn't working well for others either.

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    Quote Originally Posted by Xterra123 View Post
    . Judging by the number of rocks being removed and roots actually being cut out or shaved off
    Noooo!
    "Slow is smooth, and smooth is fast."

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  62. #62
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    Quote Originally Posted by kmj831 View Post
    Is this universal across wheel sizes for you? Or would these be slightly different for 29er vs 27.5?

    My current bike 13" in gravity mode and 13.4" in trail mode (165mm vs 150mm rear travel). At this point I don't get peddle strikes anymore, but I went from 170mm cranks to 165mm to help, and then of course adjusting to the bike.

    I live in rocky AZ and I think I would enjoy a slightly higher BB. I find it pretty interesting what people like.
    Bottom bracket height accounts for tire height. Bottom bracket drop, which is sometimes used on geometry charts, does not.

    Sag matters a lot. Most people ride xc bikes with 20% sag or so, give or take 5%.

    You have more sag with more travel up to maybe 35-40%.

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    Does BB height matter?

    Only as much as my toes.

  64. #64
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    A higher BB will be one of my main criteria next purchase.

    My 27.5 Stumpy has whacked pedals to an annoying extent. I've busted two pedals and fallen acouple of times.
    Less isn't MOAR

  65. #65
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    Quote Originally Posted by kmj831 View Post
    .

    I live in rocky AZ and I think I would enjoy a slightly higher BB. I find it pretty interesting what people like.

    I live in ride primarily in the Phoenix area so I know what you're talking about. My old Yeti 575 had a bottom bracket height of maybe 14.25 Certainly it was over 14 in. The Next Generation 575 I bought had a much lower bottom bracket somewhere around 13.5in. I noticed it right away and it took me some time to relearn how to ride some of the same type of trails without constantly smashing a pedal.

    Low lottom brackets are certainly not ideal for rocky terrain and I would prefer if my bike were back up around 14 in but it is what it is and I learned a ride what I got.

  66. #66
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    Definitely matters around here.
    My FS bike may have 30% sag, but my previous hardtail had 36mm more(-58) BB drop, and that was just a bit too much.
    I've gotten pedal strikes from upthrust roots on some of our XC trails when not paying attention, and they're pretty much inevitable on my favorite trail. Even 5mm of crankarm length can make a difference in how often the inevitable happens, though.
    We don't have a lot of huge chunky stuff, but there are lots of rocks and roots, and my rides are mostly either out-n-back or loops that can be ridden in either direction. Except for loops you choose to ride only one way, you're gonna climb the same stuff you descend sooner or later. The climbs and descents look a lot alike(short!), anyway, when your trails are continuously up and down between ridges. I don't consider it a negative, because the trails we have would mostly be straight up XC and pretty boring without all those roots and rocks.

  67. #67
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    I definitely do not want a super low BB. Our trails are too chunky to make that even remotely fun.

    I've got:

    Bike A - 13.3" BB with 130mm rear travel + 170mm cranks
    Bike B - 13.75" BB with 140mm rear travel + 175mm cranks

    Same pedals on both.

    I whack pedals on Bike A a fair bit. I rarely strike pedals on Bike B. If you do the math [sag + crank delta] the actual pedal height difference is small, but it's enough to make a huge difference in how those bikes pedal through chunk.

    I've been biking long enough that I can ratchet through a tech section just fine. The problem is when 75% of your riding is comprised of tech sections including lots of steep climbs...having to ratchet like a mofo is approximately zero fun.
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  68. #68
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    I prefer bikes with as high a BB as possible. Firstly it just helps pedal over things and pedal through turns, which is great for maintaining speed. But it also means that the suspension can be designed with a more rearward axle path for better bump compliance without having it negatively affect chain growth.
    Shorter seat tubes, taller droppers.
    Shorter chainstays, taller stacks.
    Shorter stems, taller BB's.

  69. #69
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    Quote Originally Posted by vikb View Post

    The problem is when 75% of your riding is comprised of tech sections including lots of steep climbs...having to ratchet like a mofo is approximately zero fun.
    Man, do I agree with this!! You always hear people saying "oh, just learn to ratchet". Yeah, OK. Come ride a trail full of roots and rocks and tell me how much fun you are having when you can't do anything but ratchet!


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    I love watching the videos that manufacturers put out for their bikes - fun to watch but those trails dont look like the stuff I am riding. 100-200 foot rock gardens not go well with low bottom brackets. I wish I lived where those videos were shot but it just isnt going to happen....

    So I just pulled the trigger on a new Santa Cruz Hightower. Bought the 27.5 version to get the longer travel fork and have an order in for 29er wheels. Longer fork + 29er wheels + flip chip in high position = 13.6 inch bottom bracket. These are the hoops we jump through to make a bike work as well as possible in our local area. Might still go ahead and swap out the crank for a 170 just to get a little more clearance.
    Last edited by SqueakyWheel73; 4 Weeks Ago at 03:13 AM.

  71. #71
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    Quote Originally Posted by SqueakyWheel73 View Post
    So I just pulled the trigger on a new Santa Cruz Hightower. Bought the 27.5 version to get the longer travel fork and have an order in for 29er wheels. Longer fork + 29er wheels + flip chip in high position = 13.6 inch bottom bracket. These are the hoops we jump through to make a bike work as well as possible in our local area. Might still go ahead and swap out the crank for a 170 just to get a little more clearance.

    Man -- all that and you only got to 13.6"?

    My bike sits right about there when sagged. And it's still borderline too low for the way and places I like to ride.

    Long live truly high BB's.

  72. #72
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    Quote Originally Posted by mikesee View Post
    Man -- all that and you only got to 13.6"?

    My bike sits right about there when sagged. And it's still borderline too low for the way and places I like to ride.

    Long live truly high BB's.
    Able to get 13.9" out of my new Jet 9 RDO with 140mm fork and long shocking it 3.5mm longer.

    Back in the day had a Santa Cruz VP Free that sat at a ridiculous 15.5", you could pedal through and over anything on it.

    I still don't understand the need for these stupidly low BBs on modern "Trail" bikes?

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    I recently moved from a 2011 Tracer 2 with a 14"-ish BB to a 2017 Devinci Troy with a 13.3" one. Our trails are quite technical (lots of rocks, roots and steep ups/downs) and I am getting a lot more pedal strikes on the new bike than I ever did before. I've mitigated it a bit by stepping up my ratchet game a bit but honestly the new bike handles so much better in every other respect that this is a compromise I will happily make. I can raise it a bit on the Troy by flipping it to the "steep" setting (and I know lots of folks who have done this) but I find that has a negative impact on the ridiculously good cornering behaviour it has in the slack setting. I'm finding myself hitting corners (flat and bermed) way faster than I ever did on the Tracer because the Troy just hooks up and goes around. Worth it IMO.

  74. #74
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    2002 Gary Fisher Sugar 2 BB was a ridiculous 11.9"!
    http://www.vintage-trek.com/Trek-Fis...nualFisher.pdf

    2008 Yeti 575 had a BB height of 13.25 with a 140 fork.
    https://assets.yeticycles.com/static...6e071cbd6b.pdf
    Put a 160 on it, though and it jumps to 14".

    2013 SC 5010 was at 13.14".
    Enduro Mag – First Look: Santa Cruz Blur TR 26″ vs Solo 27.5″

    My Yeti SB5c with a 160 fork and 2.6" tires is 13.6".


    I'm just not seeing the huge trend to lower bb's, but I can see having a preference one way or another.

  75. #75
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    You want the BB as low as you can stand within reason for your typical conditions cause the bikes are really on rails with a low BB.

    For me, around 11.75" functional (when at sag) on 170 mm cranks is a minimum, and that's considerably higher than some modern bikes are when at sag.

    The SB130 runs .5" lower than my current Sb5.5. That's not something I could get on well with.

  76. #76
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    Quote Originally Posted by Suns_PSD View Post
    You want the BB as low as you can stand within reason for your typical conditions cause the bikes are really on rails with a low BB.

    Riddle me this:

    What's more effective at lowering CoG -- a bike with 1/4" lower BB, and all else equal, or a bike with 1/4 *higher* BB and a 6" dropper?

    Sure, the snarky answer is 1/4" lower *and* a 6" dropper.

    Point simply being that if you want a low CoG for getting around corners faster, dropping the saddle is way more effective than lowering the BB. And then you can still pedal through chunk and up ledgy climbs, too.

    You know, for the few people that still earn their ups...

  77. #77
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    I'm glad to hear everyone complain about low bottom brackets. I'm sick of reading threads where people tell you to just "ratchet through". I suspect the people that say that tend to do more shuttleing than technical climbing.

    I have a Mach6. It's bottom bracket is at 13.6. I certainly wouldn't want to go lower; a little higher like 13.8 or 14 would be nice. I do notice that on rough sections that require pedaling, I'm often slower than I was on my Yeti ASR-SL. Not because the latter is an xc bike, but simply because I have to be very careful where I pedal whereas on the Yeti, I could just power right through. It's kinda of frustrating because I like going fast. Overall, I prefer the Mach6, but that's my main gripe about it.

    I watch a lot of this videos put out by bike companies and, aside from the massive jumps the riders are launching off, the trail looks like I could ride a cyclecross bike on it at speed. Butter smooth. "Flow trails" are fun but so is riding up and down chunk.
    Nothing but sincerity as far as the eye can see!

  78. #78
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    Quote Originally Posted by mikesee View Post
    Riddle me this:

    What's more effective at lowering CoG -- a bike with 1/4" lower BB, and all else equal, or a bike with 1/4 *higher* BB and a 6" dropper?

    Sure, the snarky answer is 1/4" lower *and* a 6" dropper.

    Point simply being that if you want a low CoG for getting around corners faster, dropping the saddle is way more effective than lowering the BB. And then you can still pedal through chunk and up ledgy climbs, too.

    You know, for the few people that still earn their ups...
    Anyone that is turning aggressively, particularly over rough terrain, places minimal weight, or none, on their saddle. Regardless or not if you run a dropper, your seat height should be such that when your outside pedal is down, you are able to remove your weight from the saddle entirely. Your shorts will still be touching your saddle, but your weight will not be. If you push down on the outside pedal with it in the 5-6 o'clock position and are unable to remove your weight from the saddle, your saddle is too high.

    So now that we have established that regardless of your dropper height, your body weight is on your pedals ad this mostly decides your CoG (small effect from bike's CoG ad your handlebars being weighted), we only have the influence of the BB height as the center of gravity decider.

    There is apparently a very important geometry number that involves perceived stability of a 2 wheeled chassis being greatly affected by where the center of gravity is in relation to the axle centers. So now we are talking about much smaller numbers really mattering quite a bit as the % change is suddenly quite dramatic.

    They use to sale engine bracket relocation kits for the 2012ish YZ450 for instance and guys spent all sort of time using math to argue that 6mm (or whatever) as a % of the bikes weight was fractions of a percent and therefore insignificant. Except it turns out this mod provided a very significant improvement in overall handling of the motorcycle in real life. Ultimately it was about a significant lowering of the CoG in comparison to the axle centers, where a few mm's made a real % difference.

    ~ take care

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    Quote Originally Posted by Suns_PSD View Post
    Anyone that is turning aggressively, particularly over rough terrain, places minimal weight, or none, on their saddle. Regardless or not if you run a dropper, your seat height should be such that when your outside pedal is down, you are able to remove your weight from the saddle entirely. Your shorts will still be touching your saddle, but your weight will not be. If you push down on the outside pedal with it in the 5-6 o'clock position and are unable to remove your weight from the saddle, your saddle is too high.

    So now that we have established that regardless of your dropper height, your body weight is on your pedals ad this mostly decides your CoG (small effect from bike's CoG ad your handlebars being weighted), we only have the influence of the BB height as the center of gravity decider.

    There is apparently a very important geometry number that involves perceived stability of a 2 wheeled chassis being greatly affected by where the center of gravity is in relation to the axle centers. So now we are talking about much smaller numbers really mattering quite a bit as the % change is suddenly quite dramatic.

    They use to sale engine bracket relocation kits for the 2012ish YZ450 for instance and guys spent all sort of time using math to argue that 6mm (or whatever) as a % of the bikes weight was fractions of a percent and therefore insignificant. Except it turns out this mod provided a very significant improvement in overall handling of the motorcycle in real life. Ultimately it was about a significant lowering of the CoG in comparison to the axle centers, where a few mm's made a real % difference.

    ~ take care
    I think the point was that a dropper allows you to crouch when cornering better than if you don't have a dropper. I know when I want to rail a corner, it helps to drop the seat.

  80. #80
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    I definitely prefer a slightly taller BB. Its the one piece of the new designs I don't like.

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    On a Knolly Warden & like the low BB. I have become a better rider and now know when not to pedal. Riding through the rough stuff with a dropped heel does come at a price though. I am more of a chin over the bar rider anyways.

  82. #82
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    Quote Originally Posted by mikesee View Post
    Riddle me this:

    What's more effective at lowering CoG -- a bike with 1/4" lower BB, and all else equal, or a bike with 1/4 *higher* BB and a 6" dropper?

    Sure, the snarky answer is 1/4" lower *and* a 6" dropper.

    Point simply being that if you want a low CoG for getting around corners faster, dropping the saddle is way more effective than lowering the BB. And then you can still pedal through chunk and up ledgy climbs, too.

    You know, for the few people that still earn their ups...
    You're not wrong here but for those of us who are running a dropper anyway, the snarky answer is the right one. A dropper is absolutely mandatory equipment for me on any trail bike given our terrain and trails. So while I could definitely stand a bit more BB clearance on my bike, in my mind the extra pedal strikes are outweighed by the positive aspects of the low BB when going down. And I do have to earn all of my descents by grinding up technical climbs. YMMV, of course, but I'm addicted to the way my Troy goes down things and if the compromise is a lower BB than is ideal for tech pedaling then I'm ok with that.

  83. #83
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    Quote Originally Posted by PissedOffCil View Post
    Yes, it's to be taken lightly. My point was that everybody talks about pedals hitting the ground, yet you have control over that in many cases. It can be annoying, I agree, but it's something to keep in mind.
    Exactly. I once rode a bike with a blown up shock without knowing it... Was sitting over 50% into its travel and I first noticed because of pedal strikes. I had to get back to my car so I finished the ride and by the end I wasn't hitting pedals nearly as much, despite an absurdly low BB.

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    Quote Originally Posted by TheDwayyo View Post
    Exactly. I once rode a bike with a blown up shock without knowing it... Was sitting over 50% into its travel and I first noticed because of pedal strikes. I had to get back to my car so I finished the ride and by the end I wasn't hitting pedals nearly as much, despite an absurdly low BB.
    I agree that you can learn to compensate for a low bb height, but there is no way that I will make the statement that a low bb height is preferable for the riding that I do. I just wonder if bike manufacturers will ever make bikes that are designed for the trails / type of riding that I do.

  85. #85
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    Quote Originally Posted by SqueakyWheel73 View Post
    I agree that you can learn to compensate for a low bb height, but there is no way that I will make the statement that a low bb height is preferable for the riding that I do. I just wonder if bike manufacturers will ever make bikes that are designed for the trails / type of riding that I do.
    About the only way to compensate for a low bb on a long and super chunky climb is to get off and walk up.
    Riding Washington State singletrack since 1986

  86. #86
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    Quote Originally Posted by Suns_PSD View Post
    Anyone that is turning aggressively, particularly over rough terrain, places minimal weight, or none, on their saddle. Regardless or not if you run a dropper, your seat height should be such that when your outside pedal is down, you are able to remove your weight from the saddle entirely. Your shorts will still be touching your saddle, but your weight will not be. If you push down on the outside pedal with it in the 5-6 o'clock position and are unable to remove your weight from the saddle, your saddle is too high.

    So now that we have established that regardless of your dropper height, your body weight is on your pedals ad this mostly decides your CoG (small effect from bike's CoG ad your handlebars being weighted), we only have the influence of the BB height as the center of gravity decider.

    There is apparently a very important geometry number that involves perceived stability of a 2 wheeled chassis being greatly affected by where the center of gravity is in relation to the axle centers. So now we are talking about much smaller numbers really mattering quite a bit as the % change is suddenly quite dramatic.

    They use to sale engine bracket relocation kits for the 2012ish YZ450 for instance and guys spent all sort of time using math to argue that 6mm (or whatever) as a % of the bikes weight was fractions of a percent and therefore insignificant. Except it turns out this mod provided a very significant improvement in overall handling of the motorcycle in real life. Ultimately it was about a significant lowering of the CoG in comparison to the axle centers, where a few mm's made a real % difference.

    ~ take care

    It's almost like you took all that time to write what I already had, albeit in a different way.

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