BB height on 29er vs 26er?

doctapow said:

Are there any rules of thumb regarding BB height on 29er frames versus conventional 26in frames?

I guess without giving it much thought, I assumed 29ers would ride higher - but I just picked a 29er hardtail on clearance the other days (mainly for the parts) and found on riding it that I was getting a lot more pedal strikes than usual.

I got home and measured the BB height at 12in - my Yeti 575 is 13.5. That seems like a big difference - enough that I could notice it.

Is the 12in height typical for a 29er frame (this is a Fuji Tahoe FYI)?

just curious.

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That is the difference in hardtail vs full suspension rather than 29" vs 26".

Full sussies have higher BBs to accommodate the suspension travel.

29er HT's have similar BB height... but more BB drop (lower relative to the hub height)... which actualy lowers the center of gravity of the bike vs a higher bb

thanks for the replies.

it seems then that the 12in BB height on my 29er HT is not unusual - the Niner website claims 11.7in for the SIR9 which is a pretty popular and mainstream frame.

I read some backthreads here stating too that the 13.5in height on the Yeti 575 is also on the high-side for a FS 26" bike - so between that and the hardtail/FS differences, it is a noticeable difference. I definitely could feel the difference.

So is 12in pretty typical BB height for a 26" hardtail as well?

doctapow said:

thanks for the replies.

it seems then that the 12in BB height on my 29er HT is not unusual - the Niner website claims 11.7in for the SIR9 which is a pretty popular and mainstream frame.

I read some backthreads here stating too that the 13.5in height on the Yeti 575 is also on the high-side for a FS 26" bike - so between that and the hardtail/FS differences, it is a noticeable difference. I definitely could feel the difference.

So is 12in pretty typical BB height for a 26" hardtail as well?

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Yes, "normal" range is 11.7-12.2" for a hardtail. Personally I prefer 12.5-13", but I also use 185mm cranks.

I noticed the same thing...

When I got a 29er, I thought I'd have less pedal strikes, instead I have more. Sure enough, my 26" FS BB is 1" higher than my 29er BB. It was disappointing...

I agree with what others have said. No reason to have a different bottom bracket height from 26 to 29 BUT there is a reason to have a different BB height with full suspension. Your hardtail is pretty normal. You'll get used to it and maybe even come to like it.

I, for one, like a relatively low BB. I had my custom 29er specced with a 11.8" bottom bracket height (70mm of drop). I run 175mm cranks and a rigid fork, so the height doesn't vary as the fork compresses. I like the feeling of being "in" the bike, rather than on it. My cranks are cheap and ancient, so I don't worry too much about the occasional strike.

OK, all a part of getting educated for me - maybe I will come to like it. It definitely feels different than by FS 26" - feels fast on the flowy parts of the single-track and more stable.

I also have relatively big platform pedals on my 29er right now which exacerbates the problem compared to the Candy's I run on my Yeti. Probably a lower profile pedal would help some.

cheers,

John_Biker said:

My cranks are cheap and ancient, so I don't worry too much about the occasional strike.

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That's funny... occasional strike? I can pretty much guarantee that any part I buy and even the frame itself will be a scratched mess in just a few months of riding time. Smooth trails are few and far inbetween in my neck of the woods (desert) and I am A-ok with that! I just bought a fancy smancy pair of Twenty6 pedals for my new Lunchbox. They are beautiful right now, but give them a ride or two... I should take a pic before I mount them on my heavily scratched month-old XT cranks

learn to ride, and pedal strikes will come less and less..

doctapow said:

Are there any rules of thumb regarding BB height on 29er frames versus conventional 26in frames?

I guess without giving it much thought, I assumed 29ers would ride higher - but I just picked a 29er hardtail on clearance the other days (mainly for the parts) and found on riding it that I was getting a lot more pedal strikes than usual.

I got home and measured the BB height at 12in - my Yeti 575 is 13.5. That seems like a big difference - enough that I could notice it.

Is the 12in height typical for a 29er frame (this is a Fuji Tahoe FYI)?

just curious.

Click to expand...

With the increased traction and overall stability of the larger wheel, I find myself enjoying a slightly higher BB (12.2") on technical climbs that I would not have been able to clear with the smaller wheels. The higher BB allows me to stay on the gas longer.

BB height and wheel diameter are NOT inextricably interwined. There is nothing unique about a particular wheel size that will dictate BB height.

As has been noted, BB heights on FS bikes are typically higher than for a HT, but you'll find that if you take into account the proper sag, the BB height will come in line with the typical HT, albeit a tad higher to account for additional suspension travel. The really high unsagged BB height is one reason I don't care for a long travel 26" wheel bike. It seems you need a step ladder just to get on 'em. I'd rather have a 4" travel 29er with minimal sag than a 5.5 or higher travel 26" bike with lot's of sag.